Willows and Violets (Malpighiales) – LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED

July 15, 2026July 16, 2026

Smoke on the Horizon

This fire temperature enhancement of this morning’s National Oceanic and Atmospheric Administration satellite image of remote areas in western Ontario shows numerous large wildfires (indicated in red) burning north of Lake Superior. Ablaze is an area of taiga, the boreal conifer and mixed forests that cover much of interior Canada. The trees that grow in these wilderness areas are adapted to the large fires that regularly incinerate vast swaths of timber. Two of the conifers, Black Spruce (Picea mariana) and Jack Pine (Pinus banksiana), require fire for regeneration and are often among the deciduous White Birch (Betula paptrifera) and Quaking Aspen (Populus tremuloides) that first recolonize burned acreage. As succession proceeds, these pioneer species are followed by growth of Balsam Fir (Abies balsamea) and Northern White Cedar (Thuja occidentalis), both of which succeed Tamarack (Larix laricina) and Black Spruce in the sphagnum bogs there. (Cooperative Institute for Research in the Atmosphere/National Oceanic and Atmospheric Administration image)

Kirtland's Warbler in Jack Pine — Just to the south of the area currently being impacted by wildfire, the Kirtland’s Warbler (Setophaga kirtlandii) nests only in young stands of Jack Pine in Michigan, Wisconsin, and Ontario. During much of the twentieth century, this Neotropical migrant was in endanger of extinction, taking refuge during the breeding season in several areas of Michigan where large fires had cleared away climax forest and Jack Pines were allowed to regenerate. Prescribed fire and block timber harvesting techniques now manage some lands specifically for Kirtland’s Warbler habitat. The species was delisted from endangered status in 2019. (United States Fish and Wildlife Service image by Vince Cavalieri)

Naturalized Northern White Cedar Growing in Rock — The Northern White Cedar is most familiar to residents of the lower Susquehanna valley as the arborvitae, an evergreen landscape tree that includes numerous cultivars and hybrids derived from the wild taiga conifer. In suburbia, this tree is abused, planted in rows to create a fast-growing but short-lived windbreak or privacy screen. How about mixing it up a little bit by adding some variety to those hedgerows? Then, think about using these beautiful trees where they’ll thrive. Northern White Cedar grows like a bonsai artist’s dream among boulders, an inspiration for mimicking their appearance in miniature, and will sometimes naturalize in this rocky terrain under mesic (moist) conditions. Northern White Cedar is a bog species in its native range to our north, so you can give strong consideration to planting scattered specimens in the wet soils of your rain garden, riparian buffer, or other soggy spot. Scatter some around, put a few in clumps, and enjoy the pizazz they can add to a dreary winter day!

White Spruce and Northern White Cedar — A look at Northern White Cedars in the susquehannawildlife.net headquarters tree nursery and, in the foreground, a White Spruce (Picea glauca), another common conifer of the boreal forests. In our area, a miniature cultivar of P. glauca known as “Dwarf Alberta Spruce” is routinely planted as a landscape specimen. On occasion, these compact plants will revert to their “wild” form and grow full-size branches to begin looking more like their ancestral parents.

The visible satellite image from just before 9 AM shows haze from the Ontario fires streaming into the northeastern United States and the Susquehanna basin. The dense, river-like band of brown smoke seen barreling through New York and New England will shift south into our region during the remainder of the day, so slow down and take it easy. How long will these fires burn? Due to the zero-fire forest management strategies of the twentieth century, some areas of taiga haven’t experienced a burn for over 100 years. The highly combustible fuel load of dry logs, limbs, and needles accumulates in these parcels with each passing year, adding to the threat of a greater frequency of explosive, far-ranging, catastrophic infernos. To reduce the proliferation of fuels and to get the boreal forests back on the every-decade-or-so natural fire regime that keeps these biomes healthy and thriving, blazes in remote wildlands that haven’t been subjected to regeneration by fire for many decades are primarily contained to protect people, infrastructure, and unique native assets, but are mostly allowed to burn. (Cooperative Institute for Research in the Atmosphere/National Oceanic and Atmospheric Administration image)

May 19, 2026June 5, 2026

The Stewards of Inland Shorebird Habitat

As they travel between coastal wintering ranges and breeding territories in Canada and Alaska, vast numbers of shorebirds pass through the lower Susquehanna region each spring and fall—though few stop here to rest, feed, and provide us with an opportunity to observe them. Prior to the construction of man-made dams and other alterations on our lotic (flowing) waterways including the river, shorebirds took advantage of lateral bars, stream deltas, and other alluvial deposits as places to loaf and re-energize. Before they were drained and filled, some of the valley’s wetlands probably included sparsely vegetated flats where shorebirds could drop in for a brief visit. Previous to their extirpation from our region, North American Beavers were the primary providers of quality habitat for shorebirds and other migrating waders on our lotic waters. Their widespread network of dams, pools, and marshes maximized floodplain function by keeping streams thoroughly connected to their wetlands, nurturing plant communities that not only provided food and shelter for the beavers and other wildlife, but provided superb buffering against erosion while protecting against sediment and nutrient imbalances in lower Susquehanna waterways.

Beaver Dam and Lodge — Beaver dams need not be large, particularly on low-gradient streams where a structure like this is sufficient to create a pool with depth adequate for building and maintaining a lodge and transporting leafy branches and other food items by water.

A beaver lodge assembled in a pool with less than three feet of water, deep enough to provide the family with a measure of protection against terrestrial predators.

Beaver Pool — Beaver pool ecosystems provide homes for hundreds of species of plants and animals, including migrating shorebirds and other waders.

Mud flats in the margins between emergent shrubs and herbaceous plant growth attract migrating shorebirds like this Solitary Sandpiper to the abundance of invertebrate life. Seasonal movements of migrating shorebirds regularly coincide with the reductions of water levels in beaver pools which typically occur between May and September each year.

During its southbound migration in September, a Least Sandpiper searches for arthropods and annelids as it visits a food-rich puddle along the periphery of a beaver pool.

A Pectoral Sandpiper feeds in shallow water near a stand of Common Cattails in a beaver pool.

During migration, rails including the Sora are attracted to dense emergent vegetation in beaver pools. Some will nest in these rodent-managed refugia.

Green Herons visit beaver pools during migration and, due to the reliability of the food supply, will often nest in their vicinity.

So how did this happen? How did the North American Beaver become a keystone species—an animal upon which the majority of other life forms within its ecosystem are so reliant? Well, it’s largely due to the fact that our beavers aren’t particularly fond of a constant stream of noise. More specifically, they don’t like the sound of running water in places where they intend to build and maintain a lodge. And so, as they begin to place sticks, mud, limbs, stones, and other materials within a noisy riffle on a stream, they create a dam, and behind it a pool—a pool that is particularly advantageous for protecting their home and providing a means of conveyance for their construction materials and food supplies.

Cascading Series of Beaver Pools — On a high-gradient segment of stream, beavers will create a cascading series of pools. Because water filters through a beaver dam instead of spilling over it, the work of these meticulous rodents soon silences the sounds of water changing altitude. No more sonorous riffle.

Beaver Dam — **Quiet please.** High seasonal stream flow and damage from storms may create areas where water begins to erode the structure of the dam. Where this condition persists, an adult beaver will soon mend the breach, just to quiet things down. Why would beavers demand such a hush upon their domain? Well, they have poor eyesight, but their hearing is excellent, and they rely upon it to detect danger.

The Louisiana Waterthrush (Parkesia motacilla), one of our earliest-arriving warblers, nests in forests along clear, high-gradient streams. In mid-April, we found this individual and three others squabbling over a breeding territory adjacent to the series of cascading beaver pools shown in the previous images.

Brook Trout and Blacknose Dace — Native denizens of coldwater streams, neither the Brook Trout nor the Eastern Blacknose Dace has any difficulty finding its way through the voids in beaver dams to ascend and descend the sequence of pools.

Beaver Dam and Pool on Low-gradient Stream — On a low-gradient segment of stream, a dam just over a foot in height may be sufficient to create a beaver pool of considerable size. Resembling the water-logged muskeg of the far north, well-established beaver pools form boggy habitats familiar to migrating shorebirds.

Water levels in the pools usually drop along with the stream’s base flow as soon as the effects of the spring thaw and rain showers subside. Feeding areas in shallow water and on muddy ground are often revealed just in time for northbound shorebirds and other waders to stop by in late April and May. These conditions often persist through the growing season and the fall migration of these birds which begins as early as late June and sometimes extends into October.

Tree Swallow at Natural Cavity — Where the pool inundates standing timber such as Red Maple and other species not used by beavers, the dead snags provide vital feeding areas for birds and other wildlife. Cavity nesters like this Tree Swallow seldom find suitable natural housing elsewhere.

Eastern Newts Among Alderfly Exuvia — The mosaic of marshlands and braided stream channels within the beaver pool complex supports an abundance of aquatic life including these breeding Eastern Newts, seen here surrounded by the exuvia left behind following a massive hatch of alderflies (Sialinae). Alderflies are a stream inhabitant during their larval stage and are indicator of clean water conditions.

**A modern-day example of the way fully functional stream floodplains used to look in the Lower Susquehanna River Watershed.** Though the pools may appear pond-like during the cooler and wetter months of the year, by summer the water levels behind the beaver dams recede as the base flow of the stream wanes. Now the true nature of the marsh, shallow pool, and braided stream complex is revealed. Unlike most man-made dams that set a fixed pool elevation regardless of flow by discharging water over the top of the structure or through a spillway or gate, beaver dams merely throttle the flow through their porous construction. Unless the beaver begins plugging small leaks as fast as the stream flow ebbs, the water level in the pools will drop. So they’re not left high and dry, lodges are located in the deepest pools, usually in close proximity to the dam and/or one of the stream courses. Though not inundated during the dry season, the soil in the pool complex is almost always damp and plants grow vigorously there, sequestering nutrients and retaining sediments in beneficial deposition patterns that actually inhibit erosion of the riparian landscape. These streams and floodplains retain their hyporheic zone and freely exchange water with the underlying water table and aquifer. It’s the ultimate floodplain management system, and the beavers don’t even know their doing all the work. (Google Maps base image)

Where another high-gradient segment of stream enters the main pool complex, beavers have created an additional series of cascading pools. The impoundments created by these dams help diffuse stormwater energy and process more nutrients and sediments within the floodplain’s wetland vegetation system. (Google Maps base image)

Sandhill Cranes in Beaver Pool — Beaver pools often refill as stream flows increase following autumn rains. The stockpiles of vegetative foods that grew within the beaver’s domain through the summer then become flooded and are a prime source of nutrition for not only the beavers, but waterfowl during both their autumn and spring migrations. Gleaning and probing Sandhill Cranes often find these habitats to their liking as well.

While North American Beavers have returned to the region, most live as “bank beavers”, residing in the river and larger creeks of the valley where they excavate shelters among the roots of Black Willows and other shoreline trees and shrubs. Floodplain encroachment, legacy sediment deposits, and just plain human intolerance have all conspired to prohibit North American Beavers from performing their magic on smaller local streams. For migrating shorebirds, this continued absence of beaver dam ecosystems has turned much of the lower Susquehanna valley into “flyover country”. Those travelers that do stop to rest and feed concentrate at the few favorable locations such as the lateral bars and the hydroelectric dam-created delta at the Conejohela Flats on the river in Lancaster County. But centralization has its drawbacks. Migrants spending time at concentration points may have a greater chance of contracting and spreading disease. Protracted heavy foraging can degrade these habitats. And over time, features such the lateral bars and delta deposits, including those on the Conejohela Flats, transition into other habitats—riparian forests. A more widespread selection of favorable stopover points for shorebirds, waders, waterfowl, and other migrants is certainly desirable.

IMITATION IS THE SINCEREST FORM OF FLATTERY

Until public sentiment sways in favor of the North American Beaver, wildlife managers are mimicking some of the attributes of their sound-inspired installations.

New Impoundment at Middle Creek Wildlife Management Area — Created by excavating a depression in heavy clay soils, this new impoundment at the Pennsylvania Game Commission’s Middle Creek Wildlife Management Area collects water directly from rainfall and from surface runoff. Its depth at no point is greater than about two or three feet. During the driest times of the year, this space will be a mudflat, and a haven for migrating shorebirds.

Shallow-water conservation impoundments designed, constructed, and managed for migratory waterfowl and waders including shorebirds are not what we typically refer to as ponds—though they are lentic (still) waters. Similar shallow freshwater impoundments at our National Wildlife Refuges are referred to as pools by the United States Fish and Wildlife Service, but smaller versions like this example at Middle Creek very closely resemble the prairie potholes created by glacial scour in the north-central United States and adjacent portions of Canada. Many populations of migratory birds are familiar with pothole ecosystems and, like the beaver pools and marshes, have relied upon them as waypoints along their journeys for centuries.

Pond and Lake Zonation — Impoundments most beneficial to migrating waterfowl and waders including shorebirds are shallow in depth. They lack the deeper waters of a pond or lake and thus have no limnetic (open water) or aphotic zones. Managed throughout as a littoral zone, impoundments grow plants in shallow water or on damp soil through the summer months to chew up nutrients accumulated in waste deposited by visiting birds. This vegetation is then flooded from late fall through early spring as forage habitat for migratory waterfowl. The timing of the fluctuations in water levels approximates those of the beaver pools and marshes on lotic (flowing) waters.

Impoundment Gate — A gate assembly is a water control structure installed to provide seasonal management of the water levels in a conservation impoundment. More than once, beavers have heard the sounds of tumbling waters inside these types of devices and tried to dam them up!

You’ve heard the line, “If you build it, they will come.” Well, it’s true. Here is a sample of the activity witnessed during the past two weeks at the new impoundment completed just several months ago at Middle Creek Wildlife Management Area along the tour route just beyond the “Stop 3” overlook.

The ubiquitous Snow Geese were among the first migratory occupants of the new impoundment. A few are currently lingering in the vicinity.

Ducks soon followed. These Blue-winged Teal were among the last to pass through earlier this month.

Wilson's Snipe — Wilson’s Snipe were among the first species of migratory shorebirds to visit the new impoundment at Middle Creek…

…as were Killdeer, a species which nests nearby.

Then, earlier this month, flocks of shorebirds including these Least Sandpipers were arriving to feed and rest.

Least Sandpiper and a Semipalmated Sandpiper — A Least Sandpiper (left) and a Semipalmated Sandpiper (right).

White-rumped, Least, and Solitary Sandpipers — Here’s a Solitary Sandpiper (right) feeding alongside a Least Sandpiper (center) and a White-rumped Sandpiper (left).

Least Sandpiper and a White-rumped Sandpiper — A Least Sandpiper (left) and a White-rumped Sandpiper (right).

Rare in our area during spring, the White-rumped Sandpiper (Calidris fuscicollis) flies north using the central flyway, then heads south along the Atlantic flyway in the fall, when it tends to be more regular here.

Rocking and teetering along as it looks for food, the Spotted Sandpiper may be one of the easiest of shorebirds to identify.

Chunky little Dunlin (Calidris alpina) with their conspicuously down-curved bills are another easy-to-identify species, particularly in the spring when their breeding (alternate) plumage includes a black belly.

Black-bellied Plovers acquire a handsome set of plumage in the spring as well.

The Semipalmated Plover doesn’t have nearly the flair for ornament its close relatives the Killdeer do; these little shorebirds wear only one ring around their neck instead of two. Think this plover is cute?,…

Speaking of legs, here’s one of dozens of Lesser Yellowlegs that visited the new impoundment during their recent northbound travels.

Though less numerous than the smaller Lesser Yellowlegs, a Greater Yellowlegs seldom goes unnoticed when dropping by the man-made pothole habitat.

Wilson's Phalarope — Everyone likes to see something unusual every now and then, and this impoundment delivers. Just yesterday, we photographed this migrating Wilson’s Phalarope (top center) among two Least Sandpipers (top left and right), a Lesser Yellowlegs (left and slightly forward of the phalarope), and a White-rumped Sandpiper (foreground).

Species of wildlife in addition to shorebirds and waterfowl have already found the new impoundment favorable…

Pairs of breeding Spot-winged Gliders (Pantala hymenaea), seen here in tandem while ovipositing, were swarming the impoundment after arriving earlier this week. These dragonflies are ofttimes unpredictable nomads and are similar in appearance to the usually more numerous Wandering Gliders. To recolonize seasonal portions of their range, both are famous for hitching a ride en masse on storm systems. They share the behavior of finding ephemeral and new bodies of water favorable for egg laying due to their low density of aquatic predators.

We watched this Snapping Turtle arrive to apparently find the newly created waters to its liking. Snapping Turtles are important consumers in a wetland ecosystem. Larger specimens may fill the role of an upper trophic level or apex predator, eliminating vulnerable mid-level consumers including other Snapping Turtles.

Because it bounces its tail up and down like a Spotted Sandpiper, you may at first glance mistake an American Pipit for a shorebird. Long known as the Water Pipit, these songbirds have been visiting the impoundment while migrating north and stopping to feed in nearby croplands.

Seen here with Least Sandpipers is a visiting Glossy Ibis.

Western Cattle Egrets visiting Middle Creek this spring have been frequenting the new impoundment.

Western Cattle Egret — With still little in the way of insects such as grasshoppers available in the surrounding landscape,…

…cattle egrets are looking to find prey like this Green Frog.

Managing saturation levels in shallow-water impoundments to resemble the seasonal variations in beaver pool and marsh systems can create lush growth and wildlife-rich environments. Take a look at some images from a project in a headwaters area of a tributary to Conewago Creek (west)…

Well-established Shallow-water Impoundment — By late July, southbound shorebirds were already using these mudflats to feed and rest. Other sections of the impoundment were dense with emergent and aquatic plants, the latter kept hydrated in deeper pools of the project by the inflow from several captured springs that supplement direct rainfall and sheet runoff to supply its water. During a seasonal drawdown, the exposure of the impoundment’s soils to direct sunlight can provide a measure of disinfection to reduce the chances of disease transmission among its populations of visiting birds and other animals.

Water Lily Growth — In the deeper pools of the impoundment, water lilies and other aquatic plants grow in lush mats to provide cover and feeding areas for resident populations of breeding reptiles and amphibians.

Immature Little Blue Heron — …and this immature Little Blue Heron, a wanderer typical of more southern latitudes.

While walking the road among tall grasses in the supporting landscape surrounding this impoundment, we were at first startled when these Sandhill Cranes strode by going the other direction. We quietly kept moving,…

Sandhill Cranes with Colt — The hatching of this colt is testimony to the vital role wetland ecosystems play in the lives of hundreds of species. Whether they be beaver pools and marshes on lotic waters or man-made shallow lentic waters, each of these habitats is filling a void that left floodplains and other critical lowland biomes faltering. While they can’t replace the full-function floodplain management provided by an active beaver colony, shallow-water impoundments can provide relief for habitat-starved populations of the animals and plants that rely upon them. A constellation of these projects on lands public or private across the lower Susquehanna watershed could help provide refuge for many of our flora and fauna with the most desperately fragmented of ranges.

So that you can relax while observing the comings and goings at a pair of the lower Susquehanna valley’s man-made impoundments, the Pennsylvania Game Commission has erected two viewing pavilions for public use on its lands…

The Haldeman Island observation pavilion is located on State Game Lands 290 just upstream from the Juniata River’s mouth on the Susquehanna at Clark’s Ferry in Dauphin County.

Haldeman Island Pavilion — It overlooks not only the island’s man-made shallow-water impoundments and neighboring grasslands, but the hacking tower used in the 1970s to reintroduce Bald Eagles from Saskatchewan to the lower Susquehanna. Interpretive signs explain the conservation stories of habitats and the eagle reintroduction program.

Middle Creek W.M.A. Observation Pavilion — The observation pavilion at Middle Creek Wildlife Management Area is of similar construction to the one at Haldeman Island. It is accessed from the parking pull-off along the tour road at its intersection with Chapel Road, just before the right turn and incline that leads to the “Stop 3” grassland overlook.

It too includes numerous interpretive signs to help visitors understand impoundment management.

During the next two weeks, the exodus of migrating shorebirds now staged and feeding upon Atlantic Horseshoe Crab eggs on Delaware Bay will commence. During the evening of their departure from the bay, many of these birds cross portions of the Lower Susquehanna River Watershed, particularly east of the river. Stormy weather and other climatic conditions may force some of them to seek a place to put down temporarily, so keeping a close eye on the new pothole-like impoundment at Middle Creek may be a prudent move. After that, waders known as “post-breeding wanderers” can show up at any time. Then, beginning as early as late June, shorebirds begin moving south on a migration that can provide us with viewing opportunities into September and beyond. See you out there!

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.

August 30, 2024August 31, 2024

Aphrodite Fritillary

The Aphrodite Fritillary (Speyeria aphrodite), also known simply as the Aphrodite, is a brush-footed butterfly of deciduous, coniferous, and mixed forests. We found this female in a grassland margin between woodlots where prescribed fire was administered during the autumn of 2022 to reduce accumulations of natural fuels and an overabundance of invasive vegetation. A goal of the burn was to promote the growth of native species including the violets (Viola species) favored as larval host plants by this and other fritillaries.

By the time these adult butterflies make their reproductive flights in late summer, the violets that serve as larval host plants have gone dormant. To find patches of ground where the violets will come to life in spring, the female Aphrodite Fritillary has an ability to sense the presence of dormant roots, probably by smell. Upon finding an area where suitable violets will begin greening up next year, she’ll deposit her eggs. The eggs overwinter, then hatch to feed on the tender new violet leaves of spring.

June 29, 2024August 30, 2024

Fish Nurseries in the Susquehanna

Resilient to the pressures of flooding, ice scour, drought, and oft times really poor water quality, Water Willow (Dianthera americana, formerly Justicia americana) is the most common herbaceous plant on the Susquehanna’s non-forested alluvial islands. Yet, few know this native wildflower by name or reputation.

Water Willow on Alluvial Island — Pure stands of emergent Water Willow endure at times brutal conditions on non-forested islands in the Susquenanna.

Water Willow (foreground) and Black Willow. — Alluvial deposits of sand, clay, gravel, and silt create ideal substrate for mats of Water Willow along shorelines of the Susquehanna and its larger tributaries. Provided the loose substrate remains moist, this emergent thrives even when water levels retreat during periods of dry weather. The woody plant in the background, the native Black Willow (Salix nigra), shares similar soil preferences but is found growing on slightly higher ground as a non-emergent tree or shrub. It is a member of the willow family (Salicaceae).

Water Willow in bloom. — In bloom now, the orchid-like flower of the Water Willow is a quick giveaway that it is not a close relative of the willow trees but is instead a member of the acanthus family (Acanthaceae) and is allied with the genus Ruellia, the wild petunias.

The spring of 2024 has been very kind to our beds of Water Willow. Rainfall in the Susquehanna watershed has been frequent enough to maintain river levels just high enough to keep the roots of the plants wet. During the interludes in storm activity, dry spells have rolled back any threat of flooding on the river’s main stem, thus eliminating chances of submerging the plants in muddy water and preventing the sun from keeping them warm, happy, and flowering early. Thundershowers throughout the basin earlier this week have now raised the river a few inches to inundate the base of the plants and make mats of Water Willow favorable places for newly hatched fry and other young fish to take refuge while they grow. Here’s a look…

The Spottail Shiner (Notropis hudsonius) is a common native minnow of the Susquehanna. This juvenile was found among several dozen small fish taking refuge in the cover of Water Willow below Conewago Falls.

The Mimic Shiner (Notropis volucellus) is generally regarded to be a native transplant from the Mississippi drainage that has become established in the Susquehanna and many of its tributaries, possibly after introduction by way of bait buckets. However, the fish tends to be very fragile and dies quickly upon handling, so its use and transport as a bait species may be impractical. The Mimic Shiner is very common in around Conewago Falls.

Juvenile Mimic Shiner — A juvenile Mimic Shiner less than one inch in length found among flooded Water Willow below Conewago Falls earlier this week.

Juvenile Quillback — One of about a dozen juvenile Quillbacks (Carpiodes cyprinus) found in Water Willow just below Conewago Falls. For spawning, local populations of this compact native species of carpsucker favor the gravel-bottomed pools among the Jurassic-Triassic boulders of the falls’ pothole rocks. Probably hatched within the last eight weeks, this specimen was just one inch long.

Spotfin/Satinfin Shiner among Water Willow Rhizomes — As summer progresses, stands of emergent Water Willow begin to expand their size by sending out rhizomes. Increasing numbers of small fish like this Spotfin/Satinfin Shiner (Cyprinella species) concentrate in the cover of the thickening vegetation.

Spotfin/Satinfin Shiners — The importance of these patches of emergent wildflowers (sounds weird, doesn’t it?) is demonstrated by the numbers of fish gathered within their underwater forest of stems and leaves by summertime.

Spotfin/Satinfin Shiners (Cyprinella species) — To protect them from burial by silt and to prevent them from being swept away by current, spawning Spotfin/Satinfin Shiners deposit their eggs in crevices of submerged rocks and wood, often in or near mats of Water Willow. Males guard the eggs until hatching. The fry must then take shelter among boulders, cobble, and plant cover. Note the breeding-condition male in the upper right.

Panfish like this non-native Green Sunfish (Lepomis cyanellus) will often choose nesting sites in deeper water adjacent to beds of Water Willow, particularly if submerged growth like this Water Stargrass adds to the availability of cover for their young after hatching.

Smallmouth Bass gather in a pool adjacent to a Water Willow-covered island. These non-native predators rely on beds of these indigenous plants to provide habitat for their young, then, after spawning, lurk in the waters surrounding them to ambush less-than-vigilant minnows and other victims.

By now you’ve come to appreciate the importance of Water Willow to the sustainability of our populations of fish and other aquatic life. Like similar habitat features that reduce sediment runoff and nutrient pollution, undisturbed stands of terrestrial, emergent, and submerged native plant species are essential to the viability of our freshwater food webs.

March 24, 2024May 13, 2026

Prescribed Fire: Controlled Burns for Forest and Non-forest Habitats

Homo sapiens owes much of its success as a species to an acquired knowledge of how to make, control, and utilize fire. Using fire to convert the energy stored in combustible materials into light and heat has enabled humankind to expand its range throughout the globe. Indeed, humans in their furless incomplete mammalian state may have never been able to expand their populations outside of tropical latitudes without mastery of fire. It is fire that has enabled man to exploit more of the earth’s resources than any other species. From cooking otherwise unpalatable foods to powering the modern industrial society, fire has set man apart from the rest of the natural world.

In our modern civilizations, we generally look at the unplanned outbreak of fire as a catastrophe requiring our immediate intercession. A building fire, for example, is extinguished as quickly as possible to save lives and property. And fires detected in fields, brush, and woodlands are promptly controlled to prevent their exponential growth. But has fire gone to our heads? Do we have an anthropocentric view of fire? Aren’t there naturally occurring fires that are essential to the health of some of the world’s ecosystems? And to our own safety? Indeed there are. And many species and the ecosystems they inhabit rely on the periodic occurrence of fire to maintain their health and vigor.

**For the war effort-** The campaign to reduce the frequency of forest fires got its start during World War II with distribution of this poster in 1942. The goal was to protect the nation’s timber resources from accidental or malicious loss due to fire caused by man-made ignition sources. The release of the Walt Disney film “Bambi” during the same year and the adoption of the Smokey the Bear mascot in 1944 softened the message’s delivery, but the public relations outreach continued to be a key element of a no-fire policy to save trees for lumber. Protection and management of healthy forest ecosystems in their entirety has only recently become a priority. (National Archives image)

Man has been availed of the direct benefits of fire for possibly 40,000 years or more. Here in the Lower Susquehanna River Watershed, the earliest humans arrived as early as 12,000 years ago—already possessing skills for using fire. Native plants and animals on the other hand, have been part of the ever-changing mix of ecosystems found here for a much longer period of time—millions to tens of millions of years. Many terrestrial native species are adapted to the periodic occurrence of fire. Some, in fact, require it. Most upland ecosystems need an occasional dose of fire, usually ignited by lightning (though volcanism and incoming cosmic projectiles are rare possibilities), to regenerate vegetation, release nutrients, and maintain certain non-climax habitat types.

But much of our region has been deprived of natural-type fires since the time of the clearcutting of the virgin forests during the eighteenth and nineteenth centuries. This absence of a natural fire cycle has contributed to degradation and/or elimination of many forest and non-forest habitats. Without fire, a dangerous stockpile of combustible debris has been collecting, season after season, in some areas for a hundred years or more. Lacking periodic fires or sufficient moisture to sustain prompt decomposition of dead material, wildlands can accumulate enough leaf litter, thatch, dry brush, tinder, and fallen wood to fuel monumentally large forest fires—fires similar to those recently engulfing some areas of the American west. So elimination of natural fire isn’t just a problem for native plants and animals, its a potential problem for humans as well.

Indiangrass on Fire — Indiangrass (seen here), Switchgrass, Big Bluestem, and Little Bluestem are native species requiring periodic forms of disturbance to eliminate competition by woody plants. Intentional fires ignited by pre-Columbian human residents of eastern North America may have been at least partially responsible for the survival and distribution of burn-reliant species in the post-glacial landscape. These warm-season grasses develop roots that penetrate deep into the soil, sometimes to depths of six feet or more, allowing them to survive severe drought and flash fire events. In the tall grass prairies, these extensive root systems allow these grasses to return following heavy grazing by roaming herds of American Bison (Bison bison). Without these habitat disturbances, warm season grasslands succumb to succession in about seven years. With the periodic occurrence of fires, these plants thrive and provide excellent wildlife habitat, erosion control, and grazing forage.

To address the habitat ailments caused by a lack of natural fires, federal, state, and local conservation agencies are adopting the practice of “prescribed fire” as a treatment to restore ecosystem health. A prescribed fire is a controlled burn specifically planned to correct one or more vegetative management problems on a given parcel of land. In the Lower Susquehanna River Watershed, prescribed fire is used to…

- - Eliminate dangerous accumulations of combustible fuels in woodlands.
  - Reduce accumulations of dead plant material that may harbor disease.
  - Provide top kill to promote oak regeneration.
  - Regenerate other targeted species of trees, wildflowers, grasses, and vegetation.
  - Kill non-native plants and promote growth of native plants.
  - Prevent succession.
  - Remove woody growth and thatch from grasslands.
  - Promote fire tolerant species of plants and animals.
  - Create, enhance, and/or manage specialized habitats.
  - Improve habitat for rare species (Regal Fritillary, etc.)
  - Recycle nutrients and minerals contained in dead plant material.

Let’s look at some examples of prescribed fire being implemented right here in our own neighborhood…

Prescribed Fire at Fort Indiantown Gap — Prescribed fire is used regularly at Fort Indiantown Gap Military Reservation in Lebanon County, Pennsylvania, to keep accumulations of woody and herbaceous fuels from accumulating on and around the training range areas where live ordinance and other sources of ignition could otherwise spark large, hard-to-control wildfires.

Prescribed fire in grassland. — A prescribed fire in late winter prevents this grassland consisting of Big Bluestem and native wildflowers from being overtaken by woody growth and invasive species. Fires such as this that are intended to interrupt the process of succession are repeated at least every three to five years.

Prescribed Fire to Control Invasive Species — In its wildlife food plots, prescribed fire is used by the Pennsylvania Game Commission to prevent succession and control invasive species such as Multiflora Rose, instead promoting the growth of native plants.

A woodlot understory choked with combustible fuels and tangles of invasive Multiflora Rose. — An example of a woodlot understory choked with combustible fuels and dense tangles of invasive Multiflora Rose. A forester has the option of prescribing a dose of dormant-season fire for a site like this to reduce the fuel load, top kill non-native vegetation, and regenerate native plants.

Precribed Fire to Eliminate Woody Growth — A dose of prescribed fire was administered on this grassland to kill the woody growth of small trees beginning to overtake the habitat by succession.

Precribed Fire Education Sign at middle creek Wildlife Management Area — The Pennsylvania Game Commission employs prescribed fire at Middle Creek Wildlife Management Area and on many of their other holdings to maintain grasslands.

Prescribed fire is used to eliminate invasive species including Multiflora Rose from grasslands at Middle Creek W.M.A. Annual burns on the property are conducted in a mosaic pattern so that each individual area of the grassland is exposed to the effects of fire only once every two to five years. Without fire or some type of mechanical or chemical intervention, succession by woody trees and shrubs would take hold after about seven years.

Prescribed fire is planned for a fraction of total grassland acreage at Middle Creek W.M.A. each year. Another section of the mosaic is targeted in the following year and yet another in the year that follows that. Because burns are conducted in the spring, grassland cover is available for wildlife throughout the winter. And because each year’s fire burns only a portion of the total grassland acreage, wildlife still has plenty of standing grass in which to take shelter during and after the prescribed fire.

Prescribed fire at Middle Creek W.M.A. provides grassland habitat for dozens of species of birds and mammals including the not-so-common Grasshopper Sparrow…

…and stocked Ring-necked Pheasants that do nest and raise young there.

Prescribed Burn Maintains Savanna-like Habitat — On a few sites in the Lower Susquehanna River Watershed , prescribed fire is being used to establish and maintain savanna-like grasslands. This one, located on a dry, south-facing slope near numerous man-made sources of ignition, can easily be dosed with periodic prescribed burns to both prevent succession and reduce fuel accumulations that may lead to a devastating extreme fire.

Pitch Pines in Savanna-like Habitat — One year following a prescribed burn, this is the autumn appearance of a savanna-like habitat with fire-tolerant Pitch Pine (Pinus rigida), Bear Oak, warm-season grasses, and a variety of nectar-producing wildflowers for pollinators. These ecosystems are magnets for wildlife and may prove to be a manageable fit on sun-drenched sites adjacent to man-made land disturbances and their sources of ignition.

Red-headed Woodpecker Adult and Juvenile — Savanna-like grasslands with oaks and other scattered large trees, some of them dead, make attractive nesting habitat for the uncommon Red-headed Woodpecker.

Wild Turkey in Savanna-like Habitat — Prescribed fire can benefit hungry Wild Turkeys by maintaining savanna-like grasslands for an abundance of grasshoppers and other insects in summer and improving the success of mast-producing oaks for winter.

In the Lower Susquehanna River Watershed, the caterpillar of the rare Eastern Buck Moth feeds on the foliage of the Bear Oak, also known as the Scrub Oak, a shrubby species that relies upon periodic fire to eliminate competition from larger trees in its early successional habitat.

Leaves of the Bear Oak in fall. The Bear Oak regenerates readily from top kill caused by fire.

Reed Canary Grass (Phalaris arundinacea) is a native cool-season grass with a colorful inflorescence in spring. But given the right situation, it can aggressively overtake other species to create a pure stand lacking biodiversity. It is one of the few native species which is sometimes labelled “invasive”.

Prescribed Burn to Reduce Prevalence of Reed Canary Grass — Prescribed fire can be used to reduce an overabundance of Reed Canary Grass and its thatch in wetlands. Periodic burning can help restore species diversity in these habitats for plants and animals including rare species such as the endangered Bog Turtle (Glyptemys muhlenbergii).

On the range areas at Fort Indiantown Gap in Lebanon County, Pennsylvania, disturbances by armored vehicles mimic the effects of large mammals such as the American Bison which periodically trampled grasses to prevent succession and the establishment of woody plants on its prairie habitat. To supplement the activity of the heavy vehicles and to provide suitable habitat for the very rare Regal Fritillary (Speyeria idalia) butterflies found there, prescribed fire is periodically employed to maintain the grasslands on the range. These burns are planned to encourage the growth of “Fort Indiantown Gap Little Bluestem” grass as well as the violets used as host plants by the Regal Fritillary caterpillars. These fires also promote growth of a variety of native summer-blooming wildflowers to provide nectar for the adults butterflies.

Depiction of Pennsylvania's Last American Bison, Killed in Union County in 1801. (Exhibit: State Museum of Pennsylvania, Harrisburg) — A last record of a wild American Bison killed in Pennsylvania was an animal taken in the Susquehanna watershed in Union County in 1801. The species is thereafter considered extirpated from the state. Since that time, natural disturbances needed to regenerate warm-season grasses have been limited primarily to fires and riverine ice scour. The waning occurrence of both has reduced the range of these grasses and their prairie-like ecosystems in the commonwealth. (Exhibit: State Museum of Pennsylvania, Harrisburg)

A male Regal Fritillary on the range at Fort Indiantown Gap, where armored vehicles and prescribed fire provide suitable prairie-like habitat for this vulnerable species.

Honey Bee Collecting Minerals After Prescribed Burn — Prescribed fires return the nutrients and minerals contained in dead plant material to the soil. Following these controlled burns, insects like this Honey Bee can often be seen collecting minerals from the ashes.

Fly Collecting Minerals from Burned Grasses — A Greenbottle Fly gathering minerals from the ash following a prescribed burn.

In Pennsylvania, state law provides landowners and crews conducting prescribed fire burns with reduced legal liability when the latter meet certain educational, planning, and operational requirements. This law may help encourage more widespread application of prescribed fire in the state’s forests and other ecosystems where essential periodic fire has been absent for so very long. Currently in the Lower Susquehanna River Watershed, prescribed fire is most frequently being employed by state agencies on state lands—in particular, the Department of Conservation and Natural Resources on State Forests and the Pennsylvania Game Commission on State Game Lands. Prescribed fire is also part of the vegetation management plan at Fort Indiantown Gap Military Reservation and on the land holdings of the Hershey Trust. Visitors to the nearby Gettysburg National Military Park will also notice prescribed fire being used to maintain the grassland restorations there.

For crews administering prescribed fire burns, late March and early April are a busy time. The relative humidity is often at its lowest level of the year, so the probability of ignition of previous years’ growth is generally at its best. We visited with a crew administering a prescribed fire at Middle Creek Wildlife Management Area last week. Have a look…

Members of a Pennsylvania Game Commission burn crew provide visitors to Middle Creek Wildlife Management Area with an overview of prescribed fire. — Members of a Pennsylvania Game Commission burn crew provide visitors to Middle Creek Wildlife Management Area with an overview of prescribed fire and the equipment and techniques they use to conduct a burn.

Burn Boss Checking Weather — Pennsylvania Game Commission Southeast Region Forester Andy Weaver will fulfill the role of Burn Boss for administering this day’s dose of fire. His responsibilities include assessing the weather before the burn and calculating a probability of ignition.

Burn Boss Briefing Crew — The Burn Boss briefs personnel with information on site layout, water supply location(s), places of refuge, emergency procedures, the event’s goals and plan of action, crew assignments, and the results of the weather check: wind from the northwest at 5 miles per hour, temperature 48 degrees, and the relative humidity 63%. Today’s patient is a parcel of warm-season grasses receiving a dose of fire to eliminate invasive non-native plants, woody growth, and thatch. The probability of ignition is 20%, but improving by the minute.

Prescribed Fire Test Burn — To begin the burn, a test fire is started in the downwind corner of the parcel, which also happens to be the bottom of the slope. Fuel ignition is good. The burn can proceed.

Igniting the Fire — Crews proceed uphill from the location of the test fire while igniting combustibles along both flanks of the area being treated.

Prescribed Fire Crew Member with Equipment — A drip torch is used to ignite the dried stems and leaves of warm-season grasses and wildflowers. Each member of the burn crew wears Nomex fire-resistant clothing and carries safety equipment including a two-way radio, a hydration pack, and a cocoon-like emergency fire shelter.

Wildfire ATV — An all-terrain vehicle equipped with various tools, a fire pump, hose, and a small water tank accompanies the crew on each flank of the fire.

Effective Fire Break — With green cool-season grasses already growing on the trails surrounding the burn zone, very little water was used to contain this prescribed fire. Where such convenient fire breaks don’t already exist, crews carry tools including chain saws, shovels, and leaf blowers to create their own. They also carry flame swatters, backpack water pumps, shovels, and other tools to extinguish fires if necessary. None of these items were needed to control this particular fire.

Halting the Process of Succession in a Grassland with Prescribed Fire — This fast-burning fire provides enough heat to damage the cambium layer of the woody tree and shrub saplings in this parcel being maintained as a grassland/wildflower plot, thus the process of succession is forestalled. Burns conducted during previous years on this and adjacent fields have also controlled aggressive growth of invasive Multiflora Rose and Olives (Elaeagnus species).

Containing the Fire on the Flanks — Crews proceed up the slope while maintaining the perimeter by igniting dry plant material along the flanks of the burn zone.

The Crew Monitors the Burn — Ignition complete, the crews monitor the fire.

Prescribed Fire: Natural Mosaic-style Burn Pattern — The Burn Boss surveys the final stages of a safe and successful prescribed fire. The fire has left behind a mosaic of burned and unburned areas, just as a naturally occurring event may have done. Wildlife dodging the flames may be taking refuge in the standing grasses, so there is no remedial attempt to go back and ignite these areas. They’ll be burned during prescribed fires in coming years.

By June, this grassland will again be lush and green with warm-season grasses and blooming wildflowers like this Common Milkweed being visited by a Great Spangled Fritillary.

And later in the summer, Eastern Tiger Swallowtails on Joe-pye Weed.

Bobolinks in Indiangrass — Bobolinks glow in the late August sun while taking flight from a stand of warm-season grasses maintained using springtime prescribed fire. The small dots on the dark background at the top of the image are multitudes of flying insects, many of them pollinators. The vegetation is predominately Indiangrass, excellent winter cover for birds, mammals, and other wildlife.

Prescribed burns aren’t a cure-all for what ails a troubled forest or other ecosystem, but they can be an effective remedy for deficiencies caused by a lack of periodic episodes of naturally occurring fire. They are an important option for modern foresters, wildlife managers, and other conservationists.

August 7, 2017August 27, 2023

Fussy Eaters

She ate only toaster pastries…that’s it…nothing else. Every now and then, on special occasions, when a big dinner was served, she’d have a small helping of mashed potatoes, no gravy, just plain, thank you. She received all her nutrition from several meals a week of macaroni and cheese assembled from processed ingredients found in a cardboard box. It contains eight essential vitamins and minerals, don’t you know? You remember her, don’t you?

Adult female butterflies must lay their eggs where the hatched larvae will promptly find the precise food needed to fuel their growth. These caterpillars are fussy eaters, with some able to feed upon only one particular species or genus of plant to grow through the five stages, the instars, of larval life. The energy for their fifth molt into a pupa, known as a chrysalis, and metamorphosis into an adult butterfly requires mass consumption of the required plant matter. Their life cycle causes most butterflies to be very habitat specific. These splendid insects may visit the urban or suburban garden as adults to feed on nectar plants, however, successful reproduction relies upon environs which include suitable, thriving, pesticide-free host plants for the caterpillars. Their survival depends upon more than the vegetation surrounding the typical lawn will provide.

The Monarch (Danaus plexippus), a butterfly familiar in North America for its conspicuous autumn migrations to forests in Mexico, uses the milkweeds (Asclepias) almost exclusively as a host plant. Here at Conewago Falls, wetlands with Swamp Milkweed (Asclepias incarnata) and unsprayed clearings with Common Milkweed (A. syriaca) are essential to the successful reproduction of the species. Human disturbance, including liberal use of herbicides, and invasive plant species can diminish the biomass of the Monarch’s favored nourishment, thus reducing significantly the abundance of the migratory late-season generation.

Monarch caterpillar after a fourth molt. The fifth instar feeding on Swamp Milkweed.

A fifth molt begets the Monarch pupa, the chrysalis, from which the showy adult butterfly will emerge.

Adult Monarch feeding on Goldenrod *(Solidago)* nectar.

Butterflies are good indicators of the ecological health of a given environment. A diversity of butterfly species in a given area requires a wide array of mostly indigenous plants to provide food for reproduction. Let’s have a look at some of the species seen around Conewago Falls this week…