Big Broad-winged Hawk Flights Are Underway

Flights of southbound Broad-winged Hawks have joined those of other Neotropical migrants to thrill observers with spectacular numbers.  In recent days, thousands have been seen and counted at many of the regions hawkwatching stations.  Now is the time to check it out!

A "kettle" of Broad-winged Hawks gaining altitude by soaring on a thermal updraft.
A “kettle” of Broad-winged Hawks gaining altitude by soaring on a thermal updraft.
Migrating Broad-winged Hawks
Broad-winged Hawks gliding away to the southwest after climbing in a column of rising warm air.
Broad-winged Hawk
A migrating Broad-winged Hawk enroute to the tropics for winter.

Other diurnal migrants are on the move as well…

Migratory Woodpeckers: Red-bellied Woodpecker and Northern Flicker
The Red-bellied Woodpecker (left) and the Northern Flicker (right) are migratory species of woodpeckers that begin heading south during the last half of September each year.
Migrating Blue Jay
Running a bit early, large numbers of Blue Jays having been moving through the area for several weeks now.
Flock of Cedar Waxwings
Flocks of Cedar Waxwings roam widely as they creep ever southward for winter.

Adding to the diversity of sightings, there are these diurnal raptors arriving in the area right now…

Juvenile Sharp-shinned Hawk
Numbers of migrating Sharp-shinned Hawks are building and will peak during the coming weeks.
Juvenile Cooper's Hawk
As will numbers of Cooper’s Hawks.
Merlin
The Merlin and other falcons peak in late September and early October.
Adult Bald Eagle
And Bald Eagles are moving throughout the fall season.

For more information and directions to places where you can observe migrating hawks and other birds, be certain to click the “Hawkwatcher’s Helper” tab at the top of this page.

The Blizzard Has Arrived: Snow Geese at Middle Creek

It’s that time of year—Snow Geese on their northbound migration, more than 100,000 of them, have arrived for a stopover at the Pennsylvania Game Commission’s Middle Creek Wildlife Management Area in Lancaster and Lebanon Counties.  Get there now to see scenes like these in person…

Snow Geese at Middle Creek Wildlife Management Area
Thousands of Snow Geese gather on the main impoundment at Middle Creek.  Presently, over 100,000 are estimated to be visiting the refuge.
Tundra Swans at Middle Creek Wildlife Management Area
More than two thousand Tundra Swans are visiting Middle Creek right now too.
female American Kestrel
A passing American Kestrel doesn’t seem to ruffle any feathers among the multitudes of Snow Geese on the lake…
Bald Eagles at Middle Creek Wildlife Management Area
…but when the local pair of Bald Eagles gets close, such as when they’re escorting a third party away from their nesting territory, …
Snow Geese at Middle Creek Wildlife Management Area
…Snow Geese lift off in a panic.
Snow Geese at Middle Creek Wildlife Management Area
Snow Geese rise above the shoreline treetops.
Snow Geese at Middle Creek Wildlife Management Area
Feeding and roosting Snow Geese take flight in the presence of a potential predator to not only make a direct escape, but also to seek a safer position toward the center of the flock, keeping away from the vulnerable areas on the periphery.
Snow Geese and Tundra Swans at Middle Creek Wildlife Management Area
Thousands of Snow Geese rise behind the placid group of Tundra Swans in the foreground.
Snow Geese at Middle Creek Wildlife Management Area
Observers along Willow Point Trail with swarming Snow Geese just ahead.
Snow Geese at Middle Creek Wildlife Management Area
In the midst of the thunderous cackle of thousands of Snow Geese.
Snow Geese at Middle Creek Wildlife Management Area
Don’t forget your camera…
Snow Geese at Middle Creek Wildlife Management Area
…for an unforgettable photo op at Willow Point.

Hey, Let’s Go to Conowingo: It’s Bald Eagle Time

Why are there dozens of people with enormous lenses on complicated cameras atop sturdy tripods gathered at Fisherman’s Park below the Conowingo Dam on the lower Susquehanna River in Maryland?  It’s Bald Eagle time, that’s why.  Here are some photos from the scene, taken just two days ago.

Dozens of observers and photographers line up along the Harford County shoreline of the Susquehanna downstream of the powerhouse at the Conowingo Hydroelectric Station, the majority awaiting the opportunity to catch a shot of a Bald Eagle grabbing a fish from the river just in front of them.  Visitors travel to Conowingo from all over the continental United States to see and photograph eagles in concentrations that are often rivaled only in less accessible areas of Alaska and Canada.
Bald Eagles migrate to the lower Susquehanna near Conowingo and the upper Chesapeake Bay to spend the early winter in congregations that can, in good years, number in the hundreds of birds. There are presently at least 60 to 80 Bald Eagles present, and numbers are increasing.
If you visit, you’ll have a chance to see Bald Eagles in the various stages of plumage transition experienced during the six years needed to acquire the familiar all-white head and tail of adulthood.  This particular immature eagle is in its third year.  Birds at this age are sometimes known as “Osprey face” Bald Eagles due to the dark stripe through the eye.  Be certain to click the “Hawkwatchers Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page to see a photographic guide to aging the eagles and other birds of prey you observe.
An adult Bald Eagle snags a fish from the Susquehanna in front of photographers and gets the cameras clicking and other eagles in the area cackling and chattering.
The majority of the Bald Eagles at Conowingo are there for the early winter only; they’ll disperse to their nesting grounds later in the season.  An exception is this mated pair that is already at their nest site adjacent to the Fisherman’s Park car lot.  They can often be seen perched in the treetops directly above visitor’s vehicles.

To reach Exelon Energy’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.

Do make an excursion to the lower Susquehanna at Conowingo soon.  To avoid crowds and parking congestion, plan to visit on a weekday.  You’ll want warm clothing, binoculars, and a camera too.

The Fisherman’s Park Bald Eagles copulating.  If you don’t know what that is, ask your mother…no, wait, on second thought, look it up on the internet.

A Visit to Bombay Hook National Wildlife Refuge

It’s surprising how many millions of people travel the busy coastal routes of Delaware each year to leave the traffic congestion and hectic life of the northeast corridor behind to visit congested hectic shore towns like Rehobeth Beach, Bethany Beach, and Ocean City, Maryland.  They call it a vacation, or a holiday, or a weekend, and it’s exhausting.  What’s amazing is how many of them drive right by a breathtaking national treasure located along Delaware Bay just east of the city of Dover—and never know it.  A short detour on your route will take you there.  It’s Bombay Hook National Wildlife Refuge, a quiet but spectacular place that draws few crowds of tourists, but lots of birds and other wildlife.

Bombay Hook National Wildlife Refuge is located just off Route 9, a lightly-traveled coastal road east of Dover, Delaware.  Note the Big Bluestem and other warm season grasses in the background.  Bombay Hook, like other refuges in the system, is managed for the benefit of the wildlife that relies upon it to survive.  Within recent years, most of the mowed grass and tilled ground that once occurred here has been replaced by prairie grasses or successional growth, much to the delight of Northern Bobwhite (Colinus virginianus) and other species.

Let’s join Uncle Tyler Dyer and have a look around Bombay Hook.  He’s got his duck stamp and he’s ready to go.

Uncle Ty’s current United States Fish and Wildlife Service Duck Stamp displayed on his dashboard is free admission to the tour road at Bombay Hook and other National Wildlife Refuges.
The refuge at Bombay Hook includes woodlands, grasslands, and man-made freshwater impoundments, but it is largely comprised of thousands of acres of tidal salt marsh bordering and purifying the waters of Delaware Bay.  These marshes are renowned wintering areas for an Atlantic population of Snow Goose known as the “Greater Snow Goose” (Anser caerulescens atlanticus).  Thousands of these birds rising over the marsh into the glowing light of a setting sun is an unforgettable sight.
Trails at various stops along the auto tour route lead to observation towers and other features. This boardwalk meanders into the salt marsh grasses and includes a viewing area alongside a tidal creek.  Our visit coincided with a very high tide induced by east winds and a new moon.
During high tide, an Eastern Cottontail (Sylvilagus floridanus) seeks higher ground near the boardwalk and the wooded edge of the salt marsh.
As the tide rises, fast-flying shorebirds scramble from flooded mudflats in the salt marsh on the east side of the tour road.
When high tide arrives in the salt marshes, shorebirds and waterfowl often concentrate in the man-made freshwater pools on the west side of the tour road.  Glaring afternoon sun is not the best for viewing birds located west of the road.  For ideal light conditions, time your visit for a day when high tide occurs in the morning and recedes to low tide in the afternoon.
A view looking west into Shearness Pool, largest of the freshwater impoundments at Bombay Hook.
Bombay Hook has many secretive birds hiding in its wetlands, but they can often be located by the patient observer.  Here, two Pied-billed Grebes feed in an opening among the vegetation in a freshwater pool.
One of Bombay Hook’s resident Bald Eagles patrols the wetlands.
American Avocets (Recurvirostra americana) gather by the hundreds at Bombay Hook during the fall.  A passing eagle will stir them into flight.
An American Avocet, a delicate wader with a peculiar upturned bill.
As soon as the tide begins receding, shorebirds and waterfowl like these Green-winged Teal begin dispersing into the salt marshes to feed on the exposed mudflats.
The woodlands and forested areas of the refuge host resident songbirds and can be attractive to migrating species like this Yellow-rumped Warbler.
For much of its course, the tour road at Bombay Hook is located atop the dike that creates the man-made freshwater pools on the western edge of the tidal salt marsh.  If you drive slowly and make frequent stops to look and listen, you’ll notice an abundance of birds and other wildlife living along this border between two habitats.  Here, a Swamp Sparrow has a look around.
Savannah Sparrows are common along the tour road where native grasses grow wild.
Bombay Hook is renowned for its rarities. One of the attractions during the late summer and autumn of 2021 was a group of Roseate Spoonbills (Platalea ajaja), vagrants from the southern states, seen here with Great Egrets and Snowy Egrets (Egretta thula).
Roseate Spoonbills and Great Egrets at Bombay Hook.

Remember to go the Post Office and get your duck stamp.  You’ll be supporting habitat acquisition and improvements for the wildlife we cherish.  And if you get the chance, visit a National Wildlife Refuge.  November can be a great time to go, it’s bug-free!  Just take along your warmest clothing and plan to spend the day.  You won’t regret it.

Migration Update

Can it be that time already?  Most Neotropical birds have passed through the Lower Susquehanna River Watershed on their way south and the hardier species that will spend our winter in the more temperate climes of the eastern United States are beginning to arrive.

Here’s a gallery of sightings from recent days…

During the past two weeks, thousands of Broad-winged Hawks, including this adult bird, crossed the skies of the lower Susquehanna valley on their way to Central and South America for our winter.
A juvenile Broad-winged Hawk passes into the sunset during its first autumn migration.
Blackpoll Warblers are among the last of the Neotropical species to transit the region.  They’ll continue to be seen locally through at least early October.
Blue-headed Vireos are the October vireo during the fall, the other species having already continued toward tropical forests for a winter vacation.
The lower Susquehanna region lies just on the northern edge of the wintering range of the Blue-gray Gnatcatcher, a species found nesting locally among treetops in deciduous woods.  Look for their numbers to swell in coming days as birds from further north begin rolling through the region on their way south.
Sharp-shinned Hawks delight visitors at ridgetop hawk watches during breezy late-September and early-October days.  They allow closer observation than high-flying Broad-winged Hawks due to their habit of cruising just above the treetops while migrating.
A Sharp-shinned Hawk glides over a lookout.
Late September/early October is falcon time at area hawk-counting stations, the Peregrine Falcon often being the most anticipated species.
Pale “Tundra Peregrines”, a subspecies that nests in the arctic, are strictly migratory birds in the Mid-Atlantic States.  They are presently passing through on their way to South America.  Like Neotropical songbirds, their long flights provide them with the luxury of never experiencing a winter season.
This Carolina Saddlebags and other migratory dragonflies, which normally leave the area by mid-September, are still lingering in the lower Susquehanna region, much to the pleasure of the falcons that feed upon them.
An male American Kestrel in pursuit of dragonflies found swarming around the lookout at Second Mountain Hawk Watch in Lebanon County, Pennsylvania.
A male American Kestrel stooping on a dragonfly.
Osprey will be among the birds of prey passing hawk watch sites during the coming two weeks.  The first week of October often provides the best opportunity for seeing the maximum variety of raptors at a given site.  On a good day, a dozen species are possible.
Seeing cinnamon-colored juvenile Northern Harriers is symbolic of the October migration flights.
Bald Eagles always thrill the crowd.
In addition to raptors, resident Common Ravens are regularly sighted by observers at hawk watches and elsewhere during the fall season.
Hawk-counting stations sometimes log movements of Red-bellied Woodpeckers during late September and early October.  This species has extended its range into the Lower Susquehanna River Watershed only during the past one hundred years, making these seasonal migration movements a recent local phenomenon.
Blue Jays are currently on the move with breeding birds from the forests of Canada and the northern United States moving south.  Hundreds can be seen passing a given observation point during an ideal morning.
Blue Jays find a pile of peanuts to be an irresistible treat.  Provide the unsalted variety and watch the show!

Be sure to click on these tabs at the top of this page to find image guides to help you identify the dragonflies, birds, and raptors you see in the Lower Susquehanna River Watershed…

    • Damselflies and Dragonflies
    • Birds of Conewago Falls
    • Hawkwatcher’s Helper: Identifying Bald Eagles and other Raptors

See you next time!

Smoky Skies in the Lower Susquehanna Region

During the coming two weeks, peak numbers of migrating Neotropical birds will be passing through the northeastern United States including the lower Susquehanna valley.  Hawk watches are staffed and observers are awaiting big flights of Broad-winged Hawks—hoping to see a thousand birds or more in a single day.

During its passage through the Lower Susquehanna River Watershed, an adult Broad-winged Hawk sails over Second Mountain Hawk Watch in Lebanon County, Pennsylvania.
A hatch-year/juvenile Broad-winged Hawk gazes toward hawk watchers on the ground.

Broad-winged hawks feed on rodents, amphibians, and a variety of large insects while on their breeding grounds in the forests of the northern United States and Canada.  They depart early, journeying to wintering areas in Central and South America before frost robs them of a reliable food supply.

The Carolina Saddlebags (Tramea carolina), this one photographed at Second Mountain Hawk Watch on September 8th, is the rarest of the lower Susquehanna region’s migratory dragonflies.  Autumn Broad-winged Hawk movements coincide with southbound flights of the Carolina Saddlebags and the more numerous migratory dragonfly species: Common Green Darner, Wandering Glider, Twelve-spotted Skimmer, and Black Saddlebags.  “Broad-wings” will often eat these and other dragonflies during migration and can sometimes be seen catching and feeding upon them while still soaring high overhead.

While migrating, Broad-winged Hawks climb to great altitudes on thermal updrafts and are notoriously difficult to see from ground level.  Bright sunny skies with no clouds to serve as a backdrop further complicate a hawk counter’s ability to spot passing birds.  Throughout the Lower Susquehanna River Watershed, the coming week promises to be especially challenging for those trying to observe and census the passage of high-flying Broad-winged Hawks.  The forecast of hot and humid weather is not so unusual, but the addition of smoke from fires in the western states promises to intensify the haze and create an especially irritating glare for those searching the skies for raptors.

Smoke from fires along the California coast and in central Utah can be seen streaming east this morning.  (NOAA/GOES image)
Smoke from western fires and humid air creates a band of haze in Ohio, Pennsylvania, New Jersey, and states to the south this morning.   (NOAA/GOES image)

 

A migrating Broad-winged Hawk in the glare of a hazy sky.  In addition to visibility problems, swarms of Spotted Lanternflies above the treetops make distant hawks difficult to discern for hawk watchers scanning the horizon with binoculars.

It may seem gloomy for the mid-September flights in 2021, but hawk watchers are hardy types.  They know that the birds won’t wait.  So if you want to see migrating “Broad-wings” and other species, you’ve got to get out there and look up while they’re passing through.

Migrating Ospreys typically fly low enough and are large enough to be spotted even during the haziest of conditions.
Bald Eagles like this fourth-year bird can ascend to great altitude, but their size usually prevents them from sneaking past a lookout unnoticed.
Peregrines escape notice not due to hazy sky conditions, but because they pass by so quickly.  They’re being seen at local hawk watches now through October.

These hawk watches in the Lower Susquehanna River Watershed are currently staffed by official counters and all welcome visitors:

    • Rocky Ridge County Park Hawk Watch—3699 Deininger Road off Mount Zion Road (Route 24) northeast of York, Pennsylvania.
    • Second Mountain Hawk Watch—off Cold Spring Road on the grounds of Fort Indiantown Gap in Lebanon County, Pennsylvania.
    • Waggoner’s Gap Hawk Watch—where Route 74 crosses Blue Mountain north of Carlisle, Pennsylvania.

—or you can just keep an eye on the sky from wherever you happen to be.  And don’t forget to check the trees and shrubs because warbler numbers are peaking too!  During recent days…

Northern Parula at Chiques Rock County Park in Lancaster County.
Black-and-white Warbler at Rocky Ridge County Park in York County.
Cape May Warbler at Chiques Rock County Park in Lancaster County.
Bay-breasted Warbler at Rocky Ridge County Park in York County.

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.

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.

Migrating Golden Eagles

Why would otherwise sensible people perch themselves atop a rocky outcrop on a Pennsylvania mountaintop for ten hours on a windy bone-numbing bitter cold and sometimes snowy November day?  To watch migrating raptors of course.

November is the time when big hawks and eagles migrate through and into the lower Susquehanna valley.  And big birds rely on big wind to create updrafts and an easy ride along the region’s many ridges.  The most observable flights often accompany the arrival of cold air surging across the Appalachian Mountains from the northwest.  These conditions can propel season-high numbers of several of the largest species of raptors past hawk-counting sites.

Observers brave howling winds on the Waggoner’s Gap lookout to census migrating late-season raptors.

Earlier this week, two windy days followed the passage of a cold front to usher-in spectacular hawk and eagle flights at the the Waggoner’s Gap Hawk Watch station on Blue Mountain north of Carlisle, Pennsylvania.  Steady 30 M.P.H. winds from the northwest on Monday, November 2, gusted to 50 M.P.H. at times.  Early that morning, two Rough-legged Hawks, rarities at eastern hawk watches, were seen.  They and two Northern Goshawks (Accipiter gentilis) provided a preview of the memorable sightings to come.  Two dozen Golden Eagles migrated past the lookout that day.  Then on November 3, thirty Golden Eagles were tallied, despite west winds at speeds not exceeding half those of the day before.

Here are some of the late-season raptors seen by hardy observers at Waggoner’s Gap on Monday and Tuesday, November 2 & 3.

In November, Red-tailed Hawks are the most common migratory raptor counted at hawk watch stations in the Susquehanna region.
An uncommon bird, a juvenile Northern Goshawk, passes the Waggoner’s Gap lookout.
An adult Golden Eagle circles on an updraft along the north face of Blue Mountain to gain altitude before continuing on its journey.
The plumage of juvenile and immature Golden Eagles often creates a sensation among crowds at a lookout.  Golden Eagles don’t attain a full set of adult feathers until their sixth year.  This individual is probably a juvenile, also known as a hatch-year or first-year bird.  At most, it could be in its second year.  Click the “Golden Eagle Aging Chart” tab on this page to learn more about these uncommon migrants and their molt sequences as they mature.
The gilded head feathers of a Golden Eagle glisten in the afternoon sun.
An adult Golden Eagle passing Waggoner’s Gap.  The population known as “Eastern Golden Eagles” winters in the Appalachian Mountains and, with increasing frequency, on the Piedmont and Atlantic Coastal Plain Provinces of the eastern United States, where it often subsists as a scavenger.
Another first-year (juvenile) or second-year Golden Eagle.
A local Red-tailed Hawk (top left) trying to bully a migrating Golden Eagle.  A dangerous business indeed.
Through December, Bald Eagles, presently the more common of our eagle species, are regular migrants at Waggoner’s Gap and other Susquehanna valley hawk watch sites.
Red-shouldered Hawks are reliable early November migrants.
An adult Red-shouldered Hawk from above.
And an adult Red-shouldered Hawk from below.
Though their numbers peak in early October, Sharp-shinned Hawks, particularly adults like this one, continue to be seen through early November.
A Northern Harrier on the glide path overhead.
Merlins, like other falcons, are more apt to be seen in late September and October, but a few trickle through in November.

While visiting a hawk watch, one will certainly have the opportunity to see other birds too.

Common Ravens are fascinating birds and regular visitors to the airspace around hawk watches.  Most are residents, but there appears to be some seasonal movement, particularly among younger birds.
Most people think of Common Loons as birds of northern lakes.  But loons spend their winters in the ocean surf, and to get there they fly in loose flocks over the Lower Susquehanna River Watershed each spring and fall.  They are regularly seen by observers at hawk watches.
Like ducks, geese, and swans, migrating Double-crested Cormorants assemble into aerodynamic V-shaped flocks to conserve energy.
Pine Siskins continue their invasion from the north.  Dozens of small flocks numbering 10 to 20 birds each continue to be seen and/or heard daily at Waggoner’s Gap.  A flock of Evening Grosbeaks (Coccothraustes vesperitinus), another irruptive species of “winter finch”, was seen there on November 3.

As a finale of sorts, near the close of the day on November 3, two Golden Eagles sailed past the north side of the Waggoner’s Gap lookout, one possessing what appeared to be a tracking transmitter on its back.  An effort was commenced by the official count staff to report the sighting to the entity monitoring the bird—to track down the tracker, so to speak.

A Golden Eagle with a backpack transmitter passing Waggoner’s Gap Hawk Watch at 3:39 P.M. Eastern Standard Time on November 3, 2020.

To see the count reports from Waggoner’s Gap and other hawk watches throughout North America, be certain to visit hawkcount.org

A Visit to Waggoner’s Gap

Nothing beats spending a day at a hawk watch lookout—except of course spending a day at a hawk watch lookout when the birds are parading through nonstop for hours on end.

Check out Waggoner’s Gap, a hawk count site located on the border of Cumberland and Perry Counties atop Blue Mountain just north of Carlisle, Pennsylvania.  It is by far the Lower Susquehanna River Watershed’s best location for observing large numbers of migrating raptors during the October and November flights.

Waggoner’s Gap is located where Route 74 crosses Blue Mountain north of Carlisle.
The entrance to a parking area for hawk watch visitors is designated by this sign located along Route 74 several hundred yards north of the summit of Blue Mountain.
Since acquiring the site in 2000, Audubon Pennsylvania has added improvements to expand the function of Waggoner’s Gap Hawk Watch to include education for both formal students and the public at large.
The site is named in honor of the late conservationist Clifford L. Jones, a business leader, a former Chairman of the Pennsylvania Public Utilities Commission, a cabinet secretary for six Pennsylvania governors (both major parties), a director on the boards of numerous conservation organizations, and an active birder.
Orange falcon silhouettes function as blazes for the trails that lead from the parking area to the lookout.  The trail and the lookout consist entirely of boulders.  Some of these move when stepped upon.  Others may be slick.  Use caution at all times.
The lookout at Waggoner’s Gap is staffed by official counters from August through December each year.  They are tasked with enumerating every migratory raptor’s passage during that period.
Sure-footed observers climb into a comfortable position among the Tuscarora quartzite boulders and begin watching the flight.
The view from the lookout is spectacular.  To the east, downtown Harrisburg can be seen in the distance.
During a recent afternoon with breezes from the “southwesterlies”, a steady stream of  migrating Sharp-shinned Hawks, including this juvenile, passed by the lookout.
Sharp-shinned Hawks were ready subjects for photography as they sailed on updrafts along the south side of the ridge.
An adult Sharp-shinned Hawk.
A second-year Sharp-shinned Hawk.
A Sharp-shinned Hawk below eye level.  Over 400 Sharp-shinned Hawks migrated past Waggoner’s Gap Hawk Watch on this particular early October day.
The local Turkey Vultures at Waggoner’s Gap seem ubiquitous at times.  They’re on the radio towers, they’re flying overhead, and a few are cruising the slopes below the crest.  But on the day of our recent visit, their numbers were eclipsed by the more than 300 “T.V.s” that migrated down the ridge.
Black Vultures, both migrants and local birds, are seen from the lookout.
Northern Harriers are a hawk watch favorite.  Their long uptilted wings, long tail, and white rump make them easy to identify, even for beginners.  Their plummeting numbers make them a treasured sighting for everyone.
A Red-tailed Hawk on a close approach.
A distant Red-shouldered Hawk.  Numbers of these migrants peak later in the season.
A Peregrine Falcon darts past the lookout.  Note the white forehead, throat, and breast.  This bird is probably a “Tundra Peregrine” (Falco peregrinus tundrius).  In the lower Susquehanna valley, this subspecies is strictly migratory, a transient in spring and fall.  “Tundra Peregrines” breed in the arctic and winter as far south as South America.
An immature Bald Eagle.  Waggoner’s Gap is a superb place for sighting eagles, especially on a breezy day.
Hundreds of Blue Jays filtered through as their southbound exodus continues.  Other songbirds of interest included Blue-headed Vireos (Vireo solitarius), Winter Wrens, Red-breasted Nuthatches, Pine Siskins, and both Ruby-crowned and Golden-crowned Kinglets.

Waggoner’s Gap is a hardy birder’s paradise.  During the latter portion of the season, excellent flights often occur on days that follow the passage of a cold front and have strong northwest winds.  But be prepared, it can be brutal on those rocks during a gusty late-October or early-November day after the leaves fall—so dress appropriately.

To see the daily totals for the raptor count at Waggoner’s Gap Hawk Watch and other hawk watches in North America, and to learn more about each site, be sure to visit hawkcount.org

A Visit to Rocky Ridge

Early October is prime time for hawk watching, particularly if you want to have the chance to see the maximum variety of migratory species.  In coming days, a few Broad-winged Hawks and Ospreys will still be trickling through while numbers of Sharp-shinned Hawks, Cooper’s Hawks, Northern Harriers, and falcons swell to reach their seasonal peak.  Numbers of migrating Red-tailed and Red-shouldered Hawks are increasing during this time and late-season specialties including Golden Eagles can certainly make a surprise early visit.

If you enjoy the outdoors and live in the southernmost portion of the lower Susquehanna valley, Rocky Ridge County Park in the Hellam Hills just northwest of York, Pennsylvania, is a must see.  The park consists of oak forest and is owned and managed by the York County Parks Department.  It features an official hawk watch site staffed by volunteers and park naturalists.  Have a look.

The hawk watch lookout is reached by following the well-marked trail at the north side of the large gravel parking area in the utility right-of-way at the end of the park entrance road (Deininger Road).
The Rocky Ridge Hawk Watch lookout includes outcrops of bedrock, a viewing deck, and grassy areas suitable for lawn chairs.
The bedrock at the lookout is an unusual quartz-cemented conglomerate that forms the Hellam Member at the base of the Cambrian Chickies Formation.
Experienced hawk watchers conduct an official count of raptors and other birds during the autumn migration in September and October each year.  Visitors are welcome.  The view is spectacular.  Check out the concrete columns glowing in the sun to the north of the lookout.
It’s the cooling towers at the Three Mile Island Nuclear Station and the smoke stacks at the Brunner Island Steam Generating Station.  Conewago Falls is located between the two.
Interpretive signage on the hawk watch deck includes raptor identification charts.
A migrating Osprey glides by the lookout.
Throughout the month, migrating Sharp-shinned Hawks will be flying in a southwesterly direction along ridges in the region, particularly on breezy days.  They are the most numerous raptor at hawk watches in the lower Susquehanna valley during the first half of October.
A Peregrine Falcon quickly passes the Rocky Ridge lookout.  These strong fliers often ignore the benefits provided by thermals and updrafts along our ridges and instead take a direct north to south route during migration.
A juvenile Red-tailed Hawk soars by.
And a little while later, an adult Red-tailed Hawk follows.
Bald Eagles, including both migratory and resident birds, are seen regularly from the Rocky Ridge lookout.
Other diurnal (daytime) migrants are counted at Rocky Ridge and some of the other regional hawk watches.  Massive flights of Blue Jays have been working their way through the lower Susquehanna valley for more than a week now.  Local hawk watches are often logging hundreds in a single day.
The utility right-of-way within which the Rocky Ridge Hawk Watch is located can be a great place to see nocturnal (nighttime) migrants while they rest and feed during the day.  Right now, Eastern Towhees are common there.
An uncommon sight, a shy Lincoln’s Sparrow (Melospiza lincolnii) in the utility right-of-way near the hawk watch lookout.  This and other nocturnal migrants will take full advantage of a clear moonlit night to continue their southbound journey.

If you’re a nature photographer, you might be interested to know that there are still hundreds of active butterflies in Rocky Ridge’s utility right-of-way.  Here are a few.

A Gray Hairstreak.
An American Copper (Lycaena phlaeas),

To see the daily totals for the raptor count at Rocky Ridge Hawk Watch and other hawk watches in North America, and to learn more about each site, be certain to visit hawkcount.org

Fire and Ice at Conewago Falls

This morning, the Lower Susquehanna River Watershed experienced remotely the effects of fire and ice.

At daybreak, the cold air mass that brought the first freeze of the season to northernmost New England gave us a taste of the cold with temperatures below 50 degrees throughout.

The air temperature at daybreak in the Gettysburg Basin east of Conewago Falls.

At sunrise, the cloudless sky had a peculiar overcast look with no warm glow on buildings, vegetation, and terrain.  Soon, the sun was well above the horizon, yet there was still a sort of darkness across the landscape.

Smoke from massive wildland fires in the Pacific Coast States created a haze that persisted throughout the day in the Susquehanna valley.
Away from traffic and the odors of agriculture and urban life, the smell of wood smoke was easily detectable.  The haze from fires almost 3,000 miles away made it appear to be an overcast day at Conewago Falls.
Due to the sudden cold, there were no insects flying above the Susquehanna during the first hour of daylight this morning, so swallows gathered in the trees to conserve energy until the hunt would be more productive.
The diabase boulders at Conewago Falls retain heat and provide an even better refuge from the cold than a dead tree on a chilly morning.  Here, a juvenile and an adult Tree Swallow (center) are surrounded by Northern Rough-winged Swallows.  Hundreds of each of these migratory species were feeding at the falls today.
Two dozen or more Barn Swallows, including this juvenile, were seen among the swarming birds.
Several late Bank Swallows, including this one (bottom center), were among the flocks of migrants at Conewago Falls this morning.  One Cliff Swallow (Petrochelidon pyrrhonota) was seen as well.
A Great Egret (Ardea alba) and a Great Blue Heron.
An Osprey searching the clear pools and rapids for a morning meal.
A juvenile Bald Eagle with the same goal in mind.
The same Bald Eagle keeping a close watch on the Osprey.  Bald Eagles frequently ambush Ospreys to steal their catch.  For a young eagle, acquiring the skill of fish theft may improve its chances of survival, at least until the Ospreys head south.

All that bright filtered sunlight was ideal for photographing butterflies along the Conewago Falls shoreline.  Have a look.

During the late morning, dozens of Monarch butterflies migrated past Conewago Falls.  This one paused to feed.
The Viceroy (Limenitis archippus) is a Monarch mimic.  Its appearance fools would-be predators into thinking it is a Monarch and possesses the same foul flavor as the milkweed-raised model.
This Variegated Fritillary (Euptoieta claudia) was among the late-season butterflies at Conewago Falls.
The Common Buckeye is presently just that, very common on flowers and moist sandy soil around the falls.
The Painted Lady is a regularly-occurring migratory species of butterfly.
The Red Admiral is typically a common to abundant migrant.  So far in 2020, they are scarce in the lower Susquehanna valley. 

A Visit to Second Mountain

If it can fly, there’s a pretty good chance it was at Second Mountain today.

What follows is a photographic chronology of some of today’s sightings at Second Mountain Hawk Watch at Fort Indiantown Gap in Lebanon County, Pennsylvania.  We begin with some of the hundreds of migratory songbirds found at the base of the mountain along Cold Spring Road near Indiantown Run during the early morning, then we continue to the lookout for the balance of the day.

A Black-and-white Warbler (Mniotilta varia) searching the trunk of a tree for insects.
A Rose-breasted Grosbeak.
A Blackburnian Warbler high in the forest canopy.
A Black-throated Green Warbler bouncing from branch to branch as it feeds.
A Chestnut-sided Warbler lurks among the foliage.
A Magnolia Warbler.
One of a hundred or more Red-eyed Vireos found swarming the treetops, and occasionally the understory, while engaging in a wild feeding frenzy.
A male American Redstart.  Judging by that gray hood, it’s probably experiencing its second fall migration.
Eyes were skyward at the Second Mountain Hawk Watch lookout as Broad-winged Hawks began streaming through during the mid-morning.
During the morning flight, Broad-winged Hawks including this adult floated by the lookout riding updrafts created by the south wind striking the face of the mountain ridge.
As the overcast became more scattered and more sunlight reached the ground, Broad-winged Hawks began riding thermal currents to gain altitude before gliding off to the southwest in continuance of their long trip to the tropics.  At times, birds would disappear into the base of the clouds before ending their climb and sailing away.
Broad-winged Hawks rely principally upon amphibians and large insects like this bush katydid (Scudderia species) for sustenance.  With freezing temperatures just around the corner, “broad-wings” must make their way to warmer climes early or risk starvation.
A Bald Eagle always gets observers looking.
A juvenile Broad-winged Hawk.
A juvenile Cooper’s Hawk.
A Broad-winged Hawk has a look around.
One never quite knows what one may see when having a look around.
A Cape May Warbler (Setophaga tigrina) in the lookout hemlock.
A Black Saddlebags, one of several migratory dragonflies seen today.
An Osprey glides through in the afternoon glare.
A speedy Merlin thrilled observers with a close approach.
One must remember that Fort Indiantown Gap is an active military installation, so from time to time training and drilling exercises may interrupt bird observation activities at the Second Mountain Hawk Watch.
Today, speedy A-10 Warthog attack aircraft piloted by members of the Maryland Air National Guard based at Glenn Martin Field thrilled observers on the lookout with several close passes during their training runs.
And repeat.
Drill complete.

The total number of Broad-winged Hawks observed migrating past the Second Mountain lookout today was 619.  To see the daily raptor counts for Second Mountain and other hawk watches in North America, and to learn more about each site, be sure to visit hawkcount.org

Big Fallout

Okay, so it happened to be cloudy with drizzle at sunrise—not the best conditions for observing birds in the treetops.  But that inclement weather effectively grounded the overnight flight of migrating songbirds leading to a really big fallout in the lower Susquehanna valley this morning.

While straining one’s neck to gaze up into the forest canopy, hundreds of migrants including warblers, vireos, tanagers, thrushes, and flycatchers could be seen.  Identifying each was impossible.

Here are of few of this morning’s arrivals.  Manually setting the camera to a slower shutter speed compensated a little bit for the backlighting caused by cloudy conditions.

Pine Warbler (Setophaga pinus).
Bay-breasted Warbler.
Black-throated Green Warbler.
Nashville Warbler.
Northern Parula (Setophaga americana).

Peak numbers of Broad-winged Hawks will pass through the area during the coming two weeks.  They most often migrate in groups, with sizes ranging from several individuals to hundreds or even thousands of birds.  Despite this being a less than ideal day for riding thermals and gliding off towards the southwest to continue their journey to the tropics, some “broad-wings” ventured aloft and were on their way soon after the drizzle subsided during mid-morning.

A Broad-winged Hawk lifts off from the cover of the forest where it spent the night.
The same Broad-winged Hawk (bottom) and an adult Bald Eagle gain altitude on a thermal updraft before the former glides away toward the southwest.

Bird Migration Highlights

The southbound bird migration of 2020 is well underway.  With passage of a cold front coming within the next 48 hours, the days ahead should provide an abundance of viewing opportunities.

Here are some of the species moving through the lower Susquehanna valley right now.

Blue-winged Teal are among the earliest of the waterfowl to begin southward migration.
Sandpipers and plovers have been on the move since July.  The bird in the foreground with these Killdeer is not one of their offspring, but rather a Semipalmated Plover (Charadrius semipalmatus), a regular late-summer migrant in the Lower Susquehanna River Watershed.
Hawk watch sites all over North America are counting birds right now.  The Osprey is an early-season delight as it glides past the lookouts.  Look for them moving down the Susquehanna as well.
Bald Eagles will be on the move through December.  To see these huge raptors in numbers, visit a hawk watch on a day following passage of a cold front when northwest winds are gusting.
Merlins were seen during this past week in areas with good concentrations of dragonflies.  This particular one at Middle Creek Wildlife Management Area in Lancaster and Lebanon Counties…
…was soon visited by another.
Check the forest canopy for Yellow-billed Cuckoos.  Some local birds are still on breeding territories while others from farther north are beginning to move through.
Ruby-throated Hummingbirds are darting through the lower Susquehanna valley on their way to the tropics.  This one has no trouble keeping pace with a passing Tree Swallow.
Nocturnal flights can bring new songbirds to good habitat each morning.  It’s the best time of year to see numbers of Empidonax flycatchers.  But, because they’re often silent during fall migration, it’s not the best time of year to easily identify them.  This one lacking a prominent eye ring is a Willow Flycatcher (Empidonax traillii).
During the past two weeks, Red-eyed Vireos have been numerous in many Susquehanna valley woodlands.  Many are migrants while others are breeding pairs tending late-season broods.
During mornings that follow heavy overnight flights, Blackburnian Warblers have been common among waves of feeding songbirds.
Chestnut-sided Warblers are regular among flocks of nocturnal migrants seen foraging among foliage at sunrise.
Scarlet Tanagers, minus the brilliant red breeding plumage of the males, are on their way back to the tropics for winter.
While passing overhead on their way south, Bobolinks can be seen or heard from almost anywhere in the lower Susquehanna valley.  Their movements peak in late August and early September.
During recent evenings, Bobolinks have been gathering by the hundreds in fields of warm-season grasses at Middle Creek Wildlife Management Area.
If you go to see the Bobolinks there, visit Stop 3 on the tour route late in the afternoon and listen for their call.  You’ll soon notice their wings glistening in the light of the setting sun as they take short flights from point to point while they feed.  Note the abundance of flying insects above the Big Bluestem and Indiangrass in this image.  Grasslands like these are essential habitats for many of our least common resident and migratory birds.

How Much Can a Bald Eagle Lift?

Here it is—just as it happened, recently in the lower Susquehanna valley.

A Bald Eagle in search of a meal.
The eagle glides in and grabs an unsuspecting Common Carp, the bird’s momentum and a head wind helping it to raise the fish out of the water.  This particular carp appears to be eighteen to twenty-four inches in length.  In that range, it could weigh anywhere from four to ten pounds or more.
But as the eagle tries to flap its wings to carry the carp skyward, it loses lift, and the weight of the fish drags the raptor down.  A carp exceeding twenty inches in length usually weighs more than five pounds, approximately half the mass of a male (about 9 lbs.) or a female (about 12 lbs.) Bald Eagle.  From a dead stop, trying to extricate a submerged fish weighing half as much again as it does is an impossible task for this or any other Bald Eagle.
The eagle fights briefly to pull the carp from the water, then abandons the effort to instead release its talons from the fish to prevent its own demise by drowning.
Free of its hold on the carp, the eagle flaps its wings briskly to get up and out of the potentially deadly situation.
Success!
Both the eagle and, presumably, the carp survive the encounter.
The eagle finds a nearby tree limb where it takes a much-needed break from fishing.
Such an event may have been fatal to an inexperienced younger Bald Eagle.  Though not an adult, this bird is no spring chicken.  Its plumage, particularly its white head with a dark line through the eye (often called an “osprey face”), is indicative of a bird in its fourth year of life.  By this time next year, it should be sporting a full set of adult feathers.  In the meantime, it should stick to eating suckers; there are plenty of those to go around.
Common Carp are classified as a minnow (Cyprinidae).  They are indigenous to Europe and are raised as a food fish in many parts of the world.  In the Lower Susquehanna River Watershed, Common Carp are an introduced species with negative impacts on native fisheries.  Those exceeding twenty inches in length begin to gain girth and weight, sometimes reaching thirty pounds at thirty inches.

SOURCES

Sedaghat, Safoura, Seyed Abbas Hoseini, Mohammad Larijani, and Khadijeh Shamekhi Ranjbar.  2013.  “Age and Growth of Common Carp (Cyprinus carpio Linnaeus, 1758) in Southern Caspian Sea, Iran”.  World Journal of Fish and Marine Sciences.  5:1.  pp.71-73.

Spotted Lanternfly in the Lower Susquehanna River Watershed

Second Mountain Hawk Watch is located on a ridge top along the northern edge of the Fort Indiantown Gap Military Reservation and the southern edge of State Game Lands 211 in Lebanon County, Pennsylvania.  The valley on the north side of the ridge, also known as St. Anthony’s Wilderness, is drained to the Susquehanna by Stony Creek.  The valley to the south is drained toward the river by Indiantown Run, a tributary of Swatara Creek.

The hawk watch is able to operate at this prime location for observing the autumn migration of birds, butterflies, dragonflies, and bats through the courtesy of the Pennsylvania Game Commission and the Garrison Commander at Fort Indiantown Gap.  The Second Mountain Hawk Watch Association is a non-profit organization that staffs the count site daily throughout the season and reports data to the North American Hawk Watch Association (posted daily at hawkcount.org).

Today, Second Mountain Hawk Watch was populated by observers who enjoyed today’s break in the rainy weather with a visit to the lookout to see what birds might be on the move.  All were anxiously awaiting a big flight of Broad-winged Hawks, a forest-dwelling Neotropical species that often travels back to its wintering grounds in groups exceeding one hundred birds.  Each autumn, many inland hawk watches in the northeast experience at least one day in mid-September with a Broad-winged Hawk count exceeding 1,000 birds.  They are an early-season migrant and today’s southeast winds ahead of the remnants of Hurricane Florence (currently in the Carolinas) could push southwest-heading “Broad-wings” out of the Piedmont Province and into the Ridge and Valley Province for a pass by the Second Mountain lookout.

The flight turned out to be steady through the day with over three hundred Broad-winged Hawks sighted.  The largest group consisted of several dozen birds.  We would hope there are probably many more yet to come after the Florence rains pass through the northeast and out to sea by mid-week.  Also seen today were Bald Eagles, Ospreys, American Kestrels, and a migrating Red-headed Woodpecker.

Migrating Broad-winged Hawks circle on a thermal updraft above Second Mountain Hawk Watch to gain altitude before gliding away to the southwest.

Migrating insects included Monarch butterflies, and the three commonest species of migratory dragonflies: Wandering Glider, Black Saddlebags, and Common Green Darner.  The Common Green Darners swarmed the lookout by the dozens late in the afternoon and attracted a couple of American Kestrels, which had apparently set down from a day of migration.  American Kestrels and Broad-winged Hawks feed upon dragonflies and often migrate in tandem with them for at least a portion of their journey.

Still later, as the last of the Broad-winged Hawks descended from great heights and began passing by just above the trees looking for a place to settle down, a most unwelcome visitor arrived at the lookout.  It glided in from the St. Anthony’s Wilderness side of the ridge on showy crimson-red wings, then became nearly indiscernible from gray tree bark when it landed on a limb.  It was the dreaded and potentially invasive Spotted Lanternfly (Lycorma delicatula).  This large leafhopper is native to Asia and was first discovered in North America in the Oley Valley of eastern Berks County, Pennsylvania in 2014.  The larval stage is exceptionally damaging to cultivated grape and orchard crops.  It poses a threat to forest trees as well.  Despite efforts to contain the species through quarantine and other methods, it’s obviously spreading quickly.  Here on the Second Mountain lookout, we know that wind has a huge influence on the movement of birds and insects.  The east and southeast winds we’ve experienced for nearly a week may be carrying Spotted Lanternflies well out of their most recent range and into the forests of the Ridge and Valley Province.  We do know for certain that the Spotted Lanternfly has found its way into the Lower Susquehanna River Watershed.

This adult Spotted Lanternfly landed in a birch tree behind the observers at the Second Mountain Hawk Watch late this afternoon.  It was first recognized by its bright red wings as it glided from treetops on the north side of the lookout.

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.

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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.

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 (Accipiter 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.

Birds of a Feather-The Basics

When we look at birds, we are fascinated by the unique structure and appearance of their feathers.  They set birds apart from all other life forms on the planet.  Feathers enable most birds to achieve a feat long envied by humans…flight.  Birds on the wing awaken a curiosity in man.  They are generally the largest animals one will see in the air.  People want to know the name of a bird they see flying by, and want to know more about it.  The method and style of bird flight can aid an observer who attempts to determine which of the world’s 10,000 bird species he or she is studying.  Body shape and bird sounds often tell us a lot about the birds we encounter.  But most often, we rely on the unique colors, patterns, and shapes of the feathers, the plumage, to identify the bird we are seeing.

To birds, feathers are survival.  They are lightweight and strong to support the mechanics of flight.  Feathers are superb insulators against the elements, and provide additional buoyancy for birds spending time on the water.  For most birds, feathers provide a coloration and a texture similar to their surroundings, enabling them to hide from predators or to stalk prey.  In the case of some species, extravagant showy plumage is acquired, at least during the breeding season, and often only by males, as a way to attract a mate, intimidate rivals, defend a territory, or lure an intruder away from a nest site.  Because they become worn and damaged, all feathers are periodically molted and replaced by fresh plumage.

The feathers worn by a young bird leaving the nest are called the juvenile plumage.  Typically, this is followed by a molt into a basic (non-breeding) plumage.  The oft times extravagant breeding feathers are the result of a molt into an alternate (breeding) plumage.

While making field observations, the species, subspecies, gender, age, and other vital statistics of a bird can often by discerned easily by noting the plumage.  In the case of some other birds, diligence, experience, research, and an exceptionally good look and/or a photograph may be required to interpret these particulars.  In still other instances, a trained expert with a specimen in the hand is the only method of learning the bird’s identity and background.

This juvenile House Wren (Troglodytes aedon) left the nest wearing plumage very similar to that of its parents.  In lieu of bright colors, the male House Wren relies upon a vigorous bubbly song and a scrappy demeanor to defend its breeding territory.  This species nests in cavities on the edges of the Riparian Woodlands of Conewago Falls.  Males may have more than one mate.  House Wrens probably migrate at night and will winter in the southern border states and further south.

The age at which birds acquire adult breeding and non-breeding plumages varies by species.  Many juvenile birds resemble adults in basic (non-breeding) plumage as soon as they leave the nest.  For these birds, there is little difference between their juvenile plumage and the appearance of the feathers which follow the molt into their first basic (non-breeding) plumage.  Bird species which sexually mature within their first year may acquire their first basic (non-breeding) plumage before arrival of their first winter, followed by an alternate (breeding) plumage by their first spring.  This is particularly true for smaller short-lived birds.  Other species, normally larger long-lived ones, may experience a sequence of molts through multiple basic (non-breeding) plumages over a period of years prior to resembling an adult.  Some of these species, such as eagles, retain their juvenile plumage for as long as a year before extensive molting into a first basic (non-breeding) plumage begins.  Still others, including many gulls, attain a first-winter (formative) plumage prior to molting into their first basic (non-breeding) set of feathers.  Sexual maturity and initiation of an annual molt to alternate (breeding) plumage, if there is one, may take as long as three to five years for these bigger birds.

For nearly all species of birds, the molts which produce basic (non-breeding) plumage occur on at least an annual basis and include a total replacement of feathers.  This process renews worn and missing plumes including the flight feathers of the wings and tail.  Any molt to alternate (breeding) plumage often excludes the replacement of the feathers of the wings and tail.  There are many exceptions to these generalities.

A mid-summer nesting species, the American Goldfinch, Spinus tristis, male (left and right) molts into a glamorous alternate plumage for the breeding season.  The adult female’s alternate plumage (top) is a subdued green-yellow and black.  Her feathers resemble the foliage around the nest and offer protection from discovery during incubation.  Juvenile plumage (bottom) is similar to that of the female, but duller with a buffy tone.  By November each of these birds will have molted into a tan-buff basic (non-breeding) plumage, the male’s with a slight yellow hue.  During their first spring, juveniles attain sexual maturity and, like the adults from the previous year, molt into alternate (breeding) plumage.  The breeding birds seen here will probably winter in the southern United States, and birds that nested to our north will arrive to remain as winter residents.  Various stages of molt can be seen simultaneously during spring and autumn migrations as populations of goldfinches from multiple latitudes intermingle as they pass through the Susquehanna River watershed.
This juvenile Spotted Sandpiper (Actitis macularius), lacks the namesake dark markings on its white underside, thus it presently resembles an adult in basic (non-breeding) plumage.  Upon reaching sexual maturity, it will molt into a spotted alternate (breeding) plumage for the nesting season during each remaining year of its life.  Females of this species defend a territory and lay eggs in a nest located among cover near the shoreline.  A female may have as many as five mates.  Males alone incubate the eggs, usually four, for 20-24 days.  The young leave the nest upon hatching and are escorted by the male for about two to three additional weeks.  They are the only sandpiper to nest on the Susquehanna River shoreline.  Spotted Sandpipers migrate to the southern border states and further south for winter.  At Conewago Falls, they arrive in late April to nest, with birds, possibly migrants from further north, remaining until well into October.  In any plumage, you can easily recognize the Spotted Sandpiper by its habit of teetering its body at the hips to pump the tail up and down.
Bald Eagles go through a series of five molts before reaching adult plumage.  The first plumage, Juvenile, is nearly all dark brown with white linings along the forward underside of the wings.  The wing and tail feathers are a bit longer than in later plumages to aid the inexperienced birds during their clumsy first flights.  Due to the additional feather length, Juveniles look larger than older birds, but they are not as heavy as their seniors.  The bird seen here flying above Conewago Falls is probably in its second year.  This plumage, Basic I, also known as “White Belly I”, is characterized by a nearly full set of new flight feathers.  Note that some of the longer Juvenile feathers are still present, giving the wings a jagged sloppy look, particularly near the center of the trailing edge.  Third-year (Basic II) birds often have at least some white belly feathers and are sometimes known as “White Belly II” Bald Eagles.  Basic II birds typically possess a complete set of adult flight feathers, so the trailing edge of the wing has a neater and more uniform appearance.

The Bald Eagle in the two photographs above is in its first year.  This plumage, known as “Juvenile”, is characterized by dark flight feathers which appear uniformly long in length when the bird is airborne.  The eye is dark brown.  The iris of the eye will lighten in the second year (Basic I) and will become cream-colored by the third year (Basic II).  The bill, which is all dark gray when the bird is in the nest, has begun the slow progression to a yellow color that will be complete in the bird’s fifth year (Basic IV).  Third year (Basic II) birds molt to white crown and throat feathers, but have a dark set of feathers through the eye producing an “Osprey face” in most individuals.  In its fourth year (Basic III), this eagle will molt to a white tail with just a thin dark brown terminal band.  The head will become nearly all white except for a few dark spots through the eye, which will have a yellow iris.  A cleaner white head and tail will develop during the fifth year (Basic IV) and will persist through the familiar adult Bald Eagle plumages (Definitive Plumage) for the remainder of its life.

The Juvenile and non-breeding (basic) plumages of late-summer may seem drab and confusing, but learning them is a worthwhile endeavor.  Consider that most of the birds coming south during the migration will be adorned in this fashion.  The birds of North America are in their greatest numerical mass of the year right now, and nearly all are females, juveniles, other non-adults, or molting males.  There are few males in breeding plumage among the autumn waves of migrants.  In the coming months, there will be an abundance of opportunities to enjoy these marvels on wings, so getting to know the birds in non-breeding feathers is time well spent.  Make haste and get ready.  For our feathered friends, it’s autumn and they’re on their way south.

Here come the confusing fall migrants.  Twelve Semipalmated Sandpipers (Calidris pusilla) and sixteen unidentified “peep” sandpipers (Calidris species) were seen feeding in Conewago Falls on August 27.  This Semipalmated Sandpiper is either an adult in worn alternate (breeding) plumage or a Juvenile.  Adults of this species molt into basic plumage on the wintering grounds.  The Semipalmated Sandpiper breeds in the high arctic tundra and winters in the West Indies and northern South America.
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SOURCES

Dunne, Pete.  2006.  Pete Dunne’s Essential Field Guide Companion.  Houghton Mifflin Company.  New York.

Hayman, Peter; John Marchant, and Tony Prater.  1986.  Shorebirds, An Identification Guide to the Waders of the World.  Houghton Mifflin Company.  New York.

Kauman, Kenn.  1996.  Lives of North American Birds.  Houghton Mifflin Company.  New York.

McCullough, Mark A.  1989.  Molting Sequence and Aging Of Bald Eagles.  The Wilson Bulletin.  101:1-10.

Summer Grasses

It has not been a good summer if you happen to be a submerged plant species in the lower Susquehanna River.  Regularly occurring showers and thunderstorms have produced torrents of rain and higher than usual river stages.  The high water alone wouldn’t prevent you from growing, colonizing a wider area, and floating several small flowers on the surface, however, the turbidity, the suspended sediment, would.  The muddy current casts a dirty shadow on the benthic zone preventing bottom-rooted plants from getting much headway.  There will be smaller floating mats of the uppermost leaves of these species.  Fish and invertebrates which rely upon this habitat for food and shelter will find sparse accommodation…better luck next year.

Due to the dirty water, fish-eating birds are having a challenging season as they try to catch sufficient quantities of prey to feed themselves and their offspring.  A family of Ospreys (Pandion haliaetus) at Conewago Falls, including recently fledged young, were observed throughout this morning and had no successful catches.  Of the hundred or more individual piscivores of various species present, none were seen retrieving fish from the river.  The visibility in the water column needs to improve before fishing is a viable enterprise again.

Ospreys competing for a suitable fishing perch.  Improving water conditions in the coming week should increase their success as predators.
Versatile at finding food, adult Bald Eagles are experienced and know to be on the lookout for Ospreys with fish, a meal they can steal through intimidation.

While the submerged plant communities may be stunted by 2017’s extraordinary water levels, there is a very unique habitat in Conewago Falls which endures summer flooding and, in addition, requires the scouring effects of river ice to maintain its mosaic of unique plants.  It is known as a Riverine Grassland or scour grassland.

The predominant plants of the Riverine Grasslands are perennial warm-season grasses.  The deep root systems of these hardy species have evolved to survive events which prevent the grassland from reverting to woodland through succession.  Fire, intense grazing by wild herd animals, poor soils, drought, and other hardships, including flooding and ice scour, will eliminate intolerant plant species and prevent an area from reforesting.  In winter and early spring, scraping and grinding by flood-driven chunk ice mechanically removes large woody and poorly rooted herbaceous growth from susceptible portions of the falls.  These adverse conditions clear the way for populations of species more often associated with North America’s tall grass prairies to take root.  Let’s have a look at some of the common species found in the “Conewago Falls Pothole Rocks Prairie”.

Big Bluestem (Andropogon gerardi), seen here growing in the cracks of a pothole rock. High water nourishes the plant by filling the crevices with nutrient-loaded sediment. This species evolved with roots over three feet deep to survive fires, trampling by bison, and drought.
Freshwater Cordgrass (Spartina pectinata) does well with its roots in water.  It creates exceptional bird habitat and grows in the falls and on ice-scoured small islands in free-flowing segments of the Susquehanna River downstream.
Switchgrass (Panicum virgatum), like Big Bluestem, is one of the tall grass prairie species and, like Freshwater Cordgrass, grows in near pure stands on ice-scoured islands.  It takes flooding well and its extensive root system prevents erosion.
Though not a grass, Water Willow (Justicia americana) is familiar as a flood-enduring emergent plant of river islands, gravel bars, and shorelines where its creeping rhizome root system spreads the plant into large masses.  These stands are often known locally as “grass beds”.  This member of the acanthus family provides habitat for fish and invertebrates among its flooded leaves and stems.  Its presence is critical to aquatic life in a year such as this.

The Conewago Falls Riverine Grassland is home to numerous other very interesting plants.  We’ll look at more of them next time.

SOURCES

Brown, Lauren.  1979.  Grasses, An Identification Guide.  Houghton Mifflin Company.  New York, NY.