LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED – A Natural History of Conewago Falls

February 11, 2026February 11, 2026

To Stave Off Starvation, Nip It in the Bud

It looks like the worst of the cold may be behind us. With temperatures trending upwards during the coming days and weeks, some species of wildlife will soon find their search for food made a whole lot easier.

White-crowned Sparrows spend the winter seeking shelter in dense tangles of early successional growth, particularly among thorny shrubs and vines. Extended periods with snow cover can make their search for food a real challenge, but we spotted this one hitting the jackpot on a bare patch of sun-drenched ground along the edge of a thicket of briars. It has found the earliest green buds of a clover or other herbaceous plant. Many songbirds in the finch, cardinal, and sparrow families turn to buds in late winter and early spring as a source of energy-rich sugars.

In woodlands, sweet sap will soon swell the buds of maples, much to the delight of Eastern Gray Squirrels whose favorite dining spot will suddenly become the treetops instead of the leaf litter. Often selected by property owners for their colorful autumn foliage and fast growth, the prevalence of both native and non-native maples in the suburban landscape helps more squirrels survive the winter to expand their numbers in the spring.

Nibbling late-winter buds is a daylong pastime for the hungry White-tailed Deity. While high-intensity twig browsing can alter forest ecology and practically eliminate understory growth and regeneration, bud snacking only tends to make some of the trees more stout than others. It’s similar to the trimming and snipping a bonsai artist may do to maintain a prized specimen.

Tree Shelters Protecting Saplings — Those of you installing stream buffers or reforesting all or part of your property may not want your newly planted trees turned into bonsai or lost entirely to hungry ungulates. If you’re seeking some relief from a browsing problem, you’ve got to nip it in the bud. Tree shelters offer protection during the first half a decade or more of your sapling’s new life. You can find these tubes for sale from many online sources including some of the local county conservation districts during their annual spring tree sales (which happen to be underway right now, hint-hint). Installing these plastic protectors may not only relieve you from the frustration of worrying about your new trees, it might also excuse you from risking involvement in the sometimes heated quarrel between the worshipers of the White-tailed Deity who practice sacrifice and those who religiously oppose it.

February 5, 2026

An Intermission Between Deep Freezes

With another round of single-digit and possibly sub-zero temperatures on the way, birds and other wildlife are taking advantage of a break in the extreme conditions to re-energize. During the past day, these species were among those attracted to the food and cover provided by the habitat plantings in the susquehannawildlife.net headquarters garden…

Dark-eyed Juncos, one of our numerous species of native sparrows, are sometimes called “snowbirds”, and for good reason. They spend the majority of their time on the ground searching for seeds and are particularly noticeable when the landscape is blanketed in white.

To make it through the winter, a Northern Mockingbird is again defending the garden’s supply of fruits adorning Common Winterberry, American Holly, and Eastern Red Cedar. Robins, starlings, waxwings, and bluebirds must be stealthy and quick if they want to grab a snack before the ever-alert mockingbird aggressively moves them on their way.

As they mature, our plantings of junipers, hollies, Eastern Hemlock, Norway Spruce, and Eastern White Pine offer the environs needed by evergreen-loving species like this Red-breasted Nuthatch to remain as winter residents instead of just seasonal transients.

January 29, 2026

In the Frozen Foods Aisle

For overwintering birds and other animals, finding enough food is especially difficult when there’s snow on the ground. And nighttime temperatures in the single digits make critical the need to replenish energy during the daylight hours. Earlier this afternoon, we found these American Robins seizing the berry-like cones from ornamental junipers in a grocery store parking lot. It was an urgent effort in their struggle for survival.

A hungry American Robin at the local Weis Market.

American Robin on Juniper — Though seldom considered ideal wildlife plants, low-growing ornamental junipers often produce an abundance of seed-containing cones that resemble berries.

American Robins Eating Juniper — In a pinch, they’ll attract dozens of robins and other fruit-eating birds as a quick source of nourishment on a windy, bitter-cold day.

American Robins Feeding on Juniper "Berries" — After all, these landscape shrubs are often derived from native species including the Creeping Juniper (Juniperus horizontalis) of Canada and the northernmost United States, a plant resembling a recumbent version of the local Eastern Red Cedar (Juniperus virginiana) with which these birds are quite familiar.

County conservation district offices will soon be taking orders for their spring tree sales. Be sure to load up on plenty of the species that offer food, cover, and nesting sites for birds and other wildlife. These sales are an economical way of adding dense-growing clusters or temperature-moderating groves of evergreens to your landscape. Plus, selecting four or five shrubs for every tree you plant can help establish a shelter-providing understory or hedgerow on your refuge. Nearly all of the varieties included in these sales produce some form of wildlife food, whether it be seeds, nuts, cones, berries, or nectar. Many are host plants for butterflies too. Acquiring plants from your county conservation district is a great opportunity to reduce the amount of ground you’re mowing and thus exposing to runoff and erosion as well!

January 21, 2026January 27, 2026

Thirty Years Ago: The Ice-jam Floods of 1996

It all started rather innocently as a typically cold early January with sheets of ice covering the river and with soils on the lands in the remainder of the lower Susquehanna watershed frozen solid. Then came the “Blizzard of ’96”, blanketing much of the valley with between 20 and 30 inches of wind-driven snow.

"Blizzard of '96" — Snowfall totals for the “Blizzard of ’96”, January 6-8, 1996. (NOAA/National Weather Service image)

In affected areas of Pennsylvania, Governor Tom Ridge closed all state roads for the duration of the snowfall event. Many would remain closed for much of the following week as drifting hampered exhaustive efforts to get impassable routes open.

Just as the recovery entered its second week, a change in the weather pattern took hold as milder air and spring-like rains hastened the melt. Clogged by snow often several feet in depth, storm sewer inlets and other drainage features failed to collect the runoff. Street and urban flooding became widespread. Some buildings, particular those with large flat roofs, experienced structural damage due to any remaining snow soaking up the additional weight of the rain. As local creeks swelled to stain snowy meadows brown, attention shifted to the icy river.

On the Susquehanna, rising waters started moving ice into accumulating piles of car-sized chunks behind dams and at choke points along the river’s course. During warmer weather, stream gauges provide a depth of water reference known as a stage (measured in feet) that corresponds to a rate of flow passing the gauge site (measured in cubic feet per second). On occasions when ice and debris block river channels during winter, these readings can fluctuate wildly and the relationship between stage and flow can become dubious. When the water is running ice-free at Harrisburg for example, a gauge reading of about 11.1 feet is indicated when the river flow rate is approximately 162,000 cubic feet per second. But due to its impact on the capability of the river channels to pass water, the presence of slow-moving and jammed ice can cause rapid and sometimes unpredictable variations in gauge readings, even when the flow rate remains steady. Impaired by an ice jam at the gauging station or just downriver, a flow of 162,000 cubic feet per second could lead to a stage measurement significantly higher than 11.1 feet, and the area of adjacent floodplain inundated by rising waters will increase to a corresponding degree. Conversely, a jam upstream of the gauging station could cause the reading to drop below 11.1 feet—at least temporarily—then look out, a dangerous surge could be forthcoming!

At Harrisburg, the ice jam behind the Dock Street Dam in January, 1996, caused devastating flooding in the city’s Shipoke neighborhood, on City Island, and in low-lying areas along the river’s west shore.

USGS Gauging Station at Harrisburg — Just upriver from the Dock Street Dam at Harrisburg, the Susquehanna at the United States Geological Survey gauging station on the east side of City Island crested at 25.08 feet on January 20, 1996. As the rising waters finally began heaving the jammed ice up and over the dam, the scouring energy of the departing glacier-like mounds would carry away two spans of the truss-construction Walnut Street Bridge on the west side of the island, and eventually collapse a third. After receding during the remainder of the day and through the night, yet another aggregation of chunked ice would cause the river to crest again on January 21st, this time at 24.66 feet. Under free-flowing conditions, these readings would correspond to a river flow of just under 600,000 cubic feet per second; that’s more than 250 million gallons per minute!

Downriver at Conewago Falls, ice jams behind the York Haven Dam and at several choke points within the riverine archipelago that extends from Haldeman Island to Haldeman Riffles in Lancaster County would be relieved as the river crested there during the afternoon of January 21st. The following photograph accurately relates the scene, minus the stench of mammalian feces and petroleum emanating from the polluted water of course.

Our friends (L to R) Rick Morton, Bob Zeager, Dan Seitz and his daughter Sierra witness the ice-choked Susquehanna River cresting below Conewago Falls on January 21, 1996. Bob awoke the previous morning inside his mobile home (left rear) to discover he was rapidly being surrounded by fast-rising water. With the ice-covered road now submerged in over three feet of river, he had no hope of getting out with his van, so he started removing clothing and a few other essentials by canoe. Dan soon arrived to move a few of his things to higher ground and de-energize both properties. We did our best to lend a hand, then we all got out of the floodplain. A short time after we had departed, Rick arrived and became concerned when he saw Bob’s van, now in almost four feet of water alongside his home. Rick parked his conveyance, also a van, on a rise in the lowland terrain, then made his way back the old Pennsylvania Canal towpath to make sure Bob wasn’t stranded. After concluding that he had already evacuated, Rick returned via the towpath to his van. He then discovered that yet another surge of quickly rising water had inundated the ice-covered section of access road by which he had arrived, so he was forced to wade out, leaving his vehicle behind. A short time later, he reached us by telephone proclaiming, “I’m out!”, and filled us in on the details. As the flood receded, Rick was able to retrieve his van on January 22nd. Bob’s van was totally destroyed and both his and Dan’s mobile homes were left uninhabitable. Though by no means their first experience with river flooding, this event proved particularly costly and stressful for Bob and Dan…the effects life-altering. The moral of the story: floodplains are for flooding, not filling, not building, and certainly not dwelling. Floodplains happen to make outstanding wildlife preserves, and that’s what this water-purifying alluvial terrace wetland is today. (Vintage 35 mm image)

January 7, 2026January 8, 2026

The Variety of Medium and Large-size Gulls Visiting for the Winter

You may find this hard to believe, but during the colder months in the lower Susquehanna valley, gulls aren’t as numerous as they used to be. In the years since their heyday in the late twentieth century, many of these birds have chosen to congregate in other areas of the Mid-Atlantic region where the foods they crave are more readily available.

As you may have guessed, the population boom of the 1980s and 1990s was largely predicated on human activities. These four factors were particularly beneficial for wintering gulls…

- 1. Disposal of food-bearing waste in open landfills
  2. High-intensity agriculture with disc plowing
  3. Gizzard Shad population boom in nutrient-impaired river/Hydroelectric power generation
  4. Fumbled Fast Food

Earthworms lifted to the soil's surface by plowing attracted Ring-billed Gulls by the thousands to Susquehanna Valley farmlands during the late twentieth century. — Earthworms lifted to the soil’s surface by plowing attracted Ring-billed Gulls by the thousands to Susquehanna Valley farmlands during the late twentieth century. (Vintage 35 mm image)

Young Gizzard Shad — Filter-feeding Gizzard Shad populations thrive in nutrient-rich waters like the Susquehanna. Their rambunctious feeding style stirs up benthic sediment deposits to release more nutrients into the water column and promote the algal blooms that often lead to detrimental eutrophic conditions. Decades ago, hundreds and sometimes thousands of gulls gathered below the river’s hydroelectric dams to feed on the seemingly endless supply of small Gizzard Shad disoriented by their passage through the turbines during electric generation. (Vintage 35 mm image)

So what happened? Why are wintering gulls going elsewhere and no longer concentrating on the Susquehanna? Well, let’s look at what has changed with our four man-made factors…

1. 1. A larger percentage of the lower Susquehanna basin’s household and food industry waste is now incinerated/Landfills practice “cover as you go” waste burial.
  2. Implementation of “no-till” farming has practically eliminated availability of earthworms and other sub-surface foods for gulls.
  3. The population explosion of invasive Asiatic Clams has reduced the Gizzard Shad’s relative abundance and biomass among filter feeders.
  4. Hold on tight! Fast food has become too expensive to waste.

The non-native population of Asiatic Clams in the Susquehanna and most of its larger tributaries exploded during the last two decades of the twentieth century. Its present-day biomass in the river is exceeded by no other macroinvertebrate species. The share of plankton and other tiny foods that the Asiatic Clam harvests from the water column is no longer available to native filter-feeders including Gizzard Shad. Hence, Gizzard Shad biomass has been reduced and far fewer are available to attract amazingly enormous flocks of hungry gulls to hydroelectric dams. (Vintage 35 mm image)

GULLS THIS WINTER

Despite larid abundance on the lower Susquehanna not being the spectacle it was during the man-made boom days, an observer can still find a variety of medium and large-sized gulls wintering in the region. We ventured out to catch a glimpse of some of the species being seen both within the watershed and very nearby.

Ring-billed Gulls on Lake Clarke — By far, most of the gulls you’ll encounter in the Lower Susquehanna River Watershed right now are Ring-billed Gulls. Some of them still drop by at the business end of the drive-thru lane looking for a lost order of fries and maybe a cheeseburger in paradise.

Ring-billed Gulls in winter plumage. — First-winter (left), second-winter (center), and adult Ring-billed Gulls on the Susquehanna.

Ring-billed and American Herring Gulls — Nearly every flock of gulls found in our area right now is composed exclusively of Ring-billed Gulls. The trick to finding other species, particularly rarities, is to look for slightly larger birds mixed among them, particularly American Herring Gulls like the first-winter (back row left) and third-winter (back row right) birds seen here. Herring and other species of similar-sized gulls seem to prefer each other’s company while on the wintering grounds.

American Herring Gulls with Ring-billed Gulls — Five American Herring Gulls with smaller Ring-billed Gulls. The bird to the upper left and the bird hunkered down to its right are adult American Herring Gulls, the three brownish birds are in their first winter.

Non-adult American Herring Gulls in flight. Always look for birds with all-pale wing tips when encountering herring gulls in flight.

Four Species of Medium-sized Gulls — Midway in size between the Ring-billed Gulls in the foreground and the first-winter American Herring Gulls in the upper left and middle right of this image is a Lesser Black-backed Gull (dark-mantled bird resting at center). The similar-sized bird in the water behind it is a first-winter Iceland Gull (Larus glaucoides), a rare visitor from the arctic.

First-winter Iceland Gull — Another look at the first-winter Iceland Gull from the previous image. Did you notice the all-white primary feathers and compare them to the dark wing tips on the Ring-billed Gulls seen here in its company?

Iceland Gull Bathing — The conspicuously pale wings of the first-winter Iceland Gull, seen here bathing in the presence of two first-winter American Herring Gulls.

Lesser Black-backed Gulls like this one observed at Blue Marsh Lake are uncommon in the Lower Susquehanna River Watershed. They are progressively more likely as you travel east toward the aforementioned Bucks County landfills where hundreds of these birds make up a core Atlantic seaboard population.

Great-black-backed Gull with Ring-billed Gulls — Great Black-backed Gulls are the most frequently encountered large gull on the Susquehanna. They’re easily identified by their enormous size and, as adults, their dark mantle.

First-winter Glaucous Gull — Rivaling the Great Black-backed Gull in size is the Glaucous Gull (Larus hyperboreus), another rare arctic visitor with pale wing tips. There are numerous reports of these unusual winter visitors from sites on Delaware Bay north to the Tullytown landfills on Delaware River where half a dozen or more have been occurring. Seen near the mouth of the Susquehanna on Chesapeake Bay at North East, Maryland, has been a first-winter bird similar to this one that we photographed at Blue Marsh Lake in Berks County, Pennsylvania.

For us, seeing a Glaucous Gull brought back memories of the last time we saw the species. It was forty-five years ago on New Year’s Day 1981 that we discovered two first-winter birds feeding on Gizzard Shad in open water on an otherwise ice-choked Susquehanna below the York Haven Dam powerhouse at Conewago Falls. Hey Doc Robert, do you remember that day?

December 21, 2025December 21, 2025

Photo of the Day

The first day of winter is the darkest day of the year. In the midst of the cold weather that accompanies it, one hardly thinks of looking for insect activity. But in subterranean environs where the temperature remains relatively constant, life goes on. We recently discovered this handsome Camel Cricket while performing some maintenance in our below-grade utility entrance. Worldwide in distribution, Camel Crickets, also known as Cave Crickets, Sand Treaders, and Spider Crickets, include hundreds of species in the family Rhaphidophoridae. Most are omnivorous residents of caves, mines, cellars, hollow logs, wood piles, wells, and other dark, temperature-stable situations where they feel their way around with their antennae while searching for food. Camel Crickets usually escape notice, keeping only nocturnal hours when venturing out from light-deprived cover and lacking the organs to produce the familiar “chirps” that call attention to other crickets during the breeding season.

December 10, 2025December 11, 2025

Observing Susquehanna Bald Eagles: A Chart for Determining Age

As part of an update to our “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” page, we’ve just added this chart for determining the age of the Bald Eagles you might observe on the lower Susquehanna River and elsewhere in coming weeks.

Bald Eagle age classes in late autumn in the Lower Susquehanna River Watershed. — Bald Eagle age classes as they typically appear during late autumn in the Lower Susquehanna River Watershed. (Click the image for a full-size PDF version of the chart)

Bald Eagles in each age class often retain their fall appearance through much of the winter. However, beginning January 1st, each bird is reclassified into the next in the series of chronological plumage designations. Consequently, during the early part of the new year until a new generation of eagles is hatched in late winter and spring, there are no birds in our area designated “hatch-year/juvenile”. After fledging, these youngest eagles, the new generation of juveniles, often show little change in appearance until after their first birthday, by which time they are already classified as second-year/Basic I immature birds. For birds other than the new generation of hatch-year/juvenile eagles, the majority of the molt that produces their new autumnal appearance each year occurs during spring and especially summer, when food is abundant and the bird’s energy needs for purposes other than growing feathers are at a minimum. Hence, by the time fall migration rolls around, the next in the successive progression of plumage changes is evident. For more details and year-round images of Bald Eagles, check out our “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” page by clicking the tab at the top of this page.

December 8, 2025

Cuisine to Crow About!

Red-shouldered Hawk and thigh of frog (cuisses de grenouille). — Our VIP guest, a discerning Red-shouldered Hawk, dining yet again on cuisses de grenouille (thigh of frog) at susquehannawildlife.net headquarters.

December 6, 2025December 6, 2025

Eagle Time At Conowingo Dam’s Fisherman’s Park

Wintering Bald Eagles are again congregating on the lower Susquehanna River, particularly in the area of Conowingo Dam near Rising Sun, Maryland. To catch a glimpse of the action earlier this week, we took a drive on U.S. Route 1 atop Conowingo’s impounding structure to reach Fisherman’s Park on the river’s west shore below the powerhouse.

Eagle Watching at Conowingo Dam — Scores of dedicated eagle watchers and photographers brave the raw weather to see and document the concentration of eagles that gather to feed and roost in the vicinity of Exelon Energy’s Fisherman’s Park.

Susquehanna at Conowingo Dam — The panoramic view of the Susquehanna from Fisherman’s Park offers excellent opportunities to witness Bald Eagle activity.

Immature Bald Eagles — When you arrive, it’s not unusual to hear the sounds of squabbling eagles immediately upon exiting the shelter of your vehicle. During our visit, we sighted probably 60 to 80 individuals of various age classes among the rocks and trees along the river shorelines below the dam.

Second-year (Basic I) Bald Eagle — Soon enough, we experienced a close fly-by from this second-year Bald Eagle.

Hatch-year (Juvenile) Bald Eagle — We were a little bit concerned to see only one hatch-year (juvenile) Bald Eagle among the birds at Fisherman’s Park. Perhaps the aggressive behavior of the large number of older and more experienced eagles in the area has these first-year individuals shying away. We discerned no third-year birds either, though they may certainly have been present.

Fourth-year (Basic III) Bald Eagle — A probable fourth-year Bald Eagle shows a white head with the remains of a dark line through the eye, a trait often more conspicuous in third-year birds often known as “osprey face” eagles.

Fifth-year (Basic IV) Bald Eagle — This probable fifth-year Bald Eagle has nearly lost the dark markings on the head and tail that differentiate immature birds from adults. A molt during the coming year will yield adult plumage and mark the completion of this bird’s sexual maturity.

Eagle Photographers at Fisherman's Park — Meanwhile, a little action gets the shutters clicking,…

Eagle Dogfight in the Incipient Stage — …a fourth-year Bald Eagle (top) is drawing the ire of an adult bird,…

Eagle Dogfight — …necessitating a reprisal for the taunting behavior.

To the delight of photographers at Conowingo, some of the eagles can be seen grabbing fish, mostly Gizzard Shad, from the tailrace area of the river below the powerhouse. But Bald Eagles are opportunistic feeders, and their feeding habits are similar to those of numerous other birds found in the vicinity of the dam at this time of year—they’re scavengers. Here’s a glimpse of some of the other scavengers found in the midst of this Bald Eagle realm…

Fish Crows are recognized by their nasal call. They’ll eat almost anything they can find including garbage, fish remains, discarded bait, lunch scraps, road kill, and more.

Visitors to Fisherman’s Park are warned to keep out of sight any food they may have stored in their cars. Black Vultures are known to peel rubber away from windows as they search for something to eat, a habit they possibly learned during productive forays to landfills where the edges of rubber coverings sometimes hide a freshly dumped buffet of potential sustenance.

During our stop at Conowingo Dam earlier this week, we saw only one Turkey Vulture, though more are certainly in the vicinity feeding on road kill and other carrion.

Like eagles, Ring-billed Gulls are opportunistic feeders, seen here looking for disoriented Gizzard Shad and other fish,…

Ring-billed Gull — …then quickly changing focus to check the humans along the shoreline for discarded bait or fumbled snack foods.

Juvenile Ring-billed Gull — Even young Ring-billed Gulls learn the value of watching people for activities that provide an opportunity to scavenge food.

While Ring-billed Gulls and other scavengers aren’t particularly fussy about what they eat, Double-crested Cormorants are;…

Double-crested Cormorant — …they’re targeting Gizzard Shad and other fish in the waters below the dam. Thus, we would categorize cormorants as predators, eating mollusks and other aquatic organisms as well.

And while you’re on the lower Susquehanna, keep an eye on the sky. Common Mergansers winter on ice-free sections of the waterway and are now arriving in the vicinity of Conowingo and elsewhere.

Bald Eagles at Heron Rookery — But if perhaps winter isn’t your thing, don’t despair. These Bald Eagles came upon last year’s Great Blue Heron rookery on the island below the dam and it seems to be giving them some ideas. If you think like an eagle, spring is just weeks away!

November 28, 2025

Maybe They’ll Stay, Maybe They Won’t

Here are a few more late-season migrants you might currently see passing through the lower Susquehanna valley. Where adequate food and cover are available, some may remain into part or all of the winter…

During the summer, Ruby-crowned Kinglets nest in northern coniferous forests. Through the colder months, these petite songbirds can often subsist on tiny insects and other invertebrates found among the bark, limbs, and buds of leafless deciduous trees and shrubs. In our region, look for wintering kinglets in woodlands that include at least a small percentage of evergreens to provide protection from frigid nighttime temperatures.

The Yellow-bellied Sapsucker is our shiest of woodpeckers. These migrants are still quite common among stands of deciduous and mixed woods, but local numbers will soon decrease as the majority of the population continues moving along to the forests of the southeastern United States for winter.

In case you were wondering…Yes, the adult Red-shouldered Hawk continues to visit the garden pond at susquehannawildlife.net headquarters. Earlier today, we watched it plunge into the shallows after a Green Frog. We’re enjoying the privilege of having it around, so we hope it decides to remain for as long as the food supply is accessible.

November 24, 2025November 24, 2025

Windy and Dark November Skies

Those cold, blustery days of November can be a real downer. But there’s a silver lining to those ominous clouds, and it comes with the waves of black and mostly dark-colored migrants that stream down the ridges of the Lower Susquehanna River Watershed on their way south at this time of year.

For protection from predators, blackbirds including these Common Grackles typically assemble into sizeable flocks numbering hundreds of birds following the nesting season. These noisy bands of passerines are currently being seen as they move south into the Piedmont and Atlantic Coastal Plain for winter.

American Crows are now working their way into the area. To avoid falling prey to owls and other predators during the night, they form often enormous roosts in well-lit urban areas. They spend their days fanning out across the landscape in search of food, primarily relying upon human-generated fare including road kill and scraps found among trash and litter for sustenance.

Formerly confined largely to remote mountainous terrain, the crow’s close relative the Common Raven has, during this century, become more widespread and tolerant of human activity.

Second Mountain Hawk Watch — Spending time at one or more of the regional hawk-counting stations during coming weeks will afford you not only the chance to see ravens, but many of our largest raptors as well. Their migration is just now reaching its peak.

Peak numbers of Red-tailed Hawks are migrating through the area right now. Though their population is in decline overall, they may appear very common along rural roadways and in suburbia during coming weeks as they try to find prey before continuing south. Inexperienced juvenile “red-tails” are particularly vulnerable to fatal traffic mishaps and other hazards during this time. Give them some room if you can.

Early November brings the last of the season’s Osprey down local ridges. Many, including this one seen earlier in the week, will fly right up until sunset to expedite their journey to warmer climes.

Bald Eagle — Always a crowd-pleaser among the observers on the lookouts are the eagles.

Juvenile Bald Eagle — Right now, migrating Bald Eagle numbers are often exceeding a dozen birds per day at local counting stations. They include those like this one in juvenile (hatch-year) plumage as well as the various molt sequences experienced by immature eagles prior to reaching maturity.

At present, Golden Eagle numbers are just starting to build. Look for the peak of their fall migration to arrive in coming weeks. Gusty days following passage of a cold front are often your best bet for seeing these regal raptors from local lookouts.

For more information on regional hawkwatching sites and raptor identification, click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page. And for more on Golden Eagles specifically, click the “Golden Eagle Aging Chart” tab.

November 5, 2025November 5, 2025

Photo of the Day

During these last mild evenings of fall, the trilling call of the Narrow-winged Tree Cricket (Oecanthus niveus) can still be heard among the withering growth of thickets, fields, and forest edges. As the temperatures plummet, the pulsating rate of this insect’s song slows proportionally. Below about 40 degrees Fahrenheit, there is silence.

November 4, 2025November 5, 2025

The Guiding Light

October 25, 2025

Leaf ID

Out and about doing some autumn “leaf peeping” this week?

Well, you’ll certainly want to check out Uncle Tyler Dyer’s fall foliage collection to help identify your finds…

Click the Trees, Shrubs, and Woody Vines tab at the top of this page to take a leap over to Uncle Ty’s leaf spectacular!

October 23, 2025October 24, 2025

Photo of the Day

Painted Turtles and Invasive Red-eared Sliders — Invasive populations of Red-eared Sliders (right) continue to grow and threaten numbers of native freshwater testudines including the Painted Turtles seen here to the left. Introduced primarily as unwanted pets, sliders are now freely reproducing throughout much of the lower Susquehanna watershed. Their ability to feed aggressively and grow to sizes significantly larger than those of our most-imperiled wetland species including the Spotted Turtle (Clemmys guttata), Wood Turtle, and endangered Bog Turtle make Red-eared Sliders a menace rivaling habitat loss and illegal collecting.

October 21, 2025October 21, 2025

Photo of the Day

Small numbers of Rusty Blackbirds are currently moving south through the Lower Susquehanna River Watershed. Look for individuals and small flocks feeding in damp woods and along lake and river shorelines. These uncommon birds nest far to our north in wet coniferous and mixed forests as well as willow thickets, often in muskeg or beaver pond-created habitat. Rusty Blackbirds spend the colder months in the wooded swamps of the southeastern and south-central United States. Loss of habitat has reduced their numbers dramatically, as has their misfortune to occasionally join flocks of foraging Red-winged Blackbirds and Common Grackles on the wintering grounds where all of these species fall victim to avicide poisons placed on feedlots to eradicate European Starlings.

October 18, 2025October 28, 2025

Robinson’s Invasion

As we begin the second half of October, frosty nights have put an end to choruses of annual cicadas in the lower Susquehanna valley. Though they are gone for yet another year, they are not forgotten. Here’s an update on one of our special finds in 2025.

During late June of 1863, the beginning of the third summer of the American Civil War, there was great consternation among the populous of the lower Susquehanna region. Hoping to bring about Union capitulation and an end to the conflict, General Robert E. Lee and his 70,000-man Army of Northern Virginia were marching north into the passes and valleys on the west side of the river. The uncontested Confederate advances posed an immediate threat to Pennsylvania’s capital in Harrisburg and cities to the east. Marching north in pursuit of Lee was the First Corps of the Army of the Potomac, the lead element of the 100,000-man Union force under the direction of newly appointed commander General George G. Meade.

Upon belatedly learning of Meade’s pursuit, Lee hastily ordered the widely separated corps of his army to concentrate on the crossroads town of Gettysburg. As the southern army’s Third Corps under General A. P. Hill approached Gettysburg from the west, they were met by Union cavalry under the leadership of General John Buford. Dismounted and formed up south to north across the Chambersburg Pike, Buford’s men held off Confederate infantry until relieved by the arrival of the Union First Corps. As he deployed his men, the First Corps’ commander, General John F. Reynolds of Lancaster, was struck by a bullet and killed.

General John C. Robinson Monument at Gettysburg — During the first day’s fighting at Gettysburg on July 1, 1863, the northernmost position in the Union First Corps’ line was held by its Second Division commanded by General John C. Robinson. His men would defend their right flank against attacks from Confederate General Richard S. Ewell’s Second Corps as they arrived from the north to face off against the Union Eleventh Corps which had arrived to take positions north of the town. During the afternoon, upon becoming outnumbered and overwhelmed, the Union forces would retreat south through the town to take up positions on Cemetery Hill by nightfall. Deployments extending south and east of Cemetery Hill would ultimately prove victorious for Union forces during the battle’s final day on July 3.

Lee's 1863 Invasion of the North — John C. Robinson’s Second Division “invaded” Pennsylvania as one of Meade’s lead elements charged with intercepting Lee’s Confederate Army. (National Park Service image)

If you visit the Gettysburg battlefield, you can find the General John C. Robinson monument at the site of his division’s first-day position along Doubleday Avenue at Robinson Avenue near the Eternal Light Peace Memorial. But that’s not the Robinson we went to Gettysburg to see.

Following up on our sight and mostly sound experiences with some Robinson’s Cicadas, an annual species of singing insect we found thriving at Gifford Pinchot State Park in York County, Pennsylvania, during late July, we spent some time searching out other locations where this native invader from the southern United States could be occurring in the Lower Susquehanna River Watershed.

During mid-August, we stumbled upon a population of Robinson’s Cicadas east of the Susquehanna in the Conewago Creek (east) watershed in Londonderry Township, Dauphin County, and made some sound recordings.

After pondering this latest discovery, we decided to investigate places with habitat characteristics similar to those at both the new Londonderry Township and the earlier Gifford Pinchot State Park locations—successional growth with extensive stands of Eastern Red Cedar on the Piedmont’s Triassic Gettysburg Formation “redbeds”. We headed south towards known populations of Robinson’s Cicadas in Virginia and Maryland to look for suitable sites within Pennsylvania that might bridge the range gap.

Our search was a rapid success. On State Game Lands 249 in the Conewago Creek (west) watershed in Adams County, we found Robinson’s Cicadas to be widespread.

Robinson's Cicada Habitat — Eastern Red Cedar, a probable host tree for Robinson’s Cicada nymphs, among successional growth on State Game Lands 249. Cedar thickets often become established on shallow or depleted soils on lands originally cleared for farming. They provide excellent cover as well as much needed breeding and feeding areas for birds, mammals, insects, and other wildlife.

Following our hunch that these lower Susquehanna Robinson’s Cicadas extended their range north through the cedar thickets of the Gettysburg Basin as opposed to hopping the Appalachians from a population reported to inhabit southwest Pennsylvania, we made our way to the battlefield and surrounding lands. We found Robinson’s Cicadas to be quite common and widespread in these areas, even occurring in the town of Gettysburg itself.

Robinson's Cicada Range in Central Pennsylvania — Populations of Robinson’s Cicadas (red) in the lower Susquehanna valley and adjacent areas of the Potomac watershed near Gettysburg. The Triassic Gettysburg Basin is shown in white with intrusions of igneous Triassic-Jurassic diabase in dark green. (United States Geological Survey base image)

Robinson's Cicada Habitat on Gettysburg Battlefield — Robinson’s Cicadas are common on much of the Gettysburg National Military Park property, particularly in the southern reaches where outlying areas are dense with Eastern Red Cedar growth to within several miles of the Mason-Dixon Line. In these tall walnuts and cedars along Confederate Avenue (that’s Little Round Top and its diabase boulders in the background) we recorded the following sound clip of a singing male.

Robinson’s Cicada probably extended its range into the lower Susquehanna valley in much the same way General John C. Robinson and the rest of the Army of the Potomac marched into Pennsylvania to meet Lee’s Confederates, by following the terrain of the Triassic Gettysburg Basin. Got a big stand of cedars near you? Be sure to have a listen for Robinson’s Cicadas next summer! (United States Geological Survey base image)

October 10, 2025

Changes Following the Season’s First Frost

Having experienced our first frost throughout much of the lower Susquehanna valley last night, we can look forward to seeing some changes in animal behavior and distribution in the days and weeks to come. Here are a few examples…

Unlike their close relatives the Tree Swallows, which include berries as well as invertebrates in their diet, Northern Rough-winged Swallows are strictly insectivores and will find it necessary to promptly move south to assure a frost-free environment where they can secure an adequate supply of food. Their one alternative: find a local sewage treatment plant where warm water attracts populations of flying insects through the remainder of autumn and maybe into winter.

Warblers too are insect eaters. Look for most of our dozens of species to evacuate the area in coming days and leave behind only the Yellow-rumped Warbler, another bird with a fondness for berries during cold weather. Into the winter months, they remain in small numbers in habitats with an abundant supply of berries like Poison Ivy, holly, wild grape, bittersweet, and Eastern Red Cedar. For lingering Yellow-rumped Warblers, thickets of cedars and other evergreens provide essential protection from frigid nighttime winds.

This Eastern Chipmunk will soon feel the pinch. Instead of eating the sweet, fruity portions of Mile-a-minute Weed berries, it’ll have to get serious about stocking its den with larger seeds, acorns, hickory nuts, and other foods to snack on through the winter. Better get busy, little friend!

October 4, 2025

Photo of the Day

Peak time for the fall migration of Monarch butterflies is here. Look for them gliding by on gentle autumn breezes or feeding on nectar-rich flowers.

September 27, 2025

Photo of the Day

Juvenile Rose-breasted Grosbeaks — These juvenile Rose-breasted Grosbeaks are among the last big southbound push of Neotropical migrants we’ll see moving through the lower Susquehanna valley in coming days. Be certain to get outside and have a look.

September 22, 2025September 22, 2025

Migrants Seeking Shelter to Weather the Storm

Less than ideal flying conditions can cause some of our migrating birds to make landfall in unusual places. Clouds and gloom caused a couple of travelers to pay an unexpected visit to the headquarters garden earlier today.

Here in our urban oasis, this Northern Parula was our first warbler of the season. We noticed it gleaning small insects from the leaves and stems of the taller trees.

Our resident Carolina Chickadees made good foraging companions for our temporary guests.

Be sure to keep an eye open for visiting migrants in your favorite garden or park during the overcast and rainy days ahead. You never know what might drop by.

September 12, 2025September 12, 2025

Tropical Treats and an Early Surprise

Crisp cool nights have the Neotropical birds that visit our northern latitudes to nest during the summer once again headed south for the winter.

Flying through the night and zipping through the forest edges at sunrise to feed are the many species of migrating vireos, warblers, and other songbirds.

A Tennessee Warbler peers from the cover of a Staghorn Sumac (Rhus typhina), a small native tree which is not, as many assume, a poisonous plant. Staghorn Sumac is in fact an excellent wildlife species with brilliant autumn colors.

Though its breeding season has come to an end, this southbound Yellow-throated Vireo was found singing its heart out in the limbs of a Staghorn Sumac early this morning.

Black-throated Green Warblers are particularly numerous right now. To see them, visit a ridgetop forest clearing at sunrise.

As the nocturnal migrants fade into the foliage to rest for the day, the movement of diurnal migrants picks up the pace.

Southbound flights of Ruby-throated Hummingbirds are reaching their peak this week with chilly temperatures hustling them along. Remember to keep your feeders clean and your nectar fresh through at least early October; they may really need the supplemental energy.

Migrating Broad-winged Hawks, sometimes traveling in large flocks known as kettles, seek out thermal updrafts to gain altitude before gliding away on a southwest heading bound for Houston, Texas. Once there, they’ll make a turn to the south and follow the gulf coastline toward the tropics for winter.

While on the crest, you might notice that the Neotropicals aren’t the only bird species heading through. Migrants like this Sharp-shinned Hawk are beginning to show up in increasing numbers with a peak expected in about two to three weeks.

To find a hawk-counting station near you, check out our “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” page by clicking the tab at the top of this page. And plan to spend some time on the lookout during your visit, you never know what you might see…

Second-year Golden Eagle — This very early Golden Eagle surprised observers at Second Mountain Hawk Watch in Lebanon County, Pennsylvania, this morning. It appears to be an immature, more specifically a second-year bird beginning molt (replacing its innermost primaries), so it may not have traveled all the way to the eastern population’s breeding areas in northern Canada for the summer. Instead, it may have wandered the vast wilderness hundreds of miles further south. Expect to see these regal eagles more regularly when adults and hatch-year juveniles from the nesting region start passing through our area, primarily during the period between Halloween and Thanksgiving. In the meantime, you’ll have time to check out our “Aging Golden Eagles” page by clicking the tab at the top of this page.

August 28, 2025

The Nighthawks and the Hummers

Chilly nights and shorter days have triggered the autumn migration of Neotropical birds. You may not have to go far to see these two travelers. Each is a species you may be able to find migrating through your neighborhood.

Common Nighthawks are large insect-eating nightjars. Watch for them feeding and migrating overhead during the late hours of the afternoon and continuing through nightfall. While skies above the Susquehanna and large tracts of forest or grassland offer the best viewing opportunities, even city residents may witness their evening flights during the coming weeks. Though nighthawk numbers appear to be in decline, as many as a hundred or more are currently being seen nightly at Pine Grove Furnace State Park along South Mountain in Cumberland County, Pennsylvania. For daytime roosting during their southbound movements, nighthawks seem to be attracted to deep shade in areas of vast forest. They will often seek sanctuary and become concentrated in “islands of darkness” like Michaux State Forest on South Mountain after passing over light-polluted urban areas such as Harrisburg and the adjoining metroplex of the Great Valley during the previous night.

Male Ruby-throated Hummingbird — Ruby-throated Hummingbirds are now moving south. It’s time to be extra vigilant about keeping your sugar-water dispensers clean and filled with fresh nectar mixture. For tips on feeding hummingbirds safely, check out our post from August 5, 2022, “Two Feeders Are Better Than One”.

August 27, 2025August 28, 2025

TOMEX Sounding Rocket Launches

Beginning this evening at about 10:44 PM EDT, and lasting until almost 11 o’clock, the gaseous clouds from two of three TOMEX+ (Turbulent Oxygen Mixing Experiment) sounding rockets launched from NASA’s Wallops Island Flight Facility near Chincoteague, Virginia, were visible in the southern skies of much of the Lower Susquehanna River Watershed. From susquehannawildlife.net headquarters, we were able to see and photograph the glowing clouds created by these vapor releases. Within minutes, the contrail-like wisps were swept away by the swift thin air of the mesosphere, the area lying just below the thermosphere and the Kármán Line—the border of outer space 100 kilometers (62 miles) above sea level. According to NASA, “This mission aims to provide the clearest 3D view yet of turbulence in the region at the edge of space.”

TOMEX+ Gas Cloud Dispersing — A gas cloud released in the mesosphere by the first of three rockets launched in quick succession from Wallops Island, Virginia, on the Delmarva Peninsula. Being the uppermost layer of the atmosphere, the mesosphere functions as an energy conduit into space and can thus be very turbulent.

TOMEX+ Gas Clouds Dispersing — Faint tracer clouds at the center of the image and in the upper right disperse in mesospheric air currents after release from two sounding rockets. The mesosphere’s thin air is responsible for creating enough friction to burn up a majority of the meteors that enter the earth’s atmosphere. A byproduct of the destruction of these meteors is atomic sodium. As part of the study, the third rocket used a laser to illuminate and excite this sodium in its area of greatest concentration, about 56 miles above sea level.

August 10, 2025August 18, 2025

Migratory Shorebirds on the Freshwater Impoundments at Bombay Hook National Wildlife Refuge

It may seem hard to believe, but the autumn migration of shorebirds and many Neotropical songbirds is now well underway. To see the former in what we hope will be large numbers in good light, we timed a visit to the man-made freshwater impoundments at Bombay Hook National Wildlife Refuge near Smyrna, Delaware, to coincide with a high-tide during the mid-morning hours. Come along for a closer look…

Bombay Hook NWR tour road at Shearness Pool — Along a large portion of its route, the tour road at Bombay Hook N.W.R. sits atop the man-made dikes that create several sizeable freshwater pools (left) along the inland border of one of the largest remaining salt marsh estuaries in the Mid-Atlantic States (right).

Tidal Creek at High Tide — Twice daily, the rising tide from Delaware Bay flows along the tidal creeks to flood Bombay Hook’s extensive marshes.

High Tide in the Bombay Hook coastal estuary. — At high tide, mudflats in Bombay Hook’s coastal estuary become inundated by salt water, forcing migratory shorebirds to relocate to bay side beaches or other higher ground to rest and feed for several hours.

Shearness Pool — At Bombay Hook, migratory shorebirds, waterfowl, and waders can find refuge from high tide in the freshwater impoundments created by capturing water along the inland west side of a system of earthen dikes.

Water Level Control System — Mechanical or stacked-board gate systems are used to control water depth in the impoundments. Levels can be adjusted seasonally to manage plant growth and create conditions favorable for use by specific groups of birds and other wildlife.

Shorebirds on Raymod Pool — A mix of mudflats and shallow water on Raymond Pool provides ideal habitat for a variety of shorebirds forced from the vast tidal marshes by the rising tide. For us, a mid-morning high tide places these birds in perfect light as they feed and loaf in the pools to the west of the tour road located atop the dikes.

Shorebirds arrive on Raymond Pool during high tide. — Migrating shorebirds arrive on Raymond Pool to find refuge from the rising tide to the east. Showing a single ring around their breast, many Semipalmated Plovers can be seen here among the Semipalmated Sandpipers, the latter the most abundant shorebird presently populating Bombay Hook. Feeding in deeper water in the background are Short-billed Dowitchers. All of these birds consume a variety of invertebrates they find both in and on the mud.

Semipalmated Plovers and Semipalmated Sandpipers arriving on a mudflat at Raymond Pool.

A Short-billed Dowitcher glides in from the salt marsh to visit the shallows of Raymond Pool for a couple of hours.

Short-billed Dowitcher and other Shorebirds — A Short-billed Dowitcher feeding among Semipalmated Plovers and Semipalmated Sandpipers.

Short-billed Dowitchers in water almost too deep for the Semipalmated Sandpipers in their company.

Black-bellied Plover and Short-billed Dowitchers — A lone Black-bellied Plover (Pluvialis squatarola) among the abundance of Short-billed Dowitchers.

A Lesser Yellowlegs arrives at Raymond Pool as a high-tide refugee.

A Greater Yellowlegs wades into shallow water to feed.

Searching through the Semipalmated Sandpipers, one could regularly find a very similar species among them.

We identified the longer-billed and slightly larger Western Sandpiper (Calidris mauri) and found the species to be present possibly by the hundreds among the masses of thousands of Semipalmated Sandpipers. These seem to be unusually high numbers for this more western species, but who’s complaining?

Western and Semipalmated Sandpipers — As we sifted through these groups of tiny shorebirds known as “peeps”, we found Western Sandpipers (top) regularly distributed among the multitudes of Semipalmated Sandpipers (bottom) we encountered.

Of course, shorebirds aren’t all there is to see at Bombay Hook. More than 100 Snowy Egrets were found on the freshwater pools alongside birds like this Semipalmated Plover.

Great Egrets could be seen stalking small fish in the channels of the pools.

And a few Green Herons were found lurking in the vegetation.

Shorebirds Feeding on Mudflat during Receding Tide — By early afternoon, we noticed the tide beginning to retreat from the saltwater marsh and mudflats opposite Shearness Pool. As shorebirds began returning there to feed, we decided to make our way to Raymond Pool to watch the exodus.

Shorebirds Depart Raymond Pool — With the high tide receding from the coastal estuary back into Delaware Bay, shorebirds promptly departed their concentrated environs on Raymond Pool to spread out over thousands of acres of salt marsh to feed.

Black-bellied Plovers and other Shorebirds Leaving Raymond Pool — More shorebirds exit Raymond Pool en route to the adjacent tidal areas to feed. This outbound group includes two Black-bellied Plovers (top center and four birds to the right).

Shorebirds Entering the Saltmarsh Estuary at Bombay Hook National Wildlife Refuge — These migrants have just begun their autumn journey from breeding grounds in Canada and Alaska to wintering areas located as far south as southern South America. For them, Bombay Hook and other refuges are irreplaceable feeding and resting locations to help them refuel for their long journey ahead. For them, a little vacation along the coast is a matter of life and death.

White-tailed Fawn — A goodwill ambassador bids us farewell at the end of our visit to Bombay Hook. Remember to support your National Wildlife Refuges by purchasing your annual Federal Duck Stamp. They’re available right now at your local United States Post Office, at the Bombay Hook visitor’s center, or online at the United States Fish and Wildlife Service website.

Planning a visit? Here are some upcoming dates with morning high tides to coax the birds out of the tidal estuary and into good light in the freshwater impoundments on the west side of the tour road…

Tuesday, August 19 at approximately 07:00 AM EDT

Wednesday, August 20 at approximately 08:00 AM EDT

Thursday, August 21 at approximately 09:00 AM EDT

Friday, August 22 at approximately 10:00 AM EDT

Saturday, August 23 at approximately 11:00 AM EDT

August 7, 2025August 7, 2025

Photo of the Day

A teneral Eastern Scissor Grinder and exuvia. — Having emerged from the soil overnight, this pale-colored teneral (soft-bodied) Eastern Scissor Grinder has shed its exuvia (left) and is currently pumping blood throughout its extremities to expand its size and unfurl its wings. During the remainder of the morning, the wings and exoskeleton will darken in color and harden in preparation for flight. As an adult, this cicada then has just weeks to complete its courtship and breeding cycle before facing inevitable doom. To see images and listen to sound clips of this and other annual species, visit our cicada page by clicking the “Cicadas” tab at the top of this page.

August 3, 2025August 23, 2025

Disasters: The Big Three

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.

July 26, 2025October 18, 2025

A Sixth Species of Annual Cicada in the Lower Susquehanna Basin: Neotibicen robinsonianus

Just as we were very pleased last month to have the opportunity to hear the sounds of the rarest of the Periodical Cicadas—the Little Seventeen-year Cicada—in the Conewago Hills of York County to thus provide our only record of the species during the Brood XIV emergence in the Lower Susquehanna River Watershed, we were this week delighted to find and record a population of what may be the valley’s rarest cicada experiencing annual flights—the Robinson’s Cicada—just a few miles away at Gifford Pinchot State Park.

Like the Little Seventeen-year Cicada, Robinson’s Cicada (Neotibicen robinsonianus) is a species found more commonly in the southern United States, occurring with scattered distribution in a range that extends west into Missouri, Kansas, and Texas. They are of rare occurrence in the lands of the Chesapeake drainage basin in Virginia and Maryland.

Populations of Swamp Cicadas, also known as Morning Cicadas, are presently in the midst of their yearly courtship rituals. Their songs are easily heard in woods, edge habitat, and suburbia throughout the region during the AM hours. It was while recording the sounds of these common insects in the Conewago Day-use Area at Gifford Pinchot State Park that we noticed a very unique song from high in the oaks, hickories, and other hardwoods along the lake. Listen to this sound clip featuring a group of serenading male Swamp Cicadas. In the background, a Robinson’s Cicada’s song consisting of a pulsing series of raspy buzzes, each about one second in duration, can be heard, particularly starting at 00:40.

The Lower Susquehanna River Watershed, and Gifford Pinchot State Park in particular, may currently represent the northern limit of the geographic range of the Robinson’s Cicada. If you’re in the area during the coming weeks, drop by the park and have a listen. And don’t forget to check out our “Cicadas” page for sound clips of all the species found in our area.

July 21, 2025July 21, 2025

Sunny Swarms of Insects

It begins on a sunny morning in spring each year, just as the ground temperature reaches sixty degrees or more…

Eastern Subterranean Termites emerge in unison from a nest located in the soil beneath a log. Each of these swarming “alates” is a potential king or queen seeking to find a location with an ample supply of fallen timber to provide food for establishment of a new colony. They are escorted to the surface by a soldier (lower center) equipped with powerful jaws for protecting the existing nest. Similar-looking worker termites tend the nest, the queen, her eggs, and their siblings, but usually remain hidden from view. The workers feed upon wood, hosting cellulose-digesting protozoa and bacteria in their guts to break down the fibers. This symbiotic relationship is an important mode of decomposition in the forest, the process that turns wood into the organic matter that enriches soil and helps it to retain more moisture.

Fungi on Fallen Log — Termites are among the numerous arthropods that join fungi and a variety of microbes to decompose dead wood and other plant matter into the nutrients and organic materials used by living plants to thrive and grow.

Green Frog Stalking a Eastern Subterranean Termite — Soon after lift off, the majority of swarming termites are consumed by swallows, swifts, and other birds, but some are discovered at ground level.

Green Frog Eating Termites — A lightning-fast strike with its tongue and this Green frog has snatched up yet another termite. Those that slip by the dragnet of terrestrial and aerial predators can sometimes start a new colony in the ground beneath a dead tree or in a vulnerable house or other wooden structure. To keep a small clan from invading your home, be certain the wood elements of your building(s) are kept dry and are not in contact with dirt, soil, bark mulch, etc. Regular inspections for evidence of their presence can head off the long-term damage termites can inflict on the stuff we construct with tree skeletons.

Of course, termites aren’t the only groups of insects to swarm. As heated runoff from slow-moving thundershowers has increased stream temperatures during the past couple of weeks, there have occurred a number of seasonal mayfly “hatches” on the Susquehanna and its tributaries. These “hatches” are actually the nuptial flights of newly emerged imago and adult mayflies. The most conspicuous of these is the Great Brown Drake.

Seen here with a much smaller and more typical regional mayfly to its left, the Great Brown Drake was for several years infamous for swarming the lights and creating traffic hazards on bridges spanning the Susquehanna. During the past two weeks, nighttime flights of these giants have ventured out to gather at well lit locations in housing and business districts more than a dozen miles from the river. Earlier this century, this proclivity to wander probably led the Great Brown Drake to first invade silty segments of the Susquehanna as a colonizer from its native range in the Mississippi watershed.

Swarms of another storm-related visitor are being seen throughout the lower Susquehanna valley right now. Have you noticed the Wandering Gliders?

Throughout the month, swarms of Wandering Gliders, the most widespread dragonflies in the world, descended on areas hit by localized slow-moving thundershowers. Large numbers of these global travelers are known to get swept up within the thermal air masses that lead to these storms. In suitable terrain within the path of the downpours, they linger to search for flooded places where they can mate and deposit eggs. Wandering Gliders frequently mistake large parking lots at shopping malls, grocery stores, etc. for wetlands and will be seen in these areas depositing eggs upon the hoods and roofs of shiny motor vehicles, surfaces which appear puddle-like in their eyes.

Mating Common Green Darners — More dragonfly swarms are yet to come. Adult Common Green Darners are presently in the Lower Susquehanna River Watershed mating and depositing eggs within vegetated ponds, lakes, and wetlands. Beginning in August, adult Common Green Darners and other migratory species including Black Saddlebags, Carolina Saddlebags, Wandering Gliders, and Twelve-spotted Skimmers will begin swarming as they feed on flying insects (including lots of mosquitos and gnats) and start working their way toward the Atlantic Coastal Plain. Along the barrier islands by September, concentrations of southbound dragonflies can reach the thousands, particularly at choke points like Cape May, New Jersey, and Cape Charles, Virginia. So be sure to keep an eye on the sky for swarms of dragonflies during coming weeks. And don’t forget to check out our “Damselflies and Dragonflies” page by clicking the tab at the top of this page.