Caspian Tern – LIFE IN THE LOWER SUSQUEHANNA RIVER WATERSHED

August 26, 2024September 13, 2024

Southbound Flights: On Their Way Both Night and Day

It’s hard to believe, but for almost two months now, sandpipers, plovers, and terns have been filtering south through the Lower Susquehanna River Watershed on their way to the Atlantic coastline as they complete the first leg of their long autumn migration—a journey that will take some species all the way to the far reaches of the South American continent for winter.

Caspian Terns and Osprey — Migrating Caspian Terns and an Osprey take a break on a lower Susquehanna valley gravel bar.

As August draws to a close, these early birds are being joined by widespread nocturnal flights of Neotropical migrants—those species, primarily songbirds, on their way to wintering grounds which lie exclusively south of the continental United States.

To catch a glimpse of these night-flying avians, your best bet may be to position yourself on the crest of a ridge or along a linear break in the forest such as a utility right-of-way where waves of warblers, vireos, flycatchers, and other Neotropical passerines sometimes feed on invertebrates after making landfall at daybreak. Pick a place where the trees are bathed in the warm light of the rising sun and be there by 7 A.M. E.D.T. The activity can be tremendous, but it usually ends between 8 and 9.

One of more than half a dozen Red-eyed Vireos seen during a daybreak fallout at Second Mountain Hawkwatch in Lebanon County earlier this week.

During sunrise, a just-arrived Blackburnian Warbler checks the foliage of a ridgetop Red Maple for insects.

A Least Flycatcher quietly searches the shrubby growth along the forest edge for a morning meal.

A Black-and-white Warbler in the first hour of sunlight after a big nocturnal flight.

A Scarlet Tanager having a look around. This individual and other migrating birds may be here for a few days before moving on.

A Black-throated Green Warbler in a treetop glowing with the light of sunrise.

A hungry Chestnut-sided Warbler inspects limbs, leaves, and twigs looking for nourishment after an all-night flight.

Diurnal migrants, birds that make their movements during the daylight hours, are ramping up their flights now as well. Broad-winged Hawks, Bald Eagles, and falcons are currently being tallied at hawk-counting stations throughout the northeast. Many of those lookouts are seeing Ruby-throated Hummingbirds, swallows, and other daytime migrants too.

Many American Kestrels transit our area in August and early September, a time coinciding with flights of migratory dragonflies, insects upon which they and another falcon, the Merlin, frequently prey.

Chimney Swifts are fast-flying diurnal migrants. They are beginning to congregate into larger groups in preparation for their departure. Some are already on the move.

Cedar Waxwings are currently being seen in roving flocks throughout the region. Their migration is less of a point-to-point flight and more of a continuous wandering in search of berries and other wild foods.

Not everyone is yet ready to go. American Goldfinches are still in the midst of their nesting cycle and won’t begin leaving until the young are on their own and colorful adult males like this one are beginning to molt into their drab winter plumage.

Autumn migration flights are an ever-changing process, with different species peaking at different times throughout the season. In these months just after the nesting season, each of these species is more numerous than at any other time of the year. And of course, the more often we as observers get out and have a look, the more of them we’ll see.

Be certain to click the “Birds” tab at the top of this page for a photo guide to the species you’re likely to see passing through the lower Susquehanna valley this fall. Nearly four months of autumn hawk migration flights lie ahead, so don’t forget to click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab to find a hawk-counting station near you, then stop by for a visit or two. See you there!

Nocturnal Migrants at Liftoff — A large nightfall liftoff of nocturnal migrating birds is shown here on this evening’s State College, Pennsylvania, Doppler Radar base velocity loop. Returns indicating birds moving toward the radar site (the white dot in the center of the color mass) are shown in green, and those indicating birds moving away are indicated in red. This is a big flight headed generally in a south-southwest direction. (NOAA/National Weather Service Doppler Radar image)

July 24, 2023August 25, 2023

Shorebirds and More at Bombay Hook National Wildlife Refuge

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

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

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

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

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

A Great Blue Heron at high tide on the edge of a tidal creek that borders Bombay Hook’s tour route at Raymond Pool.

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

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

Two more Short-billed Dowitchers on the way in.

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

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

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

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

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

American Avocets probe the muddy bottom of Raymond Pool.

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

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

A Greater Yellowlegs at Bear Swamp Pool.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

A male Atlantic Marsh Fiddler Crab peers from its den.

A Green Heron seen just before descending into the cordgrass to find fiddler crabs for dinner.

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

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

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

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

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

Indigo Buntings nest in areas of successional growth and yes, that is a Spotted Lanternfly on the grape vine at the far right side of the image.

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

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

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

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

The White-tailed Deity is common along the road to Finis Pool.

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

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

Just as quail led us into the refuge this morning, this Wild Turkey did us the courtesy of leading us to the way out in the afternoon.

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

August 20, 2021August 22, 2021

Shorebirds at Middle Creek

Late August and early September is prime time to see migrating shorebirds as they pass through the lower Susquehanna valley during their autumn migration, which, believe it or not, can begin as early as late June. These species that are often assumed to spend their lives only near the seashore are regular visitors each fall as they make their way from breeding grounds in the interior of Canada to wintering sites in seacoast wetlands—many traveling as far south as Central and South America.

Low water levels on the Susquehanna River often coincide with the shorebird migration each year, exposing gravel and sand bars as well as vast expanses of muddy shorelines as feeding and resting areas for these traveling birds. This week though, rain from the remnants of Tropical Storm Fred arrived to increase the flow in the Susquehanna and inundate most of the natural habitat for shorebirds. Those on the move must either continue through the area without stopping or find alternate locations to loaf and find food.

The draining and filling of wetlands along the river and elsewhere in the region has left few naturally-occurring options. The Conejohela Flats south of Columbia offer refuge to many migrating sandpipers and their allies, the river level there being controlled by releases from the Safe Harbor Dam during all but the severest of floods. Shorebirds will sometimes visit flooded fields, but wide-open puddles and farmland resembling mudflats is more of springtime occurrence—preceding the planting and growth of crops. Well-designed stormwater holding facilities can function as habitat for sandpipers and other wildlife. They are worth checking on a regular basis—you never know what might drop in.

Right now, there is a new shorebird hot spot in the Lower Susquehanna River Watershed—Middle Creek Wildlife Management Area. The water level in the main impoundment there has been drawn down during recent weeks to expose mudflats along the periphery of nearly the entire lake. Viewing from “Stop 1” (the roadside section of the lake in front of the refuge museum) is best. The variety of species and their numbers can change throughout the day as birds filter in and out—at times traveling to other mudflats around the lake where they are hidden from view. The birds at “Stop 1” are backlit in the morning with favorable illumination developing in the afternoon.

Have a look at a few of the shorebirds currently being seen at Middle Creek…

The Killdeer is familiar as a breeding bird in the lower Susquehanna region. Large numbers can congregate ahead of and during migration on mudflats and gravel bars.

The Least Sandpiper is one of the “peeps”, a group of very small shorebirds. This species is quite common at Middle Creek right now. Note the plants beginning to grow in the mud. Later in the fall, after the shorebirds are gone, raising the water level in the lake will flood these newly vegetated areas to provide an abundance of food for migrating waterfowl. This cycle can be repeated annually to support transient birds during what is often the most vulnerable time of their lives…fall migration.

The Baird’s Sandpiper (Calidris bairdii) is an uncommon “peep” along the east coast during autumn migration. On the lower Susquehanna it is most frequently encountered on the vegetated gravel bars in mid-river during the last days of August or first days of September each year. The mudflats and shallows at Middle Creek are providing a suitable alternative for this juvenile bird.

Numbers of Lesser Yellowlegs are increasing as flocks drop by for a rest and refueling. Bring your binoculars and your spotting scope to see the oddities that may be hiding among these groups of newly-arriving migrants.

The aquatic environs at Middle Creek attract other species as well. Here are some of the most photogenic…

The migration of Caspian Terns coincides with that of shorebirds. Just look at that blood-red bill; it’s unmistakable. Two of these big terns are currently patrolling Middle Creek’s lake and shoreline.

A female American Kestrel creates a stir among the “peeps” as it passes by. The larger falcons (the Merlin and Peregrine) can be expected to more readily take advantage of concentrations of shorebirds as a food supply.

Osprey migration is underway, and many will stop at Middle Creek while in transit.

Even if shorebirds aren’t your thing, there are almost always Bald Eagles to be seen at Middle Creek. See you there!

September 9, 2017September 4, 2019

Piles of Green Tape

A couple of inches of rain this week caused a small increase in the flow of the river, just a burp, nothing major. This higher water coincided with some breezy days that kicked up some chop on the open waters of the Susquehanna upstream of Conewago Falls. Apparently it was just enough turbulence to uproot some aquatic plants and send them floating into the falls.

Piled against and upon the upstream side of many of the Pothole Rocks were thousands of two to three feet-long flat ribbon-like opaque green leaves of Tapegrass, also called Wild Celery, but better known as American Eelgrass (Vallisneria americana). Some leaves were still attached to a short set of clustered roots. It appears that most of the plants broke free from creeping rootstock along the edge of one of this species’ spreading masses which happened to thrive during the second half of the summer. You’ll recall that persistent high water through much of the growing season kept aquatic plants beneath a blanket of muddy current. The American Eelgrass colonies from which these specimens originated must have grown vigorously during the favorable conditions in the month of August. A few plants bore the long thread-like pistillate flower stems with a fruit cluster still intact. During the recent few weeks, there have been mats of American Eelgrass visible, the tops of their leaves floating on the shallow river surface, near the east and west shorelines of the Susquehanna where it begins its pass through the Gettysburg Basin near the Pennsylvania Turnpike bridge at Highspire. This location is a probable source of the plants found in the falls today.

Uprooted American Eelgrass floating into the Pothole Rocks under the power of a north wind. Note the white thread-like pistillate flower stem to the left and the small rooted specimen to the upper right. The latter is likely a plant from the creeping rootstock on the edge of a colony. As a native aquatic species, American Eelgrass is a critical link in the Susquehanna River and Chesapeake Bay food chain. Its decimation by pollution during the twentieth century led to migration pattern alterations and severe population losses for the Canvasback *(Aythya valisineria)* duck.

American Eelgrass, a very small specimen, found growing in a low-lying Pothole Rock alongside the accumulations of freshly arriving material from upstream. Note that the creeping rootstock has leaves growing from at least three nodes on this plant. Eelgrass dislocations are regular occurrences which sometimes begin new colonies, like the small one seen here in this Diabase Pothole Rock Microhabitat.

The cool breeze from the north was a perfect fit for today’s migration count. Nocturnal migrants settling down for the day in the Riparian Woodlands at sunrise included more than a dozen warblers and some Gray Catbirds (Dumetella carolinensis). Diurnal migration was underway shortly thereafter.

A moderate flight of nocturnal migrants is indicated around NEXRAD sites in the northeastern states at 3:18 AM EDT. The outer rain bands of Hurricane Irma can be seen approaching the Florida Keys as the storm closes in on the peninsula. (NOAA/National Weather Service image)

Four Bald Eagles were counted as migrants this morning. Based on plumage, two were first-year eagles (Juvenile) seen up high and flying the river downstream, one was a second-year bird (Basic I) with a jagged-looking wing molt, and a third was probably a fourth year (Basic III) eagle looking much like an adult with the exception of a black terminal band on the tail. These birds were the only ones which could safely be differentiated from the seven or more Bald Eagles of varying ages found within the past few weeks to be lingering at Conewago Falls. There were as many as a dozen eagles which appeared to be moving through the falls area that may have been migrating, but the four counted were the only ones readily separable from the locals.

Red-tailed Hawks (Buteo jamaicensis) were observed riding the wind to journey not on a course following the river, but flying across it and riding the updraft on the York Haven Diabase ridge from northeast to southwest.

Bank Swallows (Riparia riparia) seem to have moved on. None were discovered among the swarms of other species today.

Ruby-throated Hummingbirds, Caspian Terns, Cedar Waxwings (Bombycilla cedrorum), and Chimney Swifts (Chaetura pelagica) were migrating today, as were Monarch butterflies.

Not migrating, but always fun to have around, all four wise guys were here today. I’m referring to the four members of the Corvid family regularly found in the Mid-Atlantic states: Blue Jay (Cyanocitta cristata), American Crow (Corvus brachyrhynchos), Fish Crow (Corvus ossifragus), and Common Raven (Corvus corax).

It looks like a big Blue Jay, but it’s not. This Belted Kingfisher *(Megaceryle alcyon)* takes a break after flying around the falls trying to shake a marauding Ruby-throated Hummingbird off its tail.

CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS

SOURCES

Klots, Elsie B. 1966. The New Field Book of Freshwater Life. G. P. Putnam’s Sons. New York, NY.

September 4, 2017September 4, 2019

Suggestive Selling

A Baltimore Oriole (Icterus galbula) glowed in the first sunlight of the day as it began illuminating the treetops. I’m not certain of the cause, but I often have the urge to dig into a bowl of orange sherbet after seeing one these magnificent blackbirds. That’s right, in the Americas, orioles and blackbirds are members of the same family, Icteridae. Look at blackbirds more carefully, you might see the resemblance.

Sunshine at dawn and migrating warblers were again active in the foliage. Eight species were identified today. Off to the tropics they go. To the land of palm and citrus, yes citrus…limes, lemons, grapefruits, and oranges.

The Ruby-throated Hummingbirds (Archilochus colubris) are on the way toward the gulf states, then on to Central and South America. Five dashed by the rocky lookout in the falls this morning. Remember, keep your feeders clean, wash and rinse all the parts, and refill them with a fresh batch of “nectar”, four or five parts water to one part sugar. Repeating this process daily during hot weather should keep contamination from overtaking your feeder. It’s not a bad idea to rotate two feeders. Have one cleaned, rinsed, and air drying while the second is filled and in use at your feeding station, then just swap them around. Your equipment will be just as clean as it is at the sanitary dairy…you know, where they make sherbet.

The first of the season Caspian Terns (Hydroprogne caspia), giant freshwater versions of the terns you see at the seashore, passed through the falls late this morning. Their bills are blood-red, not orange like the more familiar terns on the coast. They’re stunning.

Ring-billed Gulls (Larus delawarensis) have been at the falls for several weeks. Total numbers and the composition of the age groups in the flock change over the days, so birds appear to be trickling through and are then replaced by others coming south. The big push of southbound migrants for this and many other species that winter locally in the Mid-Atlantic region and in the southern United States is still more than a month away. There are still plenty more birds to come after the hours of daylight are reduced and the temperatures take a dip.

A Ring-billed Gull on the lookout for a morning snack. They’ll eat almost anything and do a good job of keeping the river picked clean of the remains of animals that have met misfortune. They’ll linger around landfills, hydroelectric dams, and fast-food restaurant parking lots through the winter.

Turkey Vultures *(Cathartes aura)* are common around the falls due to the abundance of carrion in the vicinity and because of the strong thermal updrafts of air over the sun-heated Pothole Rocks. These rising currents provide lift for circling vultures. We would expect migrating birds of a number of species will also take advantage of these thermals to gain altitude and extend the distance of their glides.

Some migrating butterflies were counted today. Cloudless Sulphurs, more of a vagrant than a migrant, and, of course, Monarchs. I’ll bet you know the Monarch, it’s black and orange. How can you miss them, colored orange.

That’s it, that’s all for now, I bid you adieu…I’m going to have a dip of orange sherbet, or two.