Migrating Waterfowl on Lotic Fresh Waters

Lotic vs. Lentic Freshwater Ecosystems
Some comparative attributes of unspoiled lotic vs. lentic freshwater ecosystems.  Low-gradient (slow-moving) lotic waters often create, and remain connected to, accompanying riverine wetlands (a lentic freshwater ecosystem).  These swamps, marshes, and ditches absorb, purify, and infiltrate flood waters while supporting a diverse number of plant and animal species.

We frequently perceive all waterfowl migration to be synchronized with the conspicuous movements of familiar species like Snow Geese, Tundra Swans, and Canada Geese—big flights coming south in October and November, then a return to the north in late February and March.  And we’re all quite aware of the occurrence of large gatherings of some of these migrants while they make stopovers on some of our largest lentic (still) waters—the man-made lakes and reservoirs created by damming local streams.  But did you know that there are populations of colorful waterfowl with dynamic migrations that extend throughout the winter and early spring with movements that are often continuous.  Under favorable conditions, these birds favor the lotic (flowing) waters of the river and its larger tributaries as they transit the lower Susquehanna valley.  That’s because unpolluted lotic freshwater ecosystems support a greater diversity of plants and animals than lentic waters, and therefore offer more opportunities for hungry migrating waterfowl to find food.  Let’s have a look at some of the species that visit the river during their seasonal journeys…

Ice on the Susquehanna
While the urge to head south in the autumn is largely stimulated by the shortening of the photoperiod, it is the presence of ice, particularly on glacial lakes throughout the lands to the north of the lower Susquehanna River basin, that pushes many diving ducks to finally make their way south toward the guarantee of open-water feeding areas along the coast.  This movement may occur at anytime between November and late February or, as we have seen during some of the mild winters of recent decades, it may scarcely be noticed at all.
Common Mergansers
Common Mergansers often lead they way when it comes to migratory diving ducks.  They regularly move south in conspicuous numbers by late November and December and are regularly pushing north as soon as the ice begins to melt.  During a typical year, it is not unusual for some populations of these large diving birds to remain north of us during the winter.  Then, in the days after a sudden rush of frigid polar air, an appreciable increase in ice cover will force a mid-winter movement of birds down the Susquehanna.
Heat Flux Sources Impacting Temperature in Lotic Fresh Waters
Temperatures in lotic fresh waters vary over the length of the stream or river.  They are largely determined by the collective impact of the numerous sources of heat flux depicted in this graphic.  (Environmental Protection Agency image)
Buffleheads
Buffleheads begin passing through the lower Susquehanna region in Novemeber on their way to coastal saltwater bays for the winter.  Lingering populations feed by diving in the river’s pools and riffles for benthic invertebrates including snails and insect larvae.  Lesser quantities of aquatic plant matter supplement their diet.
Common Goldeneye
Many Common Goldeneyes will remain on shallow, ice-free waters of the northern lakes and rivers sculpted by the most recent glacial event, but only until they are forced south into and through the lower Susquehanna valley by the encroachment of freezing conditions.  On the river, they are among the dozen or so species of diving ducks we see visiting or passing through during the typical late fall and early river.

 

Geomorphological Zonation of a Stream or River
During their visits to the lotic (also known as riverine) fresh waters of the Susquehanna and its largest tributaries, benthic-feeding waterfowl make short dives to take advantage of the plants, small fish, invertebrates, and other food sources inhabiting the stream bottom in the riffles and pools of the free-flowing waterway.  Substrates, listed here by size (in descending order), along with other parameters influenced by this zonation determine the variety and abundance of the forage available to migrating waterfowl and other consumers.  Ice or high water and poor visibility due to flooding can render the riffles and pools of the channel unusable for feeding.  The birds must then choose to either linger and rest without feeding or leave the lotic freshwater habitat to seek sustenance.  During a flood, this may require relocation to a nearby lentic (still) body of fresh water such as a lake or reservoir.  The presence of ice will almost invariably force the birds to fly on to the Atlantic Coastal Plain and the tidal waters of its bays and estuaries.
Hooded Mergansers
Hooded Mergansers are one of the few species of diving ducks likely to utilize flooded shoreline timber and riverine (fluvial) wetlands as refuge from high water on Susquehanna.
Pied-billed Grebe and Canvasbacks
A Pied-billed Grebe and a pair of Canvasbacks on an ice-free stretch of the lower Susquehanna in mid-winter feed and loaf in a riffle-flanked pool where a large mat of American Eelgrass, a submerged aquatic plant also known as Tapegrass or Wild Celery, grows during the summer.  The vast mosaic of riffles and pools in a river this size offers tremendous opportunities for a diverse array of aquatic species to find their niche wherein they can survive and flourish.
Bufflehead
The presence of ice forces Buffleheads and other diving ducks to gather in turbulent open water, often below a riffle or dam.  Another alternative is to continue on toward the salty bays and estuaries of the coast.  High water may push these birds into the shallows among the flooded woods to feed, but they seldom utilize heavily forested riparian wetlands as a refuge due to their need for a running start to get airborne.

 

Riffle and Pool Characteristics of High Gradient (A) and Low Gradient (B) Streams.  This graphic illustrates the change in deposition characteristics of a stream or river as its gradient decreases.  A high-gradient stream (A) has a rapid velocity, often forms falls, and tends to carry away a high volume of all but the largest of particles of potential substrates as they erode from the surrounding landscape.  On a low-gradient stream, the loss in water velocity reduces the water column’s ability to transport even the smallest of substrate particles.  Deposition of this gravel, sand, silt, and clay forms lateral bars that over time create the familiar meandering path of a naturally flowing lowland stream.  (National Park Service image)
Benthic Life in Lotic Freshwaters
Benthic substrates in lotic freshwater pools and riffles support an abundance of life forms ranging from colorful diatoms on rocks and cobble, to invertebrates including snails and insect larvae, to fishes like this young Channel Catfish.  Free of accumulations of sediment, this river bottom not only provides habitat for a healthy fishery, it facilitates the bidirectional exchange of water between the Susquehanna and its underlying aquifer.
Quillback
On the lower Susquehanna, populations of young Quillback suckers are found almost exclusively in clear, high-gradient pools.
Harlequin Duck
The Harlequin Duck winters along the rocky shores and man-made jetties of the Atlantic coast.  In summer, they nest on fast-moving, headwater streams well to our north.  Very rare on the Susquehanna, this is the first of two individuals found during March and April of 2025.  It was observed feeding in the swift waters of the high-gradient riffles and pools where the river cuts through Blue Mountain north of Harrisburg.  During previous weeks, Harlequin Ducks were being seen along the coast as far south as the mouth of the Chesapeake at Cape Charles, Virginia.  It’s very possible that some of these birds traveled north through the bay area and up the Susquehanna on their way north.

 

Fluvial Geomorphology of a Stream.  Many of the Susquehanna’s tributaries pass through each of these three erosional zones.  Along the way, they carry out the process of breaking down the mountains formed by the Allegheny orogeny, the collision of North America and Africa that created the supercontinent Pangea about 325 to 260 million years ago (during portions of both the Carboniferous and Permian periods).  Today’s main stem of the lower Susquehanna passes through a transfer zone (Zone 2), carrying eroded materials to a depositional  zone (Zone 3) located within the ancient Susquehanna canyon stretching from Havre de Grace, Maryland, to Norfolk Canyon on the edge of the continental shelf.  Within this zone, more than a 10,000-year accumulation of post-glacial sediments lies submerged by the rising waters of the Atlantic Ocean and Chesapeake Bay.  Although the present-day lower Susquehanna is largely a transfer zone, some deposition occurs along low-gradient segments of the river, particularly where its course parallels the watershed’s ridges both above and below the high-gradient rapids where its path has eroded passage through the highlands.  (National Park Service image)
Although the present-day lower Susquehanna is largely a transfer zone, some deposition occurs along low-gradient segments of the river, particularly where its course parallels the watershed’s ridges both above and below the high-gradient rapids where its path continues to erode passage through the bedrock.  On this 1908 map of the Susquehanna at Conewago Falls, alluvial terraces of gravel, sand, silt, and clay can readily been seen as pale areas nearly lacking brown contour lines along the shorelines and islands of the river.  Deposits within most of these terraces date back to the melt period following the most recent glacial event and beyond.  The delta shown at the mouth of Conewago Creek (west) includes massive volumes of material deposited by both the creek and the river.  This delta is currently known as Brunner Island, much of it developed as the site of a coal/gas-fired electric generating station.  Terrace deposits along the Susquehanna’s shorelines created extensive perched marshes and swamps (wooded marshes) fed by rains, high river water, small streams, and springs, the latter often seeping from the base of the rocky escarpments carved by the ancient Susquehanna and defining the present-day inland border of the floodplain.  We call these sites “Alluvial Terrace Wetlands”.  Few of these critical components of river morphology survive.  Those not drained for farmland were obliterated by urbanization and canal, railroad, and highway construction.  (United States Geological Survey base image: Middletown, PA, quadrangle, 1908)
Water Willow
Water Willow is a familiar emergent plant that colonizes lateral bars and other alluvial deposits in low-gradient segments of the Susquehanna.
Water Willow Roots
The fine roots of Water Willow collect sediment and absorb nutrients while creating dense cover for young fish and numerous species of invertebrates including the Virginian River Horn Snails seen here.

Prior to the nineteenth century, the low-gradient flow regime of the river both above and below the riffles at Chiques Rock (lower right on map) created prime wildlife habitat.  The natural accumulations of nutrients and substrates carried into and through the lotic waterway’s pools and riffles were cycled into an ideal growing medium for extensive mats of American Eelgrass and other aquatic plants.  This underwater forest hosted a seemingly endless abundance of invertebrates and fishes (both resident and migratory)—supporting a variety of consumer species including various populations of humans.  But soon after the mass clearing of much of the watershed’s land for farming and lumber, the mill ponds created by dams constructed on streams to power saw and grain mills became brimful with sediments eroded from the unprotected ground.  During storm events, torrents of these sediments then flowed full bore toward the Susquehanna, and began accumulating in the low-gradient segments of the river.

Legacy Sediments
Sediments left behind after the removal of mill dams are known as legacy sediments. They disconnect the stream from its historic floodplain and riverine (fluvial) wetlands, thus intensifying the impact of high water in the surrounding landscape.  As these nutrient-charged deposits wash away, they become a source of pollution in the waters of the Susquehanna and Chesapeake.
American Eelgrass
A mat of American Eelgrass growing in the flowing waters of the Susquehanna below Conewago Falls.  Eelgrass and other submerged aquatic plants provide essential habitat for a wide variety of small fish and invertebrates while also consuming nutrients deposited in the cobble, gravel, and sand substrate of the river’s pools.  Excess quantities of smaller particles of silt and clay can clog the substrate and thus inhibit the hyporheic exchange of water between the stream channel and the underlying aquifer, often diminishing the biomass and diversity of organisms inhabiting this benthic habitat.  Buried in these life-choking sediments, the river bottom becomes inhospitable to growth of submerged aquatics including eelgrass.
Susquehanna at Marietta
This low-gradient stretch of the Susquehanna at Marietta flows parallel to the Chickies Quartzite “Hellam Hills” before making a sharp right turn to punch through the ridge as a series of rapids at Chiques Rock.  Formerly a fully functional lotic ecosystem and a paradise for migrating waterfowl, this river segment is now impaired by accumulations of nutrient-laden sediments from agricultural and urban runoff.
Conewago Falls Flood Waters
Nutrient and sediment-loaded flood waters roar across the diabase boulders at the York Haven Dam and Conewago Falls, a high-gradient segment of the Susquehanna.
Flood Waters at Haldeman Riffles
They continue past Brunner Island (left power plant stacks) and through Haldeman Riffles and the Shocks Mills Railroad Bridge…
Flooding on the Marietta Broads
…into the stretch of river known as the “Marietta broads” along the base of the Chickies Quartzite “Hellam Hills”.  The low stream gradient here produces a slower current and increased deposition of sediments.
Susquehanna Flooding at Chiques Rock
As the flood surges through the riffle and pool complex at Chiques Rock, the high stream gradient maintains a velocity in the water column sufficient to keep additional sediments in suspension until they reach the low-gradient river segment just downstream at Washington Boro, site of a naturally occurring lateral bar area known as the Conejohela Flats.  These bars now lie within the man-made depositional zone known as “Lake Clarke”.  Created nearly a century ago by construction of the Safe Harbor Dam, this impoundment is accumulating astounding volumes of nutrient-loaded sediments that continue to encapsulate the flats within a stream-impairing delta.
Redheads, Canvasbacks, and a Horned Grebe
Anytime from November to April on the lower Susquehanna, a group of Redheads, Canvasbacks (3 birds to right of the middle of the picture), and a Horned Grebe (lower left) is a welcome sight in a riverine pool known to have a summertime growth of American Eelgrass.  Noted Dr. Herbert Beck in 1924 when describing the Canvasback, “Like all ducks, …, it stops to feed within the county (Lancaster) less frequently than formerly, principally because the vast beds of wild celery which existed earlier on broads of the Susquehanna, as at Marietta and Washington Borough, have now been almost entirely wiped out by sedimentation of culm.  Prior to 1875 the four or five square miles of quiet water off Marietta were often as abundantly spread with wild fowl as the Susquehanna Flats are now.  Sometimes there were as many as 500,000 ducks of various kinds on the Marietta broad at one time.”
Aythya genus ducks.
Today, seeing just dozens of Aythya genus ducks (Redheads, Canvasbacks, scaup) on the lower Susquehanna is a notable event.  If they happen to be forced down by inclement weather while migrating through, you might get lucky enough to see several hundred.
Aythya Genus Ducks
While the recovery of eelgrass/wild celery beds on the Susquehanna is trivial in scale and offers little support for numbers of waterfowl to return to historic levels, restorations on the upper Chesapeake in the vicinity of the Susquehanna Flats between Havre de Grace and Aberdeen Proving Grounds may have helped refuel a gathering of mostly Aythya genus ducks during the final days of February.  This mass of ducks, many of which were forced south from the frozen Great Lakes during the previous weeks (some by way of the ice-choked Susquehanna) were apparently making an abrupt turn to make their way back north.  Their stay was brief, but estimates by local birders put their numbers as high as one half million.  The vast majority of the concentration consisted of Aythya species: Redheads, Canvasbacks, Ring-necked Ducks, and both Lesser and Greater Scaup.  It probably included a mix of birds including both northbound migrants from further down the coast and the aforementioned refugees that had just arrived to pay a quick visit while escaping the late-season ice before turning around.
Lesser Scaup
During the past two centuries, as food supplies in the Susquehanna grew increasingly compromised for benthic feeders like these Lesser Scaup and other diving ducks, a change in distribution was necessary for survival.
Lesser Scaup in flight.
As individual species, Lesser Scaup and other waterfowl that fail to adapt to natural or man-made changes in their habitats and food supplies may see their overall global numbers falter.

Despite being located in the transfer zone, the lower Susquehanna has become a significant depositional zone along much of its length, mostly courtesy of the placement of sediment-trapping man-made dams.

Following construction of the mill dams and ponds on nearly every mile of the lower Susquehanna’s low-gradient tributary streams, enterprising parties moved on to the river.  The first significant spans were constructed using wide timber cribs filled with large rock.  They were placed to create water deep enough to allow canal boats to cross the Susquehanna at both Clark’s Ferry at the mouth of the Juniata River in Dauphin County and at Columbia/Wrightsville.  These dams also diverted water into the newly excavated canals—the Pennsylvania Eastern Division Canal (completed in 1833) which followed the river’s east shore from Clark’s Ferry to Columbia, and the Susquehanna and Tidewater Canal (completed in 1840) along the west shore from Wrightsville to Havre de Grace, Maryland.  Placement of these sediment-trapping man-made dams began a process of converting vast mileage of the lower Susquehanna from a transfer zone into a deposition zone.  In addition, layout of the canals and locks followed the contours along the base of the riverside ridges, seriously altering most of the alluvial terrace wetlands that the river had created as a feature of its floodplain during the post-glacial period.

Construction of the canal dams was just the beginning.  During the twentieth century, more massive dams would be added to the main stem of the river for hydroelectric energy production at York Haven, Safe Harbor, Holtwood, and Conowingo.  Upon their completion, the days of unassisted anadromous fish migrations were over.  On both the river and its tributaries, smaller dams including dangerous low-head dams maintain water levels for boating and recreation.  They too create current-diminishing, pseudo-lentic waters that blanket the lotic riffle and pool substrates with polluted sediments.

MAN-MADE DAMS TURN LOTIC WATERS INTO UNFLUSHED TOILETS

Sediment Deposition Behind Lower Susquehanna Dams
The construction of dams on the lower Susquehanna has converted vast mileage of the river from a lotic freshwater system into a series of man-made lentic freshwater lakes.  These areas have lost their function as a lotic transfer zone and are now a sort of dysfunctional series of depositional zones collecting vast volumes of sediment containing nutrients and other pollutants.  Within each impoundment, the reduced velocity of the river causes it to drop suspended sand first, then the finer particles of silt and clay closer to the dam.  The flow regime of riffles and pools is lost and the hyporheic zone that exchanges water between the river and the underlying aquifer is clogged.  These impaired segments of river become ripe for eutrophication: algal blooms followed by die offs that can lead to a fatal reduction of dissolved oxygen in the water column.
Gadwall
Deposits of lateral bars of sediment in low-gradient segments of the Susquehanna can create shallow water feeding habitat for puddle/dabbling ducks like these Gadwall.  Where sediment pollution is severe, benthic foods in these areas often consist mostly of invertebrates and plant matter deposited by the current, the buried substrates devoid of a functioning ecosystem and the waters subject to eutrophication.
Common Goldeneyes
Common Goldeneyes on a patch of open water on an otherwise ice-covered “Lake Clarke”, the impoundment created by Safe Harbor Dam.  While they may find this spot advantageous for loafing, the food supply over the sediment-buried substrate will be limited.
By the end of the twentieth century, accumulations of polluted sediments behind lower Susquehanna dams were nearing capacity.  There is no working plan to attenuate the massive release of these pollutants that may be triggered by a catastrophic flood.  The effort to reduce nutrient and sediment runoff remains the focus so that new loading is kept to a minimum and won’t add to the capacity problems at the dams or continue downriver to the Chesapeake at full strength when the dams are full.  Alleviating the sediment aggregation problem within the river’s impoundments is a tall order and a dilemma not easily solved.  (United States Geological Survey image)
Common Mergansers
Common Mergansers will feed where benthic substrate supports the small fish and invertebrates they prefer. They will, however, gather in extraordinary numbers on the “lakes” created by riverine dams.  Though they can only feed on what floats in with the current, hundreds or sometimes thousands of Common Mergansers will concentrate on “Conowingo Pond” during the late fall or early winter.  There, safety in numbers gives them some guarantee of protection against the multitudes of eagles that simultaneously frequent the vicinity.  Another advantage of staging on “Conowingo Pond” is its close proximity to favorable feeding areas on upper Chesapeake Bay and stretches of the Susquehanna where lotic riffles and pools offer abundant opportunities below the river’s dams.
Rusty Crayfish
Fortunately for everything else living in the benthos, Common Mergansers are big enough to devour invasive, non-native Rusty Crayfish when they find them in our lotic waterways.

TIME TO CLEAN UP OUR ACT

WHERE DOES YOUR STORMWATER GO?

 

Channelized Urban/Suburban Streams Function as Sewers. They have no attached lowlands or floodplains to absorb, purify, and infiltrate runoff from rain events.  Pollutants including litter, pet waste, lawn chemicals, tire-wear particles, hazardous fluids, and sometimes untreated human excrement flush unchecked from the municipal storm drainage system into the waterway.  Thermal shock from summer downpours washing across sun-heated pavements can kill temperature sensitive fishes and other aquatic life.  Nutrient and sediment loads from these impaired tributaries later accumulate downstream in low-gradient segments of the Susquehanna, turning the river into an open-air cesspool.  Aggressively working to implement projects that eliminate these sources of pollution are the only effective way to keep the problem from getting worse.  Making things better requires a lot more dedication and effort.  (United States Geological Survey image by Frank Ippolito)

RIPARIAN BUFFERS MAKE A DIFFERENCE…WIDER IS BETTER

Riparian Buffer
To sequester sediment and cycle nutrients (primarily nitrogen and phosphorus) contained in farm runoff, the U.S.D.A. recommends installing riparian buffers between streams and lands used for grazing and raising crops.  To protect pollinating species including bees and butterflies from pesticide drift and eroding soils rich in fertilizers, they further recommend installing a stand of wind-pollinating plants such as conifers, oaks, and birches between the field and streamside plantings.  These same conservation practices improve water quality and wildlife habitat on waterways located in residential and commercial areas as well.  (United States Department of Agriculture image, click to enlarge)

FLOODPLAIN RESTORATION

Regardless OF HOW LONG YOU’VE BEEN CONDITIONED TO THINK OTHERWISE, THIS IS A DYSFUNCTIONAL, POLLUTED CREEK—AND IT NEEDS HELP
Legacy Sediments
A channelized low-gradient stream eroding a path through deposits of legacy sediments displaces flood waters into previously unaffected areas and provides a continuing source of nutrient and sediment pollution during storm events.  These impaired waters have a diminished capacity for supporting aquatic life including fishes.
RESTORED TO ITS HISTORIC FUNCTIONS
Floodplain and Stream Restoration
On an adjacent segment of the same creek, this legacy sediment removal project restored a braided meandering channel and connected it to its newly liberated, historic floodplain.  In just their second year, the fluvial wetlands are effectively absorbing stormwater and sequestering nutrients as an attached component of the stream’s riffle and pool complex.  During our visit earlier this week, we found American Toads, Northern Leopard Frogs (Lithobates pipiens), and Northern Spring Peepers breeding here.  It’s just as Castor canadensis would have it!

“STOP HEMMING AND HAWING AROUND ALREADY”

“HEY COWBOY, HOW ‘BOUT GETTIN’ THEM FILTHY LITTLE DOGIES OUTTA DAT CRICK?”
Impaired Stream
Here’s a polluted stream in a pasture with grazing livestock.  The site is a former mill pond within which the creek eroded a channel following removal of the dam.  The animals defecate and urinate where access to water is gained at a broken down embankment of the nutrient-loaded legacy sediments deposited in the pond more than a century ago.  It’s a haphazard form of animal husbandry and a reminder that all it takes is just one stubborn jackass to foul up the whole waterway.
DIRECT SOURCES OF NITROGEN (AMMONIA) POLLUTION IN STREAMS

DID YOU KNOW that a dairy cow produces about 80 pounds of waste (excrement and urine) every day?

DID YOU KNOW that a horse produces about 50 pounds of waste (excrement and urine) every day?

DID YOU KNOW that a human produces about 3 to 4 pounds of waste (excrement and urine) every day?  The exceptions, of course, are those who continue to insist that raising farm animals in and alongside a body of water is okey-doke—a harmless practice.  These individuals tend to retain the former constituent of human waste and are thus full of it.

“ATTABOY TEX, THAT’S MORE LIKE IT!”
Stream Fencing and Livestock Crossing
Now that’s better.  Legacy sediments have been removed to reconnect the stream to its floodplain.  A livestock crossing and exclusion fencing has been installed, and a nutrient-consuming riparian buffer has been planted.  This creek segment’s pollution woes have been mitigated.  Do you have a neighbor needing this type of remedial work on their farm?  Have them call your local conservation district office for advice.  Some programs include financial assistance covering the costs of installation as well as monetary incentives for helping to clean up the water.

AND FINALLY

WHEN IT COMES TO BUILDING DAMS ON LOTIC FRESH WATERS…

Sandhill Cranes in Beaver Pond

…LEAVE IT TO THE BEAVERS
North American Beavers
North American Beavers (Castor canadensis) create habitats that connect the riffle and pool regime of a low-gradient stream to a surrounding fluvial wetland that retains sediments, cycles nutrients, and provides essential habitat for hundreds of plant and animal species.  Floodplains are for flooding.  And if a beaver floods an area, you can be guaranteed that it was already part of a floodplain.  You see, beavers don’t encroach upon humans, it’s humans doing the encroaching upon beavers.  (National Park Service image)
MAD HATTERS

DID YOU KNOW that even before the landscape was cleared for farms and a supply of timber, and before mill dams on local creeks began accumulating soil runoff from the consequently barren hillsides, all the North American Beavers, the keystone species of lower Susquehanna stream ecology, were killed and sold to make hats?  It’s no wonder things are fubar!

COMING SOON…

Horned Grebe
Horned Grebes are regular migrants and sometimes winter residents on ice-free stretches of the lower Susquehanna.  They spend their time plying the benthic substrate of the river’s clear riffles and pools for a variety of invertebrates and small fish.  Look for them moving north in coming days sporting this beautiful breeding plumage.
Common Loon
April and early May are prime time for observing Common Loons on the Susquehanna as they undertake a journey from the Atlantic surf where they spent the winter to nesting sites on northern lakes.  For this migrant in breeding plumage, clear water for sighting plenty of benthic life in the river’s riffles and pools assures a successful dive in search of energy-replenishing forage.

Photo of the Day

Tree Swallow
With southerly breezes to push them along, insectivorous songbirds are beginning to arrive throughout the lower Susquehanna valley.  By the first week of March, Tree Swallows started their push up the river corridor, relying upon the late-winter hatches of stoneflies and other cold-hardy flying insects for sustenance.  As temperatures warmed during mid-month, greater numbers of these colorful cavity nesters ventured out across upland areas in search of suitable breeding sites in grasslands and pastures near water.  Upon finding a good home in a dead tree or nest box, they’ll defend it vigorously to discourage encroachment.

The Next Wave

Our first big wave of northbound migrants has come and gone, but don’t despair; for spring is still a few days away, and we have yet to reach the end of the beginning …

Migrating Canada Geese
All but the last of the migratory Canada Geese have passed through the lower Susquehanna basin en route to their nesting grounds in the land for which they are named.  Those that remain are mostly members of a resident population established here during the latter decades of the twentieth century.
Migrating Tundra Swans
The majority of the northwest-flying Tundra Swans that wintered on the Atlantic Coastal Plain and will nest in Alaska and western Canada have now traversed our skies and are on their way through the Eastern Great Lakes region.
Snow Goose
Snow Geese too have departed.  Only stragglers like this individual with a wounded wing linger.
Migrating Ring-billed Gulls
Still moving up the river corridor are thousands of Ring-billed Gulls.  Their movements are prolonged, extending through much of the late winter and into early spring with primarily adult birds leading the way.
Red-winged Blackbird
The Red-winged Blackbird exodus continues as well with mostly male birds like this one venturing on ahead of the females to secure suitable breeding sites before the arrival of the competition.
Displaying Common Grackle
Male Common Grackles are coming north to lay claim to favorable nesting habitat too.  In an effort to fend off rivals, a male will thrust back his head and ruffle his feathers to display the colorful sheen adorning his plumage.
Fish Crow
Recognized by their nasal two-syllable calls, Fish Crows have been filtering up the valleys of the river’s main stem and its tributaries for almost a month now.  While the closely related American Crow is numerous throughout the winter in the lower Susquehanna watershed, most of our Fish Crows retreat to the Atlantic Coastal Plain during the colder months.  
Fish Crows
The Fish Crows that return early stake claims on the best nest sites, often in lowland areas where they are sometimes in direct competition with a portion of the population of American Crows that commonly breeds here.

With the arrival of the spring equinox, longer periods of daylight will accompany the return of many more species.  Be sure to get outside, then have a look around.

Look, Up in the Sky, It’s a Bird, No, Wait, It’s a Bunch of Birds!

Step outside, take a listen, and look up.  A substantial northward movement of early migrants is, at this writing, underway across the lower Susquehanna basin—primarily in the skies within five to maybe ten miles of the river corridor.  Within the last hour, we witnessed a steady parade of geese, swans, and blackbirds in the skies above the headquarters garden.  These are not birds that are staging or are in the midst of a stopover here during their journey north.  They are instead flocks taking advantage of favorable conditions to make a big jump from Chesapeake Bay and adjacent areas of the Atlantic Coastal Plain into territory to our north and northwest that was just two weeks ago in the middle of a deep freeze.  Compared to the slowpokes whose northbound movements are a bit more cautious, the shared determination of these birds to get to the nesting grounds first may be advantageous for their breeding success.

Migrating Canada Geese
At least 2,000 migrating Canada Geese passed high above as we strained to see their silhouettes in the sun-drenched haze.
Canada Geese and Blackbirds
Below them, flocks of hundreds of blackbirds including these Common Grackles and Red-winged Blackbirds filtered through.
Migrating Tundra Swans
Perhaps most spectacular were the 1,000 or more Tundra Swans that passed by.  Each year in late February or early March, we look forward to a day or more with a big push of these regal giants.  But you need to get a good look fast…
Tundra Swans
…because they’re gone in just moments for another year.

Winds from the southwest are forecast for the coming couple of days, so the movements could continue.  Head outside, enjoy the weather, and look up.

It’s Snow Goose Time at Middle Creek

In case you haven’t already heard, the Snow Geese are at last filtering north from the Atlantic Coastal Plain to congregate at the Pennsylvania Game Commission’s Middle Creek Wildlife Management Area in Lancaster and Lebanon Counties.

Snow Geese
Compared to recent years, the 2026 spring waterfowl migration has been a bit behind schedule, owing primarily to persisting layers of ice and snow.  As the cover melted from regional fields during the past week, Snow Geese were at last able to find sufficient acreage for grazing, and their numbers at Middle Creek increased rapidly.
Snow Geese at Middle Creek W.M.A.
As many as 60,000 Snow Geese have been enumerated in recent days at the refuge.
Tundra Swans at Midle Creek WMA
And more than 500 Tundra Swans are making a stopover.
Snow Geese at Willow Point
When not in the fields feeding, Snow Geese are concentrated around the small area of open water on the otherwise frozen lake, making them easily observed from the Willow Point viewing area.  If you’re planning to visit and have a look, don’t wait.  The urge to begin their 2,000-mile journey to breeding areas on the arctic tundra is strong, and as soon as conditions permit, they’ll be resuming their excursion.  This could very well be an abbreviated stay.

Start Your Own Tree Nursery

Just a reminder—there’s still time to order trees and shrubs from your local county conservation district’s annual sale, but you need to act soon…

Cumberland County Conservation District 48th Annual Tree Seedling Sale

Order by Friday, March 20, 2026

Pick Up on Thursday, April 16, 2026, or Friday, April 17, 2026

 

Dauphin County Conservation District Seedling Sale

Order by Monday, March 16, 2026

Pick Up on Thursday, April 23, 2026, or Friday, April 24, 2026

 

Franklin County Conservation District Tree Seedling Sale

Order by Tuesday, March 17, 2026

Pick Up on Thursday, April 23, 2026

 

Huntingdon County Conservation District Tree/Seedling Sale

Order by Friday, April 3, 2026

Pick Up on Thursday, April 16, 2026, or Friday, April 17, 2026

 

Lancaster County Conservation District Annual Tree Seedling Sale

Order by Friday, March 6, 2026

Pick Up on Friday, April 10, 2026

 

Lebanon County Conservation District ALL NATIVE! Tree & Plant Sale

Order by Monday, March 2, 2026

Pick Up on Friday, April 17, 2026

 

Mifflin County Conservation District Tree Sale

Order by Friday, March 6, 2026

Pick Up on Wednesday, April 15, 2026, or Thursday, April 16, 2026

 

Schuylkill County Conservation District/Sweet Arrow Lake Conservation Association 51st Annual Seedling Sale

Order by Saturday, March 21, 2026

Pick Up on Saturday, May 2, 2026

 

Snyder County Conservation District Tree Seedling Sale

Order by Monday, March 30, 2026

Pick Up on Wednesday, April 15, 2026

 

York County Conservation District Seedling Sale

Order by Sunday, March 15, 2026

Pick Up on Thursday, April 16, 2026

 

If maybe you would like to order trees but you’re not quite ready to put them in the ground, why not pot them up and start your own plant nursery.  It’s a great way to build an inventory of hardy stock for planting around your own property or for use in community or civic conservation projects.

Potting Sweetgum Seedlings
Earlier this week we potted up some bare-root seedlings in a mix of compost and sand to give them a head start before planting them in the ground either during the coming fall or in years to come.  These happen to be some young American Sweetgum trees we purchased from a nursery in Perkasie, Bucks County, Pennsylvania.
Native Tree Nursery
After watering them in, we added our new trees to the inventory we have available for stream buffers, rain gardens, reforestation, and other rewilding projects.  We’ll either stake or trim them to remedy the curved stems.
Yellow Birch Sapling
In just a season or two, we have nice robust saplings ready to install in a project or in the headquarters garden.  Starting plants in the nursery gives them the size they need to improve their chances of survival.
Norway Spruce
This is one of ten Norway Spruce trees we purchased in a pack from a local conservation district sale almost ten years ago.  We started each two-year-old seedling in a pot, then transplanted them into the ground a year later.  All have been thriving ever since.
Eastern Sycamore
Since being installed as a potted sapling reared in the headquarters nursery about fifteen years ago, this sturdy Eastern Sycamore has matured and is producing seeds relished by American Goldfinches and other birds.
Eastern Sycamore and Conifers
Growing in a streamside woodland, a really massive sycamore that got its start in your nursery could continue to provide valuable wildlife habitat over a lifespan extending one hundred, two hundred, maybe even three hundred years or more.  These long-lived denizens of the floodplain provide homes for such beloved breeding birds as Baltimore Orioles, Bald Eagles, Warbling Vireos, Yellow-throated Warblers, and several species of owls,…
Great Horned Owl Nest in Eastern Sycamore
…including this Great Horned Owl, seen currently incubating eggs inside a legacy sycamore that has been an active nest site among its neighboring Norway Spruces and Eastern White Pines for decades.
Yellow-crowned Night Herons at Nest
Yellow-crowned Night Herons, an endangered species in Pennsylvania, nesting in an Eastern Sycamore planted during the early twentieth century as a street tree very near the Susquehanna in mid-town Harrisburg.  Ordering and planting trees today is essential for their tomorrow.

Adapting to Winter Extremes

During winter’s harshest conditions, one must frequently marvel at the methods various forms of wildlife have to survive.  Take a look at some of the animals we found using their life-sustaining adaptations to find food amidst the snow-covered landscape and bitter cold air.

Blue Jay
We watched this Blue Jay digging to retrieve an acorn from beneath the tuft of leaves and dried grasses where it had apparently concealed it earlier in the season.
Blue Jay Eating Acorn
It then carried it to a nearby limb and chiseled away the husk to devour the nutritious contents.  Blue Jays are known to cache hundreds or even thousands of seeds, nuts, and acorns for winter consumption.  Want to see it for yourself?  Just put out some unshelled no-salt peanuts and watch the jays haul them away, that is if the hoarding squirrels don’t get them first!
Red-headed Woodpecker
Like other members of the Picidae family, Red-headed Woodpeckers pry and chisel away at decaying and insect-infested trees to find food during the winter.
First-winter Red-headed Woodpecker
Like jays, Red-headed Woodpeckers including this first-winter bird are very fond of acorns and will often collect them from the ground.  And like jays, they’ll cache acorns for use as a backup supply when a blanket of snow may prevent them from gathering those that remain beneath the oaks.
Wintercreeper
Native to eastern Asia, Wintercreeper (Euonymus fortunei) has escaped from mostly urban cultivation to become naturalized and often invasive in some wooded areas of the lower Susquehanna River watershed.  It can be quite aggressive, usually found growing as a climbing vine or less frequently as a shrub.  In the absence of native and more palatable foods, the berries are an attractive survival fare for members of the Turidae (thrush) family and other birds.
American Robin
We found this and several hundred more American Robins surviving the current winter weather while feeding on Wintercreeper in a suburban woods with a heavy growth of the invasive plant.
Eastern Bluebird
Several Eastern Bluebirds were seen among the Wintercreeper tangles as well.  They too are relying upon this non-native plant to provide at least a portion of the energy they need to make through blustery February nights.
Hermit Thrush
The Hermit Thrush, a species that nests in the coniferous and mixed forests of the northern United States and Canada, winters sparingly in the lower Susquehanna valley.  We found this one among the robins and bluebirds of the Wintercreeper thicket where it too was probably attracted by the supply of berries.
Brown Creeper
Frequently escaping notice in the winter woods is the Brown Creeper, another species that nests primarily in coniferous and mixed forests to our north, though it does breed in our area at scattered locations, primarily in mountainous or swampy terrain.
Brown Creeper
As their name suggests, Brown Creepers spend nearly all of their time creeping along the bark of mature trees searching for small insects, spiders, and other arthropods and their eggs.  The creeper’s diet changes little with the seasons, but you may occasionally see them visit your bird feeders in winter for a nip of suet.
Winter Wren
The petite Winter Wren exhibits mouse-like behavior as it hops and crawls among logs, rocks, and brush along the banks of wooded waterways.  Like the creeper, it is primarily an insectivore, spending much of its time escaping notice searching beneath streamside structure for its daily nourishment.  In summer, Winter Wrens nest in damp coniferous forests.
Red Fox
Seeing a Red Fox repeatedly during daylight hours is typically considered to be a sign that one may be observing a diseased animal, but we soon determined that there was nothing at all wrong with this vulpid we found patrolling a large woodland lying along the outskirts of a lower Susquehanna city.
Red Fox
Typically when the ground is covered with snow, a Red Fox will hunt for voles or mice by listening for their movements in the runways below, then leaping and pouncing to plunge snout first into the fluff to grab the pinpointed prey.  But the recent rain-soaked snow which is now frozen rock hard prohibits the usual hunting tactic, so this canine has adapted to current conditions.
Red Fox
It has switched from its habitually nocturnal schedule to a day shift in pursuit of a diurnal species of prey rodent which can currently be found in abundance at ground level.  After about forty minutes of watching this fox dart back and forth through the understory growth without ever paying much attention to us, we became certain of its target when the alarm chatter turned to a series of screams as one of the numerous Eastern Gray Squirrels that had been scurrying around fell into the fox’s grip.
Red Fox
Just as suddenly as it had begun, our Red Fox encounter ended as our visitor opted to carry away its quarry and dine in peace.  From all appearances, this particular fox’s only ailment was hunger.  By adapting to prevailing conditions, it was able to fully utilize its opportunistic feeding traits and may thus survive to pass on these qualities to the next generation of Red Foxes.  As for the squirrel, it exhibited a vulnerability that led to its demise.  This vulnerability will not be passed on to a future generation of squirrels.  Though it may run counter to public perception and understanding, the event strengthens local populations of both native species.  And so it goes.

Today’s Middle Creek Snow Goose Count: One

For those of you who may be wondering if there are Snow Geese at Middle Creek Wildlife Management Area, the answer is yes—just one!

Snow Goose
A lone Snow Goose was seen earlier today among about 100 Canada Geese, two dozen Tundra Swans, and a couple of American Black Ducks clustered around a small opening in the ice on the main impoundment at Middle Creek.

So where are the thousands of Snow Geese we’ve grown accustomed to seeing during recent decades as they gather at the refuge in February while preparing to fly north for the summer?

With much of the river and nearly all of the lower Susquehanna basin’s lakes and ponds frozen, Snow Geese and many other migratory waterfowl remain concentrated on the Atlantic Coastal Plain where salty tidewater provides ice-free conditions for feeding and loafing.  In fact, some ducks, particularly diving species, may still be evacuating freshwater locations to our north such as the Eastern Great Lakes where, during the past week, even more surface area has succumbed to freezing.  Look for migrants to begin pushing north in bigger numbers as soon as rising temperatures start to melt local ice.  (NOAA/U.S. National Ice Center image)
Freezing of the Great Lakes has not been this extensive since 2019.  New lake ice (shown in pink) has completed coverage of Lake Erie (lower left), isolated open water from the shorelines of Lake Huron (upper left), and now covers a large portion of the nearshore waters of Lake Ontario (right).  (NOAA/U.S. National Ice Center image)

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 Sparrow
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.
Eastern Gray Squirrel
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.
White-tailed Deity
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.

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 Junco
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.
Dark-eyed Junco
Juncos are seldom seen far from trees, shrubs, and brushy patches of herbaceous growth where they can find both the foods and the protective cover they need to survive the cold.
Northern Mockingbird
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.
Red-breasted Nuthatch
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. 

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.

American Robin
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!

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. 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.
Asiatic Clam
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
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.
First-winter Iceland Gull
Both this first-winter Iceland Gull and the bird from the previous three images are currently being seen just east of the Susquehanna watershed at Blue Marsh Lake in Berks County, Pennsylvania.  Additional Iceland Gulls are currently being reported in Maryland on the Susquehanna at Conowingo Dam; on upper Chesapeake Bay in Baltimore County, Maryland; and in southeastern-most Bucks County, near Tullytown, Pennsylvania, at a busy landfill site that attracts tens of thousands of gulls each winter.  Double-digit numbers of Iceland Gulls have been reported at this latter site during recent weeks.
Lesser Black-backed Gull
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?

First-winter Glaucous Gull.
First-winter Glaucous Gull.

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.

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.

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.
Second-year (Basic I) Bald Eagle
Another of the many second-year Bald Eagles seen on the Susquehanna at Conowingo Dam.
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.
Adult Bald Eagle
An adult Bald Eagle.
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.
Black Vulture
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.
Turkey Vulture
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.
Ring-billed Gulls
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.
Double-crested Cormorants
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.
Common Mergansers
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!

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…

Ruby-crowned Kinglet
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.
Yellow-bellied Sapsucker
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.
American Robin
Migrating American Robins are still transiting region, but an abundance of wild fruits can prompt hundreds to linger through winter.  Look for them near supplies of wild grape, Poison Ivy, dogwood, Virginia Creeper, hackberry, hawthorn, American Holly,…
American Robin
…Eastern Red Cedar,…
American Robin
…and Common Winterberry.
Red-shouldered Hawk
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. 

Photo of the Day

Fox Sparrow
Peak numbers of Fox Sparrows are now moving through the lower Susquehanna valley on their way south.  Nearly as large as our Catharus thrushes, these native songbirds are among the last of our regularly occurring autumn migrants.  In tangled dense thickets along the edges of fields and woodlots, small numbers may linger into winter eating berries and the seeds of herbaceous plants.

Photo of the Day…Again

Red-shouldered Hawk
Back for an afternoon visit on a limb above the pond, our surprise guest seems to find our dining experience irresistible.  During recent winters, the Green Frogs in the headquarters habitat have continued to be active through at least New Year’s Day.  If it appears we’re going to have a Red-shouldered Hawk lingering that long, perhaps we’ll be motivated to clean our windows so we might get an even better look.

Photo of the Day

Red-shouldered Hawk
Earlier this morning, we photographed this adult Red-shouldered Hawk as it took a break from its southbound journey to eye up the Green Frogs in the susquehannawildlife.net headquarters pond.  Hunger must surely outweigh timidity because this bird persisted in its hunt despite the activity of a crew of contractors noisily grinding up asphalt in the street just 40 feet away!

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.

Common Grackles
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 Crow
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.
Common Raven
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.
Common Raven
Ravens are frequently seen in small groups of just two to five birds.  During November however, they may assemble into playful bands of ten or more birds as they roam the ridges in search of suitable places to pass the winter.
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.
Red-tailed Hawk
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.
Osprey
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.
Bald Eagle
Flights right now consist primarily of Bald Eagles.
Bald Eagle
Updrafts created as strong autumn winds strike the slopes of local ridges are providing the lift needed for these birds to cover many miles per day with minimal energy expended.
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.
Bald Eagle
But nearly everyone’s favorite is the close approach of a Bald Eagle in definitive adult plumage.
Golden Eagle
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.

Photo of the Day

Rusty Blackbird
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.

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…

Northern Rough-winged Swallows
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.
Yellow-rumped Warbler
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.
Eastern Chipmunk
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!

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.

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.

Northern Parula
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.
 Red-breasted Nuthatch
It was joined by this Red-breasted Nuthatch near a trickle of water at one of the ponds.
Carolina Chickadee
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.

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.

Tennessee Warbler
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.
Yellow-throated Vireo
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.
Northern Parula
Not to be outdone, this Northern Parula joined in with a cheery tune from yet another Staghorn Sumac.
Black-throated Green Warbler
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.

Ruby-throated Hummingbird
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.
Broad-winged Hawks
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.
Broad-winged Hawks
While passing through the lower Susquehanna valley in fall, Broad-winged Hawks can be seen ascending to greater heights above almost any sun-drenched surface including large parking lots or barren fields.  But to get your best look, visit a ridgetop hawk watch where these birds circle on the rising air created by solar heating of the south-facing slopes.
Sharp-shinned Hawk
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.

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
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”.

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.
Shearness Pool
A map at Shearness Pool, the largest impoundment on the refuge, shows the location of other freshwater pools at Bombay Hook.
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
Semipalmated Plovers and Semipalmated Sandpipers arriving on a mudflat at Raymond Pool.
Short-billed Dowitcher
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
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.
Short-billed Dowitchers
Short-billed Dowitchers probe the mud with their sewing machine-like feeding style.
Short-billed Dowitchers
Seldom do they take a break long enough for an observer to their bill in its entirety.
Lesser Yellowlegs
A Lesser Yellowlegs arrives at Raymond Pool as a high-tide refugee.
Lesser Yellowlegs
Another Lesser Yellowlegs on a mudflat.
Greater Yellowlegs
A Greater Yellowlegs wades into shallow water to feed.
Semipalmated Plovers and Semipalmated Sandpipers
It’s difficult to estimate just how many Semipalmated Plovers and Semipalmated Sandpipers were seen.  There were at least 500 plovers, and they were very vocal.  The latter species was present in numbers measurable in the thousands.  We don’t think 10,000 Semipalmated Sandpipers is an overestimate.
Semipalmated Sandpipers
Searching through the Semipalmated Sandpipers, one could regularly find a very similar species among them.
Western Sandpiper
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.
Western and Semipalmated Sandpipers
A Western Sandpiper (top) photographed with a Semipalmated Sandpiper (bottom) in Bear Swamp Pool.
Snowy Egret
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 Egret
Great Egrets could be seen stalking small fish in the channels of the pools.
Green Heron
And a few Green Herons were found lurking in the vegetation.
Osprey
This Osprey briefly startled the shorebirds on Raymond Pool until they realized it posed no threat.
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

It’s Prime Time for Hummingbirds

Ruby-throated Hummingbird at Scarlet Bee Balm
Now that the nesting season is drawing to a close, Ruby-throated Hummingbirds are a bit less fussy about where they spend their time.  Even in urban settings, gardens with an abundance of nectar-producing flowers like this Scarlet Bee Balm (Monarda didyma) have a good chance of attracting them.  Hummingbirds will be wandering the landscape and starting to drift south during the coming two months, so keep your feeders clean and filled with a fresh blend of sugar water to keep them energized and happy.  If you’re feeding hummingbirds, or thinking about feeding hummingbirds, be sure to review the helpful tips contained in our post from August 5, 2022, “Two Feeders Are Better Than One”.  Their health and your peace of mind may depend on it.

Photographs in Living Color: Black and White is Beautiful

Here at susquehannawildlife.net headquarters, we really enjoy looking back in time at old black-and-white pictures.  We even have an old black-and-white television that still operates quite well.  But on a nice late-spring day, there’s no sense sitting around looking at that stuff when we could be outside tracking down some sightings of a few wonderful animals.

American Toad Tadpoles
American Toad tadpoles have hatched from clusters of eggs deposited in this wet roadside ditch furnished with a clean supply of runoff filtered through a wide shoulder of early successional growth.  Recent rains have kept their vernal nursery flooded, giving them the time they need to quickly mature into tiny toads and hop away before scorching summer heat dries up their natal home.
Water Striders mating.
Weekend rains and creek flooding haven’t stopped these Water Striders from pairing up to begin their breeding cycle.
Common Whitetail
Around streams, lakes, ponds, and wetlands, the Common Whitetail is one of our most conspicuous dragonflies.
Great Blue Heron
Now that’s what we call a big beautiful bill, on a Great Blue Heron stalking fish.
Golden-backed Snipe Flies
These mating Golden-backed Snipe Flies (Chrysopilus thoracicus) are predatory insects, as are their larvae.  They are most frequently found in bottomland woods.
Eastern Ratsnake
About three feet in length, this Eastern Ratsnake is unusual because it still shows conspicuous remnants of the diamond-patterned markings it sported as a juvenile.
Black-and-white Warbler
The plumage of the Black-and-white Warbler lacks any of the vibrant colors found in the rainbow, but is nevertheless strikingly beautiful.
Black-and-white Warbler
This male Black-and-white Warbler appears a little bit ruffled as he dries out his feathers following a brief afternoon downpour. 
Black-and-white Warbler
But as the sunshine returns, he bursts into song from a forest perch within the nesting territory he has chosen to defend.  In addition to the vocalizations, this eye-catching plumage pattern helps advertise his presence to both prospective mates and would-be trespassers alike.  But against the peeling bark of massive trees where this bird can often be found quietly feeding in a manner reminiscent of a nuthatch, the feathers can also provide a surprisingly effective means of camouflage.  

Photo of the Day

Cedar Waxwing Feeding on Juneberries
One of dozens of Cedar Waxwings seen descending upon ripe juneberries in a mini grove consisting of either Smooth Shadbush (Amelanchier laevis) or the allied and very similar-looking hybrid juneberry Amelanchier x lamarkii.  Smooth Shadbush can be grown as a shrub or small tree and is also known as Smooth Serviceberry, Allegheny Serviceberry, or Smooth Juneberry.  The hybrid Amelanchier x lamarkii is believed to be a naturally occurring cross between Smooth Shadbush (A. laevis) and either Canadian Serviceberry (A. canadensis) or Downy Serviceberry (A. arborea).  Juneberries/serviceberries/shadbushes, including a number of man-made cultivars, produce white flowers in early spring and can be obtained through numerous suppliers for inclusion in conservation projects, home gardens, or for use as street trees.  Believe it or not, the very productive planting seen here was located in a parking lot island at a busy Walmart store.

Late May Action in the Forest

Here’s a short preview of some of the finds you can expect during an outing in the Lower Susquehanna River Watershed’s forests this week…

Mountain Laurel
The Mountain Laurel, designated as Pennsylvania’s state flower, is now in bloom.
Mountain Laurel Flower Buds
The buds of the Mountain Laurel remind us of a sugary frosting freshly squeezed from a baker’s pastry bag.
Mountain Laurel Flowers
The flowers of the Mountain Laurel, an evergreen understory shrub, invite pollinators to stop by for a sweet treat.
Little Wood-Satyr
Little Wood-Satyrs (Megisto cymela) are patrolling forest edges looking for mates and, to host their eggs and larvae, the stands of grasses they find most suitable.
Zabulon Skipper
Many of the species of small butterflies we call skippers are now active. The Zabulon Skipper can be found patrolling grassy forest edges, particularly near streams, ponds, and wetlands.
Red-spotted Purple
Among the showiest of our butterflies, the Red-spotted Purple (Limenitis arthemis astyanax) is seen here on the leaves of a Black Cherry, its favored host plant.
Red-spotted Purple
Another red-spotted Purple seen picking up minerals from a dried up puddle depression on a gravel road.
Susquehanna Riverlands State Park
Butterfly observers will do well to pay a visit to the new Susquehanna Riverlands State Park on Furnace Road north of Hellam in York County, Pennsylvania.
Trail to Schull's Rock Overlook
Upon arrival at Susquehanna Riverlands, drive back the gravel road for about a mile to the parking area at the edge of the agricultural field.  Then, hike the trail through the woods and farm hedgerow to the Schull’s Rock overlook on the river.  In the forests along this route, the understory is dominated by colonial stands of Common Pawpaw trees.
Common Pawpaw
Along the lookout trail to Schull’s Rock, the Common Pawpaws’ large leaves help them to shade out potentially fast-growing competition.  In proper growing situations, pawpaws develop clonal suckers that mature over time to create colonial stands of a single genetic plant.
Common Pawpaw understory.
A Common Pawpaw understory along the approach to Schull’s Rock.
Common Pawpaw
A colonial stand of Common Pawpaw along the trail leading to Schull’s Rock.
Zebra Swallowtail
During our recent visit to Schull’s Rock, dozens of Zebra Swallowtails were seen along the trail, many in the vicinity of their sole host plant, the Common Pawpaw.  But even more were observed along the edges of the fields and woods where nectar sources like this Multiflora Rose were being visited by numbers of butterflies we normally see only among abundant species like Cabbage Whites.  Absolutely amazing!
Scull's Rock Overlook
And the view of the Susquehanna and the Shock’s Mills railroad bridge at the mouth of Codorus Creek is pretty good too!
Common Pawpaw and Hooded Warbler
You can look for colonial stands of Common Pawpaw at other parks and preserves along the lower Susquehanna as well.  Birds like this Hooded Warbler can sometimes be found among them in mature riparian forests along the steep slopes of the river gorge.
Common Pawpaw and Baltimore Oriole
A Baltimore Oriole in a Common Pawpaw along a forest edge.
Blackpoll Warbler
Meanwhile in the treetops, the spring thrust of Neotropical migrants is drawing to a close.  The Blackpoll Warbler is typically one of the last to transit the lower Susquehanna valley on its way to northern coniferous forests for summer.  They’ve had an unusually protracted movement through the region this spring, the earliest individuals reported during late April.  Though very difficult to see in the canopy of the mature trees where it feeds and sings, hearing one is often a benchmark for senior birders each spring.  Older observers have often said of the Blackpoll Warbler’s high-pitched song, a rapid series of insect-like staccato “tseet” notes, that it was the first they could no longer detect as their ears started losing sensitivity.
American Redstart
In many tracts along the lower Susquehanna this spring, the American Redstart is turning out to be the most common nesting warbler.  Conditions favoring their reproductive success in recent cycles, as well as good survival rates during their migrations and stays on wintering grounds, have filled many lowland forests with redstart songs in 2025.  Is this the start of a trend or just an exceptionally good year?  Time will tell.
Rose-breasted Grosbeak
Yet one more reason for a stroll in local forests this week is the chance to see and hear the Rose-breasted Grosbeak.  Look for these Neotropical relatives of the cardinal nesting on territories in mature stands of deciduous trees like this Yellow Poplar, a species also known as the Tuliptree.
They spend nearly all their time among the canopy foliage of the largest timber…
Rose-breasted Grosbeak
…but pause frequently to repeat a song often described as something akin to that which might be performed by a robin subjected to voice lessons.  The Rose-breasted Grosbeak is certainly a bird worth seeing and hearing.

Back in the Day: Down on the Farm

Let us travel through time for just a little while to recall those sunny, late-spring days down on the farm—back when the rural landscape was a quiet, semi-secluded realm with little in the way of traffic, housing projects, or industrialized agriculture.  Those among us who grew up on one of these family homesteads, or had friends who did, remember the joy of exploring the meadows, thickets, soggy springs, and woodlots they protected.

Low-intensity Farming
During much of the twentieth century, low-intensity agriculture provided a haven for wildlife.  Periodic disturbances helped maintain cool-season grassland and early successional habitat for a number of species we currently find in decline.

For many of us, farmland was the first place we encountered and began to understand wildlife.  Vast acreage provided an abundance of space to explore.  And the discovery of each new creature provided an exciting experience.

Distributed by the Pennsylvania Game Commission, artist Ned Smith’s wildlife posters introduced many residents of the lower Susquehanna region to its birds and mammals.  This poster of “Birds of Field and Garden” helped us learn what to expect and search for during our forays to the farm.

Today, high-intensity agriculture, relentless mowing, urban sprawl, and the increasing costs and demand for land have all conspired to seriously deplete habitat quality and quantity for many of the species we used to see on the local farm.  Unfortunately for them, farm wildlife has largely been the victim of modern economics.

For old time’s sake, we recently passed a nostalgic afternoon at Middle Creek Wildlife Management Area examining what maintenance of traditional farm habitat has done and can do for breeding birds.  Join us for a quick tour to remember how it used to be at the farm next door…

Barn Swallow
Always found nesting under the forebay of the barn, the Barn Swallow relentlessly pursued flying insects over the pond and meadow.
Eastern Meadowlark
Eastern Meadowlarks arrived during March and April to begin nesting in their namesake.  Their song, “spring-of-the-year”, heralded the new season.
Eastern Kingbird
Arriving in meadows and pastures during early May, the Eastern Kingbird provided for its nestlings by ambushing a variety of flying insects.  By August, congregations of these birds could be found gathering along ponds and streams ahead of their fall migration.
Orchard Oriole
In the cherry grove down by the creek, the Orchard Oriole would be singing incessantly to defend its territory.
American Goldfinches
Normally seed eaters through the colder months, American Goldfinches would regularly find a source of protein in the occupants of Eastern Tent Caterpillar nests.
Yellow Warbler
Along the wet margins of the creek, Yellow Warblers would nest in the shrubs and small trees.
Willow Flycatcher
The “Traill’s Flycatcher” was a familiar find in low-lying areas of successional shrubs and small trees.  Today, “Traill’s Flycatcher” is recognized as two distinct species, the Alder Flycatcher (Empidonax alnorum) and the Willow Flycatcher.  In the lower Susquehanna valley, the latter (seen here) is by far the most common of the two.
Eastern Bluebirds
During the nineteenth century, Eastern Bluebirds became a rarity on lower Susquehanna farms due to a combination of factors: pesticide (DDT) use, habitat loss, and competition with other birds for nest sites.  The species saw a resurgence beginning in the 1970s with discontinuation of DDT applications and widespread provision of nesting boxes.  Around human habitations, competition with invasive House Sparrows continues to be detrimental to their success.
Purple Martins and Tree Swallows
Purple Martins suffered a similar fate to the bluebirds.  The potential for their recovery remains dubious and they continue to be very local breeders, fussy about selection of suitable man-made provisions for nesting.  After considerable effort, Purple Martins have at last been attracted to nest in the condos placed for their use at Middle Creek Wildlife Management Area.  In the artificial gourds, there are nesting Tree Swallows, a species which also benefits from the placement of boxes intended for bluebirds.
Field Sparrow
Abandoned fields and other successional habitats were and continue to be favored homes for Field Sparrows.
Cedar Waxwing
At almost any time of year, roving bands of Cedar Waxwings would suddenly visit old field habitat looking for berries among the shrubs and other pioneering woody growth.  In early summer, after most species have already hatched their young, nesting would commence and these fruit eaters would transform into accomplished fly catchers.
Ring-necked Pheasant
During the twentieth century prior to the 1980s, Ring-necked Pheasant populations in the Lower Susquehanna River Watershed were comprised of breeding descendants of introduced birds supplemented by additional releases to maintain numbers sufficient for hunting.  Year-round populations did and can reside in mosaic landscapes of early successional and grassland habitats, the latter including hay fields left unmowed through the nesting season.
Red-winged Blackbird
Red-winged Blackbirds have always been a fixture of hay fields and meadows on farms.  While the increase in mowing frequency has reduced their nesting success, they have persevered as a species by nesting earlier than other birds and by utilizing other landscape features such as densely vegetated stormwater basins for breeding sites.
Bobolink
Do you recall the last time you saw a Bobolink nesting in a hay field near you?  Arriving in early May as a Neotropical migrant, the Bobolink requires a cool-season grassland such as hay field through at least July to complete its nesting cycle.  Even earlier this century, we remember nesting Bobolinks being more widespread on farms throughout the region.  Now, you almost have to go to Middle Creek if you want to see them.
Grasshopper Sparrow
Formerly more widespread in hay fields throughout the lower Susquehanna valley, the native Grasshopper Sparrow is yet another species falling victim to early mowing and intensive farming.
Grasshopper Sparrow
The solution to their dilemma is as advertised.  Instead of cutting the grass, why not take heed of the example set here and cut back on the tens of thousands of acres that are excessively or needlessly mowed in the Lower Susquehanna River Watershed?  How ’bout letting a significant percentage of your property regenerate as successional habitat as well?  It can and does make a difference!
Cool-season Grasses
Beautiful cool-season grasses waving in the spring breeze.  Meadows and hay fields can be managed to function as cool-season grasslands to provide nesting opportunities for many of the species we used to find down on the farm.