Pollution and Stream Impairment – LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED

October 21, 2025October 21, 2025

Today’s NOAA/GOES satellite image serves as a little reminder of the big three. That’s right, it’s the three big “natural” disasters—wildfires, inland flooding, and coastal flooding (lucky for us, our region is at present millions of years removed from severe threats posed by the tectonic disasters—earthquakes, volcanoes, and tsunamis—and is not particularly prone to frequent tornadoes). Each continues to cause an increasing volume of property damage and threaten a greater number of lives because of where and how we choose to make our homes and erect our structures.

Smoke from Canadian Wildfires and Tropical Storm Dexter — Earlier today, smoke from forest fires in central Canada sweeps through the skies of the Great Lakes, New England, and the Mid-Atlantic States north of the Mason-Dixon Line. Meanwhile off North Carolina, Tropical Storm Dexter is seen developing over warm ocean waters east of the Gulf Stream. (NOAA/GOES satellite image)

For all of human existence, the dynamics of the atmosphere have been shaping the topography and the ecosystems of the planet. In recent times, we’ve had the advantage of satellite technologies to show us spectacular images of atmospheric events as they happen. And through the various branches of science, we’ve come to understand the impact these events have upon the landscape and the people who live and/or work there.

Forestry sciences have helped us to understand how natural fuels, humidity, temperature, rainfall, soil moisture, wind, and human encroachment influence the frequency and severity of wildfires. These discoveries have led to changes in forest management and implementation of practices such as prescribed burns to reduce accumulated fuel loads. Because human development typically lowers soil moisture and brings along with it additional sources of ignition, many land managers and fire departments have warned of the ever increasing dangers of wildland-urban interface fires. These warnings have gone largely unheeded for more than four decades as millions of homes and other combustible structures have been erected within areas prone to fires capable of uncontrollable growth into disastrous conflagrations. The tinderbox wildlands—they’re a nice place to visit, but we ought not to live there!

Tropical storms and other sources of heavy precipitation bring about quite the hubbub over flooding. Meteorologists spend a lot of time explaining it all, but it’s almost as if no one pays any mind. For a people who check the weather forecast several times a day, every day of our adult life, just to get a leg up on how that weather is going to change day by day and hour by hour, you would think we would better anticipate the climatic events that happen over the long term. In particular, you would think we would have an awareness of our own individual susceptibility to flooding— a grasp of how, where, and why floods occur. You would think that repeated episodes of flooding would compel society to embrace an ethic that treated water as the valuable commodity it is. Yet, we all seem to follow the same patterns of behavior. First, we drain, dump, pipe, curb, channel, ditch, grade, pave, and pump to get the rain that falls upon our property off of our property. Then, the chump downstream gets really mad that we sent our water his way and flooded him out, so he takes the same measures to send even more water to the next poor slob down the line until finally the now polluted slurry of runoff floods the street, a cellar, a house, a business, or a stream—a stream that has been channelized so it no longer has a floodplain to absorb, hold, purify, and infiltrate the stormwater. Why was the stream channelized? So we could fill in the floodplain and build upon it of course. Two things come to mind here. First, if we’re going to be selfish enough to flood out our neighbors, then why shouldn’t we be totally selfish and keep for ourselves all the water that falls upon our place. After all, we’re going to need that water some day. And second, the floodplain is a nice place to visit, but we ought not to build there. Floodplains are for flooding; thousands of years of erosion have shaped them that way—it’s a gravity thing!

Next, we look at the lessons from geology, more specifically coastal geomorphology. Through these disciplines we know that the coastal plain—the flat land that spent most of the last 35.5 million years (the time since the meteor strike at the present-day mouth of Chesapeake Bay) as a beach or a tidal marsh—today stands mostly less than three dozen feet above sea level. We know that the sands forming barrier islands along the Atlantic seaboard, which are only several feet above sea level, shift their shape and position with the tides. Over the decades and centuries, these islands migrate and compensate for changes in climate and tidal patterns as well as sea levels. Behind their shifting dunes, vast tidal marshes are protected from seasonal storms including the periodic nor’easter or hurricane. Despite the importance of barrier island dynamics to the integrity of the bays and estuaries they protect, and despite their vulnerability to coastal storm surges, winds, and flooding, we choose to build there. In fact, the greatest population densities in the United States, and in many other countries of the world, are on the beach. It’s not because these hundreds of millions of people are fishing or loading/unloading ships for a living—it’s mostly for the view. Despite their importance to fisheries and other coastal life, we continue to alter and destroy the near-tidal areas of the the barrier islands and bays. We go to great expense to “save” for our uses the lands that should be getting inundated by rising sea levels to create new shallow tidewater zones. We waste spectacular amounts of money pumping sand back onto beaches to keep naturally migrating sediments from changing their shape and position in response to the tides. We keep putting more people and more capital at risk by urbanizing these low-lying areas. Building on the beach is absolute madness. It’s an ecological catastrophe from day one and a human catastrophe soon after.

All of the lands impacted by these natural events have two things in common. Each becomes a potential disaster area if people choose to construct their homes or businesses there. And each, if left in its wild state and given a buffer space from human activity, reacts with natural time-derived mechanisms in response to the same events. These mechanisms are often essential for provision of the unique ecosystems required by many of our most threatened wildlife species. Human encroachment into floodplains, wetlands, tidal marshes, beaches, and xeric uplands is a double-edged sword. It first decimates populations of these uncommon species by destroying and fragmenting their specialized habitats. Then, it sets the stage for the fires, floods, and other disasters that endanger the lives and property of the people living there. Considering the ramifications of building in these fire and flood susceptible areas, we can and should live somewhere else, especially when the wildlife requiring these places often can’t.

Sunset over the Susquehanna at Chiques Rock — This evening’s smoky sunset over the Susquehanna at Chiques Rock was courtesy of Canadian wildfires.

June 10, 2025June 10, 2025

Photo of the Day

June 7, 2025June 10, 2025

Common Carp: A Menace Meant for the Dinner Plate

One of the earliest non-native fish species to be widely released into North American waterways was the Common Carp. Stocks brought to the United States were likely sourced from populations already naturalized throughout much of western Europe after introductions originating from the fish’s native range in Eurasia, probably including the Danube and other watersheds east through the Volga. In western Europe, the species promised to be an abundant and easily cultivated food source. Under the same premise, carp were transported to the United States during the early 1800s and widely introduced into streams, lakes, and rivers throughout the country.

Common Carp thrive in nutrient-rich waters, particularly those subjected to sewage discharge and agricultural runoff, conditions which were already prevalent during the Common Carp’s initial introduction and have remained widespread ever since. Within these polluted streams, lakes, and ponds, introduced carp feed aggressively on benthic organisms and plants, stirring up decaying organic matter (mulm) from the substrate. This process raises turbidity in the water column and releases excessive amounts of the nutrient phosphorus resulting in unusually large algal blooms. Algal blooms can block sunlight from the longer-lived oxygen-producing vascular plants that grow in submerged environs. Growing beneath a dense cloud or blanket of algae can compromise the vigor of oxygen-producing vascular plants and disable their biochemical functions within the aquatic ecosystem. As the short-lived algae die, the bacteria that decay them begin to place increased oxygen demands on the water. With less oxygen being produced by both the vascular plants and the algae, and with oxygen consumption increased by the activity of decomposers, conditions can become fatal for fish and other organisms. This process is known as eutrophication. Because Common Carp are among the species most tolerant of eutrophic conditions, they tend to thrive in the conditions they create while the native fishes perish.

Common Carp spawn in the spring, usually from late April through June, when the water temperature is as low as 58 degrees and as high as 83 degrees Fahrenheit. This activity is often triggered by a rapid increase in water temperature. In a small lake, this may be brought on by a string of sunny days in late April or May. On larger streams and rivers, the temperature spike that initiates the spawn may not occur until warm rains and runoff enter the stream during June.

Common Carp Spawning — In water that is often less than a foot in depth, male carp follow the breeding females into egg-laying areas among debris and emergent vegetation.

Common Carp are one of the most widely farmed and eaten fish in all the world. Here in the United States, they were introduced beginning two hundred years ago because they were favorable to the palate, grew to large size quickly, and were a source of much needed food. Today, the Common Carp is seldom found on the American dinner plate. Yet, pound for pound, it is one of the most abundant fish in many of our waters, particularly in man-made lakes. Like some of our other most invasive species—including Blue Catfish, Flathead Catfish, and Northern Snakehead—Common Carp are perhaps the most edible of our freshwater fishes. For many cultures, they are an important staple. For others, they are a delicacy or holiday treat. In America, they do horrendous damage to aquatic ecosystems following establishment as a food crop that almost never gets harvested. Did you realize that on the internet, there are literally hundreds of recipes and culinary videos available to show you how to prepare delicious dishes made with Common Carp? It’s true. And for the cost of a fishing license, you can catch all you want, usually several pounds at a time. So why not give the marine fisheries a break? Take the big leap and learn to eat invasive freshwater species instead.

Common Carp Breaching — Jumpin’ gefilte fish, it’s what’s for dinner!

May 22, 2025May 24, 2025

Five Flowering Plants for Cleaner Water

Currently in the Lower Susquehanna River Watershed, you can find these five species of herbaceous plants in full bloom. As they grow, they and others like them help to purify waters within their respective ecosystems by taking up nutrients—namely, the nitrogen and phosphorus that can lead to detrimental algal blooms and eutrophication in ponds, lakes, streams, and rivers.

(United States Geological Survey image by Virginia-West Virginia Science Center)

The Marsh Blue Violet (Viola cucullata) is most frequently found growing in the wet soils of forest bottomlands, usually where springs first break the earth’s surface and begin slowly trickling away to form a small brook or join an existing stream. The blooms are recognized by their darker purple centers and their long stems.

The seldom-noticed flowers of the Soft Rush (Juncus effusus), also known as the Common Rush, emerge from the sides of its quill-like stems. This wetland species is found in damp soils, sometimes in standing water, and grows in stiff, erect clumps that persist through winter. When found in pastures, Soft Rush is seldom of interest to cattle or other livestock. It therefore doesn’t lure these animals into muddy, puddle-prone areas. When subjected to heavy grazing in dry weather and flooding during wet spells, these puddle sites may host nearly pure stands of Soft Rush, the only plant able to thrive there. When it comes to nutrient uptake in these soggy sections of the meadow, the soft Rush is the lone ranger. Soft Rush seeds are available from Ernst Conservation Seeds in Meadville, PA, and are included in many of their mixes formulated for stormwater management basins and other wet soil applications.

Larger Blue Flag (Iris versicolor) is a plant of wetlands and shorelines. It can be grown as an emergent in ponds and lakes where it will help to absorb nutrients from both the water and the underlying substrate.

The Yellow Iris (Iris pseudacorus), also known as the Water Flag, is native to Eurasia and Africa. Seen here growing as an emergent among native Common Cattails (a superb water purifier), the Yellow Iris can easily escape cultivation and become invasive. The showy flowers and water-cleansing benefits of this plant make it attractive for use in the garden or farm pond, but considerations must be made for its aggressive growth and proclivity to escape to neighboring habitats. If you’re purchasing irises for transplanting, you’re probably better off sticking with the native Larger Blue Flag; it is far less vigorous and you’ll be able to grow other aquatic species along with it.

In large ponds, lakes, and low-gradient streams, one of the best aquatic plants for sequestering nutrients and clarifying water is Spatterdock, also known as Cow-lily or Yellow Pond Lily. Spatterdock does best as an emergent in shallow water along the shoreline. It grows well in full sunshine and makes excellent habitat for wildlife. Depending on the nutrient load from fish, waterfowl, decaying vegetation, and other sources, plant cover may need to be as high as 30% or more of the surface area to keep algae from overtaking a lake or large pond. Spatterdock can often be used to help fulfill these needs while still offering open water beneath the leaves and between the stems for fish, amphibians, reptiles, and macroinvertebrates to thrive.

April 2, 2025April 3, 2025

Three Items to Add to Your Tacklebox to Be a Better Conservationist

Soon after their arrival during the late 1600s, the earliest trans-Atlantic human migrants to settle the Lower Susquehanna River Watershed began the process of eliminating many of our largest native fish species. They started by extirpating nature’s steward of lowland streams and wetlands, the North American Beaver. The beaver’s meticulously maintained dams and fisheries-friendly ponds were promptly replaced by man-made impoundments designed to permanently divert water for powering lumber and grain mills. Behind these structures, silt deposits accumulated as the forests were clear cut and the land subjected to highly erosive farming methods. Mill dams would eventually be located on nearly every mile of suitable low-gradient stream in the basin. Populations of native coldwater fishes including Brook Trout were quickly lost or left isolated in scattered headwaters.

With their navigation of creeks blocked by nearly impenetrable mill dams, seasonally migratory freshwater and anadromous fish were denied access to their traditional spawning waters. The latter then had their populations seriously depleted, and in some cases extirpated, following construction of hydroelectric dams on the lower Susquehanna during the first half of the twentieth century. The loss these latter species, including the herrings, Striped Bass, and sturgeons, all of which attain great size only because of their ability to make a sea run to access the year-round food energy available in the Atlantic, constitute a tremendous reduction in the numbers, variety, and mass of fish occurring in the river and its tributaries.

Add to these events the various sources of pollution entering the lower Susquehanna’s waterways during the intervening years including acid mine drainage, agricultural nutrients and sediments, stormwater runoff, untreated domestic and industrial sewage, illegal dumping, pesticides, etc., and one can easily understand how the watershed’s native fishery was lost as a commercial, food, and recreational resource.

Presently, the effort to restore populations of self-sustaining anadromous fishes to the lower Susquehanna is stalled due to the presence of introduced invasive species, particularly Northern Snakeheads, in the river’s waters below Conowingo Dam. Lifts that carry migrating fishes over the lower river’s hydroelectric dams during the spring run are shut down to avoid extending the range of the hoards of non-native snakeheads to waters upstream of their present location. Any translocation of anadromous fish must now be completed by manually separating desired species from among the invaders and loading them into a tank truck for transport to waters upstream of the dams. But Northern Snakeheads are currently so prevalent at Conowingo that they are overwhelming the lift used for collecting and sorting fish as well.

Any slight hope that had existed for a return of harvestable stocks of American Shad or other sea-run native species to the Susquehanna and its tributaries seems to be fading. And widespread improvements to water quality that would promote reestablishment of sustained populations of native coldwater fishes like Brook Trout are strictly a long-range goal.

Recreational anglers, however, still remain in the game—but their reward is a bit of a booby prize. To compensate fisherman for the loss of their quarry on the river and in streams, and to promote an interest in the fishing pastime and conserving waterways, the stocking of various species of “game fish” has been a continuous undertaking, particular since the middle decades of the twentieth century. Some of these introductions are planned, others, like the release of Northern Snakeheads, are unsanctioned and outright illegal. The one thing most introductions have in common is that they consist of hardy, aggressive, predatory fishes that are non-native species (or native transplants from watersheds such as the Mississippi). Their presence, especially in large concentrations and particularly during the time immediately following introduction, can have a deleterious impact on native stream inhabitants. Some introduced fish, the Flathead Catfish for example, are upon discovery deemed invasive species; others, like the Smallmouth Bass, escape such a label not because they lack negative impacts on stream communities and ecosystems, but because they have been present for extended periods of time and have thus been accepted as part of the local fishing culture.

Hatchery-raised Rainbow Trout stocked by the hundreds in a lower Susquehanna valley creek for angling. The Rainbow Trout is native to the streams and rivers of the Pacific coast of North America. An anadromous form is known as the “Steelhead”. These sea-run trout with access to marine food sources during their growth years attain more than twice the size of freshwater forms and acquire oversized hooked jaws before ascending waterways to spawn.

The creation of recreational fisheries comprised of introduced species has certainly helped maintain an interest in the fishing hobby and in the conservation of waterways. It has even been a driving force for spectacular restorations of streams that otherwise would have languished in an impaired condition with little in the way of diversity of species—native or non-native. As anglers, we are especially indebted to those who’ve devoted their time, energies, and, in some cases, a lot of money to projects that specifically seek to reestablish native waterways within the challenging landscape of the Lower Susquehanna River Watershed. With an eye on the future, perhaps now is a good time to join them and focus our passion for freshwater angling on steering fisheries management more toward the native ecosystems approach. Quality instead of quantity.

In that spirit, here are three items we can add to our tackle boxes this season to be better fisheries conservationists, instead of our own worst enemies.

**Lead-free Weights-** Replace the lead in your tackle box with tungsten or other lead-free alternatives to eliminate the potential impact this poisonous metal can have on you and wildlife like waterfowl and Bald Eagles. Make a special effort to rid your inventory of small pieces of shot that can easily be ingested by animals as they feed.

**Realistic Lures-** Add sport to your fishing by using artificial lures. Today’s selections include very realistic versions of native fishes, crayfish, frogs, and other aquatic creatures. Use these life-like imitations and you won’t need to harvest native minnows and other wildlife from populations that are already being subjected to negative impacts from stocked legions of predatory “game fish”. You’ll also eliminate the risk of introducing non-native bait species into your favorite fishing waters!

**Trash Bag-** Always bring a trash bag and carry out your litter. Be especially vigilant about monofilament fishing line.

Fisherman's Trash — Fishermen are their own worst enemies, so you’ll need to pick up after the other guy too. Show the landowners and land managers who are our hosts a little consideration.

Best of luck this fishing season. We hope your time outdoors will motivate you to get involved with efforts to keep your local waterways clean. You might even be inspired to assist with projects that are planned or currently underway in the Lower Susquehanna River Watershed to restore stream segments, wetlands, and floodplains. Many of these projects are grassroots efforts and they’d love to have your participation. Your local county conservation district can steer you towards an active restoration group near you. Give them a ring.

Rainbow Trout and "Golden Rainbow Trout" — Hatchery-raised Rainbow Trout and a “Golden Rainbow Trout” stocked for anglers in a restored segment of a stream in Lebanon County, Pennsylvania. The “Golden Rainbow Trout”, also known as the “Banana Trout”, is a Rainbow Trout color variant developed through multi-generational selective breeding of offspring produced by crossing a typical male with a yellow-mottled female mutant discovered in a hatchery in West Virginia in 1955. Today, “Golden Rainbow Trout” breed true, golden males crossed with golden females yielding golden young. The less colorful “Palomino Rainbow Trout” is produced by crossing a “Golden Rainbow Trout” with a typical Rainbow Trout.

April 1, 2025April 1, 2025

Save Money on Gas, Guaranteed

You’ve seen the advice on the internet and elsewhere—”add coke to your gas tank and lower your fuel consumption.” While the sources vary in their claims, reductions as great as 55% are often reported. But are these performance improvements real? Time for a fact check.

Uncle Tyler Dyer and his old pal Bellwood Comstock, Jr., better known by those close to him as “Woodstock”, got together and decided to try it out. For their test, Uncle Ty added a 20-ounce bottle of Coke to his tank while his science partner Woodstock tried a same-sized portion of Pepsi in his automobile.

Within days, the experiment had reached a definitive outcome. To say the least, our test techs were absolutely stunned by the results.

“Man, we can’t believe it,” exclaimed Uncle Ty.

“Spending money on gas is the least of my worries now,” noted his buddy Woodstock.

Collectively, our dynamic duo is now cutting down on carbon emissions by hundreds of pounds every month. When asked if there were any other benefits to dumping cola in the tank, Ty reminded us, “Oh, yeah, we’ve been getting great exercise, riding our bikes and walking everywhere we go. Earlier this week, we hitchhiked to a used car lot looking for bargains. Man, it was just like the old days!”

“You know,” joked Uncle Ty’s loyal sidekick Woodstock, “if everybody did this, it sure would help relieve traffic congestion too.”

March 24, 2025March 24, 2025

Wildlife in the Burn Zone

During Saturday’s Prescribed Fire Demonstration at the Pennsylvania Game Commission’s Middle Creek Wildlife Management Area, we noticed just how fast some species of wildlife return to areas subjected to burns administered to maintain grassland habitat and reduce the risk of high-intensity blazes.

Back Fire Ignition during prescribed burn demonstration. — Pennsylvania Game Commission crews ignite a back fire to contain a prescribed burn along its downwind/upslope perimeter during a demonstration at Middle Creek Wildlife Management Area on Saturday.

Dozens of recently arrived Tree Swallows swept in to patrol for flying insects as the burn was in progress.

Red-tailed Hawks and other raptors, including nocturnal owls, are frequently the first visitors attracted to the scene of a prescribed burn or wildfire. In grassland and successional habitats, they come looking for any vulnerable voles or mice that may be moving about looking for cover.

These three Eastern Meadowlarks spent the morning in the grassland areas adjacent to the prescribed fire site, mostly where a burn had been conducted one week prior. During the demonstration, one even perched and sang from the oak trees in the museum/visitor’s center parking lot.

Following the Prescribed Fire Demonstration, we decided to pay a visit to some of the parcels where burns had been administered one week earlier on the north side of Middle Creek’s main impoundment. We found a surprising amount of activity.

White-crowned and White-throated Sparrows — Apparently feeding upon slightly heat-treated seeds, sparrows were found by the dozens. White-crowned (left), White-throated (right), Song, and Savannah Sparrows were identified.

This Downy Woodpecker was finding something to its liking among the scorched leaves, stems, and twigs.

American Robins seem to find areas with lightly burnt vegetation and ash-dusted soil advantageous for finding invertebrates following a fire.

Mixed Flock of Blackbirds — We found this flock of Red-winged Blackbirds, Browned-headed Cowbirds, and a few European Starlings feeding throughout a grassland field cleared of early-successional growth by a prescribed fire administered one week ago.

Nearby, in an island of unburned grass in the same field, we found yet another Eastern Meadowlark, our fourth of the day. High-intensity agriculture, particularly early hay mowing and pesticide treatments, have mostly eliminated this and other grassland species from modern farms. Management practices like prescribed fire and delayed mowing (no spinning blades until at least early August) can maintain ideal grassland habitat for stunningly colorful blackbirds including nesting Eastern Meadowlarks, Bobolinks, and many other species as well.

American Kestrel at Nest Box — A male American Kestrel at a nest box located among Middle Creek’s warm-season and cool-season grassland habitats, the former maintained by prescribed fire, the latter by delayed mowing.

February 26, 2025August 4, 2025

Winter Survival: Generalists and Specialists

We’ve seen worse, but this winter has been particularly tough for birds and mammals in the Lower Susquehanna River Watershed. Due to the dry conditions of late summer and fall in 2024, the wild food crop of seeds, nuts, berries, and other fare has been less than average. The cold temperatures make insects hard to come by. Let’s have a look at how some of our local generalist and specialist species are faring this winter.

House Sparrows and a House Finch — House Sparrows (bottom) and House Finches (top) are generalists. To survive and thrive, they are adapted to a variety of habitats and types of food. House Sparrows live almost anywhere man-made structures are found. They are true omnivores and will eat almost anything, especially if they see something else try to eat it first. The House Sparrow’s close association with humans has allowed it to become the most widespread and successful living avian dinosaur. On a cold night, they’ll take shelter either within dense vegetation alongside a building or within the structure itself. Though not nearly as cosmopolitan, the House Finch has successfully colonized much of the eastern United States after escaping from captivity as a cage bird in New York during the middle of the twentieth century. Upon being trans-located here from the arid southwest, they adapted to suburbs and farmlands consuming primarily a granivore diet of seeds supplemented with seasonally available berries. They quickly became accustomed to offerings at bird-feeding stations as well. To survive the harsh winters in the northern sections of their range, eastern populations of House Finches are developing a pattern of migration. These movements are most evident in late fall when dozens or sometimes hundreds can be seen heading south over regional hawk-counting stations.

Northern Flicker feeding on Poison Ivy — Though they require dead trees for nesting and as places to find the grubs and adult insects upon which they primarily feed, woodpeckers including the Northern Flicker are generalists, seldom passing by a supply of fruits like these Poison Ivy berries as a source of winter food. Flickers regularly visit suburban areas where they’ll drop by at bird-feeding stations for suet. During the warmer months, they are the woodpecker most frequently seen on the ground where swarms of ants garner their full attention.

The Pileated Woodpecker is seldom found outside of mature forests where it digs relentlessly to remove grubs and other infestations from dead wood. But it is not a true specialist…

Pileated Woodpecker eating Poison Ivy — …it too finds a supply of Poison Ivy berries to be indispensable during a cold winter day.

The Ruby-crowned Kinglet is a generalist, feeding mostly on insects, but also consuming small seeds and some berries, including those of Poison Ivy. It nests well to our north in tall spruces and other evergreens. During migration and in winter, the Ruby-crowned Kinglet may be found in deciduous trees, brush, and tall grass in habitats ranging from forests to parks and suburbia. This male is displaying its seldom-seen red crown.

The Golden-crowned Kinglet, seen here on a Poison Ivy vine, is more of a specialist than the Ruby-crowned species, though the two will often occur in mixed groups during the winter. The Golden-crowned Kinglet nests in Spruce-Fir forests and in conifers within mixed woodlands. Even during migration, and particularly in winter, these birds are seldom found far from a stand of large evergreens within which they find shelter for the night.

The Hermit Thrush’s generalist lifestyle allows it to survive cold season weather in the Lower Susquehanna River Watershed. During summer, it breeds in coniferous and mixed woods from the northern parts of our valley north into Canada and feeds primarily on worms, insects, and other arthropods. During migration and in winter, the Hermit Thrush becomes a regular visitor to deciduous forests, woody parks and suburbs, particularly where a supply of wild berries is available to supplement its diet.

Iconic as it pulls earthworms from lawns during the warmer months, the generalist American Robin is fully dependent upon a crop of berries to survive winter conditions in the lower Susquehanna valley. The drought afflicted wild food crop of 2024 has led to fewer robins spending the season here and has delayed the northward push of migrating birds until the ground thaws and the earthworms make the ground rumble once again.

It’s insects for the nestlings during spring and summer, then berries through the winter for the cheerful Eastern Bluebirds, another generalist species.

American Crows are an excellent example of a generalist species. They’ll go anywhere to find food and they’ll eat almost anything. Like the House Sparrow and several other generalists, they adapt very well to human activity and actually thrive on it. Garbage anyone?

Another career generalist is the widely worshiped White-tailed Deity, a species adapted to nearly all man-made landscapes with adequate vegetation upon which to browse. Pushed to the limit during severe weather, some individuals will consume carrion and even resort to cannibalism.

You might think the Great Blue Heron is a specialist. Nope, it’s an accomplished generalist. Great blues will live, feed, and breed on almost any body of fresh or brackish water. And their diet includes almost anything that swims. In winter, you’ll even see them in fields hunting mice and voles.

The Red-shouldered Hawk is a generalist with a diet ranging from amphibians and reptiles to small rodents and large insects. Mostly regarded as a species of bottomlands, they’ll frequent woodland edges, roadsides, and suburbia during the winter months.

During its periodic winter visits to the region, the American Tree Sparrow feeds on seeds among the grasses and forbs of semi-open country with scattered short shrubs and trees. A generalist species, it will show up at backyard bird-feeding stations, particularly during periods of inclement weather. In summer, the American Tree Sparrow nests in tundra with growths of stunted willows and spruce and their diet includes insects as a source of protein for themselves and their young.

The White-crowned Sparrow has similar winter habitat preferences to the tree sparrows…

White-crowned Sparrows — …it becomes adaptable and something of a generalist when searching for food during bad winter storms.

The Savannah Sparrow is an omnivore favoring insects in summer and seeds in winter. Though very closely tied to its grassland habitat year-round, snow cover can push these birds to enter woodier environs to consume fruits like these rose hips.

Dusk and dawn during the short days of winter are the prime hunting times of a mammal specialist, the Short-eared Owl. Its presence in the lower Susquehanna valley is dependent on two dominant factors: extensive grassland habitat and an adequate population of the owl’s favored food, the Meadow Vole (Microtus pennsylvanicus). The Short-eared Owl’s requirements as a specialist species make finding a suitable place to live difficult. Unlike the generalist birds and mammals that often adapt to the widespread man-made disturbances in the region, populations of specialists frequently become fragmented, reduced in abundance, and subject to extirpation.

The Meadow Vole is a generalist rodent that can be abundant in grasslands, early successional growth, fallow fields, marshlands, and, of course, meadows. They are primarily herbivores, but will occasionally consume insects and other arthropods. Usually nocturnal, some individuals venture out along their surface runways during daylight hours becoming vulnerable to diurnal raptors including kestrels, harriers, and buteos.

Short-eared Owl patrolling a grassland for Meadow Voles — A Short-eared Owl in near darkness patrolling a grassland for Meadow Voles.

The eastward expansion of the Coyote (Canis latrans), a species of western North America’s grasslands and scrublands, and its progressive mixing with the Wolf (Canis lupus) in these eastern extensions of its range, has produced an expanding population of very adaptable generalists we call Eastern Coyotes (Canis latrans var.). These omnivorous canines colonized the Lower Susquehanna River Watershed during the last four decades to replace extirpated wolves as the top-tier natural predator in the region. Their primary diet includes Meadow Voles in grasslands and other small mammals along woodland edges and in successional habitats. Seasonally, they consume the berries of numerous wild plants. Slightly larger than their western ancestors, Eastern Coyotes with the admixture of Wolf genetics can subdue small ungulates. Like other apex predators, they are attracted to vulnerable prey and thus play a crucial role in culling the weak and diseased among their potential quarry species to assure the health and potential of populations of these species as long-term sources of food energy. The benefit to the prey species is however largely diluted in populous areas of the northeast; most venison consumed by Eastern Coyotes here is in the form of road kill. During periods of extended snow cover when small rodents and other foods become inaccessible, Eastern Coyotes, particularly young individuals, will wander into new areas seeking sustenance. Sometimes they venture into cities and suburbs where they explore the neighborhoods in search of garbage and pet foods placed outside the home. (Video clip courtesy of Tyler and Grace Good. Click image to view.)

Wildlife certainly has a tough time making it through the winter in the lower Susquehanna valley. Establishing and/or protecting habitat that includes plenty of year-round cover and sources of food and water can really give generalist species a better chance of survival. But remember, the goal isn’t to create unnatural concentrations of wildlife, it is instead to return the landscape surrounding us into more of a natural state. That’s why we try to use native plants as much as possible. And that’s why we try to attract not only a certain bird, mammal, or other creature, but we try to promote the development of a naturally functioning ecosystem with a food web, a diversity of pollinating plants, pollinating insects, and so on. Through this experience, we stand a better chance of understanding what it takes to graduate to the bigger job at hand—protecting, enhancing, and restoring habitats needed by specialist species. These are efforts worthy of the great resources that are sometimes needed to make them a success. It takes a mindset that goes beyond a focus upon the welfare of each individual animal to instead achieve the discipline to concentrate long-term on the projects and processes necessary to promote the health of the ecosystems within which specialist species live and breed. It sounds easier than it is—the majority of us frequently become distracted.

Being an individual from a population of a very successful generalist species is no guarantee of survival. This Eastern Gray Squirrel fell from a tall tree when the limbs became ice covered during a storm earlier this month. Just a freak accident? Maybe, but mistakes like this are often fatal in the natural world. This squirrel’s passing may seem brutal, but it provides a better opportunity for other squirrels and animals that share its food and cover requirements to make it through the winter. And those survivors that didn’t suffer such a fatal mistake or, more importantly, don’t possess a vulnerability that may have contributed to such a mishap will have a chance to pass those traits on to a new generation. This squirrel as an individual is gone, its species lives on, and may be stronger for its passing.

Prescribed Burn of a Grassland — Pennsylvania Game Commission crews maintain a grassland ecosystem for Short-eared Owls and other specialists using prescribed fire to prevent succession beyond its earliest stages. Among the additional specialist species benefiting from this management tool are Monarchs and other butterflies whose host plants survive early-season fire, but not competition with woody vines, shrubs, trees, and invasive herbaceous growth.

On the wider scale, it’s of great importance to identify and protect the existing and potential future habitats necessary for the survival of specialist species. And we’re not saying that solely for their benefit. These protection measures should probably include setting aside areas on higher ground that may become the beach intertidal zone or tidal marsh when the existing ones become inundated. And it may mean finally getting out of the wetlands, floodplains, and gullies to let them be the rain-absorbing, storm-buffering, water purifiers they spent millennia becoming. And it may mean it’s time to give up on building stick structures on tinderbox lands, especially hillsides and rocky outcrops with shallow, eroding soils that dry to dust every few years. We need to think ahead and stop living for the view. If you want to enjoy the view from these places, go visit and take plenty of pictures, or a video, that’s always nice—then live somewhere else. Each of these areas includes ecosystems that meet the narrow habitat requirements of many of our specialist species, and we’re building like fools in them. Then we feign victimhood and solicit pity when the calamity strikes: fires, floods, landslides, and washouts—again and again. Wouldn’t it be a whole lot smarter to build somewhere else? It may seem like a lot to do for some specialist animals, but it’s not. Because, you see, we should and can live somewhere else—they can’t.

The Allegheny Woodrat (Neotoma magister), a threatened species in Pennsylvania and a critically imperiled species in Maryland, is a habitat specialist requiring the forested rocky slopes, talus-flanked ridgetops, and caves of the Ridge and Valley Province for its nest sites and survival. Isolated populations survived within similar environs in the lower Susquehanna River valley’s Piedmont Province and on South Mountain through at least the first half of the twentieth century, but have since been extirpated. Human encroachment that fragments their habitat and promotes exposure to parasite-hosting mammals including the Raccoon (*Procyon lotor)*, carrier of the Raccoon Roundworm (Baylisascarius procyonis), could prove fatal to remaining populations of this native mammal. (National Park Service image by Rick Olsen)

The American Oystercatcher (Haematopus palliatus) is a specialist species that uses its highly adapted bill to feed on marine invertebrates including mollusks, few of which are actually oysters. Reliant upon tidal ecosystems for its survival, many of the seashore animals that make up this wader’s diet are themselves specialist species. Oystercatchers spend nearly their entire lives in tidal marshes or within the intertidal zone on beaches. They also frequent rocky jetties, particularly during high tide. This individual was photographed near the mouth of Chesapeake Bay in Northhampton County, Virginia, a location that, when the waters of the Atlantic started rising over 10,000 years ago, was the lower Susquehanna valley about 60 miles from the river’s mouth at present-day Norfolk Canyon along the edge of the continental shelf. Get the drift?

February 17, 2025February 24, 2025

Think Spring: Order Your Seedlings Now!

Our wildlife has been having a tough winter. The local species not only contend with cold and stormy weather, but they also need to find food and shelter in a landscape that we’ve rendered sterile of these essentials throughout much of the lower Susquehanna valley’s farmlands, suburbs, and cities.

Planting trees, shrubs, flowers, and grasses that benefit our animals can go a long way, often turning a ho-hum parcel of property into a privately owned oasis. Providing places for wildlife to feed, rest, and raise their young can help assure the survival of many of our indigenous species. With a little dedication, you can be liberated from the chore of manicuring a lawn and instead spend your time enjoying the birds, mammals, insects, and other creatures that will visit your custom-made habitat.

Verdant Neighborhood — What makes some neighborhoods so appealing? It’s the foresight property owners had a half a century or more ago when they planted their lawns and gardens with a variety of sturdy, long-lived trees and shrubs. They’ve not only minimized the need for mowing grass, they’ve provided the present-day residents of their home with added thermal stability during both the blazing heat of summer and the chilling cold of winter.

Fortunately for us, our local county conservation districts are again conducting springtime tree sales offering a variety of native and beneficial cultivated plants at discount prices. Listed here are links to information on how to pre-order your plants for pickup in April. Click away to check out the species each county is offering in 2025!

Cumberland County Conservation District Annual Tree Seedling Sale—

Orders due by: Friday, March 21, 2025

Pickup on: Thursday, April 24, 2025 or Friday, April 25, 2025

Zebra Swallowtail on Wildflowers — During its 2025 tree seedling sale, the Cumberland County Conservation District is offering Northeast Native Wildflower seed mix for four dollars per ounce. One ounce plants approximately 200 square feet of bare soil. This is a Zebra Swallowtail visiting nectar-rich flowers during July of the first year after sowing this mix at a site along the Susquehanna.

Dauphin County Conservation District Seedling Sale—

Orders due by: Monday, March 17, 2025

Pickup on: Thursday, April 24, 2025 or Friday, April 25, 2025

"Red-twig Dogwood" — Able to thrive in wet soils, Red-osier and Silky Dogwood shrubs are ideal plants for intercepting and polishing stormwater in swales, detention/retention basins, and rain gardens. With their crimson twigs in winter, they look great along borders among clusters of cedars, pines, spruces, and other evergreens. They make an excellent choice for soil stabilization along the shorelines of streams, ponds, and other bodies of water too. Buy a dozen or more to create a showy mass planting in your soggy spot.

Franklin County Conservation District Tree Seedling Sale—

Orders due by: Wednesday, March 19, 2025

Pickup on: Thursday, April 24, 2025

The Franklin County Conservation District is offering American Elm seedlings in bundles of 25 for 36 dollars. Start them in pots for a couple of years to really get ’em going, then find places with damp soil and plenty of room to give ’em a try. During autumn, they look great in the company of spruces, white pines, and other large evergreens.

Lancaster County Annual Tree Seedling Sale—

Orders due by: Friday, March 7, 2025

Pickup on: Friday, April 11, 2025

Norway Spruce and White Pine — We purchased these Eastern White Pine, Norway Spruce, and Common Winterberry plants from the Lancaster County Conservation District Tree Sale about four years ago. They’re filling in as understory growth in the margins beneath some thirty-year-old Eastern Hemlocks to create dense cover for resident and visiting fauna at susquehannawildlife.net headquarters.

Lebanon County Conservation District Tree and Plant Sale—

Orders due by: Monday, March 3, 2025

Pickup on: Friday, April 18, 2025

For 2025, the Lebanon County Conservation District is offering Dawn Redwood (Metasequoia glyptostroboides) trees in packs of ten for twelve dollars. Though native to Asia, these adaptable trees present little threat of naturalizing and have many positive attributes in a conservation planting. Given ample space, the Dawn Redwood, a relative of the sequoias, will rapidly grow to a towering giant. They create a particularly dramatic landscape feature when planted in clumps of three to five trees or more. With age, the trunks become stout and very sturdy. Don’t like raking? The finely divided deciduous foliage can be left where it falls in autumn. It usually disintegrates by spring to enrich the soil and promote more growth.

Three Sequoias — The genus Metasequoia was first described in 1941 based upon fossils collected in Jurassic and earlier strata from widespread locations in the northern hemisphere. Metasequoia were believed extinct until just a few years later when a small number of living Dawn Redwoods were first discovered in southern China. Now distributed around the world for cultivation, direct descendants of this wild population of Metasequoia glyptostroboides are available for nearly anyone in a temperate climate to plant and grow to exceptional size. (National Park Service image)

The Lebanon County Conservation District is also selling Bald Cypress trees. They’re offered in bundles of ten for ten dollars. These long-lived trees resemble the Dawn Redwood. Both are tolerant of damp ground, but the native Bald Cypress is the species to choose for placement along streams, in wetlands, and on other sites with standing water or saturated soil.

Bald Cypress Swamp — Wildlife rich Bald Cypress swamps currently occur on the Atlantic Coastal Plain as far north as Sussex County, Delaware. Just to the south, they’re also found along Chesapeake Bay in areas that, during the last glacial maximum when sea level was 300 to 400 feet below today’s tide lines, were the Lower Susquehanna River Watershed in portions of present-day Maryland and Virginia. The northward post-glacial range extension of Bald Cypresses is now blocked by centuries of human intervention that has eliminated, isolated, or fragmented the wetland habitats where they could potentially become established. Why not lend them a hand? Plant a cypress swamp in your flood-prone bottomland. (National Park Service image by Andrew Bennett)

York County Conservation District Seedling Sale—

Orders due by: March 15, 2025

Pickup on: Thursday, April 10, 2025

A privacy planting of sturdy, native Eastern White Pines and Northern Red Oaks thriving around the border of a parking area where they also provide shade from the sun and help infiltrate a share of the stormwater that would otherwise become runoff.

Native Northeast Wildflower and Grass mix during its first summer — This year, the York County Conservation District is offering a Showy Northeast Native Wildflower and Grass seed mix for $19.99 per quarter pound. Sure beats mowing!

If you live in Adams County, Pennsylvania, you may be eligible to receive free trees and shrubs for your property from the Adams County Planting Partnership (Adams County Conservation District and the Watershed Alliance of Adams County). These trees are provided by the Chesapeake Bay Foundation’s Keystone 10-Million Trees Partnership which aims to close a seven-year project in 2025 by realizing the goal of planting 10 million trees to protect streams by stabilizing soils, taking up nutrients, reducing stormwater runoff, and providing shade. If you own property located outside of Adams County, but still within the Chesapeake Bay Watershed (which includes all of the Susquehanna, Juniata, and Potomac River drainages), you still may have an opportunity to get involved. Contact your local county conservation district office or watershed organization for information.

Planted Riparian Buffer — As they mature, tree and shrub plantings along streams return pollution-controlling functions to floodplains and provide critical habitat for wildlife. These riparian buffers not only improve water quality for fisheries, they also create travel corridors that prevent terrestrial animal populations from becoming isolated.

A CREP Project Area — Do you own a parcel of streamside or wetland acreage that you’d like to set aside and plant for the benefit of wildlife and water quality? Contact your local county conservation district office and ask them to tell you about CREP (Conservation Reserve Enhancement Program) and other programs that may offer incentives including payment of all or a portion of the costs of plantings and other habitat improvements.

We hope you’re already shopping. Need help making your selections? Click on the “Trees, Shrubs, and Woody Vines” tab at the top of this page to check out Uncle Tyler Dyer’s leaf collection. He has most of the species labelled with their National Wetland Plant List Indicator Rating. You can consult these ratings to help find species suited to the soil moisture on your planting site(s). For example: if your site has sloped upland ground and/or the soils sometimes dry out in summer, select plants with a rating such as UPL or FACU. If your planting in soils that remain moist or wet, select plants with the OBL or FACW rating. Plants rated FAC are generally adaptable and can usually go either way, but may not thrive or survive under stressful conditions in extremely wet or dry soils.

NATIONAL WETLAND PLANT LIST INDICATOR RATING DEFINITIONS

- - OBL (Obligate Wetland Plants)—Almost always occur in wetlands.
  - FACW (Facultative Wetland Plants)—Usually occur in wetlands, but may occur in non-wetlands.
  - FAC (Facultative Wetland Plants)—Occur in wetlands and non-wetlands.
  - FACU (Facultative Upland Plants)—Usually occur in non-wetlands, but may occur in wetlands.
  - UPL (Upland Plants)—Almost never occur in wetlands.

Using these ratings, you might choose to plant Pin Oaks (FACW) and Swamp White Oaks (FACW) in your riparian buffer along a stream; Northern Red Oaks (FACU) and White Oaks (FACU) in the lawn or along the street, driveway, or parking area; and Chestnut Oaks (UPL) on your really dry hillside with shallow soil. Give it a try.

November 8, 2024November 8, 2024

Photo of the Day

Be Extra Cautious Right Now — With low relative humidity, gusty daytime breezes, and little or no rain in the forecast, many counties and local municipalities in the lower Susquehanna basin have enacted bans on open burning to prevent accidental wildfires. With these dangerous conditions prevailing, you know enough not to burn trash and leaves, or to carelessly discard ashes or smoking materials. And you’re smart enough to keep close watch on fires used for cooking and to keep them within approved enclosures such as a grill with a lid. But have you thought of eliminating another common form of ignition, this one originating from your car or truck? Your motor vehicle’s catalytic converter is hot enough to ignite dry leaves, grasses, and crop residues like corn shocks upon contact, so be extra careful where you park. Be certain that your pollution control device remains free and clear of combustibles!

November 1, 2024December 2, 2024

Eagle Time on the Ridges and River

As we enter November, migratory raptor flights through the Lower Susquehanna River Watershed transition to the bigger birds. Whether you’re on the river, on a mountain, or just outside your humble abode, persistent alertness to soaring avians can yield rewarding views of a number of late-season specialties.

Juvenile Red-tailed Hawk — Juvenile (hatch-year) Red-tailed Hawks are generally less wary and more inquisitive than the more experienced adult birds. Their curiosity frequently gets them into trouble, particularly when they try to hunt small rodents in traffic along busy roadways.

Adult Red-shouldered Hawk — Far fewer in number are migratory Red-shouldered Hawks. In our region, these denizens of bottomland forests more commonly migrate along the southern edge of the Piedmont and through the upper Atlantic Coastal Plain.

A hatch-year (juvenile) Red-shouldered Hawk — A southbound hatch-year (juvenile) Red-shouldered Hawk.

Mixed-race Peregrine Falcons, the descendants of birds reintroduced into the Mid-Atlantic States during the late twentieth century, often roam our region during the late-fall and winter months before settling into their nesting territories with the approach of spring. We spotted this one along a local ridge, but you may be more likely to see them in the city or near a bridge or dam on the river.

A visit to a ridgetop on a breezy day—particularly after passage of a cold front—may give you the chance to see numerous eagles as well.

A second-year (Basic I) Bald Eagle rolls over while pursuing an adult Bald Eagle. — A second-year (Basic I) Bald Eagle barrel rolls while pursuing an adult Bald Eagle.

This afternoon, we got lucky and were treated to a bit of an aging clinic presented by the Bald Eagles we observed and photographed. Careful determination of the age classes of raptors counted by hawkwatchers can provide an early warning of problems in the ecosystems that support populations of these top-of-the-food-chain predators. For example: during the 1950s and early 1960s, a progressively lower percentage of juvenile and other non-adult age classes among the Bald Eagles being observed forewarned of the dangers of dichlorodiphenyltrichloroethane (DDT) pesticide in the environment. The principle effect of accumulations of the DDT toxins in eagles, Ospreys, Peregrine Falcons, and other predatory birds that consumed waterfowl and/or fish was to thin their eggs shells. The result was widespread brood failure and a near total loss of new generations of offspring. Eventually, nearly all Bald Eagles being seen in areas impacted by DDT were progressively older adults, most of which failed as nesting pairs. As the adult birds began dying off, the Bald Eagle population dwindled to numbers that raised fears of the species’ extinction. Implementation of the DDT cancellation order and the Clean Water Act in 1972, and the Endangered Species Act in 1973, helped save the Bald Eagle. But our regional “Eastern Peregrine Falcon”, a bird with a shorter life span than the Bald Eagle, was unable to endure the years of DDT use, dioxin pollution, and illegal hunting and egg collecting. Its population is gone.

Hatch-year Bald Eagle — A hatch-year (juvenile) Bald Eagle is typically dark headed and in a fresh set of juvenile flight feathers that exhibit no signs of molt. If the reproduction season and the months that followed were favorable for this year’s brood of new eagles, there should be nearly as many hatch-year birds as there are adults in an overall population.

Second-year Bald Eagle — By November, second-year (Basic I) Bald Eagles are replacing many of their flight feathers and often show ragged trailing edges in the wings due to the retention of some of the well-worn and notably longer juvenile feathers. Varying amounts of white mottling are visible on the breast, belly, and underwing coverts. Due to mortality, there are usually fewer second-year Bald Eagles than there are hatch-year or adult birds.

Second-year (Basic I) Bald Eagle. — Another example of a second-year (Basic I) Bald Eagle.

Third-year Bald Eagle — Third-year (Basic II) Bald Eagles show more yellow in the bill and an “osprey face”, a white head with a wide dark line through the eye. Most of the juvenile flight feathers have been replaced, so the wing edges appear more uniform. Like the second-year eagles, there is a varying amount of white in the breast, belly, and underwing coverts. In an overall population of eagles, birds in this age class are usually less common than those that are younger or those that are adults.

Bald Eagle Age Classes: First Three Years — Composite image of Bald Eagles in typical November plumage during their first three years. To see more images like this, be certain to click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page.

Fourth-year Bald Eagle — A fourth year (Basic III) Bald Eagle will often be seen with a black-bordered tail and a thin dark line through the eye. In some birds, traces of these traits can linger into the fifth year and beyond. These plumage types are usually the least frequently observed among an overall population of Bald Eagles. (Note: In these older birds, there develops significant variation in the timing of feather molt. In rare cases, fourth-year Bald Eagles may show minimal dark color in the tail or eye line and may appear to be in near definitive adult plumage.)

A possible fifth-year (Basic IV) Bald Eagle.

Adult Bald Eagles in definitive plumage. Birds in this plumage class are often the most frequently observed because the group includes all eagles five or six years of age and older.

While the Bald Eagles are still stealing the show, cold and gusty weather should bring an increasing number of Golden Eagles our way during the remainder of the month. Some are already trickling through…

A "before-third-year" Golden Eagle. — This “before-third-year” Golden Eagle shows no visible signs of molt in its juvenile (hatch-year) plumage, but a look at the upperwing coverts is needed to properly age the bird. To learn more about the molt sequence in Golden Eagles, be sure to click the “Golden Eagle Aging Chart” tab at the top of this page.

A "before-third-year" Golden Eagle passing the lookout along with a second-year Bald Eagle. — A “before-third-year” Golden Eagle (top) passing the lookout along with a second-year Bald Eagle (bottom).

"Before-third-year" Golden Eagle. — Another “before-third-year” Golden Eagle. More are on the way!

Later this month, Bald Eagle numbers on the lower Susquehanna below Conowingo Dam (U.S. 1) near Rising Sun, Maryland, will begin to grow. Fisherman’s Park, located along the west shoreline below the dam, is an excellent place to observe and photograph scores of these regal birds. And few places provide a better opportunity to learn to differentiate Bald Eagle age classes. If you’re really lucky, a Golden Eagle or two may drop in as well. So plan to make the trip. The best time to visit is on a weekday. The parking lot can become overcrowded on weekends and will be closed under such circumstances. It’s best to avoid the long Thanksgiving weekend as well.

Migrating Adult Bald Eagles — Remember to always look up.

August 20, 2024November 22, 2024

Heat Flux Processes in Streams and Their Impact on Coldwater and Coolwater Fishes

The deluge of rain that soaked the lower Susquehanna watershed during last week is now just a memory. Streams to the west of the river, where the flooding courtesy of the remnants of Hurricane Debby was most severe, have reached their crest and receded. Sliding away toward the Chesapeake and Atlantic is all that runoff, laden with a brew of pollutants including but not limited to: agricultural nutrients, sediment, petroleum products, sewage, lawn chemicals, tires, dog poop, and all that litter—paper, plastics, glass, Styrofoam, and more. For aquatic organisms including our freshwater fish, these floods, particularly when they occur in summer, can compound the effects of the numerous stressors that already limit their ability to live, thrive, and reproduce.

One of those preexisting stressors, high water temperature, can be either intensified or relieved by summertime precipitation. Runoff from forested or other densely vegetated ground normally has little impact on stream temperature. But segments of waterways receiving significant volumes of runoff from areas of sun-exposed impervious ground will usually see increases during at least the early stages of a rain event. Fortunately, projects implemented to address the negative impacts of stormwater flow and stream impairment can often have the additional benefit of helping to attenuate sudden rises in stream temperature.

Stream Subjected to Agricultural Runoff — While a row of trees along a creek can help provide protection from the thermal impact of the sun, a vegetative riparian buffer must be much wider to be effective for absorbing, cooling, and treating runoff from fields, lawns, and paved surfaces. This buffer is too narrow to prevent surface runoff from polluting the water.

Of the fishes inhabiting the Lower Susquehanna River Watershed’s temperate streams, the least tolerant of summer warming are the trouts and sculpins—species often described as “coldwater fishes”. Coldwater fishes require water temperatures below 70° Fahrenheit to thrive and reproduce. The optimal temperature range is 50° to 65° F. In the lower Susquehanna valley, few streams are able to sustain trouts and sculpins through the summer months—largely due to the effects of warm stormwater runoff and other forms of impairment.

Sculpins, including the Blue Ridge Sculpin (Cottus caeruleomentum) seen here, are native coldwater fishes which, during the 11,000 years since the last glacial maximum, have had the availability of their favored habitat sharply reduced by warming water temperatures and a rising Atlantic. During this interval, seawater has inundated the path of the “Late” Pleistocene lower Susquehanna which passed through the section of flooded river watershed we now call Chesapeake Bay and continued across the continental shelf to what was, during the glacial maximum, the river’s mouth at Norfolk Canyon. Today, cut off from neighboring drainage basins, sculpins survive exclusively in cold headwaters, and only in those where human alterations including pollution, dams, channelization, and reduced base flow haven’t yet eliminated their isolated populations. Formerly believed to be composed of two widespread North American species, the Slimy Sculpin (Cottus cognatus) and the Mottled Sculpin (Cottus bairdii), study in recent decades is discovering that sculpin populations in the present-day lower Susquehanna and neighboring Potomac headwaters consist of at least three newly delineated species: Blue Ridge Sculpin, Potomac Sculpin (Cottus gerardi), and Checkered Sculpin (Cottus sp.), the latter an as yet undescribed species found only in the refugium of limestone springs in the Potomac drainage in West Virginia; Frederick and Washington Counties, Maryland; and Franklin County, Pennsylvania. (United States Geological Survey image)

Ice Age Susquehanna — Stare at this for a little while, you’ll figure it out…………More than 11,000 years ago, during the last glacial maximum, when sea level was about 275 feet lower than it is today, there was no Chesapeake Bay, just a great Susquehanna River that flowed to the edge of the continental shelf and its mouth at Norfolk Canyon. It was a river draining taiga forests of pine, spruce , and fir, and it carried along the waters of all the present-day bay’s tributaries and more. The section of the river’s watershed we presently call the lower Susquehanna was, at the time, the upper Susquehanna watershed. Brook Trout and sculpins had the run of the river and its tributaries back then. And the entire watershed was a coldwater fishery, with limestone and other groundwater springs providing not refuge from summer heat, but a place to escape freezing water. (United States Geological Survey base image)

Norfolk Canyon, the mouth of the Susquehanna River during the most recent glacial maximum, now lies more than 275 feet below the surface of the ocean and plunges to more than a mile in depth along the finger of out wash from the gorge. (United States Geological Survey image)

Rainbow. Brown, and Brook Trout — Tens of thousands of trout are raised in state-operated and cooperative nurseries for stocking throughout the lower Susquehanna valley. These rearing facilities are located on spring-fed headwaters with sufficient flow to assure cold temperatures year round. While the Rainbow Trout and Brown Trout (Salmo trutta) are the most commonly stocked species, the Brook Trout (Salvelinus fontinalis) is the only one native to American waters. It is the least tolerant of stream warming and still reproduces in the wild only in a few pristine headwaters streams in the region. During spring, all three of these species have been observed on rare occasions entering the fish lift facilities at the hydroelectric dams on the river, presumably returning to the Susquehanna as sea-run trout.

Coldwater fishes are generally found in small spring-fed creeks and headwaters runs. Where stream gradient, substrate, dissolved oxygen, and other parameters are favorable, some species may be tolerant of water warmer than the optimal values. In other words, these temperature classifications are not set in stone and nobody ever explained ichthyology to a fish, so there are exceptions. The Brown Trout for example is sometimes listed as a “coldwater transition fish”, able to survive and reproduce in waters where stream quality is exceptionally good but the temperature may periodically reach the mid-seventies.

The Eastern Blacknose Dace is sometimes classified as a “coldwater transition fish”. It can be found in headwaters runs as well as in creeks with good water quality.

The Longnose Dace is another “coldwater transition fish” known only from clear, clean, flowing waters.

More tolerant of summer heat than the trouts, sculpins, and daces are the “coolwater fishes”—species able to feed, grow, and reproduce in streams with a temperature of less than 80° F, but higher than 60° F. Coolwater fishes thrive in creeks and rivers that hover in the 65° to 70° F range during summer.

Creek Chubs — The Creek Chub is a familiar species of “coolwater fish” seldom found remaining in waters exceeding 80 degrees Fahrenheit.

The Yellow Perch (Perca flavescens) was perhaps the most frequently targeted coolwater “gamefish” in the Lower Susquehanna River Watershed prior to the introduction of the Northern Pike (Esox lucius) and Muskellunge (Esox masquinongy). Today’s prevalence of warmwater streams and the dozens of species of non-native predatory fishes now naturalized within them have left the Yellow Perch populations greatly reduced and all but forgotten by anglers. Out of sight, out of mind. (National Park Service image)

What are the causes of modern-day reductions in coldwater and coolwater fish habitats in the lower Susquehanna River and its hundreds of miles of tributaries? To answer that, let’s take a look at the atmospheric, cosmic, and hydrologic processes that impact water temperature. Technically, these processes could be measured as heat flux—the rate of heat energy transfer per unit area per unit time, frequently expressed as watts per meter squared (W/m²). Without getting too technical, we’ll just take a look at the practical impact these processes have on stream temperatures.

HEAT FLUX PROCESSES IN A SEGMENT OF STREAM

Heat Flux Processes on Streams and Rivers — Heat Flux Processes on Stream and River Segments. These processes could be measured as heat flux—the rate of heat energy transfer per unit area per unit time. (Environmental Protection Agency image)

- - INCOMING TEMPERATURE AND FLOW—The baseline temperature of stream water entering a given segment of waterway is obviously the chief factor determining its temperature when exiting that segment. Incoming temperature and flow also determine the water’s susceptibility to heat absorption or loss while transiting the segment. Lower flows may subject the given volume of water to a greater loss or gain of heat energy during the time needed to pass through the segment than the same volume at a higher flow. Lower flows may also reduce stream velocity and extend a given volume of water’s exposure time to the exchange of heat energy while moving through the segment. Generally speaking…
    1. …the higher the stream flow, the less a given volume of that stream’s water may be impacted by the effects of the heat flux processes within the segment.
    2. …the lower the stream flow, the more a given volume of that stream’s water may be impacted by the effects of the heat flux processes within that segment.
    3. …the temperature and flow rate of precipitation entering the segment are factors that determine the impact of its heat energy transfer to or from a given volume of the stream’s waters.
    4. …the temperature and flow rate of runoff and point-source discharges entering the segment are factors that determine the impact of their heat energy transfer to or from a given volume of the stream’s waters.

Stormwater Discharge into Channelized Creek — Stormwater from impervious surfaces including roads, parking lots, roofs, and lawns quickly impacts temperatures in small creeks. Channelized streams are availed few of the positive attributes provided by many of the heat flux processes we’re about to see. They therefore suffer from severe impairment and are exposed to temperature extremes that few aquatic organisms can survive. Runoff from sun-heated pavement during a summer thunderstorm can often exceed 100 degrees Fahrenheit and can, at sufficient flow rate, quickly raise the temperature of a small stream to well over 90 degrees.

Stormwater Runoff — Stormwater runoff not only poses a thermal threat to waterways, its a significant source of a wide variety of pollutants.

- - GROUNDWATER INPUT—In streams connected to the aquifer, the temperature in a flowing segment can be impacted by the influx of cold groundwater. With temperatures ranging from about 52° to 60° Fahrenheit, groundwater will absorb heat from the stream in summer, and warm it in the winter. In warmwater streams, coldwater and coolwater fishes will often seek areas of the substrate where groundwater is entering for use as refugium from the summer heat. Yellow Perch in the lower Susquehanna are known to exhibit this behavior.

Gaining Stream — Creeks and rivers connected to the aquifer and receiving supplemental flow from it are known as “gaining streams”. These streams frequently feed water into the aquifer as well. (United States Geological Survey image)

Losing Stream — When flowing through an area experiencing drought or an excessive removal of groundwater (lots of wells, etc.), a waterway can become a “losing stream”, one that surrenders a portion of its flow to recharge the aquifer. Further downstream, the reduced flow can make such a creek or river more susceptible to the effects of heat flux processes. (United States Geological Survey image)

Disconnected Stream — Seriously depleted aquifers can lead to a “disconnected stream”. Smaller waterways subjected to these conditions will sometimes lose all their flow to the ground, often causing a catastrophic failure of the aquatic ecosystem supported therein. (United States Geological Survey image)

Urban Flooding and Dry Streambed — Urban runoff overwhelms this small stream with polluted water than can reach temperatures of 100 degrees or more (left), then lets it high and dry with no baseflow during periods of dry weather (right) as the waterway becomes disconnected from the much-depleted aquifer.

Stormwater Retention Basin — Well-designed and properly constructed stormwater retention basins not only recharge groundwater supplies for wells and streams, they can also help prevent thermal pollution in waterways. Planted with native wetland species and allowed to thrive, they can become treasured wildlife islands in otherwise inhospitable environs. The benefits don’t stop there; plants also help sequester nutrients contained in the runoff.

- - HYPORHEIC EXCHANGE—Related to groundwater input, hyporheic exchange is the slow movement of water through the rock, sand, gravel, and soils composing the streambed, saturated shoreline, shallow aquifer, and connected floodplain of a creek or river. As a heat flux process, hyporheic exchange helps moderate extremes in seasonal water temperatures by conducting energy between the solid materials in the zone and the flowing water. Hyporheic zones are important habitats for many species of aquatic invertebrates and spawning fish. Natural chemical processes within these zones convert ammonia-producing wastes into nitrite, then nitrate, allowing it to be absorbed as food by plants growing in the stream or in the alluvium within the zone. Vegetation removal, channelization, legacy sediments, silt deposits, and man-made walls and dams can negate the benefits of hyporheic exchange.

Hyporheic Exchange — Exchange of surface and ground water within the hyporheic zone is most directly associated with high-gradient (left) and meandering (right) segments of streams. (United States Geological Survey image)

Legacy Sediments and Fill — Very common on streams in the lower Susquehanna valley are these accumulations of legacy sediments at the sites of former mill ponds. After the dams were removed, the creeks began eroding their way down through the mire as they tried to reestablish their floodplains and find their native substrate. These trapped waterways are not only cut off from their hyporheic zones, they’re now a major source of nutrient and sediment pollution. Misguided landowners like this one frequently dump fill into these sites to “save their land” and “control flooding”. The fill and materials added to “shore up the banks” do nothing to fix what ails the creek, but instead displace more water to make the impact of flooding even more widespread.

Flooplain and Stream Restoration — Rehabilitation projects that remove legacy sediments help restore hyporheic exchange by reconnecting the stream to its underlying geology, its floodplain, and its wetlands. Rising waters remain in the floodplain where they get a good bio-scrubbing and help replenish the creek and groundwater supply. As the experts say, “floodplains are for flooding.”

- - ATMOSPHERIC EXCHANGE (CONVECTION, EVAPORATION)—Primarily a process by which a stream loses heat energy and cools its waters, atmospheric exchange is also a means by which a warm air mass can relinquish heat to cooler waters and thus increase their temperature. This phenomenon can be dramatically enhanced when a stream passes through a so-called urban heat island where air temperatures remain warm through the night. Convection, the movement of heat energy through a fluid (liquid or gas), causes warmer, less-dense water to rise to the surface of a stream, particularly where there is minimal turbulence. When the air above is cooler than the water’s surface layer, the stream will conduct heat energy across the water/atmosphere interface causing the warmed air molecules to rise in a convection column. If the atmospheric relative humidity is less than 100%, some surface water will vaporize—a process that expends more of the stream’s heat energy. The rate of convective and evaporative cooling in a given stream segment is directly related to the degree of difference between the water temperature and air temperature, and to the relative humidity in the air mass above the lake, creek, or river. The mechanical action of stream turbulence including rapids, riffles, and falls increases the contact area between air and water to maximize the atmospheric exchange of heat energy. The convective air current we call surface wind has a turbulent wave-producing effect on water that can also maximize atmospheric exchange; think of a cold autumn wind robbing heat energy from a warm lake or river or a hot summer wind imparting its heat to a cooler creek. These exchanges are both conductive in nature (air-to-water/water-to-air) and evaporative, the latter being expedited by the movement of dry air over warm water.

Usually classified as one of the coolwater fishes, the bottom-dwelling Tessellated Darter can thrive in the warmer creeks and in the main stem of the Susquehanna by inhabiting riffles where atmospheric exchange in the form of increased evaporation helps reduce temperatures and convective currents carry the cooler, well-oxygenated water to the streambed.

Three mile Island Unit 1 Cooling Towers — Humans utilize the concept of atmospheric exchange, adopting the phenomena of evaporation and convection to cool the hot waters produced during electric generation and other industrial processes before discharge into a lake or river.

- - STREAMBED CONDUCTIVE EXCHANGE—In the lower Susquehanna watershed, there may be no better natural example of streambed conductive exchange than the Triassic-Jurassic diabase pothole bedrocks of Conewago Falls on the river at the south end of Three Mile Island.

During sunny days, the massive diabase pothole rocks at Conewago Falls absorb solar (shortwave) radiation, then conduct that heat energy into the flowing water, often continuing to pass the accumulated warmth into the river during the night. On cloudy days, the riverbed collects longwave atmospheric radiation, a heat flux process that yields significantly less energy for conduction into the rapids, riffles, and pools of the falls. During periods of low river flow, the heating effect of streambed conductive exchange can become magnified. Compared to conditions that prevail when torrents of turbid water are rushing through the falls, partially exposed bedrock surrounded by clear water collects radiated energy much more efficiently, then conducts the heat to a greatly reduced volume of passing water. During summer and autumn, this process can create a mix of temperature zones within the falls with warmer water lingering in slow-moving pools and cooler water flowing in the deeper fast-moving channels. Along the falls’ mile-long course, a haven is created for aquatic organisms including warmwater and some coolwater fishes, oft times attracting anglers and a variety of hungry migrating birds as well.

Classified as one of our coolwater fishes, the Fallfish finds favorable conditions for feeding, growing, and spawning in the well-oxygenated waters of Conewago Falls.

Though the lower Susquehanna River is classified as a warmwater fishery, the Northern Hog Sucker (Hypentelium nigricans), another of our native coolwater fishes, finds the fast-moving waters of Conewago Falls to its liking. Northern Hog Suckers are known to inhabit streams cold enough to host trout. They exhibit remarkable home range fidelity, sometimes spending their entire lives occupying the same several hundred feet of waterway. Northern Hog Suckers are often designated an indicator of good water quality, intolerant of many stream impairment parameters. Their presence in Conewago Falls provides testament to the quality of the warmwater fishery there.

Severely Impaired Channelized Stream — An unnatural example. The reduced base flow in this channelized and severely impaired creek has been rendered vulnerable to the negative impacts of several heat flux processes including streambed conductive exchange. Urban stormwater/surfacewater inflow, solar (shortwave) radiation, and heat conducted into the stream from the masonry walls, curbs, and raceway can all conspire to cook aquatic organisms with life-quenching summer water temperatures exceeding 90 degrees Fahrenheit.

- - SOLAR (SHORTWAVE) RADIATION—The sun provides the energy that fuels the earth’s complex climate. The primary heat flux process that heats our planet is the absorption of solar radiation in the shortwave spectrum, which includes ultraviolet, visible, and infrared frequencies at the upper end of the longwave spectrum. Streams and other bodies of water absorb the greatest amounts of solar (shortwave) radiation during the weeks around summer solstice when the sun at mid-day is closer to zenith than at any other time of the year. However, the heating impact of the radiation may be greatest when the volume of water in the creek, river, or lake is at its minimum for the year—often during early fall.

The Sun — The rate, measured in watts per square meter, at which solar (shortwave) energy is directly radiated to a given area on the earth’s surface (including streams and other waters) is determined by: solar activity, the angle of the sun in the sky, aspect (slope) of the receiving surface, the opacity of the overlying atmosphere, and the distance of the earth from the sun. The former varies with the year’s seasons, the time of day, and the latitude of a given area. The latter is currently at its annual minimum when earth is at perihelion during the early days of January, thus providing the northern hemisphere with a little bump in radiation during the shortest days of the year when the sun is at its lowest angle in the sky. (NASA image)

Solar (Shortwave) Radiation — A varying portion of the solar (shortwave) radiation reaching the earth is reflected back into space by clouds. A smaller share is absorbed by the atmosphere, thus heating it. An even lesser quantity is reflected back into space by water and land. The remainder of the energy is absorbed by the planet’s surfaces, its water and land. (NASA image)

- - INCIDENT SHORTWAVE RADIATION—Also known as insolation (incoming solar radiation), incident shortwave radiation is the sum total energy of both the direct solar radiation that travels to the earth’s surface unaffected by the atmosphere and the diffuse radiation, waves that have been weakened and scattered by constituents of the atmosphere before reaching the planet’s surface. On a cloudy day, the warming of terrestrial surfaces including streams and other bodies of water is the result of diffuse radiation. On days with any amount of sunshine at all, both direct and diffuse radiation heat our waters and lands.

Pumkinseed — Warmwater fishes such as the native Pumpkinseed (Lepomis gibbosus) thrive in sun-drenched 70-to-85-degree waters as long as other heat flux processes prevent sudden temperature increases and oxygen depletion.

Mowed Stream Bank — Mowed stream banks offer a waterway no protection from incoming solar (shortwave) radiation, nor terrestrial forms of impairment including nutrient-rich stormwater runoff and silt.

- - REFLECTED SHORTWAVE RADIATION—known as albedo, reflected solar (shortwave) radiation is energy directed away from the earth’s surface before being absorbed. A surface’s albedo value is basically determined by its color, black having little reflective value, white and silvery surfaces reflecting nearly all solar (shortwave) radiation away. A surface with no reflective properties has an albedo value of 0, while a totally reflective surface has a value of 1. Clean snow with a value of about 0.85 to 0.9 (85% to 90%) is a highly reflective surface; yellow snow isn’t as good. A stream, river, or lake blanketed with ice and snow will absorb very little solar energy and will rely upon other heat flux processes to trigger a melt and thaw. The surface of open water has a varying albedo value determined mostly by the angle of the sun. Solar radiation striking the water’s surface at a low angle is mostly reflected away, while that originating at an angle closer to zenith is more readily absorbed.

Forested Stream — To avoid the heating effects of solar (shortwave) and atmospheric longwave radiation, coldwater and coolwater fishes require streams offering protection from full exposure to direct sunlight and cloud cover. Runs and creeks flowing beneath a closed canopy of forest trees are shielded from 25% or more of incoming radiation and are thus able to better maintain thermal stability during the most vulnerable period of the year for temperature-sensitive fishes, May through October.

- - LONGWAVE RADIATION—Radiation in the longwave spectrum is composed of infrared waves at frequencies lower than those of the shortwave spectrum. Longwave radiation, sometimes just called infrared radiation, is produced by the earth and its atmosphere and is propagated in all directions, day and night. It warms mostly the lower atmosphere which in turn warms the earth’s surface including its waters. Some longwave energy can even be radiated into the waterway from its own streambed—and the stream can return the favor. Other forms of mass surrounding a stream such as a rocky shoreline or a man-made structure such as bridge pier can trade longwave radiation with a waterway. The effect of these latter exchanges is largely trivial and never rivals the heat flux transfer of warm to cold provided by conduction.

Longwave Radiation — Longwave radiation emissions slow as the temperature of the emitting mass decreases, just as they also increase with temperature of the mass. Longwave radiation emissions therefore decrease with altitude along with the temperature of the water vapor, carbon dioxide, methane, and other gases that produce them. As such, the highest reaches of the atmosphere have a greatly reduced capability of shedding longwave radiation into space. At ground level, lakes, creeks, and streams receive their greatest dose of longwave radiation while beneath the cover of low-lying clouds or fog. (NASA image)

- - CANOPY RADIATION—Trees emit longwave radiation that may have a limited heat flux impact on waterway temperature. This radiation is diffuse, of scattered effect, and scarcely detectable, particularly beneath multilayered dense canopies. Some of the infrared energy transmitted by the tree canopy is radiated skyward as well.
  - WATER RADIATION—Water, like all earthly matter composed of vibrating molecules, emits longwave radiation. This heat flux process provides an ongoing cooling effect to streams, rivers, lakes, and oceans—warmer ones shedding infrared energy at a faster rate than those that are cold.

Now that we have a basic understanding of the heat flux processes responsible for determining the water temperatures of our creeks and rivers, let’s venture a look at a few graphics from gauge stations on some of the lower Susquehanna’s tributaries equipped with appropriate United States Geological Survey monitoring devices. While the data from each of these stations is clearly noted to be provisional, it can still be used to generate comparative graphics showing basic trends in easy-to-monitor parameters like temperature and stream flow.

Each image is self-labeled and plots stream temperature in degrees Fahrenheit (bold blue) and stream discharge in cubic feet per second (thin blue).

West Conewago Creek 90 Days — The West Conewago Creek drains much of the Gettysburg Basin’s Triassic redbeds in Adams and northern York Counties in Pennsylvania and includes a small headwaters area in northern Maryland. The gauge station is located just a over a mile upstream from the waterway’s mouth on the Susquehanna just below Conewago Falls. Right through the summer heatwave, this 90-day graph shows a consistent daily pattern of daytime rises in temperature and nighttime cooling. To the right, a rapid cool down can be seen coinciding with two periods of high water, the first from a series of heavy thundershowers, the second from flooding caused by the remnants of Hurricane Debby. Notice that the early August downpours were so heavy that they cooled the hot surface runoff and waterway quickly, without creating a rise in stream temperature at the gauging station. Had this monitoring device been located on a small tributary in an area with an abundance of impervious surfaces, there would probably have been a brief rise in stream temperature prior to the cooldown. (United States Geological Survey image)

The daily oscillations in temperature reflect the influence of several heat flux processes. During the day, solar (shortwave) radiation and convection from summer air, especially those hot south winds, are largely responsible for the daily rises of about 5° F. Longwave radiation has a round-the-clock influence—adding heat to the stream during the day and mostly shedding it at night. Atmospheric exchange including evaporative cooling may help moderate the rise in stream temperatures during the day, and certainly plays a role in bringing them back down after sunset. Along its course this summer, the West Conewago Creek absorbed enough heat to render it a warmwater fishery in the area of the gauging station. The West Conewago is a shallow, low gradient stream over almost its entire course. Its waters move very slowly, thus extending their exposure time to radiated heat flux and reducing the benefit of cooling by atmospheric exchange. Fortunately for bass, catfish, and sunfish, these temperatures are in the ideal range for warmwater fishes to feed, grow, and reproduce—generally over 80° F, and ideally in the 70° to 85° F range. Coolwater fishes though, would not find this stream segment favorable. It was consistently above the 80° F maximum and the 60° to 70° F range preferred by these species. And coldwater fishes, well, they wouldn’t be caught dead in this stream segment. Wait, scratch that—the only way they would be caught in this segment is dead. No trouts or sculpins here.

The Codorus Creek drains primarily the carbonate valleys of York County to the south of the West Conewago watershed. This gauge station is located about a mile upstream from the creek’s mouth on the Susquehanna just below Haldeman Riffles. The graphic pattern is very similar to that of the West Conewago’s: daily heating and cooling cycles and a noticeable drop in stream temperature in early August caused by a day of thundershowers followed by the remnants of Hurricane Debby. (United States Geological Survey image)

Look closely and you’ll notice that although the temperature pattern on this chart closely resembles that of the West Conewago’s, the readings average about 5 degrees cooler. This may seem surprising when one realizes that the Codorus follows a channelized path through the heart of York City and its urbanized suburbs—a heat island of significance to a stream this size. Before that it passes through numerous impoundments where its waters are exposed to the full energy of the sun. The tempering factor for the Codorus is its baseflow. Despite draining a smaller watershed than its neighbor to the north, the Codorus’s baseflow (low flow between periods of rain) was 96 cubic feet per second on August 5th, nearly twice that of the West Conewago (51.1 cubic feet per second on August 5th). Thus, the incoming heat energy was distributed over a greater mass in the Codorus and had a reduced impact on its temperature. Though the Codorus is certainly a warmwater fishery in its lower reaches, coolwater and transitional fishes could probably inhabit its tributaries in segments located closer to groundwater sources without stress. Several streams in its upper reaches are in fact classified as trout-stocked fisheries.

This is a zoomed-in look at the previous graph showing the impact of a rainfall event on the water temperatures in Codorus Creek. Unlike the sharp declines accompanying the deluge of flood waters during the two events in early August, these lesser storms in late June generated just enough runoff to capture heat energy from impervious surfaces and warm the creek, temporarily breaking the daily heating/cooling cycle. Upstream in the immediate area of the runoff, the impact on the stream and/or its tributaries was probably much more dramatic, certainly raising temperatures into the nineties or above. (United States Geological Survey image)

Kreutz Creek drains a carbonate bedrock area of York County and flows parallel to the Lincoln Highway (US 30) to enter the Susquehanna at Wrightsville. The gauging station is about one mile upstream from the creek’s mouth. (United States Geological Survey image)

The Kreutz Creek gauge shows temperature patterns similar to those in the West Conewago and Codorus data sets, but notice the lower overall temperature trend and the flow. Kreutz Creek is a much smaller stream than the other two, with a flow averaging less than one tenth that of the West Conewago and about one twentieth of that in the Codorus. And most of the watershed is cropland or urban/suburban space. Yet, the stream remains below 80° F through most of the summer. The saving graces in Kreutz Creek are reduced exposure time and gradient. The waters of Kreutz Creek tumble their way through a small watershed to enter the Susquehanna within twenty-four hours, barely time to go through a single daily heating and cooling cycle. As a result, their is no chance for water to accumulate radiant and convective heat over multiple summer days. The daily oscillations in temperature are less amplified than we find in the previous streams—a swing of about three degrees compared to five. This indicates a better balance between heat flux processes that raise temperature and those that reduce it. Atmospheric exchange in the stream’s riffles, forest cover, and good hyporheic exchange along its course could all be tempering factors in Kreutz Creek. From a temperature perspective, Kreutz Creek provides suitable waters for coolwater fishes.

Muddy Creek drains portions of southern York County through rolling farmland and woodlots. There are no large impoundments or widespread urban impacts in the watershed, which may help explain its slightly lower temperature trends. (United States Geological Survey image)

Muddy Creek is a trout-stocked fishery, but it cannot sustain coldwater species through the summer heat. Though temperatures in Muddy Creek may be suitable for coolwater fishes, silt, nutrients, low dissolved oxygen, and other factors could easily render it strictly a warmwater fishery, inhabited by species tolerant of significant stream impairment.

Chiques Creek drains mostly limestone farmland in northwestern Lancaster County. The gauging station is located near the stream’s mouth on the Susquehanna at Chiques (Chickies) Rock. Oscillations in temperature again resemble the other waterways, but daily highs remain almost entirely below 80 degrees. (United States Geological Survey image)

A significant number of stream segments in the Chiques watershed have been rehabilitated to eliminate intrusion by grazing livestock, cropland runoff, and other sources of impairment. Through partnerships between a local group of watershed volunteers and landowners, one tributary, Donegal Creek, has seen riparian buffers, exclusion fencing, and other water quality and habitat improvements installed along nearly ever inch of its run from Donegal Springs through high-intensity farmland to its mouth on the main stem of the Chiques just above its confluence with the Susquehanna. The improved water quality parameters in the Donegal support native coldwater sculpins and an introduced population of reproducing Brown Trout. While coldwater habitat is limited to the Donegal, the main stem of the Chiques and its largest tributary, the Little Chiques Creek, both provide suitable temperatures for coolwater fishes.

Limestone Formation on Little Chiques Creek — Streams in the Chiques Creek and similar limestone watersheds often pass through areas with significant bedrock formations. Heat flux processes including groundwater input, hyporheic exchange, and streambed conductive exchange can have a greater influence on water temperature along these segments.

The Common Shiner (Luxilus cornutus), a fish tolerant of warmwater streams, prefers cool, clear waters for spawning. For protection from late-spring and summer heat, breeding males may seek a section of creek with a streambed inflow of limestone groundwater to defend as their nesting territory.

A closeup of the Chiques Creek graph showing what appears to be a little bump in temperature caused by surface runoff during a couple of late-May showers. Stream rehabilitation is an ongoing process and the pressures of land disturbances both old and new present challenges to those who make it their passion to fix the wrongs that have been inflicted upon our local waters. Even the exemplary Donegal Creek faces new threats from urbanization in one of its headwater areas several miles to the northwest of the historic springs. (United States Geological Survey image)

Conewago Creek (East) drains primarily Triassic redbed farmlands in Dauphin, Lancaster, and Lebanon Counties. Much of the headwaters area is forested but is experiencing an increasing rate of encroachment by housing and some commercial development. Conewago Creek (East) enters the Susquehanna on the east side of Conewago Falls at Three Mile Island. The watershed is equipped with three U.S.G.S. gauge stations capable of providing temperature data. This first one is located just over a mile upstream of the creek’s mouth. (United States Geological Survey image)

Despite its meander through and receipt of water from high-intensity farmland, the temperature of the lower Conewago (East) maxes out at about 85° F, making it ideal for warmwater fishes and even those species that are often considered coolwater transition fishes like introduced Smallmouth Bass, Rock Bass, Walleye, and native Margined Madtom. This survivable temperature is a testament to the naturally occurring and planted forest buffers along much of the stream’s course, particularly on its main stem. But the Conewago suffers serious baseflow problems compared to other streams we’ve looked at so far. Just prior to the early August storms, flow was well below 10 cubic feet per second for a drainage area of more than fifty square miles. While some of this reduced flow is the result of evaporation, much of it is anthropogenic in origin as the rate of groundwater removal continues to increase and a recent surge in stream withdraws for irrigation reaches its peak during the hottest days of summer.

Juvenile Rock Bass — A juvenile Rock Bass.

A closer look at the Conewago Creek (East) graphic shows the temperature drop associated with a series of thundershowers and the remnants of Hurricane Debby in early August. Despite the baseflow being below five cubic feet per second, the cooling effect of the downpours as measured in the area of the gauge was significant enough to overwhelm any heating of runoff that may have occurred as precipitation drained across hardened soils or man-made impervious surfaces. (United States Geological Survey image)

A little side note—the flow rate on the Conewago at the Falmouth gauge climbed to about 160 cubic feet per second as a result of the remnants of Hurricane Debby while the gauge on the West Conewago at Manchester skyrocketed to about 20,000 cubic feet per second. Although the West Conewago’s watershed (drainage area) is larger than that of the Conewago on the east shore, it’s larger only by a multiple of two or three, not 125. That’s a dramatic difference in rainfall!

The Bellaire monitoring station on Conewago Creek (East) is located on the stream’s main stem just downstream from the mouth of Little Conewago Creek, a tributary with its origins in farmland and woodlots. (United States Geological Survey image)

The temperatures at the Bellaire monitoring station, which is located upstream of the Conewago’s halfway point between its headwaters in Mount Gretna and its mouth, are quite comparable to those at the Falmouth gauge. Although a comparison between these two sets of data indicate a low net increase in heat absorption along the stream’s course between the two points, it also suggests sources of significant warming upstream in the areas between the Bellaire gauge and the headwaters.

Data from the gauge site on the Little Conewago Creek shows a temperature averaging about five degrees cooler than the gauge several miles downstream on the main stem of the Conewago at Bellaire. (United States Geological Survey image)

The waters of the Little Conewago are protected within planted riparian buffers and mature woodland along much of their course to the confluence with the Conewago’s main stem just upstream of Bellaire. This tributary certainly isn’t responsible for raising the temperature of the creek, but is instead probably helping to cool it with what little flow it has.

Juvenile Eastern Blacknose Dace (top) and a juvenile Longnose Dace. — A stream like the Little Conewago Creek with daily temperatures that remain mostly below 80 degrees and retreat to 75 degrees or less during the night can be suitable for coldwater transition fishes like these juvenile Eastern Blacknose Dace (top) and Longnose Dace.

Though mostly passing through natural and planted forest buffers above its confluence with the Little Conewago, the main stem’s critically low baseflow makes it particularly susceptible to heat flux processes that raise stream temperatures in segments within the two or three large agricultural properties where owners have opted not to participate in partnerships to rehabilitate the waterway. The headwaters area, while largely within Pennsylvania State Game Lands, is interspersed with growing residential communities where potable water is sourced from hundreds of private and community wells—every one of them removing groundwater and contributing to the diminishing baseflow of the creek. Some of that water is discharged into the stream after treatment at the two municipal sewer plants in the upper Conewago. This effluent can become quite warm during processing and may have significant thermal impact when the stream is at a reduced rate of flow. A sizeable headwaters lake is seasonally flooded for recreation in Mount Gretna. Such lakes can function as effective mid-day collectors of solar (shortwave) radiation that both warms the water and expedites atmospheric exchange.

Upper Conewago Creek (East) Watershed — The Conewago Creek (East) Watershed from the Bellaire U.S.G.S. Gauging Station (lower left) upstream to the headwaters in Mount Gretna. (United States Geological Survey image)

Though Conewago Creek (East) is classified as a trout-stocked fishery in its upper reaches in Lebanon County, its low baseflow and susceptibility to warming render it inhospitable to these coldwater fishes by late-spring/early summer.

Despite being considered a warmwater fish, the River Chub (Nocomis micropogon) will ascend streams like the Conewago to seek cooler, gravel-bottomed waters for spawning. Reduced baseflow has probably rendered the stream currently too small for this species on Pennsylvania State Game Lands in Colebrook where this specimen was photographed in 2018.

The Golden Shiner, another warmwater fish, often ascends streams to enter cooler water. Juvenile Golden Shiners like this one will move into shallower headwaters not only to seek reduced temperatures, but to escape large predatory fishes as well.

Irrigation using stream water. — Irrigation of agricultural fields using a large portion of the already diminished baseflow in the Conewago Creek (East) just downstream of the Bellaire gauging station. Despite millions of dollars in investment to rehabilitate this Susquehanna valley stream, the riparian buffers and other practices can have little effect when the creek gets sucked down to just a trickle. Low baseflow is a hard nut to crack. It’s best prevented, not corrected.

Hammer Creek, a trout-stocked fishery, originates, in part, within Triassic conglomerate in the Furnace Hills of Lebanon County, then flows north into the limestone Lebanon Valley where it picks up significant flow from other tributaries before working its way south back through the Furnace Hills into the limestone farmlands of Lancaster County. From there the stream merges with the Cocalico Creek, then the Conestoga River, and at last the Susquehanna. Note the tremendous daily temperature oscillations on this headwaters stream as it surges about 15 degrees each day before recovering back close to groundwater temperature by sunrise the next day. (United States Geological Survey image)

The removal of two water supply dams on the headwaters of Hammer Creek at Rexmont eliminated a large source of temperature fluctuation on the waterway, but did little to address the stream’s exposure to radiant and convective heat flux processes as it meanders largely unprotected out of the forest cover of Pennsylvania State Game Lands and through high-intensity farmlands in the Lebanon Valley. Moderating the temperature to a large degree is the influx of karst water from Buffalo Springs, located about two miles upstream from this gauging station, and other limestone springs that feed tributaries which enter the Hammer from the east and north. Despite the cold water, the impact of the stream’s nearly total exposure to radiative and other warming heat flux processes can readily be seen in the graphic. Though still a coldwater fishery by temperature standards, it is rather obvious that rapid heating and other forms of impairment await these waters as they continue flowing through segments with few best management practices in place for mitigating pollutants. By the time Hammer Creek passes back through the Furnace Hills and Pennsylvania State Game Lands, it is leaning toward classification as a coolwater fishery with significant accumulations of sediment and nutrients. But this creek has a lot going for it—mainly, sources of cold water. A core group of enthusiastic landowners could begin implementing the best management practices and undertaking the necessary water quality improvement projects that could turn this stream around and make it a coldwater treasure. An organized effort is currently underway to do just that. Visit Trout Unlimited’s Don Fritchey Chapter and Donegal Chapter to learn more. Better yet, join them as a volunteer or cooperating landowner!

Male Creek Chub — The male Creek Chub, one of our coolwater fishes, develops head tubercles and becomes flushed with color during spawning season. Hammer Creek not only provides a home for the Creek Chub, its cold headwaters provide refuge for a population of native Brook Trout too.

Like no other example we’ve looked at so far, this closeup of the Hammer Creek graphic shows temperature bumps correlating with the stormwater runoff from early August’s rains. Because the stream flow is small and the precipitation rate was not as great at this location, the effect of heat flux from runoff is more readily apparent. (United States Geological Survey image)

Brook Trout adult and juvenile. (United States Fish and Wildlife Service image by Ryan Hagerty)

For coldwater fishes, the thousands of years since the most recent glacial maximum have seen their range slowly contract from nearly the entirety of the once much larger Susquehanna watershed to the headwaters of only our most pristine streams. Through no fault of their own, they had the misfortune of bad timing—humans arrived and found coldwater streams and the groundwater that feeds them to their liking. Some of the later arrivals even built their houses right on top of the best-flowing springs. Today, populations of these fishes in the region we presently call the Lower Susquehanna River Watershed are seriously disconnected and the prospect for survival of these species here is not good. Stream rehabilitation, groundwater management, and better civil planning and land/water stewardship are the only way coldwater fishes, and very possibly coolwater fishes as well, will survive. For some streams like Hammer Creek, it’s not too late to make spectacular things happen. It mostly requires a cadre of citizens, local government, project specialists, and especially stakeholders to step up and be willing to remain focused upon project goals so that the many years of work required to turn a failing stream around can lead to success.

Riparian Buffer — Riparian buffers with fences to exclude livestock can immediately begin improving water quality. With establishment of such vegetative buffers, the effects of stressors that otherwise eliminate coldwater and coolwater fishes from these segments will begin to diminish.

You’re probably glad this look at heat flux processes in streams has at last come to an end. That’s good, because we’ve got a lot of work to do.

You Don't Have Time to Mow, We've Got Work to Do — Add one more benefit to the wildflower meadow, it infiltrates stormwater to recharge the aquifer much better than mowed grass. And another related plus, it reduces runoff and its thermal pollution. Besides, you don’t have time to mow grass, because we have work to do!

Our native coldwater fishes including the Potomac Sculpin will survive only if we protect and expand the scattered few habitats where they have taken refuge. They have no choice but to live in these seriously threatened places, but we do. So let’s give ’em some space. How ’bout it? (United States Fish and Wildlife Service image by Ryan Hagerty)

May 22, 2024May 23, 2024

Photo of the Day

Paulownia in Flower — While in flower, this extensive stand of Princess Trees (Paulownia tomentosa) straddling Second Mountain north of Harrisburg might be mistaken for a series of boulder outcrops. Native to eastern Asia, the fast-growing Princess Tree has escaped cultivation to become naturalized in many parts of eastern North America. You’ll currently notice the showy purple blooms on many forested ridges and hilltops throughout the Lower Susquehanna River Watershed. Paulownia tomentosa is also known as the Phoenix Tree, a name derived from its ability, due to its extensive root system, to regenerate following fire. This fast-growing invasive therefore calls for measures in addition to prescribed burns for control within infected forests. Mechanical and/or chemical methods of removal are frequently required.

May 13, 2024May 14, 2024

See Food and an Oriole Doubleheader

The rain and clouds have at last departed. With blue skies and sunshine to remind us just how wonderful a spring afternoon can be, we took a stroll at Memorial Lake State Park in Lebanon County, Pennsylvania, to look for some migratory birds.

Though running just a few days later than usual, Indigo Buntings have arrived to begin nesting.

This Common Loon dropped by Memorial Lake during a storm several days ago and decided to stay awhile. It’s a species that winters in oceanic waters along the Atlantic seaboard and nests on glacial lakes to our north.

Shoreline Vegetation at Memorial Lake — **Clear Water-** Memorial Lake is one of the few man-made lakes in the Lower Susquehanna River Watershed to be appropriately vegetated with an abundance of submerged, floating, and emergent plants. As a result, the water from Indiantown Run that passes through the impoundment is minimally impacted by nutrient loads and the algal blooms they can cause. Buffers of woody and herbaceous growth along the lake’s shorelines provide additional nutrient sequestering and help prevent soil erosion and siltation.

The breeding season has begun for Neotropical migrants including this Baltimore Oriole, which we found defending a nesting territory in a stand of Black Walnut trees.

Along the edge of the lake, this Orchard Oriole and its mate were in yet another stand of tall walnut trees.

Early in the season and early in the day, we started seeing Common Nighthawks flying above wooded areas north of the lake at 4 o’clock this afternoon. After all the raw and inclement weather they’ve experienced in recent days, the warm afternoon was probably their first opportunity to feed on flying insects in quite a while.

What? You thought we were gonna drop in on Maryland’s largest city for a couple of ball games and some oysters, clams, and crab cakes—not likely.

March 28, 2024March 28, 2024

Chesapeake Bay Maritime Accidents and Their Impact on Susquehanna Wildlife

Tuesday’s collision of the container ship Dali into Baltimore’s Francis Scott Key Bridge and the nearly immediate collapse of the span into the chilly waters below reminds us just how unforgiving and deadly maritime accidents can be. Upon termination of rescue and recovery operations, salvage and cleanup will be prioritized as the next steps in the long-term process of reopening the navigable waters to ship traffic and construction of a new bridge. Part of the effort will include monitoring for leaks of fuels and other hazardous materials from the ship, its damaged cargo containers, and vehicles and equipment that were on the bridge when it failed.

Dali vs. Francis Scott Key Bridge — Damage to the hull of the Dali and to the cargo containers on her deck could lead to leaks of hazardous liquids or other materials into Chesapeake Bay. (United States Army Corps of Engineers Baltimore image)

On the waters and shores of today’s Chesapeake, numerous county, state, and federal agencies, including the United States Coast Guard, monitor and inspect looking for conditions and situations that could lead to point-source or accidental discharges of petroleum products and other hazardous materials into the bay. Many are trained, equipped, and organized for emergency response to contain and mitigate spills upon detection. But this was not always the case.

Through much of the twentieth century, maritime spills of oil and other chemicals magnified the effects of routine discharges of hazardous materials and sanitary sewer effluent into the Chesapeake and its tributaries. The cumulative effect of these pollutants progressively impaired fisheries and bay ecosystems leading to noticeable declines in numbers of many aquatic species. Rather frequently, spills or discharges resulted in conspicuous fish and/or bird kills.

One of the worst spills occurred near the mouth of the Potomac River on February 2, 1976, when a barge carrying 250,000 gallons of number 6 oil sank in a storm and lost its cargo into the bay. During a month-long cleanup, the United States Coast Guard recovered approximately 167,000 gallons of the spilled oil, the remainder dispersed into the environment. A survey counted 8,469 “sea ducks” killed. Of the total number, the great majority were Horned Grebes (4,347 or 51.3%) and Long-tailed Ducks (2,959 or 34.9%). Other species included Surf Scoter (Melanitta perspicillata) (405 or 4.8%), Common Loon (195 or 2.3%), Bufflehead (166 or 2.0%), Ruddy Duck (107 or 1.3%), Common Goldeneye (78 or 0.9%), Tundra Swan (46 or 0.5%), Greater Scaup (19 or 0.2%), American Black Duck (12 or 0.2%), Common Merganser (11 or 0.1%), Canvasback (10 or 0.1%), Double-crested Cormorant (10 or 0.1%), Canada Goose (8 or 0.1%), White-winged Scoter (Melanitta deglandi) (7 or 0.1%), Redhead (5 or 0.1%), gull species (10 or 0.1%), miscellaneous ducks and herons (13 or 0.2%) and unidentified (61 or 0.7%). During the spring migration, a majority of these birds would have made their way north and passed through the lower Susquehanna valley. The accident certainly impacted the occurrence of the listed species during that spring in 1976, and possibly for a number of years after.

Horned Grebe during migration on the Susquehanna near Haldeman Riffles. — Of the 8,469 birds killed by the February 2, 1976, oil spill on the Chesapeake, 51.3% (4,347) were Horned Grebes. Many of them would have migrated north through the Lower Susquehanna River Watershed during the coming spring.

The Federal Water Pollution Control Act Amendments of 1972, commonly known as the Clean Water Act, put teeth into the original FWCPCA of 1948 and began reversing the accumulation of pollutants in the bay and other bodies of water around the nation. Additional amendments in 1977 and 1987 have strengthened protections and changed the culture of “dump-and-run” disposal and “dilution-is-the-solution” treatment of hazardous wastes. During the late nineteen-seventies and early nineteen-eighties, emergency response teams and agencies began organizing to control and mitigate spill events. The result has been a greater awareness and competency for handling accidental discharges of fuels and other chemicals into Chesapeake Bay and other waterways. These improvements can help minimize the environmental impact of the Dali’s collision with the Francis Scott Key Bridge in Baltimore.

Oil spills and other pollution in the Chesapeake can impact populations of migratory fish including the anadromous Hickory Shad which are presently transiting the bay on their way to the waters of the Susquehanna below Conowingo Dam.

SOURCES

Roland, John V., Moore, Glenn E., and Bellanca, Michael A. 1977. “The Chesapeake Bay Oil Spill—February 2, 1976: A Case History”. International Oil Spill Conference Proceedings (1977). 1977 (1): 523-527.

February 22, 2024February 24, 2024

Time to Order Trees and Shrubs for Spring

It’s that time of year. Your local county conservation district is taking orders for their annual tree sale and it’s a deal that can’t be beat. Order now for pickup in April.

The prices are a bargain and the selection includes the varieties you need to improve wildlife habitat and water quality on your property. For species descriptions and more details, visit each tree sale web page (click the sale name highlighted in blue). And don’t forget to order packs of evergreens for planting in mixed clumps and groves to provide winter shelter and summertime nesting sites for our local native birds. They’re only $12.00 for a bundle of 10.

Mature Trees in a Suburban Neighborhood — It’s the most desirable block in town, not because the houses are any different from others built during the post-war years of the mid-twentieth century, but because the first owners of these domiciles had the good taste and foresight to plant long-lived trees on their lots, the majority of them native species. Pin Oak, Northern Red Oak, Yellow Poplar, Flowering Dogwood (Cornus florida), Eastern Red Cedar, Eastern White Pine, Eastern Hemlock, Norway Spruce, and American Holly dominate the landscape and create excellent habitat for birds and other wildlife. These 75-year-old plantings provide an abundance of shade in summer and thermal stability in winter, making it a “cool” place to live or take a stroll at any time of the year.

Cumberland County Conservation District Annual Tree Seedling Sale—

Orders due by: Friday, March 22, 2024

Pickup on: Thursday, April 18, 2024 or Friday, April 19, 2024

Cumberland County Conservation District is taking orders for Common Winterberry, the ideal small shrub for wet soil anywhere on your property. To get berries, you’ll need both males and females, so buy a bunch and plant them in a clump or scattered group.

To live for a century or more like this towering giant, a Pin Oak needs to grow in well-drained soils with adequate moisture. These sturdy shade providers do well along streams and on low ground receiving clean runoff from hillsides, roofs, streets, and parking areas. As they age, Pin Oaks can fail to thrive and may become vulnerable to disease in locations where rainfall is not adequately infiltrated into the soil. Therefore, in drier areas such as raised ground or slopes, avoid the Pin Oak and select the more durable Northern Red Oak for planting. This year, Pin Oaks are available from the Cumberland and Lancaster County Conservation Districts, while Dauphin, Lancaster, Lebanon, and York Counties are taking orders for Northern Red Oaks.

The Cumberland County Conservation District is again offering a “Showy Northeast Native Wildflower and Grass Mix” for seeding your own pollinator meadow or garden. It consists of more than twenty species including this perennial favorite, Purple Coneflower.

Dauphin County Conservation District Seedling Sale—

Orders due by: Monday, March 18, 2024

Pickup on: Thursday, April 18, 2024 or Friday, April 19, 2024

The Eastern Redbud is small tree native to our forest edges, particularly in areas of the Piedmont Province with Triassic geology (Furnace Hills, Conewago Hills, Gettysburg/Hammer Creek Formations, etc.) Also known as the Judas Tree, the redbud’s brilliant flowers are followed by heart-shaped leaves. As seen here, it is suitable for planting near houses and other buildings. Eastern Redbud seedlings are being offered through tree sales in Dauphin, Cumberland, and Lancaster Counties.

Lancaster County Annual Tree Seedling Sale—

Orders due by: Friday, March 8, 2024

Pickup on: Friday, April 12, 2024

The Yellow Poplar, often called Tuliptree or Tulip Poplar for its showy flowers, is a sturdy, fast-growing deciduous tree native to forests throughout the Lower Susquehanna River Watershed. Its pole-straight growth habit in shady woodlands becomes more spreading and picturesque when the plant is grown as a specimen or shade tree in an urban or suburban setting. The Yellow Poplar can live for hundreds of years and is a host plant for the Eastern Tiger Swallowtail butterfly. It is available this year from the Lancaster County Conservation District.

The American Sweetgum, also known as Sweet Gum, is a large, long-lived tree adorned with a mix of vibrant colors in autumn.

American Goldfinches and Pine Siskin on Sweet Gum — Ever wonder where all the American Goldfinches and particularly the Pine Siskins go after passing through our region in fall? Well, many are headed to the lowland forests of the Atlantic Coastal Plain where they feed on an abundance of seeds contained in spiky American Sweetgum fruits. In the Piedmont and Ridge and Valley Provinces of the Lower Susquehanna River Watershed, American Sweetgum transplants can provide enough sustenance to sometimes lure our friendly finches into lingering through the winter.

Sweet Gum in a Beaver Pond — The American Sweetgum is a versatile tree. It can be planted on upland sites as well as in wet ground along streams, lakes, and rivers. In the beaver pond seen here it is the dominate tree species. This year, you can buy the American Sweetgum from the Lancaster County Conservation District.

Silky Dogwood Stream Buffer — “Red-twig Dogwoods” make ideal mass plantings for streamside buffers and remain showy through winter, even on a gloomy day. They not only mitigate nutrient and sediment pollution, they provide excellent food and cover for birds and other wildlife. Both Silky and Red-osier Dogwoods are available for sale through the Lancaster County Conservation District as part of their special multi-species offers, the former is included in its “Beauty Pack” and the latter in its “Wildlife Pack”. The similar Gray Dogwood (Cornus racemosa) is being offered for sale by the York County Conservation District.

Lebanon County Conservation District Tree and Plant Sale—

Orders due by: Friday, March 8, 2024

Pickup on: Friday, April 19, 2024

Common Pawpaw flower — The unique maroon flowers of the Common Pawpaw produce banana-like fruits in summer. These small native trees grow best in damp, well-drained soils on slopes along waterways, where they often form clonal understory patches. To get fruit, plant a small grove to increase the probability of pollination. The Common Pawpaw is a host plant for the Zebra Swallowtail butterfly. It is available through both the Lebanon and Lancaster County sales.

The Eastern Red Cedar provides excellent food, cover, and nesting sites for numerous songbirds. Planted in clumps of dozens or groves of hundreds of trees, they can provide winter shelter for larger animals including deer and owls. The Eastern Red Cedar is being offered for purchase through both the Lebanon and Lancaster County Conservation Districts.

Hybrid American Chestnut — Care to try your hand at raising some chestnuts? Lebanon County Conservation District has hybrid American Chestnut seedlings for sale.

Perry County Conservation District Tree Sale—

Orders due by: Sunday, March 24, 2024

Pickup on: Thursday, April 11, 2024

Pollinator Garden — In addition to a selection of trees and shrubs, the Perry County Conservation District is again selling wildflower seed mixes for starting your own pollinator meadow or garden. For 2024, they have both a “Northeast Perennials and Annuals Mix” and a “Butterfly and Hummingbird Seed Mix” available. Give them a try so you can give up the mower!

Again this year, Perry County is offering bluebird nest boxes for sale. The price?—just $12.00.

Eastern Bluebird — Wait, what?,…twelve bucks,…that’s cheaper than renting!

York County Conservation District Seedling Sale—

Orders due by: Friday, March 15, 2024

Pickup on: Thursday, April 11, 2024

Buttonbush flower — The Buttonbush, a shrub of wet soils, produces a cosmic-looking flower. It grows well in wetlands, along streams, and in rain gardens. Buttonbush seedlings are for sale from both the York and Lancaster County Conservation Districts.

To get your deciduous trees like gums, maples, oaks, birches, and poplars off to a safe start, conservation district tree sales in Cumberland, Dauphin, Lancaster, and Perry Counties are offering protective tree shelters. Consider purchasing these plastic tubes and supporting stakes for each of your hardwoods, especially if you have hungry deer in your neighborhood.

Deciduous Tree Planting Protected by Shelters — Tree shelters protect newly transplanted seedlings from browsing deer, klutzy hikers, visually impaired mower operators, and other hazards.

There you have it. Be sure to check out each tree sale’s web page to find the selections you like, then get your order placed. The deadlines will be here before you know it and you wouldn’t want to miss values like these!

January 10, 2024January 18, 2024

Piscivorous Waterfowl Visiting Lakes and Ponds

Heavy rains and snow melt have turned the main stem of the Susquehanna and its larger tributaries into a muddy torrent. For fish-eating (piscivorous) ducks, the poor visibility in fast-flowing turbid waters forces them to seek better places to dive for food. With man-made lakes and ponds throughout most of the region still ice-free, waterfowl are taking to these sources of open water until the rivers and streams recede and clear.

Common Mergansers — The Common Merganser is a species of diving duck with a primary winter range that, along the Atlantic Coast, reaches its southern extreme in the lower Susquehanna and Potomac watersheds. Recently, many have left the main stem of the muddy rivers to congregate on waters with better visibility at some of the area’s larger man-made lakes.

Common Mergansers Feeding — Common Mergansers dive to locate and capture prey, primarily small fish. During this century, their numbers have declined along the southern edge of their winter range, possibly due to birds remaining to the north on open water, particularly on the Great Lakes. In the lower Susquehanna valley, some of these cavity-nesting ducks can now be found year-round in areas where heavy timber again provides breeding sites in riparian forests. After nesting, females lead their young to wander widely along our many miles of larger rivers and streams to feed.

Several Common Mergansers Intimidating a Male with a Freshly Caught Fish — The behavior of these mergansers demonstrates the stiff competition for food that can result when predators are forced away from ideal habitat and become compressed into less favorable space. On the river, piscivores can feed on the widespread abundance of small fish including different species of minnows, shiners, darters, and more. In man-made lakes stocked for recreational anglers with sunfish, bass, and other predators (many of them non-native), small forage species are usually nonexistent. As a result, fish-eating birds can catch larger fish, but are successful far less often. Seen here are several mergansers resorting to intimidation in an effort to steal a young bass away from the male bird that just surfaced with it. While being charged by the aggressors, he must quickly swallow his oversize catch or risk losing it.

With a hard freeze on the way, the fight for life will get even more desperate in the coming weeks. Lakes will ice over and the struggle for food will intensify. Fortunately for mergansers and other piscivorous waterfowl, high water on the Susquehanna is expected to recede and clarify, allowing them to return to their traditional environs. Those with the most suitable skills and adaptations to survive until spring will have a chance to breed and pass their vigor on to a new generation of these amazing birds.

January 6, 2024January 6, 2024

Birds of Snow-covered Farmland

When the ground becomes snow covered, it’s hard to imagine anything lives in the vast wide-open expanses of cropland found in the Lower Susquehanna River Watershed’s fertile valleys.

Snow-covered Farm Field — A snow-covered field with no standing vegetation. For nearly all wild birds, mammals, and other animals, modern agricultural practices offer no means of sustenance, particularly during the winter months.

Yet, there is one group of birds that can be found scrounging a living from what little exists after a season of high-intensity farming. Meet the Horned Lark.

Horned Larks occur year-round in the lower Susquehanna region. Birds found wintering here are hardy individuals that breed in the arctic tundra, terrain reminiscent of our treeless farmlands. Another population of larks seems to have adapted to no-till farming, nesting with some success in unplowed fields during the early part of the growing season. The impact of herbicide application on survival of these broods could be a topic of research for an energetic student out there…hint, hint.

A Flock of Horned Larks — Nearly invisible on bare ground, Horned Larks are much more conspicuous after a fresh snowfall. For protection from predators, they gather in flocks. During the days of raw manure application, 300 to 500 larks could be found attracted to a freshly spread strip in a snow-covered field. Modern liquid manure, which contains fewer undigested seeds and grains for larks, is not as attractive to these and other birds.

Horned Larks in Snow — During severe storms, we’ve seen Horned Larks remain active throughout the night. We’ve even witnessed them taking shelter by burying themselves in the snow.

Horned Lark in Flight — To find food, Horned Larks are constantly on the move…

Horned Lark — …seeking out bare ground or the seed-bearing tops of plant stems that remain exposed above the snow.

Horned Larks Feeding at Roadside — Following storms, Horned Larks often gather along roadsides where snow removal has revealed “weed” seeds and other tiny morsels that, though they are almost imperceptible to us, are a meal for a Horned Lark.

A Horned Lark munching "weed" seeds. — A Horned Lark munching “weed” seeds.

Horned Larks and Lapland Longsrurs — Flocks of wintering Horned Larks will sometimes contain one or more of the several much less numerous species with a similar proclivity for tundra-like environs during the colder months. We examined this gathering a little bit more closely…

Lapland Longspurs and Horned Larks — …and found these Lapland Longspurs (Calcarius lapponicus). In winter, Lapland Longspurs (the two streaked birds: one to the far left and the other high-stepping the white line) can be hard to discern from the earth tones of farmland habitat. Breeding males, however, are a brilliant white with a chestnut-colored nape and a black bib, mask, and cap. On rare occasions, these males in spectacular alternate plumage can be found in the lower Susquehanna valley prior to their departure to nesting areas near the treeline in northern Canada and Alaska.

A close-up image (through the windshield) of a roadside flock of Horned larks and three Lapland Longspurs (top, far right, and third from bottom).

If you decide to take a little post-storm trip to look for Horned Larks and Lapland Longspurs, be sure to drive carefully. Do your searching on quiet rural roads with minimal traffic. Stop and park only where line-of-sight and other conditions allow it to be done safely. Use your flashers and check your mirrors often. Think before you stop and park—don’t get stuck or make a muddy mess. And most important of all, be aware that you’re on a roadway—get out of the way of traffic.

If you’re not going out to look for larks and longspurs, we do have a favor to ask of you. Please remember to slow down while you’re driving. Not only is this an accident-prone time of year for people in cars and trucks, it’s a dangerous time for birds and other wildlife too. They’re at greatest peril of getting run over while concentrated along roadsides looking for food following snow storms.

The American Pipit is another barren-field specialist that can be found feeding at roadside following snowstorms, particularly when they coincide with the bird’s migration in late fall or early spring. (Vintage 35 mm image)

The Snow Bunting (Plectrophenax nivalis), like the Lapland Longspur, occurs among flocks of Horned Larks in winter. Other barren-ground birds you’ll see feeding along country roads following significant snowfalls include Savannah and Vesper Sparrows.

During mild winters, Killdeer may linger in farmlands where they are more easily heard than seen…until it snows.

December 30, 2023July 23, 2025

Want Healthy Floodplains and Streams? Want Clean Water? Then Make Room for the Beaver

I’m worried about the beaver. Here’s why.

Imagine a network of brooks and rivulets meandering through a mosaic of shrubby, sometimes boggy, marshland, purifying water and absorbing high volumes of flow during storm events. This was a typical low-gradient stream in the valleys of the Lower Susquehanna River Watershed in the days prior to the arrival of the waves of trans-Atlantic human migrants that started to inundate the area during the seventeenth century. Then, a frenzy of trapping, tree chopping, mill building, and stream channelization accompanied the east to west surge of settlement across the region. The first casualty: the indispensable lowlands manager, the North American Beaver (Castor canadensis).

Beaver Traps — Nineteenth-century beaver traps on display in the collection of the State Museum of Pennsylvania in Harrisburg. Soon after their arrival, trans-Atlantic migrants (Europeans) established trade ties to the “trans-Beringia”/”Pacific-rim” migrants (“Indians”) already living in the lower Susquehanna valley and recruited them to cull the then-abundant North American Beavers. By the early 1700s, beaver populations (as well as numbers of other “game” animals) were seriously depleted, prompting the Conoy, the last of the Indian peoples to reside on the lower Susquehanna, to disperse to the north. The traps pictured here are samples of the types which were subsequently used by the European settlers to eventually extirpate the North American Beaver from the Lower Susquehanna River Watershed during the 1800s.

Without the widespread presence of beavers, stream ecology quickly collapsed. Pristine waterways were all at once gone, as were many of their floral and faunal inhabitants. It was a streams-to-sewers saga completed in just one generation. So, if we really want to restore our creeks and rivers, maybe we need to give the North American Beaver some space and respect. After all, we as a species have yet to build an environmentally friendly dam and have yet to fully restore a wetland to its natural state. The beaver is nature’s irreplaceable silt deposition engineer and could be called the 007 of wetland construction—doomed upon discovery, it must do its work without being noticed, but nobody does it better.

North American Beaver diorama on display in the State Museum of Pennsylvania in Harrisburg. Beavers were reintroduced to the Susquehanna watershed during the second half of the twentieth century.

A beaver dam on a small stream in the Lower Susquehanna River Watershed. — A beaver dam and pond on a small stream in the Lower Susquehanna River Watershed.

Floodplain Wetlands Managed by North American Beavers — Beaver dams not only create ponds, they also maintain shallow water levels in adjacent areas of the floodplain creating highly-functional wetlands that grow the native plants used by the beaver for food. These ecosystems absorb nutrients and sediments. Prior to the arrival of humans, they created some of the only openings in the vast forests and maintained essential habitat for hundreds of species of plants as well as animals including fish, amphibians, reptiles, and birds. Without the beaver, many of these species could not, and in their absence did not, exist here.

The beaver lodge provides shelter from the elements and predators for a family of North American Beavers. — Their newly constructed lodge provides shelter from the elements and from predators for a family of North American Beavers.

Sandhill Cranes Visit a Beaver-managed Floodplain in the lower Susquehanna valley — Floodplains managed by North American Beavers can provide opportunities for the recovery of the uncommon, rare, and extirpated species that once inhabited the network of streamside wetlands that stretched for hundreds of miles along the waterways of the Lower Susquehanna River Watershed.

Sora Rail in Beaver Pond — Beaver Ponds and their attached wetlands provide nesting habitat for uncommon birds like this Sora rail.

Wood Duck feeding on Lesser Duckweed in Beaver Pond — Lesser Duckweed grows in abundance in beaver ponds and Wood Ducks are particularly fond of it during their nesting cycle.

Sandhill Cranes feeding among Woolgrass in a Beaver Pond — Beaver dams maintain areas of wet soil along the margins of the pond where plants like Woolgrass sequester nutrients and contain runoff while providing habitat for animals ranging in size from tiny insects to these rare visitors, a pair of Sandhill Cranes (Antigone canadensis).

Sandhill Cranes feeding among Woolgrass in a floodplain maintained by North American Beavers.

Few landowners are receptive to the arrival of North American Beavers as guests or neighbors. This is indeed unfortunate. Upon discovery, beavers, like wolves, coyotes, sharks, spiders, snakes, and so many other animals, evoke an irrational negative response from the majority of people. This too is quite unfortunate, and foolish.

North American Beavers spend their lives and construct their dams, ponds, and lodges exclusively within floodplains—lands that are going to flood. Their existence should create no conflict with the day to day business of human beings. But humans can’t resist encroachment into beaver territory. Because they lack any basic understanding of floodplain function, people look at these indispensable lowlands as something that must be eliminated in the name of progress. They’ll fill them with soil, stone, rock, asphalt, concrete, and all kinds of debris. You name it, they’ll dump it. It’s an ill-fated effort to eliminate these vital areas and the high waters that occasionally inundate them. Having the audacity to believe that the threat of flooding has been mitigated, buildings and poorly engineered roads and bridges are constructed in these “reclaimed lands”. Much of the Lower Susquehanna River Watershed has now been subjected to over three hundred years-worth of these “improvements” within spaces that are and will remain—floodplains. Face it folks, they’re going to flood, no matter what we do to try to stop it. And as a matter of fact, the more junk we put into them, the more we displace flood waters into areas that otherwise would not have been impacted! It’s absolute madness.

By now we should know that floodplains are going to flood. And by now we should know that the impacts of flooding are costly where poor municipal planning and negligent civil engineering have been the norm for decades and decades. So aren’t we tired of hearing the endless squawking that goes on every time we get more than an inch of rain? Imagine the difference it would make if we backed out and turned over just one quarter or, better yet, one half of the mileage along streams in the Lower Susquehanna River Watershed to North American Beavers. No more mowing, plowing, grazing, dumping, paving, spraying, or building—just leave it to the beavers. Think of the improvements they would make to floodplain function, water quality, and much-needed wildlife habitat. Could you do it? Could you overcome the typical emotional response to beavers arriving on your property and instead of issuing a death warrant, welcome them as the talented engineers they are? I’ll bet you could.

December 27, 2023December 27, 2023

Photo of the Day

Wildflower Meadow Project underway at East Donegal Riverfront Park — Here’s something to look forward to in the new year. The good citizens of East Donegal Township in Lancaster County have partnered with Alliance for the Chesapeake Bay to establish an extensive wildflower meadow on what had been a mowed field of turf grass at Riverside Park in the Susquehanna floodplain near Marietta. As the photo shows, the lawn plants have been eliminated in preparation for seeding with a diverse assortment of native grasses and wildflowers to provide habitat for birds and pollinators including butterflies, bees, and other insects. Once established, the meadow’s extensive vegetative growth will help reduce stormwater runoff by better infiltrating rainfall to recharge the aquifer. During flood events, the plantings will provide soil stabilization and increase the ability of the acreage to uptake nutrients, thus reducing the negative impact of major storms on the quality of water in the river and in Chesapeake Bay. Check the project’s progress by stopping by from time to time in 2024!

September 24, 2023June 19, 2024

Four Common Grasshoppers

Grasshoppers are perhaps best known for the occasions throughout history when an enormous congregation of these insects—a “plague of locusts”—would assemble and rove a region to feed. These swarms, which sometimes covered tens of thousands of square miles or more, often decimated crops, darkened the sky, and, on occasion, resulted in catastrophic famine among human settlements in various parts of the world.

The largest “plague of locusts” in the United States occurred during the mid-1870s in the Great Plains. The Rocky Mountain Locust (Melanoplus spretus), a grasshopper of prairies in the American west, had a range that extended east into New England, possibly settling there on lands cleared for farming. Rocky Mountain Locusts, aside from their native habitat on grasslands, apparently thrived on fields planted with warm-season crops. Like most grasshoppers, they fed and developed most vigorously during periods of dry, hot weather. With plenty of vegetative matter to consume during periods of scorching temperatures, the stage was set for populations of these insects to explode in agricultural areas, then take wing in search of more forage. Plagues struck parts of northern New England as early as the mid-1700s and were numerous in various states in the Great Plains through the middle of the 1800s. The big ones hit between 1873 and 1877 when swarms numbering as many as trillions of grasshoppers did $200 million in crop damage and caused a famine so severe that many farmers abandoned the westward migration. To prevent recurrent outbreaks of locust plagues and famine, experts suggested planting more cool-season grains like winter wheat, a crop which could mature and be harvested before the grasshoppers had a chance to cause any significant damage. In the years that followed, and as prairies gave way to the expansive agricultural lands that presently cover most of the Rocky Mountain Locust’s former range, the grasshopper began to disappear. By the early years of the twentieth century, the species was extinct. No one was quite certain why, and the precise cause is still a topic of debate to this day. Conversion of nearly all of its native habitat to cropland and grazing acreage seems to be the most likely culprit.

The critically endangered Eskimo Curlew (Numenius borealis), a species not photographed since 1962 and not confirmed since 1963, fed on Rocky Mountain Locusts during its spring migration through the Great Plains. Excessive hunting and conversion of grasslands to agriculture are believed responsible for the bird’s demise. (United States Fish and Wildlife Service image by Christina Nelson)

In the Mid-Atlantic States, the mosaic of the landscape—farmland interspersed with a mix of forest and disturbed urban/suburban lots—prevents grasshoppers from reaching the densities from which swarms arise. In the years since the implementation of “Green Revolution” farming practices, numbers of grasshoppers in our region have declined. Systemic insecticides including neonicotinoids keep grasshoppers and other insects from munching on warm-season crops like corn and soybeans. And herbicides including 2,4-D (2,4-Dichlorophenoxyacetic acid) have, in effect, become the equivalent of insecticides, eliminating broadleaf food plants from the pasturelands and hayfields where grasshoppers once fed and reproduced in abundance. As a result, few of the approximately three dozen species of grasshoppers with ranges that include the Lower Susquehanna River Watershed are common here. Those that still thrive are largely adapted to roadsides, waste ground, and small clearings where native and some non-native plants make up their diet.

Here’s a look at four species of grasshoppers you’re likely to find in disturbed habitats throughout our region. Each remains common in relatively pesticide-free spaces with stands of dense grasses and broadleaf plants nearby.

CAROLINA GRASSHOPPER

Dissosteira carolina

Carolina Grasshopper wing — The Carolina Grasshopper is most readily detected and identified when it flies. The colors of the wings resemble those of the Mourning Cloak butterfly.

Great Black Wasp on goldenrod. — Carolina Grasshoppers are among the preferred victims of Great Black Wasps (Sphex pensylvanicus). A female wasp stings the grasshopper to paralyze it, then drags it away to one of numerous cells in an underground burrow where she lays an egg on it. The body of the disabled grasshopper then provides nourishment for the larval wasp.

DIFFERENTIAL GRASSHOPPER

Melanoplus differentialis

An adult female Differential Grasshopper with fully developed wings.

An adult female Differential Grasshopper

TWO-STRIPED GRASSHOPPER

Melanoplus bivittatus

An adult female Two-striped Grasshopper.

RED-LEGGED GRASSHOPPER

Melanoplus femurrubrum

The Red-legged Grasshopper may currently be our most abundant and widespread species.

Protein-rich grasshoppers are an important late-summer, early-fall food source for birds. The absence of these insects has forced many species of breeding birds to abandon farmland or, in some cases, disappear altogether.

Beginning in the early 1930s, the Western Cattle Egret (Bubulcus ibis), a notoriously nomadic species, transited the Atlantic from Africa to colonize the Americas…and they did it without any direct assistance from humans. During the 1970s and early 1980s, a nesting population of Western Cattle Egrets on river islands adjacent to the Susquehanna’s Conejohela Flats off Washington Boro was the largest inland rookery in the northeastern United States. The Lancaster County Bird Club censused the birds each August and found peak numbers in 1981 (7,580). During their years of abundance, V-shaped flocks of cattle egrets from the rookery islands ventured into grazing lands throughout portions of Lancaster, York, Dauphin, and Lebanon Counties to hunt grasshoppers. These daily flights were a familiar summertime sight for nearly two decades. Then, in the early 1980s, reductions in pastureland acreage and plummeting grasshopper numbers quickly took their toll. By 1988, the rookery was abandoned. The cattle egrets had moved on. (Vintage 33 mm image)

During the summer and early fall, juvenile and adult Ring-necked Pheasants feed heavily on grasshoppers. Earlier and more frequent mowing along with declining numbers of grasshoppers on farmlands due to an increase in pesticide use were factors contributing to the crash of the pheasant population in the early 1980s.

To the delight of Wild Turkeys, each of the four species of grasshoppers shown above frequents clearings and roadsides adjacent to forest areas. While changes in grasshopper distribution have been detrimental to populations of birds like pheasants, they’ve created a feeding bonanza for turkeys.

Wild Turkeys feeding on grasshoppers along a forest road. — Wild Turkeys feeding on an abundance of grasshoppers along a forest road.

American Kestrel Feeding on Grasshopper — An American Kestrel feeds on a grasshopper while ignoring the abundance of Spotted Lanternflies swarming the adjacent utility pole. In Susquehanna valley farmlands, grasshopper and kestrel numbers are down. Lanternflies, on the other hand, have got it made.

Early Successional Growth — Maintaining areas bordering roads, forests, wetlands, farmlands, and human development in a state of early succession can provide and ideal mix of mature grasses and broadleaf plants for grasshoppers, pollinators, birds, and other wildlife.

September 11, 2023September 12, 2023

A Visit to a Beaver Pond

To pass the afternoon, we sat quietly along the edge of a pond created recently by North American Beavers (Castor canadensis). They first constructed their dam on this small stream about five years ago. Since then, a flourishing wetland has become established. Have a look.

A beaver lodge. — The beaver lodge was built among shrubs growing in shallow water in the middle of the pond.

Woolgrass in a beaver pond. — Woolgrass (Scirpus cyperinus) is a bulrush that thrives as an emergent and as a terrestrial plant in moist soils bordering the pond.

A male Common Whitetail dragonfly keeping watch over his territory.

A Twelve-spotted Skimmer perched on Soft Rush.

A Blue Dasher dragonfly seizing a Fall Field Cricket (Gryllus pennsylvanicus).

A Spicebush Swallowtail visiting Cardinal Flower. — A Spicebush Swallowtail visiting a Cardinal Flower.

A Green Heron looking for small fish, crayfish, frogs, and tadpoles.

A Green Heron stalks potential prey. — The Green Heron stalking potential prey.

A Wood Duck feeding on Lesser Duckweed. — A Wood Duck feeding on the tiny floating plant known as Lesser Duckweed (Lemna minor).

A Least Sandpiper feeding along the muddy edge of a beaver pond. — A Least Sandpiper poking at small invertebrates along the muddy edge of the beaver pond.

A Solitary Sandpiper testing the waters for proper feeding depth.

A Pectoral Sandpiper searches for its next morsel of sustenance.

A Sora rail in a beaver pond. — The Sora (Porzana carolina) is a seldom seen rail of marshlands including those created by North American Beavers. Common Cattails, sedges, and rushes provide these chicken-shaped wetland birds with nesting and loafing cover.

Isn’t that amazing? North American Beavers build and maintain what human engineers struggle to master—dams and ponds that reduce pollution, allow fish passage, and support self-sustaining ecosystems. Want to clean up the streams and floodplains of your local watershed? Let the beavers do the job!

September 8, 2023September 8, 2023

Photo of the Day

The Broad-necked Root Borer (Prionus laticollis) is one of the Lower Susquehanna River Watershed’s largest insects. Its larvae feed on woody roots for more than two years before pupating and thereafter emerging as adult beetles. The distribution of root borers is not totally random. They are often attracted to distressed trees and shrubs. This particular specimen was found along a forest road where herbicide application, soil dehydration, and a recent wildfire has weakened and killed numerous oaks, poplars, and maples. As they feed, root borer larvae will help begin the process of reducing the remains of these trees into soil nutrients that will benefit regeneration of forest plants at this site.

August 18, 2023May 20, 2024

Shorebirds and Stormwater Retention Ponds

Your best bet for finding migrating shorebirds in the lower Susquehanna region is certainly a visit to a sandbar or mudflat in the river. The Conejohela Flats off Washington Boro just south of Columbia is a renowned location. Some man-made lakes including the one at Middle Creek Wildlife Management Area are purposely drawn down during the weeks of fall migration to provide exposed mud and silt for feeding and resting sandpipers and plovers. But with the Susquehanna running high due to recent rains and the cost of fuel trending high as well, maybe you want to stay closer to home to do your observing.

Fortunately for us, migratory shorebirds will drop in on almost any biologically active pool of shallow water and mud that they happen to find. This includes flooded portions of fields, construction sites, and especially stormwater retention basins. We stopped by a new basin just west of Hershey, Pennsylvania, and found more than two dozen shorebirds feeding and loafing there. We took each of these photographs from the sidewalk paralleling the south shore of the pool, thus never flushing or disturbing a single bird.

Stormwater retentrion basin. — Designed to prevent stream flooding and pollution, this recently installed stormwater retention basin along US 322 west of Hershey, Pennsylvania, has already attracted a variety of migrating plovers and sandpipers.

Two of more than a dozen Least Sandpipers found busily feeding in the inch-deep water.

A Lesser Yellowlegs searching for small invertebrates.

Male Twelve-spotted Skimmers patrol the airspace above a pair of Least Sandpipers. Dragonflies and other aquatic insects are quick to colonize the waters held in well-engineered retention basins. Proper construction and establishment of a functioning food chain/web in these man-made wetlands prevents them from becoming merely temporary cesspools for breeding mosquitos.

So don’t just drive by those big puddles, stop and have a look. You never know what you might find.

A Semipalmated Sandpiper (middle right) joins a flock of Least Sandpipers.

Pectoral Sandpipers (two birds in the center) are regular fall migrants on the Susquehanna at this time of year. They are most frequently seen on gravel and sand bars adjacent to the river’s grassy islands, but unusually high water for this time of year prevents them from using this favored habitat. As a result, you might be lucky enough to discover Pectoral Sandpipers on almost any mudflat in the area.

Two Pectoral Sandpipers and five smaller but very similar Least Sandpipers. — Two Pectoral Sandpipers and five smaller, but otherwise very similar, Least Sandpipers.

A Killdeer (right), a Semipalmated Plover (upper right), and a Least and Pectoral Sandpiper (left). — A Killdeer (right), a Semipalmated Plover (upper right), and Least and Pectoral Sandpipers (left).

August 7, 2023August 7, 2023

Be on the Lookout: Black-bellied Whistling Ducks

Those mid-summer post-breeding wanders continue to delight birders throughout the Mid-Atlantic States. One colorful denizen of ponds and wetlands that has yet to put in an appearance in the Lower Susquehanna River Watershed this year is the Black-bellied Whistling Duck. You might remember this species from earlier posts describing the fortieth anniversary of your editor’s journey to the Lower Rio Grande Valley of Texas. Like many other birds, the Black-bellied Whistling Duck has been extending its range north from Texas, Florida, and other states along the Gulf Coastal Plain. Populations of these waterfowl are chiefly resident birds with some short-distance movement to find suitable habitat for feeding and nesting. They are not usually migratory, so summertime wandering may be the mechanism for their discovery of new habitats advantageous for nesting in areas north of their current home.

Presently, at least two dozen Black-bellied Whistling Ducks are being seen regularly at a stormwater retention pond in a housing subdivision along Amalfi Drive west of Smyrna, Delaware. This small population of avian tourists has spent at least two summers in the area. Just yesterday, Black-bellied Whistling Ducks were seen and photographed about ten miles to the east at Bombay Hook National Wildlife Refuge. Nine were counted there while 27 were being watched simultaneously at the Amalfi site. Earlier this week, a single Black-bellied Whistling Duck visited the John Heinz National Wildlife Refuge in Philadelphia, indicating that the influx of these vagrants has transited the entire Delmarva Peninsula and entered Pennsylvania. So while you’re out watching for those first southbound migrants of the year, be on the lookout for wayward wanderers too—wanderers like Black-bellied Whistling Ducks!

Black-bellied Whistling Ducks in a stormwater retention pond west of Smyrna, Delaware.

July 24, 2023August 25, 2023

Shorebirds and More at Bombay Hook National Wildlife Refuge

Have you purchased your 2023-2024 Federal Duck Stamp? Nearly every penny of the 25 dollars you spend for a duck stamp goes toward habitat acquisition and improvements for waterfowl and the hundreds of other animal species that use wetlands for breeding, feeding, and as migration stopover points. Duck stamps aren’t just for hunters, purchasers get free admission to National Wildlife Refuges all over the United States. So do something good for conservation—stop by your local post office and get your Federal Duck Stamp.

2023-2024 Federal Duck Stamp. Your Federal Duck Stamp is your free pass to visit the nation's National Wildlife Refuges including Bombay Hook National Wildlife Refuge on Delaware Bay near Smyrna, Delaware. — Your Federal Duck Stamp is your admission ticket for entry into many of the country’s National Wildlife Refuges including Bombay Hook National Wildlife Refuge on Delaware Bay near Smyrna, Delaware.

Still not convinced that a Federal Duck Stamp is worth the money? Well then, follow along as we take a photo tour of Bombay Hook National Wildlife Refuge. Numbers of southbound shorebirds are on the rise in the refuge’s saltwater marshes and freshwater pools, so we timed a visit earlier this week to coincide with a late-morning high tide.

This pair of Northern Bobwhite, a species now extirpated from the Lower Susquehanna River Watershed and the rest of Pennsylvania, escorted us into the refuge. At Bombay Hook, they don’t waste your money mowing grass. Instead, a mosaic of warm-season grasses and early successional growth creates ideal habitat for Northern Bobwhite and other wildlife.

Shearness Pool at Bombay Hook N.W.R. — Twice each day, high tide inundates mudflats in the saltwater tidal marshes at Bombay Hook prompting shorebirds to move into the four man-made freshwater pools. Birds there can often be observed at close range. The auto tour route through the refuge primarily follows a path atop the dikes that create these freshwater pools. Morning light is best when viewing birds on the freshwater side of the road, late-afternoon light is best for observing birds on the tidal saltwater side.

Semipalmated Sandpipers stream into Raymond Pool to escape the rising tide in the salt marsh.

Semipalmated Sandpipers and Short-billed Dowitcher — More Semipalmated Sandpipers and a single Short-billed Dowitcher (Limnodromus griseus) arrive at Raymond Pool.

Two more Short-billed Dowitchers on the way in.

Sandpipers, Avocets, Egrets, and Mallards — Recent rains have flooded some of the mudflats in Bombay Hook’s freshwater pools. During our visit, birds were often clustered in areas where bare ground was exposed or where water was shallow enough to feed. Here, Short-billed Dowitchers in the foreground wade in deeper water to probe the bottom while Semipalmated Sandpipers arrive to feed along the pool’s edge. Mallards, American Avocets, and egrets are gathered on the shore.

Semipalmated Sandpipers, Short-billed Dowitchers, and Forster's Terns — Hundreds of Semipalmated Sandpipers, several Short-billed Dowitchers, and some Forster’s Terns (Sterna forsteri) crowd onto a mud bar at Bear Swamp Pool.

Semipalmated Sandpipers, Forster's Terns, and a Short-billed Dowitcher — A zoomed-in view of the previous image showing a tightly packed crowd of Semipalmated Sandpipers, Forster’s Terns, and a Short-billed Dowitcher (upper left).

Short-billed Dowitchers, American Avocets, and a Snowy Egret in Raymond Pool. A single Stilt Sandpiper (Calidris himantopus) can been seen flying near the top of the flock of dowitchers just below the egret.

Stilt Sandpiper among Short-billed Dowitchers — Zoomed-in view of a Stilt Sandpiper (Calidris himantopus), the bird with white wing linings.

American Avocets probe the muddy bottom of Raymond Pool.

Dunlin and Short-billed Dowitchers — Among these Short-billed Dowitchers, the second bird from the bottom is a Dunlin. This sandpiper, still in breeding plumage, is a little bit early. Many migrating Dunlin linger at Bombay Hook into October and even November.

This Least Sandpiper found a nice little feeding area all to itself at Bear Swamp Pool.

A Greater Yellowlegs at Bear Swamp Pool.

Marsh Wren singing — The chattering notes of the Marsh Wren’s (Cistothorus palustris) song can be heard along the tour road wherever it borders tidal waters.

Marsh Wren Nest — This dome-shaped Marsh Wren nest is supported by the stems of Saltwater Cordgrass (Sporobolus alterniflorus), a plant also known as Smooth Cordgrass. High tide licks at the roots of the cordgrass supporting the temporary domicile.

By far the most common dragonfly at Bombay Hook is the Seaside Dragonlet (Erythrodiplax berenice). It is our only dragonfly able to breed in saltwater. Seaside Dragonlets are in constant view along the impoundment dikes in the refuge.

Red-winged Blackbirds are still nesting at Bombay Hook, probably tending a second brood.

Look up! A migrating Bobolink passes over the dike at Shearness Pool.

Mute Swans and Canada Geese — Non-native Mute Swans and resident-type Canada Geese in the rain-swollen Shearness Pool.

A pair of Trumpeter Swans (Cygnus buccinator) as seen from the observation tower at Shearness Pool. Unlike gregarious Tundra and Mute Swans, pairs of Trumpeter Swans prefer to nest alone, one pair to a pond, lake, or sluggish stretch of river. The range of these enormous birds was restricted to western North America and their numbers were believed to be as low as 70 birds during the early twentieth century. An isolated population consisting of several thousand birds was discovered in a remote area of Alaska during the 1930s allowing conservation practices to protect and restore their numbers. Trumpeter Swans are slowly repopulating scattered east coast locations following recent re-introduction into suitable habitats in the Great Lakes region.

A hen Wood Duck (second from right) escorts her young. — Wood Ducks in Bear Swamp Pool.

Black-necked Stilt and young. — A Bombay Hook N.W.R. specialty, a Black-necked Stilt and young at Bear Swamp Pool.

As the tide recedes, shorebirds leave the freshwater pools to begin feeding on the vast mudflats exposed within the saltwater marshes. Most birds are far from view, but that won’t stop a dedicated observer from finding other spectacular creatures on the bay side of the tour route road.

Tidal Marshes — Bombay Hook National Wildlife Refuge protects a vast parcel of tidal salt marsh and an extensive network of tidal creeks. These areas are not only essential wildlife habitat, but are critical components for maintaining water quality in Delaware Bay and the Atlantic.

The shells of expired Atlantic Horseshoe Crabs were formerly widespread and common among the naturally occurring flotsam along the high tide line on Delaware Bay. We found just this one during our visit to Bombay Hook. Man has certainly decimated populations of this ancient crustacean during recent decades.

Boardwalk Trail — As the tide goes out, it’s a good time for a quick walk into the salt marsh on the boardwalk trail opposite Raymond Pool.

Among the Saltmarsh Cordgrass along the trail and on the banks of the tidal creek there, a visitor will find thousands and thousands of Atlantic Marsh Fiddler Crabs (Minuca pugnax).

A male Atlantic Marsh Fiddler Crab peers from its den.

A juvenile Clapper Rail (Rallus crepitans crepitans) emerges from the cover of the cordgrass along a tidal creek to search for a meal.

Glossy Ibis leave their high-tide hiding place in Shearness Pool to head out into the tidal marshes for the afternoon.

Great Black-backed Gulls, Herring Gulls, and possibly other species feed on the mudflats exposed by low tide. — Great Black-backed Gulls, Herring Gulls, and possibly other species feed on the mudflats exposed by low tide in the marshes opposite Shearness Pool.

Ospey — An Osprey patrols the vast tidal areas opposite Shearness Pool.

No visit to Bombay Hook is complete without at least a quick loop through the upland habitats at the far end of the tour route.

Blue Grosbeaks (Passerina caerulea) are common nesting birds at Bombay Hook. This one was in shrubby growth along the dike at the north end of Shearness Pool.

Trumpet Creeper and Poison Ivy — These two native vines are widespread at Bombay Hook and are an excellent source of food for birds. The orange flowers of the Trumpet Vine are a hummingbird favorite and the Poison Ivy provides berries for numerous species of wintering birds.

Pileated Woodpecker in Sweet Gum — The Pileated Woodpecker is one of the numerous birds that supplements its diet with Poison Ivy berries. The tree this individual is visiting is an American Sweetgum (Liquidambar styraciflua), a species native to the Atlantic Coastal Plain in Delaware. The seed balls are a favorite winter food of goldfinches and siskins.

Red-bellied Slider and Painted Turtle — Finis Pool has no frontage on the tidal marsh but is still worth a visit. It lies along a spur road on the tour route and is located within a deciduous coastal plain forest. Check the waters there for basking turtles like this giant Northern Red-bellied Cooter (Pseudemys rubiventris) and much smaller Painted Turtle.

Fowler's Toad — Fowler’s Toads (Anaxyrus fowleri) breed in the vernal ponds found in the vicinity of Finis Pool and elsewhere throughout the refuge.

Turk's Cap Lily — The National Wildlife Refuge System not only protects animal species, it sustains rare and unusual plants as well. This beauty is a Turk’s Cap Lily (Lilium superbum), a native wildflower of wet woods and swamps.

We hope you’ve been convinced to visit Bombay Hook National Wildlife Refuge sometime soon. And we hope too that you’ll help fund additional conservation acquisitions and improvements by visiting your local post office and buying a Federal Duck Stamp.

June 30, 2023June 30, 2023

Take a Deep Breath This Independence Day Weekend

The gasoline and gunpowder gang’s biggest holiday of the year has arrived yet again. Where does all the time go?

In observance of this festive occasion, we’ve decided to take a look at all the stuff that’s floating around in the atmosphere before all the motor travel, celebratory fires, and exciting explosions get underway.

We’ll start with the smoke from wildfires in Canada…

In the margins between the water vapor clouds, a smoky haze can be seen across the Mid-Atlantic States this morning. To warn residents of the potential health impacts, air quality alerts have been issued by numerous state and local agencies. (NOAA/GOES image)

Near the top of this image, ember-red areas denote the locations of some of the hottest forest fires presently burning in remote portions of northern Quebec. (NOAA/GOES Fire Temperature Composite image)

Wildfires are now burning in every province in Canada. Note the smoky haze that is visible between the water vapor clouds as it drifts from Alberta, Manitoba, and Saskatchewan through the Great Lakes and into the Mid-Atlantic States. (NOAA/GOES image)

If you think that smoke accounts for all the particulate matter now obscuring skies in the northern half of the western hemisphere, then have a gander at this…

As it often does at this time of year, dust from the Sahara Desert in northern Africa is blowing into the Caribbean Islands and Amazonia. This morning’s full-disk satellite image shows both the smoke from wildfires in Canada and a well-defined earth-tone cloud of desert dust streaming west across the Atlantic from Africa. (NOAA/GOES image)

As you can see, natural processes are currently providing a plentiful load of particulates in our skies. There’s no real need to aggravate yourself and the situation by sitting in traffic or burning your groceries on the barbecue. And you can let those cult-like homeowner chores for later. After all, running the mower, whacker, and blower will only add to the airborne pollutants. While celebrating this Fourth of July, why risk mangling fingers on your throwing hand or catching the neighbor’s house on fire when you could just relax and quietly eat ice cream or watermelon? Yeah, that’s more like it.

June 18, 2023June 18, 2023

A Few Plants with Wildlife Impact in June

Here’s a look at some native plants you can grow in your garden to really help wildlife in late spring and early summer.

The Larger Blue Flag (Iris versicolor) and Soft Rush (Juncus effusus) in flower in mid-June. — The showy bloom of a Larger Blue Flag (Iris versicolor) and the drooping inflorescence of Soft Rush (Juncus effusus). These plants favor moist soils in wetlands and damp meadows where they form essential cover and feeding areas for insects, amphibians, and marsh birds. Each is an excellent choice for helping to absorb nutrients in a rain garden or stream-side planting. They do well in wet soil or shallow water along the edges of garden ponds too.

The fruits of Smooth Shadbush (Amelanchier laevis), also known as Allegheny Serviceberry, Smooth Serviceberry, or Smooth Juneberry, ripen in mid-June and are an irresistible treat for catbirds, robins, bluebirds, mockingbirds, and roving flocks of Cedar Waxwings.

Common Milkweed and Eastern Carpenter Bee — Also in mid-June, the fragrant blooms of Common Milkweed attract pollinators like Eastern Carpenter Bees,…

Common Milkweed and Honey Bee — …Honey Bees,…

Common Milkweed and Banded Hairstreak — …and butterflies including the Banded Hairstreak (Satyrium calanus). In coming weeks, Monarch butterflies will find these Common Milkweed plants and begin laying their eggs on the leaves. You can lend them a hand by planting milkweed species (Asclepias) in your garden. Then watch the show as the eggs hatch and the caterpillars begin devouring the foliage. Soon, they’ll pupate and, if you’re lucky, you’ll be able to watch an adult Monarch emerge from a chrysalis!

June 7, 2023June 8, 2023

Photo of the Day

The Sun in Wildfire Smoke — Nearly a full hour before it set below the western horizon, the sun faded into the clouds of Canadian wildfire smoke filling the skies of the lower Susquehanna valley and was gone. Look closely…the haze filtered the sun’s glare so completely that several sunspots are visible.

June 7, 2023June 7, 2023

The Smoke is About to Get Even Thicker

Forest Fire Smoke Plume — The smoky haze from forest fires burning to our north in Canada is about to cast a yet darker orange-brown shadow. A very dense plume is, at the moment of this writing, quickly approaching the Lower Susquehanna River Watershed. Low pressure to our northeast is concentrating this 400-mile-wide wall of airborne particulates and steering it in our direction. (NOAA/GOES image)

Watch the cloud on the move—click here for a GIF animation of this image.

June 5, 2023June 8, 2023

The Value of Water

Are you worried about your well running dry this summer? Are you wondering if your public water supply is going to implement use restrictions in coming months? If we do suddenly enter a wet spell again, are you concerned about losing valuable rainfall to flooding? A sensible person should be curious about these issues, but here in the Lower Susquehanna River Watershed, we tend to take for granted the water we use on a daily basis.

This Wednesday, June 7, you can learn more about the numerous measures we can take, both individually and as a community, to recharge our aquifers while at the same time improving water quality and wildlife habitat in and around our streams and rivers. From 5:30 to 8:00 P.M., the Chiques Creek Watershed Alliance will be hosting its annual Watershed Expo at the Manheim Farm Show grounds adjacent to the Manheim Central High School in Lancaster County. According to the organization’s web page, more than twenty organizations will be there with displays featuring conservation, aquatic wildlife, stream restoration, Honey Bees, and much more. There will be games and custom-made fish-print t-shirts for the youngsters, plus music to relax by for those a little older. Look for rain barrel painting and a rain barrel giveaway. And you’ll like this—admission and ice cream are free. Vendors including food trucks will be onsite preparing fare for sale.

And there’s much more.

To help recharge groundwater supplies, you can learn how to infiltrate stormwater from your downspouts, parking area, or driveway…

Urban Runoff — Does your local stream flood every time there’s a downpour, then sometimes dry up during the heat of summer? Has this problem gotten worse over the years? If so, you may be in big trouble during a drought. Loss of base flow in a stream or river is a sure sign of depleted groundwater levels in at least a portion of its drainage basin. Landowners, both public and private, in such a watershed need to start infiltrating stormwater into the ground instead of allowing it to become surface runoff.

Rain Garden Model — You can direct the stormwater from your downspout, parking area, or driveway into a rain garden to help recharge the aquifer that supplies your private or public well and nearby natural springs. Displays including this model provided by Rapho Township show you how.

…there will be a tour of a comprehensive stream and floodplain rehabilitation project in Manheim Memorial Park adjacent to the fair grounds…

Legacy Sediments — Have you seen banks like these on your local stream? On waterways throughout the Lower Susquehanna River Watershed, mill dams have trapped accumulations of sediments that eroded from farm fields prior to the implementation of soil conservation practices. These legacy sediments channelize creeks and disconnect them from their now buried floodplains. During storms, water that would have been absorbed by the floodplain is now displaced into areas of higher ground not historically inundated by a similar event.

Adjacent to the Manheim Farm Show grounds, the Chiques Creek Stream Restoration Project in Manheim Memorial Park has reconnected the waterway to its historic floodplain by removing a dam and the legacy sediments that accumulated behind it.

Legacy Sediments Removed — Chiques Creek in Manheim following removal of hundreds of truck loads of legacy sediments. High water can again be absorbed by the wetlands and riparian forest of the floodplain surrounding this segment of stream. There are no incised banks creating an unnatural channel or crumbling away to pollute downstream waters with nutrients and sediment. Projects similar to this are critical to improving water quality in both the Susquehanna River and Chesapeake Bay. Closer to home, they can help municipalities meet their stormwater management (MS4) requirements.

Bank-full Bench — Mark Metzler of Rettew Associates guides a tour of the Chiques Creek rehabilitation. Here, cross vanes, stone structures that provide grade control along the stream’s course, were installed to gently steer the center of the channel away from existing structures. Cross vanes manipulate the velocity of the creek’s flow across its breadth to dissipate potentially erosive energy and more precisely direct the deposition of gravel and sediment.

…and a highlight of the evening will be using an electrofishing apparatus to collect a sample of the fish now populating the rehabilitated segment of stream…

…so don’t miss it. We can hardly wait to see you there!

The 2023 Watershed Expo is part of Lancaster Conservancy Water Week.

May 27, 2023June 1, 2023

Forty Years Ago in the Lower Rio Grande Valley: Day Seven

Back in late May of 1983, four members of the Lancaster County Bird Club—Russ Markert, Harold Morrrin, Steve Santner, and your editor—embarked on an energetic trip to find, observe, and photograph birds in the Lower Rio Grande Valley of Texas. What follows is a daily account of that two-week-long expedition. Notes logged by Markert some four decades ago are quoted in italics. The images are scans of 35 mm color slide photographs taken along the way by your editor.

DAY SEVEN—May 27, 1983

“Bentsen State Park”

“6 A.M. alarm rang. After breakfast we walked an hour or more. At 8:15 we phoned Father Tom for more information. We next went back to Anzalduas County Park in hopes of seeing a Hook-billed Kite. It is now 11:30 and NO luck. Steve got his first lifer — Red-billed Pigeon. We parked on a dirt dike and they went walking. I took a nap.”

Based on new tips from Father Tom, we had back-tracked east along the Rio Grande to look for Hook-billed Kite, Red-billed Pigeon (Patagioenas flavirostris), and other species before continuing west toward Falcon Dam in coming days. The pigeon was yet another specialty with a range that extends north from Central America into the subtropical riparian forests of the Lower Rio Grande Valley.

Anzalduas County Park is located along the Rio Grande at the Anzalduas Diversion Dam, part of a network of flood control projects initiated in the 1930s to reign in the “untamed river”. Construction on this particular dam began in 1956 and was completed in 1960. Operation of diversion and flood control dams on the Rio Grande has functionally eliminated stream meander along its present course, thus the delta that is the Lower Rio Grande Valley will cease to experience the morphological changes that create wetlands, resacas, and other natural features in the floodplain. Thought to be excellent ideas at the time, most of these projects were based on a blurred vision of the connection between streams, their floodplains, and the watershed’s aquifer. This condition has manifested itself as a blindness to the finite nature of water supplies, particular where consumption rates are still sharply rising while groundwater recharge is diminishing.

Anzalduas Diversion Dam and Interior Floodway System — The Anzalduas Diversion Dam redirects water from the Rio Grande to supply an irrigation canal on the Mexico side of the river. In addition, the Anzalduas Reservoir supplies domestic water for Reynosa, Matamoros, and other towns south of the border. To control flooding on the river downstream, a spillway on the north side of the reservoir created by the dam diverts high water into a seventy-mile-long dike-lined interior floodway that discharges the excess flow into the Gulf of Mexico. A portion of the floodway utilizes the channel of the Arroyo Colorado through the Harlingen area. On the map, irrigated lands are shaded green and urban space is yellow. (International Boundary Water Commission-United States Section base image)

In addition to the Red-billed Pigeon, we found Brown-headed Cowbirds at Anzalduas County Park. Flying over the adjacent reservoir/river there were Caspian Terns. We identified some turtles too—Red-eared Sliders.

Lone Rider — Back in 1983, we saw very few people in any of the parks or refuges along the Rio Grande. From atop the flood control levee, I photographed this lone rider having a look around the interior floodway adjacent to Anzalduas County Park. Today, this area is at times bustling with border patrol activity that includes the use of armored vehicles and mounted officers. Shallow waters on the downstream side of the dam provide a busy crossing point for migrants and smugglers and the park itself was used as a migrant camp during the SARS-CoV-2 outbreak. Border barrier design follows the levee as well as parts of the interior floodway itself. As a result, many of these parks and refuges will be bisected or left entirely on the south side of the wall, a “no man’s land ” between it and the river.

“After my nap, I took pictures of the place and of the men coming back. Then to the McAllen Sewage Ponds where we had some luck — Eared Grebe and others.”

The McAllen Sewage Ponds were like a little oasis for waterbirds. Though not a specialty of the Lower Rio Grande Valley, the Eared Grebe (Podiceps nigricollis) was a western species we were happy to have seen. A Gulf Coast species, Mottled Duck (Anas fulvigula), was another welcome find. Other sightings included Least Grebe, 100 Ruddy Ducks, Northern Shoveler, Mallard, Black-bellied Whistling Duck, American Coot, Common Gallinule, Spotted Sandpiper, White-faced Ibis (Plegadis chihi), Black-necked Stilt, Franklin’s Gull, Least Tern (Sternula antillarum), Scissor-tailed Flycatcher, Great-tailed Grackle, and Bronzed Cowbird.

Swimming around in the McAllen Sewage Ponds was a Nutria (Myocastor coypus), also known as the Coypu, a mammal resembling a giant muskrat—remember, things really are bigger in Texas.

“Next to the Time Out Camp Ground to check with a couple I met in February. They had moved, their space was empty. Back to Bentsen State Park. On the way we bought a watermelon for supper’s dessert. Rain almost all P.M. Raining now 8:00 P.M. Before supper we checked again for the Tropical Parula with no luck. The watermelon was very good for dessert.”

Details received this morning from Father Tom suggested we check the area of the Bentsen Rio Grande Valley State Park campground near a large Spanish Moss-draped tree for the nesting Tropical Parulas. I don’t recall what kind of tree it was, but the paved road circled the area surrounding it indicating that those who had designed the campground had purposely preserved this massive specimen as something unique. Despite its prominence, no sights or sounds of the Tropical Parulas were found. We reached the conclusion that we were a little late; they were gone for the year. To soothe our sorrows, we ate watermelon—very refreshing!

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Forty Years Ago in the Lower Rio Grande Valley: Day Seven