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.

Red-eyed Vireo
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.
Blackburnian Warbler
During sunrise, a just-arrived Blackburnian Warbler checks the foliage of a ridgetop Red Maple for insects.
Least Flycatcher
A Least Flycatcher quietly searches the shrubby growth along the forest edge for a morning meal.
Black-and-white Warbler
A Black-and-white Warbler in the first hour of sunlight after a big nocturnal flight.
Scarlet Tanager
A Scarlet Tanager having a look around.  This individual and other migrating birds may be here for a few days before moving on.
Black-throated Green Warbler
A Black-throated Green Warbler in a treetop glowing with the light of sunrise.
Chestnut-sided Warbler
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.

Broad-winged Hawk
While many diurnal migrants gather in flocks as a method of defense against predators, Broad-winged Hawks congregate as a reconnaissance measure.  Not waiting around for strong autumn winds to be deflected upwards by the region’s numerous ridges, these Neotropical birds migrate early enough in the season to rely upon thermal updrafts from sun-heated surfaces to provide lift, gain altitude, and save energy during their long trip.  By traveling in groups, there are collectively able to better locate and utilize rising air columns as they progress southwesterly along their route.  Broad-winged Hawks travel to Central and South America for winter.  Their numbers in the Lower Susquehanna River Watershed will peak during the third week of September.
American Kestrel
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
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 Waxwing
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.
American Goldfinch
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!

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)

Snow Geese, Bald Eagles, and More at Middle Creek Wildlife Management Area

To take advantage of this unusually mild late-winter day, observers arrived by the thousands to have a look at an even greater number of migratory birds gathered at the Pennsylvania Game Commission’s Middle Creek Wildlife Management Area.  Here are some highlights…

Trails at Middle creek Wildlife Management Area
Multitudes of Sunday hikers enjoyed the warm afternoon on Middle Creek’s many trails.
Painted Turtles
In one of Middle Creek’s numerous impoundments, newly emerged Painted Turtles bask in the sunshine.
Brown-headed Cowbird
Native blackbirds, particularly males including this Brown-headed Cowbird, are arriving to stake out a claim on suitable breeding territory.
Red-winged Blackbirds
Male Red-winged Blackbirds visit the feeding station at the Middle Creek W.M.A. Visitor’s Center.
Brown-headed Cowbird and Red-winged Blackbird
Brown-headed Cowbirds regularly maintain close association with Red-winged Blackbirds, a frequent victim of the former’s nest parasitism, the practice of laying and abandoning their eggs in a host species’ abode.  By early May, adult “red-wings” can often be seen tending fledged cowbird young raised at the expense of their own progeny.
Common Grackles displaying.
Male Common Grackles display their colors in an attempt to establish dominance.
White-crowned Sparrow
Visitor’s to Middle Creek’s Willow Point Trail not only had a chance to see thousands of geese and other waterfowl, but they might also get a good look at some of the handsome White-crowned Sparrows that have been there during recent weeks.
Tree Swallow
The first Tree Swallows of the season have arrived to stake a claim to nest boxes located throughout the refuge’s grasslands.
Killdeer
Bare croplands and muddy shorelines around Middle Creek’s lakes and ponds are attracting migrating Killdeer.  Some will stay to nest.
Ring-billed Gulls
Hundreds of Ring-billed Gulls arrived during the late afternoon to spend the night on the main lake.
Red-tailed Hawk
A Red-tailed Hawk was seen hunting mice and exhibiting territorial behavior.  It is probably protecting a nest site somewhere on the refuge.
Canada Geese
Canada Geese could be seen coming and going, with migratory birds apparently supplementing the resident flock.  This group flushed when a Bald Eagle passed close by.
Bald Eagles
You could hold a Bald Eagle I.D. clinic at Middle Creek W.M.A. right now.  Dozens of birds of varying age classes could be seen in the trees surrounding the main lake and the larger ponds.  Currently, fifty or more could be present.  At least one Golden Eagle has been seen as well.
Adult Bald Eagle
An adult Bald Eagle in definitive plumage investigating the inhabitants of the lake.
Second-year Bald Eagle
This Bald Eagle in its second calendar year is not yet one year of age, but it has already begun replacing dark body feathers with a light plumage that will earn it the nickname “white belly” for this and its third year.  It will start molting its long hatch-year (juvenile) flight feathers soon after its first birthday.
Second-year Bald Eagle and Red-tailed Hawk
Another second-year immature Bald Eagle, this one being scolded by the aforementioned territorial Red-tailed Hawk.  Though showing some wear in the tail, this eagle still has a full set of lengthy hatch-year (juvenile) flight feathers and remains mostly dark below when compared to the bird of the same age class seen in the previous image.  As in other birds, diet, genetics, stress, climatic conditions, and many other factors will frequently vary the timing of molt among individuals in a population of Bald Eagles.
Third-year Bald Eagle
An immature Bald Eagle in its third calendar year still retaining numerous long juvenile wing and tail feathers.   In coming months, as it reaches its second birthday, it will begin replacing the remaining older plumage with a set of new flight feathers.
Fourth-year Bald Eagle
An immature Bald Eagle in its fourth calendar year approaches its third birthday with a rather conspicuous long juvenile feather remaining in each wing.  These feathers will soon be replaced.  In addition, the body plumage will darken, the head will begin to show more white, and the bill will become yellow.  In about two more years, the bird will attain its familiar adult definitive plumage.  Click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page to learn more about determining the age of these and other birds of prey.
Snow Geese and Observers at Middle Creek W.M.A.
Bald Eagles draw a crowd, but the real attraction at Middle Creek W.M.A. in late winter is Snow Geese,…
Snow Geese
…thousands of them.
Snow geese at Middle Creek W.M.A.
Migratory Snow Geese, an annual spectacle at Middle Creek.
Snow Geese and hundreds of onlookers.
Snow Geese and hundreds of delighted onlookers.

Snow Geese at M.C.W.M.A.

Snow geese at Middle Creek W.M.A.
The late afternoon sky filled with Snow Geese.
Short-eared Owl at M.C.W.M.A.
As daylight waned and the Snow Geese returned to the main lake for the night, more than one hundred lucky observers were treated to the rare sight of several Short-eared Owls (Asio flammeus) emerging to hunt the refuge’s managed grasslands for mice and voles.  For many of these visitors, it was a memorable first-time experience.

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.

Northern Bobwhite
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.
Great Blue Heron
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
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.
Short-billed Dowitchers
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.
Short-billed Dowitchers
More Short-billed Dowitchers arriving to feed in Raymond Pool.
Semipalmated Sandpipers
Hundreds of Semipalmated Sandpipers gathered in shallow water where mudflats are usually exposed during mid-summer in Raymond Pool.
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
Short-billed Dowitchers wading to feed in the unusually high waters of Raymond Pool.
Short-billed Dowitchers, American Avocets, and a Snowy Egret
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
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.
Least Sandpiper
This Least Sandpiper found a nice little feeding area all to itself at Bear Swamp Pool.
Lesser Yellowlegs
Lesser Yellowlegs at Bear Swamp Pool.
Lesser Yellowlegs
Lesser Yellowlegs at Bear Swamp Pool
Greater Yellowlegs
A Greater Yellowlegs at Bear Swamp Pool.
Caspian Tern
A Caspian Tern patrolling Raymond 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.
Seaside Dragonlet
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 Blackbird
Red-winged Blackbirds are still nesting at Bombay Hook, probably tending a second brood.
Bobolink
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.
Trumpeter Swans
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.
Great Egret
A Great Egret prowling Shearness Pool.
Snowy Egret
A Snowy Egret in Bear Swamp Pool.
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.

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.
Atlantic Horseshoe Crab
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.
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.
Atlantic Marsh Fiddler Crabs
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).
Atlantic Marsh Fiddler Crabs
Atlantic Marsh Fiddler Crabs and their extensive system of burrows help prevent the compaction of tidal soils and thus help maintain ideal conditions for the pure stands of Saltwater Cordgrass that trap sediments and sequester nutrients in coastal wetlands.
Atlantic Marsh Fiddler Crab
A male Atlantic Marsh Fiddler Crab peers from its den.
Great Egret
Herons and egrets including this Great Egret are quite fond of fiddler crabs.  As the tide goes out, many will venture away from the freshwater pools into the salt marshes to find them.
Green Heron
A Green Heron seen just before descending into the cordgrass to find fiddler crabs for dinner.
Clapper Rail
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
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 Bunting
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 Grosbeak
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.
White-tailed Deity
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.
Wild Turkey
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.

A Limpkin’s Journey to Pennsylvania: A Waffle House Serving Escargot at Every Exit

Mid-summer can be a less than exciting time for those who like to observe wild birds.  The songs of spring gradually grow silent as young birds leave the nest and preoccupy their parents with the chore of gathering enough food to satisfy their ballooning appetites.  To avoid predators, roving families of many species remain hidden and as inconspicuous as possible while the young birds learn how to find food and handle the dangers of the world.

But all is not lost.  There are two opportunities for seeing unique birds during the hot and humid days of July.

First, many shorebirds such as sandpipers, plovers, dowitchers, and godwits begin moving south from breeding grounds in Canada.  That’s right, fall migration starts during the first days of summer, right where spring migration left off.  The earliest arrivals are primarily birds that for one reason on another (age, weather, food availability) did not nest this year.  These individuals will be followed by birds that completed their breeding cycles early or experienced nest failures.  Finally, adults and juveniles from successful nests are on their way to the wintering grounds, extending the movement into the months we more traditionally start to associate with fall migration—late August into October.

For those of you who find identifying shorebirds more of a labor than a pleasure, I get it.  For you, July can bring a special treat—post-breeding wanderers.  Post-breeding wanderers are birds we find roaming in directions other than south during the summer months, after the nesting cycle is complete.  This behavior is known as “post-breeding dispersal”.  Even though we often have no way of telling for sure that a wandering bird did indeed begin its roving journey after either being a parent or a fledgling during the preceding nesting season, the term post-breeding wanderer still applies.  It’s a title based more on a bird sighting and it’s time and place than upon the life cycle of the bird(s) being observed.  Post-breeding wanderers are often southern species that show up hundreds of miles outside there usual range, sometimes traveling in groups and lingering in an adopted area until the cooler weather of fall finally prompts them to go back home.  Many are birds associated with aquatic habitats such as shores, marshes, and rivers, so water levels and their impact on the birds’ food supplies within their home range may be the motivation for some of these movements.  What makes post-breeding wanderers a favorite among many birders is their pop.  They are often some of our largest, most colorful, or most sought-after species.  Birds such as herons, egrets, ibises, spoonbills, stilts, avocets, terns, and raptors are showy and attract a crowd.

While it’s often impossible to predict exactly which species, if any, will disperse from their typical breeding range in a significant way during a given year, some seem to roam with regularity.  Perhaps the most consistent and certainly the earliest post-breeding wanderer to visit our region is the “Florida Bald Eagle”.  Bald Eagles nest in “The Sunshine State” beginning in the fall, so by early spring, many of their young are on their own.   By mid-spring, many of these eagles begin cruising north, some passing into the lower Susquehanna valley and beyond.  Gatherings of dozens of adult Bald Eagles at Conowingo Dam during April and May, while our local adults are nesting and after the wintering birds have gone north, probably include numerous post-breeding wanderers from Florida and other Gulf Coast States.

So this week, what exactly was it that prompted hundreds of birders to travel to Middle Creek Wildlife Management Area from all over the Mid-Atlantic States and from as far away as Colorado?

Birders observing something special at Middle Creek Wildlife Management Area on July 10, 2023.

Was it the majestic Great Blue Herons and playful Killdeer?

Great Blue Heron
Great Blue Heron and a Killdeer.

Was it the colorful Green Herons?

Green Heron
Green Heron

Was it the Great Egrets snapping small fish from the shallows?

Great Egret
Great Egret

Was it the small flocks of shorebirds like these Least Sandpipers beginning to trickle south from Canada?

Least Sandpipers
Least Sandpipers

All very nice, but not the inspiration for traveling hundreds or even thousands of miles to see a bird.

It was the appearance of this very rare post-breeding wanderer…

Limpkin at Middle Creek Wildlife Management Area
A Limpkin at Middle Creek Wildlife Management Area in Lancaster County.  The Limpkin (Aramus guarauna) is the only surviving member of the family Aramidae.

…Pennsylvania’s first record of a Limpkin, a tropical wading bird native to Florida, the Caribbean Islands, and South America.  Many observers visiting Middle Creek Wildlife Management Area had never seen one before, so if they happen to be a “lister”, a birder who keeps a tally of the wild bird species they’ve seen, this Limpkin was a “lifer”.

The Limpkin is an inhabitant of vegetated marshlands where it feeds almost exclusively upon large snails of the family Ampullariidae, including the Florida Applesnail (Pomacea paludosa), the largest native freshwater snail in the United States.

Native and Non-native Range of Florida Applesnail
In the United States, the native range of the Limpkin lies within the native range of the Florida Applesnail, shown here in gold.  Introduced populations of the snail are shown in brown.  (United States Geological Survey Nonindigenous Aquatic Species image)
A spectacular nineteenth-century rendition of the Florida Applesnail, including an egg mass, illustrated by Helen E. Lawson in Samuel S. Haldeman’s “Monograph of the Freshwater Univalve Mollusca of the United States”.

Observations of the Limpkin lingering at Middle Creek Wildlife Management Area have revealed a pair of interesting facts.  First, in the absence of Florida Applesnails, this particular Limpkin has found a substitute food source, the non-native Chinese Mystery Snail (Cipangopaludina chinensis).  And second, Chinese Mystery Snails have recently become established in the lakes, pools, and ponds at the refuge, very likely arriving as stowaways on Spatterdock (Nuphar advena) and/or American Lotus (Nelumbo lutea), native transplants brought in during recent years to improve wetland habitat and process the abundance of nutrients (including waterfowl waste) in the water.

A Chinese Mystery Snail.
The Chinese Mystery Snail is the largest freshwater snail in the Lower Susquehanna River Watershed.  (Vintage 35 mm image)
By hitching a ride on aquatic transplants like this Spatterdock, non-native freshwater snails are easily vectored into new areas outside their previous range.
Spatterdock, a native species also known as Yellow Pond Lily or Cow Lily.
Spatterdock, a native species also known as Yellow Pond Lily or Cow Lily, flowering in August.
American Lotus in flower at Middle Creek Wildlife Management Area.
Blooming American Lotus transplants in a pool at Middle Creek Wildlife Management Area during August.
The Limpkin at Middle Creek W.M.A. capturing a Chinese Mystery Snail.
The Limpkin at Middle Creek W.M.A. capturing a Chinese Mystery Snail.
The Limpkin at Middle Creek carrying a Chinese Mystery Snail.
The Limpkin at Middle Creek carrying a Chinese Mystery Snail.
Limpkin holding Chinese Mystery Snail
The Limpkin is seen here maneuvering the the snail in its bill, a set of mandibles specially adapted for extracting the bodies of large freshwater snails from their shells.
Limpkin Grasping Chinese Mystery Snail
The tweezers-like tip of the bill is used to grasp the shell by the rim of the opening or by the “trapdoor” (operculum) that protects the snail inside.
Chinese Mystery Snail
A posed Chinese Mystery Snail showing its “trapdoor”, the operculum protecting the soft body tissue when the animal withdraws inside.  The tips of the Limpkin’s bill close tightly like the end of a tweezers to grasp the operculum and remove it and the snail’s body from the shell.  (Vintage 35 mm image)
Limpkin Removing Chinese Mystery Snail from Shell
The tweezers-tipped bill, which is curved slightly to the right in some Limpkins, is slid into the shell to grasp the snails body and remove it for consumption.  The entire extraction process takes 10 to 30 seconds.

The Middle Creek Limpkin’s affinity for Chinese Mystery Snails may help explain how it was able to find its way to Pennsylvania in apparent good health.  Look again at the map showing the range of the Limpkin’s primary native food source, the Florida Applesnail.  Note that there are established populations (shown in brown) where these snails were introduced along the northern coast of Georgia and southern coast of South Carolina…

Native and Non-native Range of Florida Applesnail
Native (gold) and non-native (brown) ranges of the Florida Applesnail.  (United States Geological Survey Nonindigenous Aquatic Species image)

…now look at the latest U.S.G.S. Nonindigenous Aquatic Species map showing the ranges (in brown) of established populations of non-native Chinese Mystery Snails…

Range (in brown) of established populations of non-native Chinese Mystery Snails.  (United States Geological Survey Nonindigenous Aquatic Species image)

…and now imagine that you’re a happy-go-lucky Limpkin working your way up the Atlantic Coastal Plain toward Pennsylvania and taking advantage of the abundance of food and sunshine that summer brings to the northern latitudes.  It’s a new frontier.  Introduced populations of Chinese Mystery Snails are like having a Waffle House serving escargot at every exit along the way!

Be sure to click the “Freshwater Snails” tab at the top of this page to learn more about the Chinese Mystery Snail and its arrival in the Lower Susquehanna River Watershed.  Once there, you’ll find some additional commentary about the Limpkin and the likelihood of Everglade Snail Kites taking advantage of the presence of Chinese Mystery Snails to wander north.  Be certain to check it out.

Everglade Snail Kite
The endangered Everglade Snail Kite (Rostrhamus sociabilis plumbeus), a Florida Applesnail specialist, has survived in part due to its ability to adapt to eating the non-native Pomacea maculata applesnails which have become widespread in Florida following releases from aquaria.  The adaptation?…a larger body and bill for eating larger snails.  (National Park Service image)

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


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


DAY ELEVEN—May 31, 1983

“AOK Camp, Texas — 7 Miles S. of Kingsville”

“Went south to the 1st rest stop south of Sarita — No Tropical Parula.  Lots of other birds.  We added Summer Tanager and Lesser Goldfinch.”

The Sarita Rest Area along Route 77 was like a little oasis of taller trees in the Texas scrubland.  We received reports from the birders we met yesterday at Falcon Dam that recently, Tropical Parula had been seen there.  We searched the small area and listened carefully, but to no avail.  For these warblers, nesting season was over.  We were surprised to find Lesser Goldfinches in the trees.  Back in 1983, the coastal plain of Texas was pretty far east for the species.  Steve was a bit skeptical when we first spotted them, but once they came into plain view, he was a believer.  I recall him finally exclaiming, “They are Lesser Goldfinches.”  Summer Tanager was another wonderful surprise.  Today, the Sarita Rest Area remains a stopping point for birders in south Texas.  Both Lesser Goldfinch and Tropical Parula were seen there this spring.

After our roll of dice at the Sarita Rest Area, we continued south through the King Ranch en route back to Brownsville.

“Saw a Coyote on the way.”

Western Coyote
We spotted this Lower Rio Grande Coyote (Canis latrans microdon) near a watering hole on the King Ranch property along Route 77 near Sarita, Texas.  (Vintage 35 mm image)
Scissor-tailed Flycatcher
A Scissor-tailed Flycatcher on a fence along Route 77 at the King Ranch.  (Vintage 35 mm image)

“Took Steve to the airport and drove out to Boca Chica where Harold went swimming.” 

The drive from Brownsville out Boca Chica Boulevard to the Gulf of Mexico passes through about 18 miles of the outermost flats of the river delta that is the Lower Rio Grande Valley.  This area is of course susceptible to the greatest impacts from tropical weather, especially hurricanes.  During our visit, we passed a small cluster of ranch houses about two or three miles from the beach.  This was the village known as Boca Chica.  Otherwise, the area was desolate and left to the impacts of the weather and to the wildlife.

The mouth of the Rio Grande, and thus the international border with Mexico, was and still is about two miles south of Boca Chica Beach.  Before the construction of dams and other flood control measures on the river, the path of the Rio Grande through the alluvium deposits on this outer section of delta would vary greatly.  Accumulations of eroded material, river flooding, tides, and storms would conspire to change the landscape prompting the river to seek the path of least resistance and change its course.  Surrounding the segments of abandoned channel, these changes leave behind valuable wetlands including not only the resacas of the Lower Rio Grande Valley, but similar features in tidal sections of the outer delta.  When left to function in their natural state, deltas manage silt and pollutants in the waters that pass through them using ancient physical, biological, and chemical processes that require no intervention from man.

Harold was determined to go for a swim in the Gulf of Mexico before boarding a flight home.  We all liked the beach.  Why not?  You may remember trips to the shore in the summertime.  Back in the pre-casino days, we used to go to Atlantic City, New Jersey, to visit Steel Pier.  For the first three quarters of the twentieth century, Steel Pier was the Jersey Shore’s amusement park at sea.  There were rides, food stands, arcades, daily concerts with big name acts, diving shows, and ballroom dances.

There were, back then, attractions at Steel Pier that were creatively promoted to give the visitor the impression that they were going to see something more profound or amazing than was was delivered.  You know, things advertised to draw you in, but its not quite what you expected.

For example, there was an arcade game promising to show you a chicken playing baseball.  Okay, I’ll bite.  Turns out the chicken did too.  You put your money in the machine and watched as the chicken came out and rounded the diamond eating poultry food as it was offered at each of the bases.  Hmmm…to suggest that this was a chicken playing baseball seems like a bit of a stretch.

They had a diving bell there too.  Wow!  We’ll go below the waves and view the fish, octopi, and other sights through the water-tight windows while we descend to the ocean floor.  You would pay to get inside, then they would lower the bell down through a hole in the pier.  Once below the rolling surf, you would get to look at the turbid seawater sloshing around at the window like dirty suds in a washing machine.  If you were lucky, some trash might briefly get stuck on the glass.  To imply that this was a chance to see life beneath waves was B. S., and I don’t mean bathysphere.

Then there was a girl riding a diving horse.  You would hike all the way to the end of the pier and watch the preliminary show with these divers plunging through a hole in the deck and into the choppy Atlantic below.  They were very good, but no, we never saw Rodney Dangerfield do a “Triple Lindy” there.  And then it was time for the finale.  Wow, is that horse going to dive in the ocean?  How do they get the horse back up on the pier?  Forget it.  Instead of that, they walked poor Mr. Ed up a ramp into a box, then the girl climbs on his back, the door opens, and she nudges Ol’ Ed to into a plunge followed by a thumping splash into a swimming pool on the deck.  Not bad, but not what we were expecting.  Since we had to walk almost  a quarter of a mile out to sea to get there, they kinda led us to believe that the amazing equine was going to leap into the Atlantic—horse hockey!

Preceding all this fun was a guy back in the early 1930s, William Swan, who, in June 1931, flew a “rocket-powered plane” at Bader Field outside Atlantic City.  The plane was actually a glider on which a rocket was fired producing about 50 pounds of thrust to boost it airborne after assistants got it rolling by pushing it.  In newspaper articles and on newsreels afterward, he would promote the future of rocket planes carrying passengers across the ocean at 500 miles per hour.  Using a glider equipped with pontoons for landing in the ocean, he promised to make several flights daily from Steel Pier.  Those who came to see him may have, at best, watched him fire small rockets he had attached to his craft—little more.

What does all this have to do with Boca Chica Beach?  It turn out two years later, William Swan is hyping a new innovation—a rocket-powered backpack.  He’d demonstrate it during a skydiving exhibition at the Del-Mar Beach Resort, a cluster of 20 cabins and community buildings on Boca Chica Beach.  According to his deceptive promotions, Swan would jump out of a plane and light flares as he fell.  Then he’d ignite the backpack rocket and land on the shoreline in front of the crowd.  The event was expected to draw 3,000 carloads of people.  When the big day came, just over 1,000 cars showed up. The event was a bust and the weather was bad, cloudy with a mist over the gulf.  During a break in the clouds, the pilot took Swan aloft.  Swan ordered him out to sea and to 8,500 feet, a higher altitude than planned.  Then he jumped.  He dropped the flares, which didn’t then ignite, and neither did the rocket.  He opened his chute at 6,000 feet and the crowd watched as Swan drifted into the mist offshore and was never seen again.  There were rumors both that he used the stunt as a way to flee to Mexico to start a new life and that he had committed suicide.  Others believed he died accidentally.  To learn the full story of Billy Swan, check out The Rocketeer Who Never Was, by Mark Wade.

Forward fifty years to our visit to Boca Chica Beach.  The Del-Mar Beach Resort, built in the 1920s as a cluster of 20 cabins and a ballroom, was gone.  It was destroyed by a hurricane later in the same year Swan disappeared—1933.  The resort, which was hoped would be the start of a seaside vacation city, never reopened.  In 1983, we saw just a handful of beach goers and the birds, that’s it.  One could look down to the south and see the area of the Rio Grande’s mouth and Mexico, but there were no structures of note.  It was peaceful and alive with wildlife.  We were sorry we didn’t have more time there.

“Here we added Least Tern, Brown Pelican and Sandwich Tern.”

Laughing Gulls on the sands of Boca Chica beach
Laughing Gulls on the sands of Boca Chica Beach.  (Vintage 35 mm image)
Royal Tern
A Royal Tern (Thalasseus maximus) along the Gulf of Mexico shore at Boca Chica Beach.  (Vintage 35 mm image)
Least Tern
Least Terns are a sand-nesting species, thus are vulnerable to disturbances created by recreational use of beaches.  (Vintage 35 mm image)
Brown Pelicans
Back in 1983, finding Brown Pelicans (Pelicanus occidentalis) wasn’t as easy as it is today.  Back then, their numbers were still recovering from a severe population crash caused by the effects of D.D.T., which thinned eggs shells and precipitated widespread nesting failures.  (Vintage 35 mm image)

Today, the Village of Boca Chica and Boca Chica Beach are the location of SpaceX’s South Texas Launch Facility.  Those of the village’s ranch houses built in 1967 that have survived hurricane devastation over the years have been incorporated into the “Starbase” production and tracking facility.  The launch pad and testing area is along the beach just behind the dunes at the end of Boca Chica Boulevard.

The latest launch, just more than a month ago, was the maiden flight of “Starship”, a 394-foot behemoth that is the largest rocket ever flown.  The “Super Heavy Booster” first stage’s 33 Raptor engines produce 17.1 million pounds of thrust making Starship the most powerful rocket ever flown.  See, things really are bigger in Texas.

Last month’s unmanned orbital test launch ended when the Starship spacecraft failed to separate at staging.  As the booster section commenced its roll manuever to return to the launch pad, the entire assembly began tumbling out of control.  It exploded and rained debris into the gulf along a stretch of the downrange trajectory.

Boca Chica and Starbase
The Village of Boca Chica is now the SpaceX “Starbase” production and tracking complex. The rockets are rolled two miles out Boca Chica Boulevard to the beach-side launch pad.  Areas in dark blue are units in the Lower Rio Grande Valley National Wildlife Refuge.  (United States Fish and Wildlife Service image)

Development of Starbase is opposed by many due to noise, safety, and environmental concerns.  Boca Chica Boulevard (Texas Route 4) is frequently closed due to activity at the launch pad site, thus excluding residents and tourists from visiting the beach.  With over 1,200 people already working at Starbase, demand for housing in the Brownsville area has increased.  Some have accused SpaceX CEO Elon Musk of promoting gentrification of the area—running up housing prices to force out the lower-income residents.  He has responded with a vision of a new city at Boca Chica, his “space port”.

Does history have an applicable lesson for us here?  When Musk talks about going to the Moon and Mars, or ferrying a hundred people around the world on his Starship, is it just another Steel Pier-style deception?  Is Musk a modern-day William Swan?  A very talented marketer?  Could be.  And is the whole thing setting up a large-scale replay of the Del-Mar Beach Resort’s demise in 1933?  Is building a city on the outer edges of a river delta asking for an outcome similar to the one suffered by New Orleans during Hurricane Katrina?  It’s likely.  After all, building on or near a beach, floodplain, or delta is a short-sighted venture to begin with.  If the party doing the developing doesn’t suffer the consequences of defying the laws of nature, one of the poor suckers in the successive line of buyers and occupants will.  This isn’t rocket science folks.  Its weather, climate, and erosion, and its been altering coastlines, river courses, and the composition and distribution of life forms on this planet for millions of years.  And guess what.  These factors will continue to alter Earth for millions of years more after man the meddler is long gone.  You’re not going to stop their effects, and you’re not going to escape their wrath by ignoring them.  So if you’re smart, you’ll get out of their way and stay there!

Billy Swan was probably broke when he came to Boca Chica.  He reportedly borrowed 20 bucks from the resort operator just to cover his personal expenses during his backpack rocket event.  Elon Musk comes to Boca Chica with over 100 billion dollars and capital from other private investors to boot.   Despite some obvious exaggerations about colonizing the Moon, Mars, and other celestial bodies, he just might be able to at least get people there for short-term visits.  And that’s quite an accomplishment.

Jezero Crater on the surface of Mars.  Ravaging and overpopulating the Earth with an eye on migrations to the Moon and Mars for refuge is silliness.  I don’t know about you, but I’d rather spend time at a pristine beach like Boca Chica than time at this rocky hole.  These desolate orbs might be nice places to visit, but I wouldn’t want to live there, and neither would you.  (NASA Jet Propulsion Laboratory image)

“Then took Harold to the airport.  We left him at 3:30 and headed north on Route 77, got as far as Victoria.  Had a flat on the way.  Larry had the spare on in 10 minutes.  We stopped at a picnic area for the nite, because we could not find the camping area.”

If we were going to have a flat, we had it at the right place.  We were just outside Raymondville, Texas, at a newly constructed highway interchange.  The wide, level shoulder allowed us to get the camper off to the side of the road in a safe place to jack it up and change the tire.  Easy.  We were thereafter homeward bound.

Photo of the Day

A juvenile Ring-billed Gull with a freshly caught Gizzard Shad is pursued by a hungry adult Great Black-backed Gull on the Susquehanna at Conowingo Dam.
A juvenile Ring-billed Gull with a freshly caught Gizzard Shad is pursued by a hungry adult Great Black-backed Gull on the Susquehanna at Conowingo Dam.

An Encore of the Susquehanna Seawatch

In late March and early April, a rainy night and fog at daybreak can lead to an ideal morning for spotting migratory waterfowl and seabirds during their layover on the lower Susquehanna.  Visibility was just good enough to spot these birds at Harrisburg, Pennsylvania, most of them feeding at midriver.

Northern Shovelers are regular migrants, more often seen on ponds and in wetlands than on the river.
A pair of American Wigeons head upriver.
A Horned Grebe.
A small flock of northbound Buffleheads.
Ring-necked Ducks.
Lesser Scaup, eight of the more than 100 seen along Front Street in Harrisburg at the Pennsylvania Governor’s Residence.  Note how the white bar on the wing’s secondaries becomes diffused and dusky in the primaries.
Lesser Scaup spend the winter on bays and lakes to our south.
More Scaup, the lead bird with bright white extending through the secondaries into the primaries is possibly a Greater Scaup (Aythya marila).
Long-tailed Ducks, formerly known as Oldsquaw, are a diving duck that winters on the Great Lakes and on bays along the Atlantic Coast.  They nest on freshwater ponds and lakes in the tundra of Canada and Alaska.
A male Common Merganser.
This pair of Hooded Mergansers may be nesting in a tree cavity nearby.
The local Peregrine Falcon grabbed a passing Common Grackle…
…prompting the more than 100 Bonaparte’s Gulls in the vicinity to quickly depart and fly upstream.
Birds of Conewago Falls in the Lower Susquehanna River Watershed: Northern Flicker
It pays to keep an eye on the trees along the shoreline too.  Migrants like this Northern Flicker are beginning to come through in numbers.

Seawatch on the Susquehanna

Birds that one might expect to see wintering among the surf and in tidal waters along the Atlantic coast are currently making their way up the Susquehanna on a route that will ultimately lead most to nesting sites in Canada.  To see them as pass, one needs simply to find a good vantage point along the river from which to begin watching.  Here are some of today’s sightings from the Veteran’s Memorial Bridge (Route 462) at Columbia/Wrightsville, Pennsylvania.

Birds/Waterfowl of Conewago Falls in the Lower Susquehanna River Watershed: Red-breasted Mergansers
Red-breasted Mergansers spend the winter primarily on saltwater bays.  They are regular springtime migrants on the lower Susquehanna in late March and early April each year.
Birds/Waterfowl of Conewago Falls in the Lower Susquehanna River Watershed: Red-breasted Merganser
A male Red-breasted Merganser.
Double-crested Cormorants spend the winter in a variety of salt and brackish water habitats.  Some birds breed on the lower Susquehanna, but the vast majority nest to the north of the Great Lakes.
Birds of Conewago Falls in the Lower Susquehanna River Watershed: Ring-billed Gull
Ring-billed Gulls winter throughout the Atlantic Coastal Plain and nest as far south as the Great Lakes region.
Birds of Conewago Falls in the Lower Susquehanna River Watershed: Bonaparte's Gulls
Bonaparte’s Gulls winter on the Atlantic from the surf zone to several miles offshore.  In the southern states, some pass the colder months on inland lakes.
Birds of Conewago Falls in the Lower Susquehanna River Watershed: Bonaparte's and ring-billed Gulls
Bonaparte’s Gulls and a few Ring-billed Gulls swarm over the lower Susquehanna River at the Route 30 bridge.
Birds of Conewago Falls in the Lower Susquehanna River Watershed: Bonaparte's Gulls
While in flight, Bonaparte’s Gulls can resemble terns.
Birds of Conewago Falls in the Lower Susquehanna River Watershed: Bonaparte's Gulls.
Bonaparte’s Gulls headed upriver.
Birds of Conewago Falls in the Lower Susquehanna River Watershed: Bonaparte's Gulls
Bonaparte’s Gulls are regular spring migrants on the lower Susquehanna in late March and early April each year.

A Visit to the Post Office, for Just One Stamp

It’s been more than a year and a half since Uncle Tyler Dyer has been on one of our outings.  He’s been laying low, keeping to himself—to protect his health.  So he was quite excited when we made our way to the Delaware coast to have a look at some marine and beach life at Cape Henlopen State Park.

Uncle Ty hadn’t visited the Atlantic shoreline here for almost two decades, and he was more than a bit startled at what he saw…

Cape Henlopen State Park has spectacular wild dunes and pine forests, but notice how clean the high-tide line is on the beach.  This is not a good sign.  During our walks, we found not one mollusk shell (clam, scallop, snail, etc.), skate egg case, whelk egg case, dead fish, or other sign of benthic life from the adjacent surf and sea.
We found the remains of Mole Crabs (Emerita talpoida), also known as sand fleas, a crustacean that burrows into the surf-washed sands of the beach, but there were no signs of life from deeper waters.
One of a dozen or so Lesser Black-backed Gulls (Larus fuscus) observed consuming Mole Crabs. There was little else for these birds to eat.  Sanderlings (Calidris alba) and other shorebirds typically found foraging along the surf’s edge were totally absent.
Atlantic Ghost Crabs (Ocypode quadrata) live in the predominantly dry sands of the beach, above the high tide line.  Missing were the remains of aquatic crabs, including Atlantic Horseshoe Crabs (Limulus polyphemus), and other invertebrates that are often found washing in with the tide.
If you want to see an Atlantic Horseshoe Crab, you may have no better option than to visit the aquariums at the state park’s nature center.

A nearly sterile beach might be delightful for barefoot sunbathers and the running of the dogs, but Uncle Ty isn’t the barefoot type.  He likes his sandals and a slow peaceful stroll with plenty of flora and fauna to have a look at.  We could tell he was getting bored.  So we headed home.

Along the way, Uncle Ty asked to stop at the Post Office.  He wanted to get a stamp.  Thinking he was going to fire off a terse letter of protest to the powers that be about what he saw at the beach, we obliged.

Soon, Uncle Ty trotted down the steps of the Post Office with his stamp.

Uncle Tyler Dyer with his one stamp.  The 2021-2022 Federal Duck Stamp is available at most local Post Offices.  According to the United States Fish and Wildlife Service, ninety-eight percent of the $25 purchase price goes directly to acquiring and protecting wetland habitat.

Uncle Ty bought a duck stamp, so naturally we asked him when he decided to take up hunting.  He explained, “Man, I gave that stuff up when I was thirteen.  I’ve got the Thoreau/Walden mindset—hunting is something of an adolescent pursuit.”

It turns out Uncle Ty bought a duck stamp to support wetland acquisition and improvements, not only to benefit ducks and other wildlife living there, but to improve water quality.  In Delaware, tidal estuary restoration work is underway at both the Prime Hook and Bombay Hook National Wildlife Refuges on Delaware Bay.  These projects will certainly enhance the salt marsh’s filtration capabilities and just might improve the populations of benthic life in the bay and adjacent ocean at Cape Henlopen.

Uncle Ty tossed the stamp atop the dashboard and we were again on our way, but we weren’t going directly home.  We made a stop along the way.  A stop we’ll share with you next time.

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…

Wood Ducks atop the dam.
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!

Conowingo Dam: Cormorants, Eagles, Snakeheads and a Run of Hickory Shad

Meet the Double-crested Cormorant,  a strangely handsome bird with a special talent for catching fish.  You see, cormorants are superb swimmers when under water—using their webbed feet to propel and maneuver themselves with exceptional speed in pursuit of prey.

Like many species of birds that dive for their food, Double-crested Cormorants run across the surface of the water to gain speed for a takeoff.  Smaller wings may make it more difficult to get airborne, but when folded, they provide improved streamlining for submerged swimming.

Double-crested Cormorants, hundreds of them, are presently gathered along with several other species of piscivorous (fish-eating) birds on the lower Susquehanna River below Conowingo Dam near Rising Sun, Maryland.  Fish are coming up the river and these birds are taking advantage of their concentrations on the downstream side of the impoundment to provide food to fuel their migration or, in some cases, to feed their young.

Double-crested Cormorants, mostly adult birds migrating toward breeding grounds to the north, are gathered on the rocks on the east side of the river channel below Conowingo Dam.  A Great Blue Heron from a nearby rookery can be seen at the center of the image.
Bald Eagles normally gather in large numbers at Conowingo Dam in the late fall and early winter.  Presently there are more than 50 there, and the majority of them are breeding age adults.  Presumably they are still on their way north to nest.  Meanwhile, local pairs are already feeding young, so it seems these transient birds are running a bit late.  Many of them can be seen on the rocks along the east side of the river channel,…
…on the powerline trestles on the island below the dam…
…in the trees along the east shore,…
…and in the trees surrounding Fisherman’s Park on the west shore.

In addition to the birds, the movements of fish attract larger fish, and even larger fishermen.

Anglers gather to fish the placid waters below the dam’s hydroelectric powerhouse .  Only a few of the generating turbines are operating, so the flow through the dam is minimal.
Some water is being released along the west shoreline to attract migratory river herring to the west fish lift for sorting and retention as breeding stock for a propagation program.  The east lift, the passage that hoists American Shad (Alosa sapidissima) to a trough that allows them to swim over the top of the dam to waters upriver, will begin operating as soon as these larger migratory fish begin arriving.

The excitement starts when the sirens start to wail and the red lights begin flashing.  Yes friends, it’s showtime.

Red lights and sirens are a warning that additional flow is about to be released from the dam.  Boaters should anticipate rough water and persons in and along the river need to seek higher ground immediately.
Gates are opened at mid-river to release a surge of water through the dam.
The wake from the release quickly reaches the shoreline, raising the water level in moments.
Experienced anglers know that the flow through the dam gets fish moving and can improve the catch significantly, especially in spring when many species are ascending the river.

Within minutes of the renewed flow, birds are catching fish.

A Double-crested Cormorant with a young Channel Catfish (Ictalurus punctatus).
A Double-crested Cormorant fleeing others trying to steal its Channel Catfish.
Another Double-crested Cormorant eating a Channel Catfish.  Did you realize that Channel Catfish were an introduced species in the Susquehanna River system?
An Osprey with a stick, it’s too busy building a nest right now to fish.
Great Blue Herons swallow their prey at the spot of capture, then fly back to the nest to regurgitate a sort of “minced congealed fish product” to their young.

Then the anglers along the wave-washed shoreline began catching fish too.

This young man led off a flurry of catches that would last for the remainder of the afternoon.
Though Gizzard Shad are filter feeders that don’t readily take baits and lures, they are regularly foul-hooked and reeled in from the large schools that ascend the river in spring.
Gizzard Shad are very abundant in the lower Susquehanna, providing year-round forage for many species of predatory animals including Bald Eagles.
A Double-crested Cormorant swallowing a Gizzard Shad.
This angler soon helped another fisherman by landing his large catch, a Northern Snakehead (Channa argus).
The teeth of a Northern Snakehead are razor sharp.  It is an aggressive non-native invasive species currently overtaking much of the Lower Susquehanna River Watershed.  Anglers are encouraged to fish for them, catch them, keep them, and kill them at the site of capture.  Never transport a live Northern Snakehead  anywhere at any time.  It is illegal in both Maryland and Pennsylvania to possess a live snakehead. 
Northern Snakehead advisory sign posted at Exelon Energy’s Conowingo Fishermen’s Park.
A stringer of Northern Snakeheads.  This species was imported from Asia as a food fish, so it has excellent culinary possibilities.  It’s better suited for a broiler or frying pan than a river or stream.
Another stringer of Northern Snakeheads.  It’s pretty safe to say that they have quickly become one of the most abundant predatory fish in the river.  Their impact on native species won’t be good, so catch and eat as many as you can.  Remember, snakeheads swim better in butter and garlic than in waters with native fish.
This foul-hooked Shorthead Redhorse (Moxostoma macrolepidotum), a native species of sucker, was promptly released.
Striped Bass are anadromous fish that leave the sea in spring to spawn in fresh water.  They ascend the Susquehanna in small numbers, relying upon the operation of the fish passages at the Conowingo, Holtwood, Safe Harbor, and York Haven Dams to continue their journey upstream.  During spring spawning, Striped Bass in the Susquehanna River and on the Susquehanna Flats portion of the upper Chesapeake Bay are not in season and may not be targeted, even for catch-and-release.  This accidental catch was immediately turned loose.
After removal from the hook, this hefty Smallmouth Bass was returned to the river.  Many anglers are surprised to learn that Smallmouth Bass are not native to the Susquehanna basin.
This angler’s creel contains a Northern Snakehead (left) and a Walleye (right).  Did you know that the Walleye (Sander vitreus) is an introduced species in the Susquehanna watershed?
By late afternoon, anglers using shad darts began hooking into migrating Hickory Shad (Alosa mediocris), a catch-and-release species in Maryland.
Hickory Shad are recognized by their lengthy lower jaw.  They are anadromous herring that leave the sea to spawn in freshwater streams.  Hickory Shad ascend the Susquehanna as far as Conowingo Dam each year, but shy away from the fish lifts.  Downriver from the dam, they do ascend Deer Creek along the river’s west shore and Octoraro Creek on the east side.  In Pennsylvania, the Hickory Shad is an endangered species.
A Hickory Shad angled on a dual shad dart rig.  During the spring spawning run, they feed mostly on small fish, and are the most likely of the Susquehanna’s herring to take the hook.
Simultaneous hook-ups became common after fours hours worth of release water from the dam worked its way toward the mouth of the river and got the schools moving.  Water temperatures in the mid-to-upper-fifties trigger the ascent of Hickory Shad.  On the Susquehanna, those temperatures were slow to materialize in the spring of 2021, so the Hickory Shad migration is a bit late.
Catch-and-release fishing for Hickory Shad appears to be in full swing not only at the dam, but along the downstream shoreline to at least the mouth of Deer Creek at Susquehanna State Park too.
Many Hickory Shad could be seen feeding on some of the millions of caddisflies (Trichoptera) swarming on the river.  These insects, along with earlier hatches of Winter Stoneflies (Taeniopterygidae), not only provide forage for many species of fish, but  are a vital source of natural food for birds that migrate up the river in March and April each year.  Swallows, Ring-billed Gulls, and Bonaparte’s Gulls are particularly fond of snatching them from the surface of the water.
A Winter Stonefly (Taeniopterygidae) from an early-season hatch on the Susquehanna River at the Veteran’s Memorial Bridge at Columbia/Wrightsville, Pennsylvania.  (March 3, 2021)
Just below Conowingo Dam, a lone fly fisherman was doing a good job mimicking the late-April caddisfly hatch, successfully reeling in numerous surface-feeding Hickory Shad.
You may have noticed the extraordinary number of introduced fish species listed in this account of a visit to Conowingo Dam.  Sorry to say that there are two more: the Flathead Catfish (Pylodictis olivaris) and the Blue Catfish (Ictalurus furcatus).  Like the Northern Snakehead, each has become a plentiful invasive species during recent years.  Unlike the Northern Snakehead, these catfish are “native transplants”, species introduced from populations in the Mississippi River and Gulf Slope drainages of the United States.  So if you visit the area, consider getting a fishing license and catching a few.  Like the snakeheads, they too are quite palatable.

The arrival of migrating Hickory Shad heralds the start of a movement that will soon include White Perch, anadromous American Shad, and dozens of other fish species that swim upstream during the springtime.  Do visit Fisherman’s Park at Conowingo Dam to see this spectacle before it’s gone.  The fish and birds have no time to waste, they’ll soon be moving on.

To reach Exelon’s Conowingo Fisherman’s Park from Rising Sun, Maryland, follow U.S. Route 1 south across the Conowingo Dam, then turn left onto Shuresville Road, then make a sharp left onto Shureslanding Road.  Drive down the hill to the parking area along the river.  The park’s address is 2569 Shureslanding Road, Darlington, Maryland.

A water release schedule for the Conowingo Dam can be obtained by calling Exelon Energy’s Conowingo Generation Hotline at 888-457-4076.  The recording is updated daily at 5 P.M. to provide information for the following day.

And remember, the park can get crowded during the weekends, so consider a weekday visit.

Common Goldeneyes, Buffleheads, and Migrating Canada Geese

Spring migration is underway and waterfowl are on the move along the lower Susquehanna River.  Here is a sample of sightings collected during a walk across the Veteran’s Memorial Bridge at Columbia-Wrightsville this morning.

At the Veteran’s Memorial Bridge, the Susquehanna was cresting this morning after recent rains and accompanying snow melt.
An overnight breeze from the southwest and calm winds during the morning hours created ideal conditions for flocks of Canada Geese to begin migrating north from Chesapeake Bay through the lower Susquehanna valley.
These three Common Mergansers and a Common Goldeneye (right) are some of the hundreds of diving ducks presently gathered on the river in the vicinity of the Veteran’s Memorial Bridge.
Common Goldeneyes and a first-winter male Bufflehead (upper right).  All of the ducks seen today in the waters surrounding the bridge are benthic feeders, diving to the river bottom to pluck invertebrates from the substrate.
A male Common Goldeneye (Bucephala clangula).
A female Common Goldeneye.
A pair of Common Goldeneyes in flight.
A pair of Buffleheads in flight.
Common Goldeneyes repositioning for another series of feeding dives.
During the morning flight, thousands of Canada Geese were seen moving north in flocks numbering about 50 to 100 birds each.  The bird in the lower right was one of thousands of Ring-billed Gulls seen headed upriver as well.
As they pass over the lower Susquehanna region, migrating Canada Geese are typically observed flying much higher than flocks from the local resident populations, often reaching the cruising altitudes of aircraft.  Aviators are always alert for flights of resident geese around airfields.  But to prevent bird strikes during days like today when thousands of migratory geese traverse the airspace, air traffic controllers can become extra busy relaying the location and altitude of potential targets to pilots flying aircraft entering areas where birds have been reported.

This is, of course, just the beginning of the great spring migration.  Do make a point of getting out to observe the spectacle.  And remember, keep looking up—you wouldn’t want to miss anything.

2020: A Good Year

You say you really don’t want to take a look back at 2020?  Okay, we understand.  But here’s something you may find interesting, and it has to do with the Susquehanna River in 2020.

As you may know, the National Weather Service has calculated the mean temperature for the year 2020 as monitored just upriver from Conewago Falls at Harrisburg International Airport.  The 56.7° Fahrenheit value was the highest in nearly 130 years of monitoring at the various stations used to register official climate statistics for the capital city.  The previous high, 56.6°, was set in 1998.

Though not a prerequisite for its occurrence, record-breaking heat was accompanied by a drought in 2020.  Most of the Susquehanna River drainage basin experienced drought conditions during the second half of the year, particularly areas of the watershed upstream of Conewago Falls.  A lack of significant rainfall resulted in low river flows throughout late summer and much of the autumn.  Lacking water from the northern reaches, we see mid-river rocks and experience minimal readings on flow gauges along the lower Susquehanna, even if our local precipitation happens to be about average.

Back in October, when the river was about as low as it was going to get, we took a walk across the Susquehanna at Columbia-Wrightsville atop the Route 462/Veteran’s Memorial Bridge to have a look at the benthos—the life on the river’s bottom.

As we begin our stroll across the river, we quickly notice Mallards and a Double-crested Cormorant (far left) feeding among aquatic plants.  You can see the leaves of the vegetation just breaking the water’s surface, particularly behind the feeding waterfowl.  Let’s have a closer look.
An underwater meadow of American Eelgrass (Vallisneria americana) as seen from atop the Veteran’s Memorial Bridge at Columbia-Wrightsville.  Also known as Freshwater Eelgrass, Tapegrass, and Wild Celery, it is without a doubt the Susquehanna’s most important submerged aquatic plant.  It grows in alluvial substrate (gravel, sand, mud, etc.) in river segments with moderate to slow current.  Water three to six feet deep in bright sunshine is ideal for its growth, so an absence of flooding and the sun-blocking turbidity of muddy silt-laden water is favorable.
Plants in the genus Vallisneria have ribbon-like leaves up to three feet in length that grow from nodes rooted along the creeping stems called runners.  A single plant can, over a period of years, spread by runners to create a sizable clump or intertwine with other individual plants to establish dense meadows and an essential wildlife habitat.
An uprooted segment of eelgrass floats over a thick bed of what may be parts of the same plant.  Eelgrass meadows on the lower Susquehanna River were decimated by several events: deposition of anthracite coal sediments (culm) in the late-nineteenth and early-twentieth centuries, dredging of the same anthracite coal sediments during the mid-twentieth century, and the ongoing deposition of sediments from erosion occurring in farm fields, logged forests, abandoned mill ponds, and along denuded streambanks.  Not only has each of these events impacted the plants physically by either burying them or ripping them out by the roots, each has also contributed to the increase in water turbidity (cloudiness) that blocks sunlight and impairs their growth and recovery.
A submerged log surrounded by beds of eelgrass forms a haven for fishes in sections of the river lacking the structure found in rock-rich places like Conewago Falls.  A period absent of high water and sediment runoff extended through the growing season in 2020 to allow lush clumps of eelgrass like these to thrive and further improve water quality by taking up nutrients, particularly nitrogen and phosphorus.  Nutrients used by vascular plants including eelgrass become unavailable for feeding detrimental algal blooms in downstream waters including Chesapeake Bay.
Small fishes and invertebrates attract predatory fishes to eelgrass beds.  We watched this Smallmouth Bass leave an ambush site among eelgrass’s lush growth to shadow a Common Carp as it rummaged through the substrate for small bits of food.  The bass would snatch up crayfish that darted away from the cover of stones disturbed by the foraging carp.
Sunfishes are among the species taking advantage of eelgrass beds for spawning.  They’ll build a nest scrape in the margins between clumps of plants allowing their young quick access to dense cover upon hatching.  The abundance of invertebrate life among the leaves of eelgrass nourishes feeding fishes, and in turn provides food for predators including Bald Eagles, this one carrying a freshly-caught Bluegill.

These improvements in water quality and wildlife habitat can have a ripple effect.  In 2020, the reduction in nutrient loads entering Chesapeake Bay from the low-flowing Susquehanna may have combined with better-than-average flows from some of the bay’s lesser-polluted smaller tributaries to yield a reduction in the size of the bay’s oxygen-deprived “dead zones”.  These dead zones typically occur in late summer when water temperatures are at their warmest, dissolved oxygen levels are at their lowest, and nutrient-fed algal blooms have peaked and died.  Algal blooms can self-enhance their severity by clouding water, which blocks sunlight from reaching submerged aquatic plants and stunts their growth—making quantities of unconsumed nutrients available to make more algae.  When a huge biomass of algae dies in a susceptible part of the bay, its decay can consume enough of the remaining dissolved oxygen to kill aquatic organisms and create a “dead zone”.  The Chesapeake Bay Program reports that the average size of this year’s dead zone was 1.0 cubic miles, just below the 35-year average of 1.2 cubic miles.

Back on a stormy day in mid-November, 2020, we took a look at the tidal freshwater section of Chesapeake Bay, the area known as Susquehanna Flats, located just to the southwest of the river’s mouth at Havre de Grace, Maryland.  We wanted to see how the restored American Eelgrass beds there might have fared during a growing season with below average loads of nutrients and life-choking sediments spilling out of the nearby Susquehanna River.  Here’s what we saw.

We followed the signs from Havre de Grace to Swan Harbor Farm Park.
Harford County Parks and Recreation’s Swan Harbor Farm Park consists of a recently-acquired farming estate overlooking the tidal freshwater of Susquehanna Flats.
Along the bay shore, a gazebo and a fishing pier have been added.  Both provide excellent observation points.
The shoreline looked the way it should look on upper Chesapeake Bay, a vegetated buffer and piles of trees and other organic matter at the high-water line.  There was less man-made garbage than we might find following a summer that experienced an outflow from river flooding, but there was still more than we should be seeing.
Judging by the piles of fresh American Eelgrass on the beach, it looks like it’s been a good year.  Though considered a freshwater plant, eelgrass will tolerate some brackish water, which typically invades upper Chesapeake Bay each autumn due to a seasonal reduction in freshwater inflow from the Susquehanna and other tributaries.  Saltwater can creep still further north when the freshwater input falls below seasonal norms during years of severe drought.  The Susquehanna Flats portion of the upper bay very rarely experiences an invasion by brackish water; there was none in 2020.
As we scanned the area with binoculars and a spotting scope, a raft of over one thousand ducks and American Coots (foreground) could be seen bobbing among floating eelgrass leaves and clumps of the plants that had broken away from their mooring in the mud.  Waterfowl feed on eelgrass leaves and on the isopods and other invertebrates that make this plant community their home.
While coots and grebes seemed to favor the shallower water near shore, a wide variety of both diving and dabbling ducks were widespread in the eelgrass beds more distant.  Discernable were Ring-necked Ducks, scaup, scoters, Long-tailed Ducks, Redheads, American Wigeons, Gadwall, Ruddy Ducks, American Black Ducks, and Buffleheads.

We noticed a few Canvasbacks (Aythya valisineria) on the Susquehanna Flats during our visit.  Canvasbacks are renowned as benthic feeders, preferring the tubers and other parts of submerged aquatic plants (a.k.a. submersed aquatic vegetation or S.A.V.) including eelgrass, but also feeding on invertebrates including bivalves.  The association between Canvasbacks and eelgrass is reflected in the former’s scientific species name valisineria, a derivitive of the genus name of the latter, Vallisneria.

Canvasbacks on Chesapeake Bay.  (United States Fish and Wildlife Service image by Ryan Hagerty)

The plight of the Canvasback and of American Eelgrass on the Susquehanna River was described by Herbert H. Beck in his account of the birds found in Lancaster County, Pennsylvania, published in 1924:

“Like all ducks, however, it stops to feed within the county 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 (anthracite coal waste).  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.”

Beck quotes old Marietta resident and gunner Henry Zink:

“Sometimes there were as many as 500,000 ducks of various kinds on the Marietta broad at one time.”

The abundance of Canvasbacks and other ducks on the Susquehanna Flats would eventually plummet too.  In the 1950s, there were an estimated 250, 000 Canvasbacks wintering on Chesapeake Bay, primarily in the area of the American Eelgrass, a.k.a. Wild Celery, beds on the Susquehanna Flats.  When those eelgrass beds started disappearing during the second half of the twentieth century, the numbers of Canvasbacks wintering on the bay took a nosedive.  As a population, the birds moved elsewhere to feed on different sources of food, often in saltier estuarine waters.

Canvasbacks were able to eat other foods and change their winter range to adapt to the loss of habitat on the Susquehanna River and Chesapeake Bay.  But not all species are the omnivores that Canvasbacks happen to be, so they can’t just change their diet and/or fly away to a better place.  And every time a habitat like the American Eelgrass plant community is eliminated from a region, it fragments the range for each species that relied upon it for all or part of its life cycle.  Wildlife species get compacted into smaller and smaller suitable spaces and eventually their abundance and diversity are impacted.  We sometimes marvel at large concentrations of birds and other wildlife without seeing the whole picture—that man has compressed them into ever-shrinking pieces of habitat that are but a fraction of the widespread environs they once utilized for survival.  Then we sometimes harass and persecute them on the little pieces of refuge that remain.  It’s not very nice, is it?

By the end of 2020, things on the Susquehanna were getting back to normal.  Near normal rainfall over much of the watershed during the final three months of the year was supplemented by a mid-December snowstorm, then heavy downpours on Christmas Eve melted it all away.  Several days later, the Susquehanna River was bank full and dishing out some minor flooding for the first time since early May.  Isn’t it great to get back to normal?

The rain-and-snow-melt-swollen Susquehanna from Chickies Rock looking upriver toward Marietta during the high-water crest on December 27th.
Cresting at Columbia as seen from the Route 462/Veteran’s Memorial Bridge.  A Great Black-backed Gull monitors the waters for edibles.
All back to normal on the Susquehanna to end 2020.
Yep, back to normal on the Susquehanna.  Maybe 2021 will turn out to be another good year, or maybe it’ll  just be a Michelin or Firestone.

SOURCES

Beck, Herbert H.  1924.  A Chapter on the Ornithology of Lancaster County, Pennsylvania.  The Lewis Historical Publishing Company.  New York, NY.

White, Christopher P.  1989.  Chesapeake Bay, Nature of the Estuary: A Field Guide.  Tidewater Publishers.  Centreville, MD.

City Life: Gulls, Dabbling Ducks, and More

So you aren’t particularly interested in a stroll through the Pennsylvania woods during the gasoline and gunpowder gang’s second-biggest holiday of the year—the annual sacrifice-of-the-White-tailed-Deity ritual.  I get it.  Two weeks and nothing to do.  Well, why not try a hike through the city instead?  I’m not kidding.  You might be surprised at what you see.  Here are some photographs taken today during several strolls in Harrisburg, Pennsylvania.

First stop was City Island in the Susquehanna River—accessible from downtown Harrisburg or the river’s west shore by way of the Market Street Bridge.

From the middle of the Susquehanna River, City Island offers a spectacular view of the downtown Harrisburg skyline.  In summer, it’s the capital city’s playground.  During the colder months, it’s a great place to take a quiet walk and find unusual birds.
This Bald Eagle was in mature trees along the river shoreline near the Harrisburg Senator’s baseball stadium.
Ring-billed Gulls gather on the “cement beach” at the north end of City Island.
One of a dozen or so Herring Gulls seen from the island’s north end. This particular bird is a juvenile.
A Ring-billed Gull and some petite Bonaparte’s Gulls.  Really good birders will tell you to always check through flocks of these smaller gulls carefully.  It turns out they’re onto something.  Look closely at the gull to the right.
A bright red bill and more of a crescent shape to the black spot behind the eye, that’s an adult Black-headed Gull (Chroicocephalus ridibundus) in winter plumage, a rare bird on the Susquehanna.  Black-headed Gulls have colonized North America from Europe, breeding in Iceland, southernmost Greenland, and rarely Newfoundland.

Okay, City Island was worth the effort.  Next stop is Wildwood Park, located along Industrial Road just north of the Pennsylvania Farm Show complex and the Harrisburg Area Community College (HACC) campus.  There are six miles of trails surrounding mile-long Wildwood Lake within this marvelous Dauphin County Parks Department property.

A flock of Killdeer at the south end of Wildwood Lake.  From November through February, a walk along the south and west sides of the impoundment can be a photographer’s dream. The light is suitable in the morning, then just keeps getting better as the day wears on.
Is this probable Carolina/Black-capped Chickadee hybrid a resident at Wildwood or just a visitor from a few miles to the north?  Currently, pure Black-capped Chickadees (Poecile atricapillus) nest in the mountains well to the north of Harrisburg, and pure Carolina Chickadees nest south of the city.  Harrisburg possibly remains within the intergrade/hybrid zone, an area where the ranges of the two species overlap, but probably not for long.  During recent decades, this zone has been creeping north, at times by as much as a half mile or more each year.  So if the capital city isn’t Carolina Chickadee territory yet, it soon will be.
Another chickadee likely to be a hybrid, this one with some white in the greater wing coverts like a Black-capped, but with a call even more rapid than that of the typical Carolina, the species known for uttering the faster “chick-a-dee-dee-dee”.  It sounded wired, like it had visited a Starbucks all morning.
In the lower Susquehanna valley, Carolina Chickadees have already replaced hybrids and pure Black-capped Chickadees as nesting birds in the Piedmont hills south of Harrisburg and the Great Valley.  This Carolina Chickadee was photographed recently in the Furnace Hills at Middle Creek Wildlife Management Area in northern Lancaster County.  The transition there was probably complete by the end of the twentieth century.  Note the characteristic overall grayish appearance of the wings and the neat lower border of the black bib on this bird, 
For comparison, a bird presumed to be a pure Black-capped Chickadee photographed earlier this month in Lebanon County, Pennsylvania.  This fall, “Black-caps”, like many other northern perching birds, are moving south to invade the lower elevations and milder climes of the Piedmont and Atlantic Coastal Plain Provinces.  Note the extensive areas of white in the wings, the long tail, the buffy flanks, and the jagged edge of the black bib.
Along Wildwood Lake’s west shore, an adult male Sharp-shinned Hawk was soon attracted to the commotion created by bantering chickadees and other songbirds.
Yellow during the first year, the eyes of the Sharp-shinned Hawk get redder as the bird ages.
Also along the west border of Wildwood Lake, temperatures were warm enough to inspire Painted Turtles (Chrysemys picta) to seek a sun bath atop logs in the flooded portions of the abandoned Pennsylvania Canal.

And now, without further ado, it’s time for the waterfowl of Wildwood Lake—in order of their occurrence.

A pair of Wood Ducks (hen left, drake right) with American Black Ducks and Canada Geese.
A pair of Northern Pintails.
A pair of American Wigeons (Mareca americana).
A hen (left) and drake (right) Gadwall.
Mallards.
A female Northern Shoveler.
An American Black Duck.
Canada Geese.
You just knew there had to be a booby prize, a “Blue Suede” (a.k.a. Blue Swede), a domestic variety of Mallard.
It’s a Green-winged Teal (Anas crecca) sampler.  Clockwise from left: a juvenile male, a female, and an adult male.
A drake and two hen Green-winged Teal.  Isn’t that great light by late afternoon?

See, you don’t have to cloak yourself in bright orange ceremonial garments just to go for a hike.  Go put on your walking shoes and a warm coat, grab your binoculars and/or camera, and have a look at wildlife in a city near you.  You never know what you might find.

SOURCES

Taylor, Scott A., Thomas A. White, Wesley M. Hochachka, Valentina Ferretti, Robert L. Curry, and Irby Lovette.  2014.  “Climate-Mediated Movement of an Avian Hybrid Zone”.  Current Biology.  24:6  pp.671-676.

Bald Eagles Arriving at Conowingo Dam

You need to see this to believe it—dozens, sometimes hundreds, of Bald Eagles doing their thing and you can stand or sit in just one place to take it all in.

Conowingo Dam on the Susquehanna River near Darlington, Maryland, attracts piscivores galore.  Young Gizzard Shad (Dorosoma cepedianum) and other small fishes are temporarily stunned as they pass through the turbines and gated discharges at the hydroelectric facility’s power house.  Waiting for them in the rapids below are predatory fishes including Striped Bass (Morone saxatilis), White Perch (Morone americana), several species of catfishes, and more.  From above, fish-eating birds are on the alert for a disoriented turbine-traveler they can easily seize for a quick meal.

U.S. Route 1 crosses the Susquehanna River atop the Conowingo Dam.  Conowingo Fisherman’s Park, the observation site for the dam’s Bald Eagles and other birds, is located downstream of the turbine building along the river’s west (south) shore.  As the name implies, the park is a superb location for angling.
Heed this warning.  Close your windows and sunroof or the vultures will subject your vehicle’s contents to a thorough search for food.  Then they’ll deposit a little consolation prize on your paint.
Scavenging Black Vultures congregate by the hundreds at Conowingo Dam to clean up the scraps left behind by people and predators.  They’ll greet you right in the parking lot.
Photographers line up downstream of the turbine building for an opportunity to get the perfect shot of a Bald Eagle.
The operator of the Conowingo Hydroelectric Generating Station, Exelon Energy, provides clean comfortable facilities for fishing, sightseeing, and wildlife observation.
There’s almost always a Peregrine Falcon zooming around the dam to keep the pigeons on their toes.
Double-crested Cormorants on the boulders that line the channel below the dam.  Hundreds are there right now.
Double-crested Cormorants dive for fish near the power house discharge, which, while just one small generator is operating, seems nearly placid.  The feeding frenzy really gets going when Conowingo begins generating with multiple large turbines and these gently flowing waters become torrential rapids filled with disoriented fishes.
Ring-billed Gulls seek to snag a small fish from the water’s surface.
After successfully nabbing shad or perch, these Double-crested Cormorants need to swallow their catch fast or risk losing it.  Stealing food is a common means of survival for the gulls, eagles, and other birds found here.
Where do migrating eagles go?  There are, right now, at least 50 Bald Eagles at Conowingo Dam, with more arriving daily.  Numbers are likely to peak during the coming weeks.
Eagles can be seen perched in the woods along both river shorelines, even in the trees adjacent to the Conowingo Fisherman’s Park car lot.  Others take stand-by positions on the boulders below the dam.
To remind visiting eagles that they are merely guests at Conowingo, a resident Bald Eagle maintains a presence at its nest on the wooded slope above Fisherman’s Park.  Along the lower Susquehanna, female Bald Eagles lay eggs and begin incubation in January.
When an eagle decides to venture out and attempt a dive at a fish, that’s when the photographers rush to their cameras for a chance at a perfect shot.
The extraordinary concentrations of Bald Eagles at Conowingo make it an excellent place to study the plumage differences between birds of various ages.
Here’s a first-year Bald Eagle, also known as a hatch-year or juvenile bird.
A second-year or Basic I immature Bald Eagle.  Note the long juvenile secondaries giving the wings a ragged-looking trailing edge.
A third-year or Basic II immature Bald Eagle.
A second-year/Basic I immature Bald Eagle (top) and a third-year/Basic II immature Bald Eagle (bottom).
A second-year/Basic I immature Bald Eagle (bottom) and a third-year/Basic II immature Bald Eagle (top).  Note the white feathers on the backs of eagles in these age classes.
A third-year/Basic II immature Bald Eagle perched in a tree alongside the parking area.  Note the Osprey-like head plumage.
A sixth-year or older adult Bald Eagle in definitive plumage (left) and a fourth-year or Basic III immature Bald Eagle (right).
If you want to see the Bald Eagles at Conowingo Dam, don’t wait.  While many birds are usually present throughout the winter, the large concentrations may start dispersing as early as December when eagles begin wandering in search of other food sources, particularly if the river freezes.
A pair of Bald Eagles is already working on a nest atop this powerline trestle downstream of Conowingo Dam.  By late December, most adult eagles will depart Conowingo to begin spending their days establishing and defending breeding territories elsewhere.  Any non-adult eagles still loitering around the dam will certainly begin receiving encouragement from the local nesting pair(s) to move along as well.

To reach Exelon’s Conowingo Fisherman’s Park from Rising Sun, Maryland, follow U.S. Route 1 south across the Conowingo Dam, then turn left onto Shuresville Road, then make a sharp left onto Shureslanding Road.  Drive down the hill to the parking area along the river.  The park’s address is 2569 Shureslanding Road, Darlington, Maryland.

As Bald Eagle numbers continue to increase, expect the parking lot to become full during weekends and over the Thanksgiving holiday.  To avoid the crowds, plan to visit during a weekday.

You can get the generating schedule for the Conowingo Dam by calling the Conowingo Generation Hotline at 888-457-4076.  The recording is updated daily at 5 P.M. to provide information for the following day.

Clean Slate for 2020

Inside the doorway that leads to your editor’s 3,500 square foot garden hangs a small chalkboard upon which he records the common names of the species of birds that are seen there—or from there—during the year.  If he remembers to, he records the date when the species was first seen during that particular year.  On New Year’s Day, the results from the freshly ended year are transcribed onto a sheet of notebook paper.  On the reverse, the names of butterflies, mammals, and other animals that visited the garden are copied from a second chalkboard that hangs nearby.  The piece of paper is then inserted into a folder to join those from previous New Year’s Days.  The folder then gets placed back into the editor’s desk drawer beneath a circular saw blade and an old scratched up set of sunglasses—so that he knows exactly where to find it if he wishes to.

A quick glance at this year’s list calls to mind a few recollections.

The 2019 bird list included 48 species, the 47 on the board plus Ruby-throated Hummingbird, which was logged on a slip of paper found tucked into the edge of the frame.

This Green Frog, photographed on New Year’s Day 2019, was “out and about” along the edge of the editor’s garden pond.  Due to the recent mild weather, Green Frogs were active during the current New Year’s holiday as well.
On a day with strong south winds in late February or during the first two weeks of March, there is often a conspicuous northbound spring flight of migrating waterfowl, gulls, and songbirds that crosses the lower Susquehanna valley as it departs Chesapeake Bay.  These Tundra Swans were among the three thousand seen from the garden patio on March 13, 2019.  A thousand migrating Canada Geese, 500 Red-winged Blackbirds, numerous Ring-billed Gulls, and some Herring Gulls were seen during the same afternoon.
This juvenile Cooper’s Hawk was photographed through the editor’s kitchen window.  From its favorite perch on this arbor it would occasionally find success snagging a House Sparrow from the large local flock.  It first visited the garden in November, the species being absent there since early spring.  Unlike previous years, there was no evidence of a breeding pair in the vicinity during 2019.
Plantings that provide food and cover for wildlife are essential to their survival.  Native flowers including Trumpet Vine (Campsis radicans) and Partridge Pea provide nourishment for the Ruby-throated Hummingbirds that visit the editor’s garden, but they really love a basket or pot filled with Mexican Cigar (Cuphea ignea) too.  The latter (seen here) can be grown as a houseplant and moved outdoors to a semi-shaded location in summer and early fall.  But remember, it’s tropical, so you’ll need to bring it back inside when frost threatens.
A Swamp Sparrow is an unusual visitor to a small property surrounded by paved parking lots and treeless lawns.  Nevertheless, aquatic gardens and native plants helped to attract this nocturnal migrant, seen here eating seeds from Indiangrass.  It arrived on September 30 and was gone on October 2.

Before putting the folder back into the drawer for another year, the editor decided to count up the species totals on each of the sheets and load them into the chart maker in the computer.

Despite the habitat improvements in the garden, the trend is apparent.  Bird diversity has not cracked the 50 species mark in 6 years.  Despite native host plants and nectar species in abundance, butterfly diversity has not exceeded 10 species in 6 years.

It appears that, at the very least, the garden habitat has been disconnected from the home ranges of many species by fragmentation.  His little oasis is now isolated in a landscape that becomes increasingly hostile to native wildlife with each passing year.  The paving of more parking areas, the elimination of trees, shrubs, and herbaceous growth from the large number of rental properties in the area, the alteration of the biology of the nearby stream by hand-fed domestic ducks, light pollution, and the outdoor use of pesticides have all contributed to the separation of the editor’s tiny sanctuary from the travel lanes and core habitats of many of the species that formerly visited, fed, or bred there.  In 2019, migrants, particularly “fly-overs”, were nearly the only sightings aside from several woodpeckers, invasive House Sparrows (Passer domesticus), and hardy Mourning Doves.  Even rascally European Starlings became sporadic in occurrence—imagine that!   It was the most lackluster year in memory.

The Tufted Titmouse was a daily visitor to the garden through 2018.  This one was photographed investigating holes in an old magnolia there during the spring of that year.  There were no Tufted Titmouse sightings in the garden in 2019.  This and other resident species, especially cavity-nesters, appear to be experiencing at least a temporary decline.
Breeding birds including Northern Cardinals may have had a difficult year.  In the editor’s garden, a pair were still feeding and escorting one of their young in early October.  The infestation of the editor’s town by domestic house and feral cats may have contributed to the failure of earlier broods, but a lack of food is also a likely factor.

If habitat fragmentation were the sole cause for the downward trend in numbers and species, it would be disappointing, but comprehendible.  There would be no cause for greater alarm.  It would be a matter of cause and effect.  But the problem is more widespread.

Although the editor spent a great deal of time in the garden this year, he was also out and about, traveling hundreds of miles per week through lands on both the east and the west shores of the lower Susquehanna.  And on each journey, the number of birds seen could be counted on fingers and toes.  A decade earlier, there were thousands of birds in these same locations, particularly during the late summer.

At about the time of summer solstice in June each year, Common Grackles begin congregating into roving summer flocks that will grow in size to assure their survival during the autumn migration, winter season, and return north in the spring.  From his garden, the editor saw just one flock of less than a dozen birds during the summer of 2019.  He saw none during his journeys through other areas of the Susquehanna valley.  Flocks of one hundred birds or more did not materialize until the southbound movements of grackles passed through the region in October and November.

In the lower Susquehanna valley, something has drastically reduced the population of birds during breeding season, post-breeding dispersal, and the staging period preceding autumn migration.  In much of the region, their late-spring through summer absence was, in 2019, conspicuous.  What happened to the tens of thousands of swallows that used to gather on wires along rural roads in August and September before moving south?  The groups of dozens of Eastern Kingbirds (Tyrannus tyrannus) that did their fly-catching from perches in willows alongside meadows and shorelines—where are they?

Several studies published during the autumn of 2019 have documented and/or predicted losses in bird populations in the eastern half of the United States and elsewhere.  These studies looked at data samples collected during recent decades to either arrive at conclusions or project future trends.  They cite climate change, the feline infestation, and habitat loss/degradation among the factors contributing to alterations in range, migration, and overall numbers.

There’s not much need for analysis to determine if bird numbers have plummeted in certain Lower Susquehanna Watershed habitats during the aforementioned seasons—the birds are gone.  None of these studies documented or forecast such an abrupt decline.  Is there a mysterious cause for the loss of the valley’s birds?  Did they die off?  Is there a disease or chemical killing them or inhibiting their reproduction?  Is it global warming?  Is it Three Mile Island?  Is it plastic straws, wind turbines, or vehicle traffic?

The answer might not be so cryptic.  It might be right before our eyes.  And we’ll explore it during 2020.

A clean slate for 2020.

In the meantime, Uncle Ty and I going to the Pennsylvania Farm Show in Harrisburg.  You should go too.  They have lots of food there.

Tundra Swan Migration

There was a hint of what was to come.  If you were out and about before dawn this morning, you may have been lucky enough to hear them passing by high overhead.  It was 5:30 A.M. when I opened the door and was greeted by that distinctive nasal whistle.  Stepping through the threshold and into the cold, I peered into the starry sky and saw them, their feathers glowing orange in the diffused light from the streets and parking lots below.  Their size and snow-white plumage make Tundra Swans one of the few species of migrating birds you’ll ever get to visibly discern in a dark moonless nighttime sky.

The calm air at daybreak and through the morning transitioned to a steady breeze from the south in the afternoon.  Could this be it?  Would this be that one day in late February or the first half of March each year when waterfowl (and other birds too) seem to take advantage of the favorable wind to initiate an “exodus” and move in conspicuous numbers up the lower Susquehanna valley on their way to breeding grounds in the north?  Well, indeed it would be.  And with the wind speeding up the parade, an observer at a fixed point on the ground gets to see more birds fly by.

In the late afternoon, an observation location in the Gettysburg Basin about five miles east of Conewago Falls in Lancaster County seemed to be well-aligned with a northwesterly flight path for migrating Tundra Swans.  At about 5:30 P.M., the clear sky began clouding over, possibly pushing high-flying birds more readily into view.  During the next several hours, over three thousand Tundra Swans passed overhead, flocks continuing to pass for a short time after nightfall.  There were more than one thousand Canada Geese, the most numerous species on similar days in previous years.  Sometimes on such a day there are numerous ducks.  Not today.  The timing, location, and conditions put Tundra Swans in the spotlight for this year’s show.

Tundra Swans flying northwest, paralleling the Susquehanna five miles distant.
Tundra Swans winter on the Atlantic Coastal Plain and often stage their northbound movements on the Piedmont along the lower Susquehanna River and at the nearby Middle Creek Wildlife Management Area.  The birds seen this evening are possibly coming directly from the coast or Chesapeake Bay.  With five hours of favorable wind helping them along, covering one hundred miles or more in an afternoon would be no problem.
High-flying Tundra Swans on their way to breeding grounds on, you guessed it, the arctic tundra in Alaska and northwestern Canada.
Tundra Swans in the largest flocks, sometimes consisting of more than 200 birds, were often detected by their vocalizations as they approached.
Tundra Swan flights continued after sunset and nightfall.
All of the high-flying migratory Canada Geese seen this evening were on a more northerly course than the northwest-bound swans.  These geese probably spent the winter on the Atlantic Coastal Plain near Chesapeake Bay and are now en route to breeding grounds in, you guessed it again, Canada.  They are not part of the resident Canada Goose population we see nesting throughout the lower Susquehanna valley.

Other migrants moving concurrently with the waterfowl included Ring-billed Gulls, Herring Gulls (6+), American Robins (50+), Red-winged Blackbirds (500+), and Common Grackles (100+).

Though I’ve only seen such a spectacle only once during a season in recent years, there certainly could be another large flight of ducks, geese, or swans yet to come. The breeze is forecast to continue from southerly directions for at least another day.  Keep you eyes skyward, no matter where you might happen to be in the lower Susquehanna valley.  These or other migratory species may put on another show, a “big day”, just for you.

 

Bonaparte’s Invasion

The warm weather late last week and the several inches of rain that followed have left the farm fields of the lower Susquehanna valley a soggy muddy mess…waterlogged.  Runoff has made its way down the tributaries to raise the waters of the river and fill up its banks.

Migrating gulls find it difficult to locate food when the Susquehanna becomes a silty turbid torrent.  It’s not at all unusual to find hundreds of them enjoying a feast of earthworms in the agricultural uplands when conditions such as these exist.  As you may have guessed,  the birds alluded to are the familiar Ring-billed Gulls, the same species seen mooching french fries and other snacks in fast-food restaurant parking lots.  They are by far the most common inland gull in eastern North America.

A flock of gulls feeding in farmland in the Gettysburg Basin northeast of Conewago Falls.  Gulls frequently feed in wet farm fields where earthworms are the prized meal.

Ring-billed Gulls are notorious for loafing and feeding in flocks which seldom include other species of gulls.  They are frequently the smallest gull found in their inland habitats, so it is understandable that they may avoid the company of the larger and often more aggressive species.

However, today I was reminded that one must be ever vigilant and check for other species among those flocks presumed to consist solely of Ring-billed Gulls, particularly during times when the river is so inhospitable to passing migrants.

A few Ring-billed Gulls can be seen in this flock consisting almost entirely of noticeably smaller Bonaparte’s Gulls.
Bonaparte’s Gulls are easily recognized by their small size, black heads, and flashy white primary feathers in the wings.  They are the only small gull commonly found in the Mid-Atlantic states.
Two Ring-billed Gulls (upper left and upper center) are outflanked by Bonaparte’s Gulls.  Bonaparte’s Gulls spend the winter feeding in the surf along the Atlantic coast.  As spring migrants they peak in April, closely following the Susquehanna River as they journey through the area.  The adults will continue to the northwest, passing through the Great Lakes region to nesting areas in Canada.
Adult Bonaparte’s Gulls in breeding (alternate) plumage have conspicuous black heads.
Several first-year Bonaparte’s Gulls in basic plumage can found among the adults in this image.  Most notable is the one to the right of center (flying left).  Note its lack of flashy white in the primary feathers of the wings, a black tail bar, and the dark spot behind the eye instead of a black hood.  The black spot behind the eye is characteristic of all Bonaparte’s Gulls in basic (non-breeding) plumage, including adults.  Bonaparte’s Gulls mature in two years.
Bonaparte’s Gulls invade the farmlands of the Gettysburg Basin.  Despite their common name, they seem uninterested in french fries and similar cuisine.

Winter Won’t Let Go…the Birds Don’t Care

It seems as though the birds have grown impatient for typical spring weather to arrive.  The increase in hours of daylight has signaled them that breeding time is here.  No further delays can be entertained.  They’ve got a schedule to keep.

Thursday, March 29:  Winds began blowing from the southwest, breaking a cold spell which had persisted since last week’s snowfall.  Birds were on the move ahead of an approaching rainy cold front.

Friday, March 30:  Temperatures reached 60 degrees at last.  Birds were again moving north through the day, despite rain showers and a change in wind direction—from the northwest and cooler following the passage of the front in the late morning.

Flocks of Double-crested Cormorants followed the Susquehanna River north in numerous V-shaped flocks during the recent several days.
There were Turkey Vultures by the hundreds on the way north.
And nearly as many Black Vultures too.

Saturday, March 31:  It was cooler, but birds were still on the wing headed north.

At sunrise, a migrating Northern Flicker stopped by at a suet feeder to refuel.

Osprey pairs have arrived at nest sites on the lower Susquehanna.

Sunday, April 1:  The morning was pleasant, but conditions became cooler and breezy in the afternoon.  Migratory and resident birds began feeding ahead of another storm.

A distant flock of fast-flying Bonaparte’s Gulls (Chroicocephalus philadelphia) moves expeditiously up the Susquehanna at Conewago Falls as winds begin to pick up during the late morning.  Are they hurrying to get north of the path of the forthcoming weather system?
A Mourning Dove (Zenaida macroura) feeds in anticipation of a snowy night ahead.
A male Downy Woodpecker devours a late-afternoon meal.
This Tufted Titmouse (Baeolophus bicolor), a cavity-nesting species, is distracted by a potential new home.
Dark-eyed Juncos winter in the lower Susquehanna valley.  During the month of April, they will begin departing for their breeding grounds, some nesting in the mountains just to our north.
Tufted Titmouse…still house hunting.
A male American Goldfinch is progressing through molt into a showy breeding (alternate) plumage.
A male House Finch takes a break from its melodious song to feed before the arrival of our next spring snow.  His mate is already incubating eggs in a nest not far away.
Northern Cardinals (Cardinalis cardinalis) feed through the late afternoon, often as the last birds out-and-about before darkness.  This male remains close to his mate as she forages beneath nearby shrubs.

Monday, April 2: Snow fell again, overnight and through the morning—a couple of inches.  Most of the snow had melted away by late afternoon.

Horned Larks are plentiful in large open bare-soil (tilled) farmlands in winter, particularly near fresh manure.  Their sandy-tan coloration hides them well, and they are seldom noticed unless spotted at roadside following snow storms.  Horned Larks are migratory ground-nesting birds found in many sparsely vegetated habitats including tundra, parched fields and prairies, beaches, and even airports.  There is a breeding population in the lower Susquehanna valley which may be increasingly attracted to favorable nesting habitat created in some no-till fields, possibly using a window of opportunity between the demise of cold-season cover crops and the ascendency of the warm-season crops to complete a brood cycle.  Comparing the site selection and success rates of nesting Horned Larks under various crop management methods, including reactions to herbicide use, could be an enlightening study project for inquisitive minds. (Hint-Hint)
The dainty Chipping Sparrow has arrived. This species commonly nests in small trees, often in suburban gardens.

A Flock of Seagulls?

At the moment there is a heavy snow falling, not an unusual occurrence for mid-February, nevertheless, it is a change in weather.  Forty-eight hours ago we were in the midst of a steady rain and temperatures were in the sixties.  The snow and ice had melted away and a touch of spring was in the air.

Big Bluestem in the Riverine Grasslands is inundated by the rising waters of the Susquehanna at Conewago Falls.   The river ice has been dispersed by the recent mild temperatures and rains.

Anyone casually looking about while outdoors during these last several days may have noticed that birds are indeed beginning to migrate north in the lower Susquehanna valley.  Killdeer, American Robins, Eastern Bluebirds, Red-winged Blackbirds, and Common Grackles are easily seen or heard in most of the area now.

Just hours ago, between nine o’clock this morning and one o’clock this afternoon, there was a spectacular flight of birds following the river north, their spring migration well underway.  In the blue skies above Conewago Falls, a steady parade of Ring-billed Gulls was utilizing thermals and riding a tailwind from the south-southeast to cruise high overhead on a course toward their breeding range.

Ring-billed Gulls swarm in a thermal updraft above Conewago Falls to gain altitude prior to streaming off to the north and continuing their journey.
Ring-billed Gulls climbing to heights sometimes exceeding 1,000 feet before breaking off and gliding away to the north.

The swirling hoards of Ring-billed Gulls attracted other migrants to take advantage of the thermals and glide paths on the breeze.  Right among them were 44 Herring Gulls, 3 Great Black-backed Gulls, 12 Tundra Swans (Cygnus columbianus), 10 Canada Geese, 3 Northern Pintails (Anas acuta), 6 Common Mergansers, 3 Red-tailed Hawks, a Red-shouldered Hawk, 6 Bald Eagles (non-adults), 8 Black Vultures, and 5 Turkey Vultures.

A first-year Herring Gull (top center) is a standout in a “kettle” of Ring-billed Gulls.
How many Ring-billed Gulls passed by today?  More than 18,000…with emphasis on MORE THAN.  You see, early this afternoon, the handy-dandy clicker-counter used to tick off and tally the big flights of birds as they pass by quit clicking and counting.  Therefore, 18,000 is the absolute minimum number of Ring-billed Gulls seen migrating north today.  Hopefully the trusty old oil can will get the clicker working again soon.

In the afternoon, the clouds closed in quickly, the flight ended, and by dusk more than an inch of snow was on the ground.  Looks like spring to me.

Migrating North?

CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS

A steady stream of birds was on the move this morning over Conewago Falls.  There were hundreds of Ring-billed Gulls, scores of Herring Gulls, and a few Great Black-backed Gulls to dominate the flight.  Then too there were thirteen Mallards, Turkey Vultures and a Black Vulture, twenty or more American Robins, a half a dozen Bald Eagles (juvenile and immature birds), a couple of Red-winged Blackbirds, and, perhaps most unusual of all, a flock of a dozen Scoters (Melanitta species), a waterfowl typical of the Mid-Atlantic surf in winter.  All of these birds were diligently following the river, and into a headwind no less.

“Hold on just a minute there, buster,” you may say, “I’ve looked at the migration count by dutifully clicking on the logo above and there is nothing but zeroes on the count sheet for today.  The season totals have not changed since the previous count day!”

Ah-ha, my dedicated friend, correct you are.  It seems that today’s bird flight was solely in one direction.  And that direction was upriver, moving north into a north breeze, on a heading which conflicts with all logic for creatures that should still be headed south for winter.  As a result, none of the birds observed today were counted on the “Autumn Migration Count”.

You might say, “Don’t you know that Winter Solstice was three days ago, so autumn and autumn migration is over.”

Okay, point well taken.  I should therefore clarify that what we title as “Autumn Migration Count” is more accurately a census of birds, insects, and other creatures transiting from northerly latitudes to more favorable latitudes to the south for winter.  This transit can begin as early as late June and extend into the first weeks of winter.  While most of this movement is motivated by the reduced hours of daylight during the period, late season migrants are often responding to ice, bad weather, or lack of food to prompt a journey further south.  Migration south in late December and January occurs even while the amount of daylight is increasing slightly in the days following the Winter Solstice.

So what of the birds seen flying north today?  There was some snow cover that has melted away, and the ice that formed on the river a week ago is gone due to the milder than normal temperatures this week.

One may ask, “Were the birds seen today migrating north?”

Let’s look at the species seen moving upriver today a try to determine their motivation.

First, and perhaps most straight-forward, is the huge flight of gulls.  Wintering gulls on the Susquehanna River near Conewago Falls tend to spend their nights in flocks on the water or on treeless islands and rocky outcrops in the river.  Many hundreds, sometimes thousands, find such favorable sites along the fifteen mile stretch of river from Conewago Falls downstream to Lake Clarke and the Conejohela Flats at Washington Boro.  Each morning most of these gulls venture out to suburbia, farmland, landfill, hydroelectric dams, and other sections of river in search of food.  Gulls are very able fliers and easily cover dozens of miles outbound and inbound each day in search of food.  Many of the gulls seen this morning were probably on their way to the Harrisburg metropolitan area to eat trash.  Barring any extraordinary buildups of ice on this section of river, one would expect these gulls to remain and make these daily excursions to food sources through early spring.

Ring-billed Gulls fly upriver through the Pothole Rocks at Conewago Falls.
Herring Gulls stream upriver through Conewago Falls on their way to fine dining.

Second, throughout the season Bald Eagles have been tallied on the migration count with caution.  Flight altitude, behavior, plumage, and the reaction of the “local” eagles to these transients was carefully considered before counting an eagle as a migrant.  They roam a lot, particularly when young, and range widely to feed.  The movement of eagles up the river today was probably food related.  A gathering of adult, juvenile, and immature Bald Eagles could be seen more than a half mile upstream from the migration count lookout.  Those moving up the river seemed to assemble with the “locals” there throughout the morning.  White-tailed Deities occasionally drown, particularly when there is thin or unstable ice on the river (as there was last week) and they attempt to tread upon it.  Then, their bodies are often stranded among rocks, in trees, or on the crown of the dam.  After such a mishap, their carcasses become meals for carrion-eaters in the falls.  Such an unfortunate deity, or another source of food, may have been attracting the eagles in numbers today.

A distant gathering of Bald Eagles at the south end of Three Mile Island in upper Conewago Falls.

Next, Black and Turkey Vultures often roam widely in search of food.  The small numbers seen headed up-river today would tend to mean very little when trying to determine if there is a trend or population shift.  Again, food may have been luring them upriver from nearby roosts.

And finally, the scoters, Mallards, American Robins, and Red-winged Blackbirds may have been wandering as well.  Toward mid-day, the wind speed picked up and the direction changed to the east.  This raises the possibility that these and others of the birds seen today may sense a change in weather, and may seek to take flight from the inclement conditions.  Prompted by the ocean breeze and in an attempt to avoid a storm, was there some movement away from the Atlantic Coastal Plain to the upper Piedmont today?  Many species may make these types of reactive movements.  Is it possible that some birds flee or avoid ever-changing storm tracks and alter there wintering locations based on jet streams, water currents, and other climatic conditions?  Probably.  These are interesting dynamics and something worthy of study outside the simpler methods of a migration count.

A Ring-billed Gull begins feeding as storm clouds approach Conewago Falls at mid-day.  This and other gull species travel widely in their winter range to find food and safe roosting sites.  For them, northward spring migration usually begins no earlier than late February.

Conewago Lineman

…And if it snows that stretch down south won’t ever stand the strain…                                                                  –Jimmy Webb

The lower Susquehanna valley’s first snowfall of the season arrived yesterday.  By this morning it measured just an inch in depth at Conewago Falls, more to the south and east, less to the west and north.  By mid-morning a cold fresh to moderate breeze from the northwest was blowing through the falls and stirring up ripples on the river.

Light snow on the Conewago Falls Pothole Rocks this morning.

Gulls sailed high overhead on the wind, taking a speedy ride downriver toward Chesapeake Bay, the Atlantic coast, and countless fast-food restaurant parking lots where surviving winter weather is more of a sure thing.  Nearly a thousand Ring-billed Gulls soared past the migration count lookout today.  Thirteen Herring Gulls and four Great Black-backed Gulls were among them.

Other migrants today included a Mallard, twenty-nine American Black Ducks, two Bald Eagles, eleven Black Vultures, fifteen Turkey Vultures, five American Goldfinches, and fifteen Red-winged Blackbirds.  The wintery weather seems to be prompting these late-season travelers to be on their way.

CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS

You know, today was like many other days at the falls.  As I arrive, I have the habit of checking all the power line towers on both river shorelines to see what may be there awaiting discovery.  More often than not, something interesting is perched on one or more of the structures…

…sometimes there are large flocks of European Starlings…
…other times there might be one or more Turkey Vultures…
…or possibly a Bald Eagle or two…
…or maybe the fastest-flying bird on the planet…
…or perhaps, wait; what’s he doing up there?

Yes friends, while the birds migrated through high above, down below a coordinated effort was underway to replace some of the electric transmission cable that stretches across the Susquehanna River at Conewago Falls.  As you’ll see, this project requires precise planning, preparation, and skill.  And it was fascinating to watch!

A helicopter is used to raise/lower men and equipment to/from the top of the towers.
A crew doing preparation work is lifted from a tower on the west shore of Conewago Falls.
A crew member is raised to a tower on the east shore of Conewago Falls to begin the next phase of the project.
Crew members are positioned on the two towers on the west shore.
The helicopter hovers in a stand-by position above the Pothole Rocks.  By keeping the chopper downwind from and below the wires being replaced, the pilot avoids putting rotor wash into the work area.   Note the linemen on the upper left side of each tower.  These men monitored the pulleys as the old cable, followed by the new, was pulled from the west shore to the east.
At the ready, the pilot skillfully hovers his craft, nose into the gusty wind, just 100 feet to the east of the migration count site on the Pothole Rocks.
Even as the chopper maintained position near and immediately over the count lookout, migrating birds continued to be seen streaming in a downriver direction high above.
A migrating immature Bald Eagle passes overhead, apparently undaunted by the commotion created by the use of a helicopter to tend the crew advancing replacement wire across the river below.
With the new cable in place, workers are lifted from the towers and lowered to the ground where they can get out of the cold wind after a job well done.

Loading Up For Winter

A very light fog lifted quickly at sunrise.  Afterward, there was a minor movement of migrants: forty-nine Ring-billed Gulls, a few Herring Gulls, a Red-shouldered Hawk following the river to the southeast, and small flocks totaling nine Cedar Waxwings and twenty-eight Red-winged Blackbirds.

A Belted Kingfisher in the morning fog.
A Ring-billed Gull calls as active migrants pass overhead on their way downriver.
CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS

In the Riparian Woodland, small mixed flocks of winter resident and year-round resident birds were actively feeding.  They must build and maintain a layer of body fat to survive blustery cold nights and the possible lack of access to food during snowstorms.  There’s no time to waste; nasty weather could bring fatal hardship to these birds soon.

A Carolina Chickadee (Poecile carolinensis) feeds on the seeds of an Eastern Sycamore (Platanus occidentalis), also known as American Sycamore.  Chickadees are generalist feeders, eating invertebrates and suet at feeding stations in addition to the seeds of many plants.  Carolina Chickadees are year-round residents at Conewago Falls.
A fast-moving Golden-crowned Kinglet zips from limb to limb to grab tiny insects and other invertebrates.  During the winter, these petite birds will carefully probe the bark and crevices of trees to glean enough food to survive.  Golden-crowned Kinglets are winter residents at Conewago Falls.  In spring, they will depart to nest in coniferous forests.
A Downy Woodpecker (Picoides pubescens) searches an infected tree for insects.  They are year-round residents.
Carolina Wrens (Thryothorus ludovicianus) are considered year-round residents at Conewago Falls, though they may withdraw to the south during severe winters.  Carolina Wrens sing year-round.  Today, their loud melody echoed through the Riparian Woodland all morning.
The tiny bob-tailed Winter Wren is an elusive ground-dwelling winter resident at the falls.  You may hear their scolding chatter from rocky areas and tree logs where they climb around mouse-like in search of small invertebrates.  Their song is a fast jumble of dainty musical trills that can sometimes be heard echoing through the Riparian Woodland in winter.  In spring, they’ll depart to nest in damp coniferous forests.

Culinary Reminder

It was a crisp clear morning with birdless blue skies.  The migration has mostly drawn to a close; very little was seen despite a suitable northwest breeze to support a flight.   There were no robins and no blackbirds.  Not even a starling was seen today.  The only highlights were a Bufflehead (Bucephala albeola) and a couple of Swamp Sparrows.

A Swamp Sparrow is coaxed from the dense leafy cover of the Riverine Grasslands of Conewago Falls.
CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS

And now ladies and gentlemen, boys and girls, it’s time for a Thanksgiving Day culinary reminder from the local Conewago Falls Turkey…

“That’s the Conewago Falls Turkey Vulture if you don’t mind.  And I’m here to remind you that this Thanksgiving, you don’t have to fight your way in there to get first pickings of the feast.  Take it from me, let those flavors and aromas intensify over time.  And juices, who needs juices?  Let that stuff congeal so everything sticks to your ribs.  Are you paying attention?  I’m telling you, just back off, let the crowd die down, then get in there and devour those leftovers.  They’re the best.  You’ll thank me later!”

Anthropoavians

Temperatures plummeted to well below freezing during the past two nights, but there was little sign of it in Conewago Falls this morning.  The fast current in the rapids and swirling waters in flooded Pothole Rocks did not freeze.  Ice coated the standing water in potholes only in those rocks lacking a favorable orientation to the sun for collecting solar heat during the day to conduct into the water during the cold nights.

On the shoreline, the cold snap has left its mark.  Ice covers the still waters of the wetlands.  Frost on exposed vegetation lasted until nearly noontime in shady areas.  Insect activity is now grounded and out of sight.  The leaves of the trees tumble and fall to cover the evidence of a lively summer.

The nocturnal bird flight is narrowing down to just a few species.  White-throated Sparrows, a Swamp Sparrow (Melospiza georgiana), and Song Sparrows are still on the move.  Though their numbers are not included in the migration count, hundreds of the latter are along the shoreline and in edge habitat around the falls right now.  Song Sparrows are present year-round, migrate at night, and are not seen far from cover in daylight, so migratory movements are difficult to detect.  It is certain that many, if not all of the Song Sparrows here today have migrated and arrived here recently.  The breeding population from spring and summer has probably moved further south.  And many of the birds here now may remain for the winter.  Defining the moment of this dynamic, yet discrete, population change and logging it in a count would certainly require different methods.

Song Sparrows are now abundant in the brushy edges of fields and woodlands.  They may even break into song on sunny days.

Diurnal migration was foiled today by winds from southerly directions and moderating temperatures.  The only highlight was an American Robin flight that extended into the morning for a couple of hours after daybreak and totaled over 800 birds.  This flight was peppered with an occasional flock of blackbirds.  Then too, there were the villains.

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They’re dastardly, devious, selfish, opportunistic, and abundant.  Today, they were the most numerous diurnal migrant.  Their numbers made this one of the biggest migration days of the season, but they are not recorded on the count sheet.  It’s no landmark day.  They excite no one.  For the most part, they are not recognized as migrants because of their nearly complete occupation of North America south of the taiga.  If people build on it or alter it, these birds will be there.  They’re everywhere people are.  If the rotten attributes of man were wrapped up into one bird, an “anthropoavian”, this would be it.

Meet the European Starling (Sturnus vulgaris).  Introduced into North America in 1890, the species has spread across the entire continent.  It nests in cavities in buildings and in trees.  Starlings are aggressive, particularly when nesting, and have had detrimental impacts on the populations of native cavity nesting birds, particularly Red-headed Woodpeckers, Purple Martins (Progne subis), and Eastern Bluebirds.  They commonly terrorize these and other native species to evict them from their nest sites.  European Starlings are one of the earlier of the scores of introduced plants and animals we have come to call invasive species.

Noisy flocks of European Starlings are right at home on man-made structures in city and country.

Today, thousands of European Starlings were on the move, working their way down the river shoreline and raiding berries from the vines and trees of the Riparian Woodlands.  My estimate is between three and five thousand migrated through during the morning.  But don’t worry, thousands more will be around for the winter.

European Starlings mob a Sharp-shinned Hawk from above, a common behavior.
An Eastern Bluebird feeds on the few berries left untouched by passing European Starlings.

Feathered Fallout

The NOAA National Weather Service radar images from last evening provided an indication that there may be a good fallout of birds at daybreak in the lower Susquehanna valley.  The moon was bright, nearly full, and there was a gentle breeze from the north to move the nocturnal migrants along.  The conditions were ideal.

Rising from daytime roosts in New York and Pennsylvania, then streaming south in moonlit skies, migrating birds are recorded as echoes on this post-sunset composite NEXRAD loop from last evening.  (NOAA/National Weather Service image)

The Riparian Woodlands at Conewago Falls were alive with migrants this morning.  American Robins and White-throated Sparrows were joined by new arrivals for the season: Brown Creeper (Certhia americana), Ruby-crowned Kinglets (Regulus calendula), Golden-crowned Kinglets (Regulus satrapa), Dark-eyed Junco (Junco hyemalis), and Yellow-rumped Warbler (Setophaga coronata).  These are the perching birds one would expect to have comprised the overnight flight.  While the individuals that will remain may not yet be among them, these are the species we will see wintering in the Mid-Atlantic states.  No trip to the tropics for these hardy passerines.

American Robins continued migratory flight into the first hour of daylight this morning.  Their calls are commonly heard at night as migrating individuals pass overhead.
White-throated Sparrows are nocturnal migrants, and are a familiar find on woodland edges and at suburban feeding stations through the winter.
Dark-eyed Juncos, also nocturnal migrants, are common winter residents in the Lower Susquehanna River Watershed, frequently visiting bird feeders.
Heavy rain earlier this week in the Susquehanna River drainage basin has flooded most of the Pothole Rocks; the rapids of Conewago Falls have returned.
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A Quick Getaway

It was a placid morning on Conewago Falls with blue skies dotted every now and then by a small flock of migrating robins or blackbirds.  The jumbled notes of a singing Winter Wren (Troglodytes hiemalis) in the Riparian Woodland softly mixed with the sounds of water spilling over the dam.  The season’s first Wood Ducks (Aix sponsa), Blue-winged Teal (Spatula discors), Herring Gull (Larus argentatus), Horned Larks (Eremophila alpestris), and White-throated Sparrows (Zonotrichia albicollis) were seen.

There was a small ruckus when one of the adult Bald Eagles from a local pair spotted an Osprey passing through carrying a fish.  This eagle’s effort to steal the Osprey’s catch was soon interrupted when an adult eagle from a second pair that has been lingering in the area joined the pursuit.  Two eagles are certainly better than one when it’s time to hustle a skinny little Osprey, don’t you think?

But you see, this just won’t do.  It’s a breach of eagle etiquette, don’t you know?  Soon both pairs of adult eagles were engaged in a noisy dogfight.  It was fussing and cackling and the four eagles going in every direction overhead.  Things calmed down after about five minutes, then a staring match commenced on the crest of the dam with the two pairs of eagles, the “home team” and the “visiting team”, perched about 100 feet from each other.  Soon the pair which seems to be visiting gave up and moved out of the falls for the remainder of the day.  The Osprey, in the meantime, was able to slip away.

In recent weeks, the “home team” pair of Bald Eagles, seen regularly defending territory at Conewago Falls, has been hanging sticks and branched tree limbs on the cross members of the power line tower where they often perch.  They seem only to collect and display these would-be nest materials when the “visiting team” pair is perched in the nearby tower just several hundred yards away…an attempt to intimidate by homesteading.  It appears that with winter and breeding time approaching, territorial behavior is on the increase.

The second migrating Osprey of the day ran the gauntlet of marauding eagles without incident.

In the afternoon, a fresh breeze from the south sent ripples across the waters among the Pothole Rocks.  The updraft on the south face of the diabase ridge on the east shore was like a highway for some migrating hawks, falcons, and vultures.  Black Vultures (Coragyps atratus) and Turkey Vultures streamed off to the south headlong into the wind after leaving the ridge and crossing the river.  A male and female Northern Harrier (Circus hudsonius), ten Red-tailed Hawks, two Red-shouldered Hawks (Buteo lineatus), six Sharp-shinned Hawks, and two Merlins crossed the river and continued along the diabase ridge on the west shore, accessing a strong updraft along its slope to propel their journey further to the southwest.  Four high-flying Bald Eagles migrated through, each following the east river shore downstream and making little use of the ridge except to gain a little altitude while passing by.

(Top and Middle) Turkey Vultures riding the fresh breeze and teetering to-and-fro on up-tilted wings.  This wing posture is known as a dihedral.  (Bottom) More than 100 migrating Black Vultures climbed high on the afternoon breeze to make an oblique crossing of the river and maintain a southbound course.

Late in the afternoon, the local Bald Eagles were again airborne and cackling up a storm.  This time they intercepted an eagle coming down the ridge toward the river and immediately forced the bird to climb if it intended to pass.  It turned out to be the best sighting of the day, and these “home team” eagles found it first.  It was a Golden Eagle (Aquila chrysaetos) in crisp juvenile plumage.  On its first southward voyage, it seemed to linger after climbing high enough for the Bald Eagles to loose concern, then finally selected the ridge route and crossed the river to head off to the southwest.

Ring-billed Gulls began feeding during the afternoon as clouds preceding stormy weather approached.
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State of Confusion

The humid rainy remains of Hurricane Nate have long since passed by Pennsylvania, yet mild wet weather lingers to confuse one’s sense of the seasons.  This gloomy misty day was less than spectacular for watching migrating birds and insects, but some did pass by.  Many resident animals of the falls are availing themselves of the opportunity to continue active behavior before the cold winds of autumn and winter force a change of lifestyle.

Warm drizzle at daybreak prompted several Northern Spring Peepers (Pseudacris crucifer crucifer) to begin calling from the wetlands in the Riparian Woodlands of Conewago Falls.  An enormous chorus of these calls normally begins with the first warm rains of early spring to usher in this tiny frog’s mating season.  Today, it was just a few “peeps” among anxious friends.

The tiny Northern Spring Peeper is recognized by the dark “X” across its back.  Soon, shelter must be found among loose bark and fallen logs to commence hibernation.  Emergence, often prompted by warm spring rains, will quickly be followed by a growing chorus of breeding calls as sometimes hundreds of these frogs assemble in vernal pools where mating will then occur.

Any additional river flow that resulted from the rains of the previous week is scarcely noticeable among the Pothole Rocks.  The water level remains low, the water column is fairly clear, and the water temperatures are in the 60s Fahrenheit.

It’s no real surprise then to see aquatic turtles climbing onto the boulders in the falls to enjoy a little warmth, if not from the sun, then from the stored heat in the rocks.  As usual, they’re quick to slide into the depths soon after sensing someone approaching or moving nearby.  Seldom found anywhere but on the river, these skilled divers are Common Map Turtles (Graptemys geographica), also known as Northern Map Turtles.  Their paddle-like feet are well adapted to swimming in strong current.  They are benthic feeders, feasting upon a wide variety of invertebrates found among the stone and substrate of the river bottom.

Adult Common Map Turtles hibernate communally on the river bottom in a location protected from ice scour and turbulent flow, often using boulders, logs, or other structures as shelter from strong current.  The oxygenation of waters tumbling through Conewago Falls may be critical to the survival of the turtles overwintering downstream.  Dissolved oxygen in the water is absorbed by the nearly inactive turtles as they remain submerged at their hideout through the winter.  Though Common Map Turtles, particularly males, may occasionally move about in their hibernation location, they are not seen coming to the surface to breathe.

The Common Map Turtles in the Susquehanna River basin are a population disconnected from that found in the main range of the species in the Great Lakes and upper Mississippi basin.  Another isolated population exists in the Delaware River.

Common Map Turtles, including this recently hatched young seen in August, are often observed climbing onto rocks in the river.
Note the oversize swimming fin adaptations of the feet on this adult Common Map Turtle found among the Pothole Rocks in Conewago Falls.  Young and adults are capable of navigating some strong current to feed and escape danger.
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SOURCES

Committee on the Status of Endangered Wildlife in Canada.  2002.  Status Report of the Northern Map Turtle.  Canadian Wildlife Service.  Ottawa, Ontario.

Summer Breeze

A moderate breeze from the south placed a headwind into the face of migrants trying to wing their way to winter quarters.  The urge to reach their destination overwhelmed any inclination a bird or insect may have had to stay put and try again another day.

Blue Jays were joined by increasing numbers of American Robins crossing the river in small groups to continue their migratory voyages.  Killdeer (Charadrius vociferous) and a handful of sandpipers headed down the river route.  Other migrants today included a Cooper’s Hawk (Astur cooperii), Eastern Bluebirds (Sialia sialis), and a few Common Mergansers (Mergus merganser), House Finches (Haemorhous mexicanus), and Common Grackles (Quiscalus quiscula).

The afternoon belonged to the insects.  The warm wind blew scores of Monarchs toward the north as they persistently flapped on a southwest heading.  Many may have actually lost ground today.  Painted Lady (Vanessa cardui) and Cloudless Sulphur butterflies were observed battling their way south as well.  All three of the common migrating dragonflies were seen: Common Green Darner (Anax junius), Wandering Glider (Pantala flavescens), and Black Saddlebags (Tramea lacerata).

The warm weather and summer breeze are expected to continue as the rain and wind from Hurricane Nate, today striking coastal Alabama and Mississippi, progresses toward the Susquehanna River watershed during the coming forty-eight hours.

This Great Blue Heron was joined by numerous other fishermen and a good number of sightseers in the falls today.
A colorful young Northern Water Snake (Nerodia sipedon) takes advantage of the sun-heated surface of a Pothole Rock to remain nimble and active.  Cooler weather will soon compel this and other reptiles to find shelter for winter hibernation.
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Swallows by the Thousands

A fresh breeze from the north brought cooler air and a reminder that summer is gone and autumn has arrived.

Fast-moving dark clouds provided a perfect backdrop for viewing passing diurnal migrants.  Bald Eagles utilized the tail wind to cruise down the Susquehanna toward Chesapeake Bay and points further south.  A migrating Merlin began a chase from which a Northern Flicker narrowly escaped by finding shelter among Pothole Rocks and a few small trees.  The season’s first American Black Duck (Anas rubripes), Common Loon (Gavia immer), Yellow-bellied Sapsucker (Sphyrapicus varia), and American Pipits (Anthus rubescens) moved through.

Blue Jays continued their hesitant crossings of the river at Conewago Falls.  The majority completed the journey by forming groups of a dozen or more birds and following the lead of a lone American Robin, a Northern Flicker, or, odd as it appeared, a small warbler.

By far the most numerous migrants today were swallows.  Thousands of Northern Rough-winged Swallows and hundreds of Tree Swallows were on the wing in search of what was suddenly a sparse flying insect supply.  To get out of the brisk wind, some of the more resourceful birds landed on the warm rocks.  To satisfy their appetite, many were able to pick crawling arthropods from the surface of the boulders.  They swallow them whole.

A few of the thousands of swallows seen at Conewago Falls today.
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Blue Jay Way

The Neotropical birds that raised their young in Canada and in the northern United States have now logged many miles on their journey to warmer climates for the coming winter.  As their density decreases among the masses of migrating birds, a shift to species with a tolerance for the cooler winter weather of the temperate regions will be evident.

Though it is unusually warm for this late in September, the movement of diurnal migrants continues.  This morning at Conewago Falls, five Broad-winged Hawks (Buteo platypterus) lifted from the forested hills to the east, then crossed the river to continue a excursion to the southwest which will eventually lead them and thousands of others that passed through Pennsylvania this week to wintering habitat in South America.  Broad-winged Hawks often gather in large migrating groups which swarm in the rising air of thermal updrafts, then, after gaining substantial altitude, glide away to continue their trip.  These ever-growing assemblages from all over eastern North America funnel into coastal Texas where they make a turn to south around the Gulf of Mexico, then continue on toward the tropics.  In the coming weeks, a migration count at Corpus Christi in Texas could tally 100,000 or more Broad-winged Hawks in a single day as a large portion of the continental population passes by.  You can track their movement and that of other diurnal raptors as recorded at sites located all over North America by visiting hawkcount.org on the internet.  Check it out.  You’ll be glad you did.

Nearly all of the other migrants seen today have a much shorter flight ahead of them.  Red-bellied Woodpeckers (Melanerpes carolinus), Red-headed Woodpeckers (Melanerpes erythrocephalus), and Northern Flickers (Colaptes auratus) were on the move.  Migrating American Robins (Turdus migratorius) crossed the river early in the day, possibly leftovers from an overnight flight of this primarily nocturnal migrant.  The season’s first Great Black-backed Gulls (Larus marinus) arrived.  American Goldfinches are easily detected by their calls as they pass overhead.  Look carefully at the goldfinches visiting your feeder, the birds of summer are probably gone and are being replaced by migrants currently passing through.

By far, the most conspicuous migrant today was the Blue Jay.  Hundreds were seen as they filtered out of the hardwood forests of the diabase ridge to cautiously cross the river and continue to the southwest.  Groups of five to fifty birds would noisily congregate in trees along the river’s edge, then begin flying across the falls.  Many wary jays abandoned their small crossing parties and turned back.  Soon, they would try the trip again in a larger flock.

Sensing that they are being watched, Blue Jays are hesitant to fly across the narrow Susquehanna at Conewago Falls without first assembling into a flock.  The local constabulary often penalizes those who freelance and do not move in orderly groups.

A look at this morning’s count reveals few Neotropical migrants.  With the exception of the Broad-winged Hawks and warblers, the migratory species seen today will winter in a sub-tropical temperate climate, primarily in the southern United States, but often as far north as the lower Susquehanna River valley.  The individual birds observed today will mostly continue to a winter home a bit further south.  Those that will winter in the area of Conewago Falls will arrive in October and later.

The Great Blue Heron (Ardea herodius) can be found year-round at Conewago Falls, provided there is open water and adequate food.  Migrants from breeding colonies to the north will soon supplement the local population.
The Double-crested Cormorant (Phalacrocorax auritus) is a summer resident at Conewago Falls.  Migration of the local population and of those from further north will soon begin.  All will be gone by the time ice forms on the river.  Cormorants are often seen drying their feathers in sunlight following a series of feeding dives.

The long-distance migrating insect so beloved among butterfly enthusiasts shows signs of improving numbers.  Today, more than two dozen Monarchs were seen crossing the falls and slowly flapping and gliding their way to Mexico.

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Yellowlegs for Breakfast

A few nocturnal migrants flew through the moonlit night to arrive at Conewago Falls for a sunrise showing this morning.  A dozen warblers were in the treetops and a Wood Thrush (Hylocichla mustelina) chattered away in the understory of the Riparian Woodlands.  Three species of shorebirds were in the falls and on the Pothole Rocks: Least Sandpiper (Calidris minutilla), Lesser Yellowlegs (Tringa flavipes), and Greater Yellowlegs (Tringa melanoleuca).

A Greater Yellowlegs (right) and two Lesser Yellowlegs sandpipers dropped by for breakfast.

The diurnal migration was highlighted by a Merlin (Falco columbarius), an Osprey, and a Bald Eagle, each flying down the river.  Most of the other birds in the falls seemed content to linger and feed.  There’s no need to hurry folks, only trouble lurks down there in paradise at the moment.

A light to moderate flight of nocturnal migrants in the eastern United States is displayed on NOAA National Weather Service NEXRAD radar at 4:58 AM EDT.  The eye of Hurricane Irma can be seen approaching the Florida Keys.  (NOAA/National Weather Service image)
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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.
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SOURCES

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