Photo of the Day

A juvenile Scarlet Tanager
We have at last reached the autumnal equinox, a day when everything is even stephen, equal time both with and without sunlight.  Southbound birds like this juvenile Scarlet Tanager can now freely be called “fall migrants”, even though the majority of tanagers and other Neotropical species departed for warmer climes earlier this month, technically during the summer season.

Pot o’ Gold on the Ridgetops

Bathed in glowing sunshine, a very large fallout of migrating Neotropical songbirds enlivened the forest edge atop Second Mountain in northern Lebanon County, Pennsylvania, this morning.  While last night’s flight was widespread beneath a dome of atmospheric high pressure covering the Mid-Atlantic States, this is a look at some of the 500 -1,000 migrants observed feeding on insects and other natural foods at just this single location.

Blackpoll and Black-throated Green Warblers
As the composition of the nightly flights begins to transition to species that start their migration later in the season, numbers of birds like the Blackpoll Warbler (top) are beginning to rival those of the heretofore very common Black-throated Green Warbler (bottom).
Blackpoll Warbler
A Blackpoll Warbler.
Bay-breasted Warbler
The Bay-breasted Warbler, another common species found among the fallout flock.
Tennessee Warbler
The Tennessee Warbler was today’s most abundant migrant with at least 200 birds seen moving among the other species.
Tennessee Warbler
A newly arrived Tennessee Warbler at sunrise.
Tennessee Warbler
A Tennessee Warbler snatches breakfast.
Magnolia Warbler
The Magnolia Warbler was another common find among today’s migrants.
Magnolia Warbler
A Magnolia Warbler.
Nashville Warbler
A Nashville Warbler among tangles of Mile-a-minute Weed.
Nashville Warbler
A Nashville Warbler.
Black-throated Blue Warbler
Black-throated Blue Warbler.
Adult Male Black-throated Blue Warbler
An adult male Black-throated Blue Warbler.
Northern Parula
An acrobatic Northern Parula.
Blackburnian Warbler
Blackburnian Warblers continue their southerly trek.
American Redstart
An American Redstart.
 Chestnut-sided Warbler
A Chestnut-sided Warbler feeding on Mile-a-minute Weed berries.
 Cape May Warbler
A Cape May Warbler.
Adult Male Cape May Warbler
A handsome adult male Cape May Warbler.
Swainson's Thrush
A Swainson’s Thrush.
Scarlet Tanager
Scarlet Tanagers continue to work their way south through the Lower Susquehanna River Watershed.
Olive-sided Flycatcher
A composite image of an uncommon find, a large-headed Olive-sided Flycatcher seen perched atop a dead tree snag.
Philadelphia Vireo
A brief encounter with a Philadelphia Vireo, another uncommon species.
Blue-headed Vireo
A Blue-headed Vireo, typically the last of its genus to move south in the fall, put in a welcome appearance among the hundreds of migrants.
Ruby-throated Hummingbird
A favorite diurnal migrant, the Ruby-throated Hummingbird, was seen feeding on flowers that grew from the remains of garden waste dumped illegally along the mountain road last autumn.

Many of the observers at the Second Mountain Hawk Watch commented that this morning’s fallout was by far the best they had seen anywhere in the region during recent years.  Others believed it to be the best they had ever seen.  It was indeed less like a “wave” of migrants and more like a “tsunami”.  Choosing a good viewing location and being there at the right time can improve your chances of seeing a spectacle like this.  The good news is, it looks like another big flight is currently underway, so finding a forest edge on a ridgetop or along a utility right-of-way just might pay off for you early tomorrow morning.

Nocturnal migrating birds, a southwest-bound flight down the ridges of central Pennsylvania as indicated by Doppler radar between 10:30 and 11:30 PM EDT on September 11, 2024.  (NOAA/National Weather Service image)

This Week’s Review of the Morning Fallouts

Clear, cool nights have provided ideal flight conditions for nocturnal Neotropical migrants and other southbound birds throughout the week.  Fix yourself a drink and a little snack, then sit down and enjoy this set of photographs that includes just some of the species we found during sunrise feeding frenzies atop several of the Lower Susquehanna River Watershed’s ridges.  Hurry up, because here they come…

Black-throated Green Warbler
A Black-throated Green Warbler.
Black-throated Green Warbler
The Black-throated Green Warbler was perhaps the most frequently identified treetop warbler during the most recent four mornings.
Black-throated Green Warbler
A Black-throated Green Warbler with a unique variation in the crown plumage.
Blackburnian Warbler
The Blackburnian Warbler was another plentiful species.
Cape May Warblers
Cape May Warblers have an affinity for conifers like this Eastern White Pine.
Cape May Warbler
But when traveling in mixed flocks with other migrants, Cape May Warblers can also be found feeding in the crown foliage of deciduous trees.
Tennessee Warbler
This adult Tennessee Warbler appears to be adorned in a very worn set of plumage…
Tennessee Warbler
…and its traveling companion looks like it’s overdue for a new set of feathers as well.
Nashville Warbler
Like the Tennessee Warbler, the Nashville Warbler was common among mixed flocks.
Nashville Warbler
A Nashville Warbler atop a Black Cherry.
Chestnut-sided Warbler
This Chestnut-sided Warbler was one of several found among the more common species of migrants.
Chestnut-sided Warbler
A Chestnut-sided Warbler.
Chestnut-sided Warbler
We were lucky enough to spot this male Chestnut-sided Warbler sporting his namesake flank feathers.
 Black-and-white Warbler
A Black-and-white Warbler uses its nuthatch-like feeding behavior to search the tree bark for edible invertebrates.
Common Yellowthroat
To see the Common Yellowthroat, one must cease looking upward into the high canopy and instead give the aching neck a rest by peering into the low vegetation at the forest edge.
Magnolia Warbler
While checking the low growth, keep an eye open for other migrants among the shrubs and tangles. This Magnolia Warbler glows in the rays of a rising sun as it searches for a meal after a long night of travel.
House Wren
Here we found a perky little House Wren.
Eastern Wood-Pewee
Back in the middle and upper reaches of the trees, we find what has been by far the most numerous of the flycatchers seen during our visits to fallout sunrises.  Eastern Wood-Pewees are appearing in very good numbers and can be seen quarreling and battling for hunting perches from which they are ambushing flying insects.
 Eastern Wood-Pewee
An Eastern Wood-Pewee fiercely defending its hunting perch.
Eastern Wood-Pewee
An Eastern Wood-Pewee.
Least Flycatcher
The numbers of migrating Least Flycatchers and other members of the genus Empidonax may be reaching their seasonal peak this week.
Scarlet Tanagers
Scarlet Tanagers are currently a common find following nocturnal flights.
Scarlet Tanager
A Scarlet Tanager peers down from the top of a Red Maple.
Rose-breasted Grosbeak
Did you hear a loud squeak in the treetops?  It could be a southbound Rose-breasted Grosbeak stopping by for the day.
Rose-breasted Grosbeak
A Rose-breasted Grosbeak in a dead tree snag.
Swainson's Thrush
The Neotropical thrushes are beginning to move south now as well.  We found this newly arrived Swainson’s Thrush at Rocky Ridge County Park in York County during sunrise this morning.
Red-eyed Vireo
Not surprisingly, the Red-eyed Vireo is one of the most numerous of the migrants seen feeding in the deciduous canopy following a nocturnal flight event.  It’s not at all unusual to see dozens filing the trees around a ridgetop overlook or along a forest edge.  Be certain to check these congregations carefully, especially the groups of birds feeding in the lower branches of tall timber or in the tops of smaller trees.  This week we found…
Yellow-throated Vireo
…several hungry Yellow-throated Vireos arriving after nocturnal flights,…
Philadelphia Vireo
…and a Philadelphia Vireo (Vireo philadelphicus) at the hawkwatch at Rocky Ridge County Park in York County.
Red-breasted Nuthatch
Though not a Neotropical migrant, the easier-heard-than-seen Red-breasted Nuthatch is beginning to wander south into the lower Susquehanna region.  Most of these birds will eventually continue on to the pine forests of the southern United States for winter, but a few could remain to become seasonal visitors at feeding stations.
Ruby-throated Hummingbird
Ruby-throated Hummingbirds are on the move; their migration to the tropics is well underway and nearing its peak.  Ruby-throats are diurnal migrants that do a majority of their flying during the hours of daylight.  The notable exception: the nighttime portion of the long southbound flight some of the birds make to cross the Gulf of Mexico.
Red-headed Woodpecker
The Red-headed Woodpecker is another diurnal migrant.   This denizen of temperate climates is currently beginning to move to its wintering grounds, an area that extends from the latitudes of the lower Susquehanna south to the Gulf of Mexico and central Texas.
Juvenile Red-headed Woodpecker
A juvenile Red-headed Woodpecker during a brief pit stop.
Cedar Waxwings
The flights of roving bands of masked Cedar Waxwings continue.  Their numbers appear to be an improvement over those of 2023.
Broad-winged Hawk
At regional hawk-counting stations, observers are seeing more Broad-winged Hawks and other species beginning to move through.
"Kettling" Broad-winged Hawks
The frequency of Broad-winged Hawks passing the lookouts one at a time is giving way to the occurrence of larger and larger “kettling” groups that search out thermal updrafts to save energy while migrating.  By mid-September each of these “kettles” can include one hundred birds or more.  On the peak days, the daily Broad-winged Hawk totals can reach one thousand or more.
Broad-winged Hawk
A Broad-winged Hawk soaring to gain lift from a thermal updraft above a hawkwatch lookout.

The migration is by no means over; it has only just begun.  So plan to visit a local hawkwatch or other suitable ridgetop in coming weeks.  Arrive early (between 7 and 8 AM) to catch a glimpse of a nocturnal migrant fallout, then stay through the day to see the hundreds, maybe even thousands, of Broad-winged Hawks and other diurnal raptors that will pass by.  It’s an experience you won’t forget.

Broad-winged Hawk Gliding Away to the Southwest
A Broad-winged Hawk gliding away to the southwest.

Be certain to click the “Birds” tab at the top of this page for a photo guide to the species you’re likely to see passing south through the lower Susquehanna valley in coming months.  And don’t forget to click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab to find a hawk-counting station near you.

More birds are on the way.  Here’s a look at this evening’s liftoff of nocturnal migrants detected by National Weather Service Radar in State College, Pennsylvania.  (NOAA/National Weather Service Doppler Radar image)

Southbound Flights: On Their Way Both Night and Day

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

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

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

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

Red-eyed Vireo
One of more than half a dozen Red-eyed Vireos seen during a daybreak fallout at Second Mountain Hawkwatch in Lebanon County earlier this week.
Blackburnian Warbler
During sunrise, a just-arrived Blackburnian Warbler checks the foliage of a ridgetop Red Maple for insects.
Least Flycatcher
A Least Flycatcher quietly searches the shrubby growth along the forest edge for a morning meal.
Black-and-white Warbler
A Black-and-white Warbler in the first hour of sunlight after a big nocturnal flight.
Scarlet Tanager
A Scarlet Tanager having a look around.  This individual and other migrating birds may be here for a few days before moving on.
Black-throated Green Warbler
A Black-throated Green Warbler in a treetop glowing with the light of sunrise.
Chestnut-sided Warbler
A hungry Chestnut-sided Warbler inspects limbs, leaves, and twigs looking for nourishment after an all-night flight.

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

Broad-winged Hawk
While many diurnal migrants gather in flocks as a method of defense against predators, Broad-winged Hawks congregate as a reconnaissance measure.  Not waiting around for strong autumn winds to be deflected upwards by the region’s numerous ridges, these Neotropical birds migrate early enough in the season to rely upon thermal updrafts from sun-heated surfaces to provide lift, gain altitude, and save energy during their long trip.  By traveling in groups, there are collectively able to better locate and utilize rising air columns as they progress southwesterly along their route.  Broad-winged Hawks travel to Central and South America for winter.  Their numbers in the Lower Susquehanna River Watershed will peak during the third week of September.
American Kestrel
Many American Kestrels transit our area in August and early September, a time coinciding with flights of migratory dragonflies, insects upon which they and another falcon, the Merlin, frequently prey.
Chimney Swifts
Chimney Swifts are fast-flying diurnal migrants.  They are beginning to congregate into larger groups in preparation for their departure.  Some are already on the move.
Cedar Waxwing
Cedar Waxwings are currently being seen in roving flocks throughout the region.  Their migration is less of a point-to-point flight and more of a continuous wandering in search of berries and other wild foods.
American Goldfinch
Not everyone is yet ready to go.  American Goldfinches are still in the midst of their nesting cycle and won’t begin leaving until the young are on their own and colorful adult males like this one are beginning to molt into their drab winter plumage.

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

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

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

Arboreal Birds and Tent Caterpillars

During the past week, we’ve been exploring wooded slopes around the lower Susquehanna region in search of recently arrived Neotropical birds—particularly those migrants that are singing on breeding territories and will stay to nest.  Coincidentally, we noticed a good diversity of species in areas where tent caterpillar nests were apparent.

Eastern Tent Caterpillar Nest
The conspicuous nest of the Eastern Tent Caterpillar (Malacosoma americanum), a native species of moth.  The first instar of the larval caterpillars hatch in early spring from egg masses laid on the limbs of the host tree by an adult female moth during the previous spring.  Soon after they begin feeding on the host tree’s first tender shoots, these tiny, seldom-noticed larvae start communal construction of a silk tent to act as a shelter and greenhouse-like solar collector that will both provide protection from the elements and expedite their growth.
Eastern Tent Caterpillar
The familiar last instar of the Eastern Tent Caterpillar is the most consumptive stage of the animal’s life.  After feeding in the treetops, they will descend to the ground and seek a sheltered location to pupate.  Adult moths emerge in several weeks to take to the air, mate, and produce eggs to be deposited on a host tree for hatching next year.  The favorite host tree in forests of the Lower Susquehanna River Watershed: native Black Cherry.

Here’s a sample of the variety of Neotropical migrants we found in areas impacted by Eastern Tent Caterpillars.  All are arboreal insectivores, birds that feed among the foliage of trees and shrubs searching mostly for insects, their larvae, and their eggs.

Yellow-throated Vireo
The Yellow-throated Vireo nests, feeds, and spends the majority of its time feeding among canopy foliage.
Eastern Wood-Pewee
The Eastern Wood-Pewee is a flycatcher found in mature woodlands.  It feeds not only among the limbs and leaves, but is an aerial predator as well.
Northern Parula
The Northern Parula nests in mature forests along rivers and on mountainsides, particularly where mature trees are draped with thick vines.
Hooded Warbler
The Hooded Warbler (Setophaga citrina) is found among thick understory growth on forested slopes.
Ovenbird
The Ovenbird builds a domed, oven-like nest on the ground and forages in the canopy.
Kentucky Warbler
The Kentucky Warbler (Geothlypis formosa) nests in woodland undergrowth, often near steep, forested slopes.
Worm-eating Warbler
The Worm-eating Warbler (Helmitheros vermivorum) nests among woody understory growth on forested hillsides.
Scarlet Tanager
The Scarlet Tanager is often difficult to observe because of its affinity for the canopy of mature forest trees.

In the locations where these photographs were taken, ground-feeding birds, including those species that would normally be common in these habitats, were absent.  There were no Gray Catbirds, Carolina Wrens, American Robins or other thrushes seen or heard.  One might infer that the arboreal insectivorous birds chose to establish nesting territories where they did largely due to the presence of an abundance of tent caterpillars as a potential food source for their young.  That could very well be true—but consider timing.

Already Gone-  By the time Neotropical migrants arrive in our area, the larval stages of the Eastern Tent Caterpillar’s life cycle are already coming to an end.  The nests that these native insects constructed to capture the energy of the springtime sun have allowed the larvae to exit and browse foliage when conditions were suitable, then return for shelter when they were not.  While inside, the larvae could move among the chambers of their structure to find locations with a temperature that best suited their needs.  Therein the solar heating and communal warmth sped up digestion and growth.
Eastern Tent Caterpillar
Eastern Tent Caterpillar larvae are now in their bristly final-instar stage and the majority have already moved to the ground to each seek a place to pupate and metamorphose into an adult moth.  Arboreal Neotropical birds have scarcely had a chance to feed upon them, and ground-feeding species seem to lack any temptation.  As for the adult moths, they fly only at night and live for just one day, offering little in the way of food for aerial, arboreal, or ground-feeding birds.
Wild Turkey
Having left arboreal environs, Eastern Tent Caterpillar larvae are now food for ground-feeding birds like our resident Wild Turkeys.  They need only get past the bristly hairs on the caterpillar’s back and the foul taste that may result from its limited diet of cyanogenic Black Cherry leaves.
Yellow-billed Cuckoo
The arboreal Yellow-billed Cuckoo (seen here) and its close relative the Black-billed Cuckoo (Coccyzus erythropthalmus) are the two species of birds in our area known to regularly feed on bristly tent caterpillars.  But having just arrived from the tropics to nest, they’ll need to rely on other insects and their larvae as sources of food for their young.
Black Cherry defoliated by Eastern Tent Caterpillars.
Final-instar Eastern Tent Caterpillars often defoliate Black Cherry trees before moving to the ground to pupate. Their timing allows them to feed on the fresh foliage while it is still young and tender, and to largely avoid becoming food for the waves of Neotropical birds that arrive in the lower Susquehanna basin in May.

So why do we find this admirable variety of Neotropical bird species nesting in locations with tent caterpillars?  Perhaps it’s a matter of suitable topography, an appropriate variety of native trees and shrubs, and an attractive opening in the forest.

American Redstart
An American Redstart singing in a Black Cherry.  Unlike others in the vicinity, this tree nestled among several very large Eastern White Pines showed no signs of tent caterpillar activity.  It may be that for one reason or another, no adult female moth deposited her eggs on this particular tree.  During our visits, Black Cherry was but one of the diverse variety of native trees and shrubs found growing on the sloping topography that created attractive habitat for the nesting birds we found.  We happened to notice that a majority, but not all, of those Black Cherry trees were impacted by Eastern Tent Caterpillars.
Black Cherry in Flower
The end of the Eastern Tent Caterpillar’s larval surge may spell the end of their nests for the year, but it’s not the end for the Black Cherry and other host trees in the Prunus (cherry) and Malus (apple) genera.  Because it’s still early in the season, they have plenty of time to re-leaf and many will still flower and produce fruit.  Those flowers and foliage will attract numerous other insects (including pollinators) that benefit breeding birds.
Blue-winged Warbler
The Blue-winged Warbler inhabits shrubby breaks in the forest such as this utility right-of-way where Black Cherry trees have sprouted after their seeds arrived in waste deposited by fruit-eating (frugivorous) birds.  Already attractive to a variety of insectivores, these openings soon lure egg-laying Eastern Tent Caterpillar moths to the cherry trees growing therein.  Even in dense forest, a small clearing created by a cluster of dead trees makes good bird habitat and will sooner or later be visited by fruit-eating species that will inadvertently sow seeds of Black Cherry, starting yet another stand of host trees for Eastern Tent Caterpillars.  It’s the gap in the forest that often attracts the birds, some of which plant the host trees, which sometimes entice Eastern Tent Caterpillar moths to lay their eggs.
Red-Eyed Vireo
Adapt and Reuse-  A Red-eyed Vireo visits an Eastern Tent Caterpillar nest…
Red-eyed Vireo
…and ignores the few remaining occupants that could easily be seized to instead collect silk to reinforce its own nest.

Here in the Lower Susquehanna River Watershed, the presence of Eastern Tent Caterpillar nests can often be an indicator of a woodland opening, natural or man-made, that is being reforested by Black Cherry and other plants which improve the botanical richness of the site.  For numerous migratory Neotropical species seeking favorable places to nest and raise young, these regenerative areas and the forests surrounding them can be ideal habitat.  For us, they can be great places to see and hear colorful birds.

Scarlet Tanager
Our Lucky Break-  This Scarlet Tanager descended from the treetops to feed on spiders in a small forest clearing.

A Pre-dawn Thunderstorm and a Fallout of Migrating Birds

In recent days, the peak northbound push of migratory birds that includes the majority of our colorful Neotropical species has been slowed to a trickle by the presence of rain, fog, and low overcast throughout the Mid-Atlantic States.  Following sunset last evening, the nocturnal flight resumed—only to be grounded this morning during the pre-dawn hours by the west-to-east passage of a fast-moving line of strong thundershowers.  The NOAA/National Weather Service images that follow show the thunderstorms as well as returns created by thousands of migrating birds as they pass through the Doppler Radar coverage areas that surround the lower Susquehanna valley.

Sterling, Virginia, Doppler Radar west of Washington, D.C., at 4:00 A.M. E.D.T. indicates a dense flight of northbound migrating birds located just to the south of the approaching line of rain and thunderstorms over the State College, Pennsylvania, radar coverage area.  (NOAA/National Weather Service image)
More northbound birds are indicated at 4 A.M. by the radar station located at Dover, Delaware…  (NOAA/National Weather Service image)
…and by the Mount Holly, New Jersey, radar site.  (NOAA/National Weather Service image)
Many of the migrating birds shown here over the Binghamton, New York, radar station at 4 A.M. probably overflew the lower Susquehanna region earlier in the night.  (NOAA/National Weather Service image)
And these birds over Albany, New York’s, radar station at 4 A.M. are mostly migrants that passed north over New Jersey and easternmost Pennsylvania last evening and during the wee hours of this morning.  (NOAA/National Weather Service image)

Just after 4 A.M., flashes of lightning in rapid succession repeatedly illuminated the sky over susquehannawildlife.net headquarters.  Despite the rumbles of thunder and the din of noises typical for our urban setting, the call notes of nocturnal migrants could be heard as these birds descended in search of a suitable place to make landfall and seek shelter from the storm.  At least one Wood Thrush and a Swainson’s Thrush (Catharus ustulatus) were in the mix of species passing overhead.  A short time later at daybreak, a Great Crested Flycatcher was heard calling from a stand of nearby trees and a White-crowned Sparrow was seen in the garden searching for food.  None of these aforementioned birds is regular here at our little oasis, so it appears that a significant and abrupt fallout has occurred.

White-crowned Sparrow
A White-crowned Sparrow in the headquarters garden at daybreak.  It’s the first visit by this species in a decade or more.

Looks like a good day to take the camera for a walk.  Away we go!

Gray Catbird
Along woodland edges, in thickets, and in gardens, Gray Catbirds were everywhere today.  We heard and/or saw hundreds of them.
American Redstart
During our travels, American Redstarts were the most frequently encountered warbler.  Look for them in low-lying forested habitats.
Many early-arriving Baltimore Orioles have already begun building nests.  But widespread territorial fighting today may be an indication that some latecomer orioles became trespassers after dropping in on existing territories during the morning fallout.
Red-eyed Vireo
Red-eyed Vireos are difficult to see but easily heard in forested areas throughout the Lower Susquehanna River Watershed.
Scarlet Tanager
If the oriole isn’t the showiest of the Neotropical migrants, then the Scarlet Tanager is certainly a contender…
Scarlet Tanager
Listen for their burry, robin-like song in the treetops of mature upland forests.
Wood Thrush
No woodland chorus is complete without the flute-like harmony of the Wood Thrush.  Look and listen for them in rich forests with dense understory vegetation.
Eastern Wood-Pewee
The Eastern Wood-Pewee, another forest denizen, has an easy song to learn…a series of ascending “pee-a-wee” phrases interspersed with an occasional descending “pee-urr”.  It was one of the few flycatchers we found today, but more are certainly on the way.  Their numbers should peak in coming days.
Yellow-rumped Warbler
Yellow-rumped Warblers can be especially numerous during migration but tend to peak prior to the arrival of the bulk of the Neotropical species.  This was the only “yellow-rump” we encountered today.  The majority have already passed through on their way to breeding grounds to our north.
Common Yellowthroat
If today you were to visit a streamside thicket or any type of early successional habitat, you would probably find this perky little warbler there, the Common Yellowthroat.
Yellow Warbler
The Yellow Warbler likes streamside thickets too.  You can also find them along lakes, ponds, and wetlands, especially among shrubby willows and alders.
White-crowned Sparrow
While nowhere near the headquarters garden, we ran into another White-crowned Sparrow in less-than-ideal habitat.  This one was in a row of trees in a paved parking lot.
Bobolink
Not all songbirds migrate at night. The Bobolink is an example of a diurnal (day-flying) migrant.  They’re currently arriving in hay fields that are spared the mower until after nesting season.
Blue-gray Gnatcatcher
While looking for Neotropical species and other late-season migrants, we also found numerous early arrivals that had already begun their breeding cycles.  We discovered this Blue-gray Gnatcatcher on its nest in a Black Walnut tree…
Blue-gray Gnatcatcher
…then, later in the day, we found this one in its nest, again in a Black Walnut tree.  Note the freshly emerging set of leaves and flower clusters.  With many tree species already adorned in a full set of foliage, open canopies in stands of walnuts we found growing in reforested areas seemed to be good places to see lots of migrants and other birds today.  It’s hard to say whether birds were more numerous in these sections of woods or were just easier to observe among the sparse leaf cover.  In either case, the nut-burying squirrels that planted these groves did us and the birds a favor.

There’s obviously more spring migration to come, so do make an effort to visit an array of habitats during the coming weeks to see and hear the wide variety of birds, including the spectacular Neotropical species, that visit the Lower Susquehanna River Watershed each May.  You won’t regret it!

Wood Ducks
Wood Ducks arrived in February and March to breed in the lower Susquehanna valley.  Soon after hatching in April or May, the young leave the nest cavity to travel under the watchful gaze of their ever-vigilant mother as they search for food along our local waterways.  If you’re fortunate, you might catch a glimpse of a brood and hen while you’re out looking at the more than one hundred species of birds that occur in our region during the first half of May.  Good luck!

Surf’s Up: The Waves Keep Rolling In

“Waves” of warblers and other Neotropical songbirds continue to roll along the ridgetops of southern Pennsylvania.  The majority of these migrants are headed to wintering habitat in the tropics after departing breeding grounds in the forests of southern Canada.  At Second Mountain Hawk Watch, today’s early morning flight kicked off at sunrise, then slowed considerably by 8:30 A.M. E.D.T.  Once again, in excess of 400 warblers were found moving through the trees and working their way southwest along the spine of the ridge.  Each of the 12 species seen yesterday were observed today as well.  In addition, there was a Northern Parula and a Canada Warbler.  Today’s flight was dominated by Bay-breasted, Blackburnian, Black-throated Green, and Tennessee Warblers.

A Blackburnian Warbler at sunrise on Second Mountain.
A Blackburnian Warbler at sunrise on Second Mountain.
A hungry Blackburnian Warbler feeding on insects.
A hungry Blackburnian Warbler feeding on insects.
Black-throated Green Warbler on Second Mountain.
Black-throated Green Warblers were a plentiful species among both yesterday’s and today’s waves of Neotropical migrants.
A juvenile Black-throated Green Warbler on Second Mountain
A juvenile Black-throated Green Warbler.
Tennessee Warbler on Second Mountain.
One of the scores of Tennessee Warblers seen on Second Mountain early this morning.
Cape May Warbler
Cape May Warblers were still common today, but not moving through in the numbers seen yesterday.
A male Black-throated Blue Warbler on Second Mountain.
A male Black-throated Blue Warbler.
Magnolia Warbler on Second Mountain.
Compared to yesterday’s flight, lesser numbers of Magnolia Warblers were seen today.
An adult male Wilson's Warbler on Second Mounatin.
An adult male Wilson’s Warbler was a good find among the hundreds of birds swarming the ridgetop.
Nashville Warbler
This Nashville Warbler spent much of the day in the tangles of Mile-a-minute Weed surrounding the lookout.

Other interesting Neotropical migrants joined the “waves” of warblers…

Red-eyed Vireo
Red-eyed Vireo numbers were higher than yesterday.
Warbling Vireo
This Warbling Vireo was found peering from the cover of the shady forest.
Rose-breasted Grosbeaks
A minimum of six Rose-breasted Grosbeaks were identified including the juvenile male seen here in first-fall plumage.  Other good sightings were Scarlet Tanagers, an adult male Baltimore Oriole, and a dozen or more Ruby-throated Hummingbirds.
Least Flycatcher on second Mountain.
Three Least Flycatchers were heard calling and seen chasing one another through a stand of dead timber on the south slope below the lookout.
Broad-winged Hawk
After the warbler flight settled, the task of counting migrating raptors commenced.  Five Broad-winged Hawks including this one were tallied as they glided away to the southwest for a winter vacation in the tropics of Central and South America.

Catch a Wave While You’re Sittin’ on Top of the World

During the recent couple of mornings, a tide of Neotropical migrants has been rolling along the crests of the Appalachian ridges and Piedmont highlands of southern Pennsylvania.  In the first hours of daylight, “waves” of warblers, vireos, flycatchers, tanagers, and other birds are being observed flitting among the sun-drenched foliage as they feed in trees along the edges of ridgetop clearings.  Big fallouts have been reported along Kittattiny Ridge/Blue Mountain at Hawk Mountain Sanctuary and at Waggoner’s Gap Hawk Watch.  Birds are also being seen in the Furnace Hills of the Piedmont.

Here are some of the 300 to 400 warblers (a very conservative estimate) seen in a “wave” found working its way southwest through the forest clearing at the Second Mountain Hawk Watch in Lebanon County this morning.  The feeding frenzy endured for two hours between 7 and 9 A.M. E.D.T.

Tennessee Warblers at Second Mountain Hawk Watch.
Tennessee Warblers (Leiothlypis peregrina) were very common among the migrants seen this morning on Second Mountain.
Tennessee Warbler at Second Mountain Hawk Watch.
An adult male Tennessee Warbler.
Nashville Warbler at Second Mountain Hawk Watch.
A Nashville Warbler.
Chestnut-sided Warbler at Second Mountain Hawk Watch.
A Chestnut-sided Warbler.
Cape May Warbler at Second Mountain Hawk Watch.
Cape May Warblers were another common species during the morning flight.
Magnolia Warbler at Second Mountain Hawk Watch.
Magnolia Warblers were frequently observed as well.
Black-and-white Warbler at Second Mountain Hawk Watch.
A Black-and-white Warbler exhibiting its nuthatch-like feeding behavior.
Blackburnian Warbler at Second Mountain Hawk Watch.
A Blackburnian Warbler.
Black-throated Green Warbler at Second Mountain Hawk Watch.
Black-throated Green Warblers were numerous.
Bay-breasted Warbler at Second Mountain Hawk Watch.
A Bay-breasted Warbler.
Wilson's Warbler at Second Mountain Hawk Watch.
This was the only Wilson’s Warbler discerned among the hundreds of warblers seen in a “wave” on Second Mountain this morning.

Not photographed but observed in the mix of species were several Black-throated Blue Warblers and American Redstarts.

In addition to the warblers, other Neotropical migrants were on the move including two Common Nighthawks, a Broad-winged Hawk, a Least Flycatcher (Empidonax minimus), and…

Scarlet Tanager at Second Mountain Hawk Watch.
At least half a dozen Scarlet Tanagers were in the treetops.
Ruby-throated Hummingbird at Second Mountain Hawk Watch.
And no less than 23 Ruby-throated Hummingbirds were counted cruising southbound past the lookout at Second Mountain Hawk Watch today.

Then, there was a taste of things to come…

Red-breasted Nuthatch at Second Mountain Hawk Watch.
One of 3 Red-breasted Nuthatches filling the air on the mountaintop with calls reminiscent of a toy tin horn.  Will this summer’s forest fires in Canada prompt a significant invasion of this and other birds including winter finches in coming months?  Time will tell.

Seeing a “wave” flight is a matter of being in the right place at the right time.  Visiting known locations for observing warbler fallouts such as hawk watches, ridgetop clearings, and peninsular shorelines can improve your chances of witnessing one of these memorable spectacles by overcoming the first variable.  To overcome the second, be sure to visit early and often.  See you on the lookout!

Photo of the Day

Scarlet Tanager in a Pin Oak
Following a heavy nocturnal flight, an observer can often see Neotropical migrants in unusual places.  For arboreal species looking to rest and feed after a long night of flying, large native trees in almost any location can be attractive.  This Scarlet Tanager was found not in its typical habitat, a deciduous forest, but in an enormous Pin Oak (Quercus palustris) surrounded by manicured lawn.  

Something in the Air Tonight

There’s something in the air tonight—and it’s more than just a cool comfortable breeze.

(NOAA/National Weather Service image)

It’s a major nocturnal movement of southbound Neotropical birds.  At daybreak, expect a fallout of migrants, particularly songbirds, in forests and thickets throughout the region.   Warblers, vireos, flycatchers, thrushes, Scarlet Tanagers, and Rose-breasted Grosbeaks pass through in mid-September each year, so be on the lookout!

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.

The Layover

After nearly a full week of record-breaking cold, including two nights with a widespread freeze, warm weather has returned.  Today, for the first time this year, the temperature was above eighty degrees Fahrenheit throughout the lower Susquehanna region.  Not only can the growing season now resume, but the northward movement of Neotropical birds can again take flight—much to our delight.

A rainy day on Friday, May 8, preceded the arrival of a cold arctic air mass in the eastern United States.  It initiated a sustained layover for many migrating birds.

Bobolinks (Dolichonyx oryzivorus) in flocks of as many as fifty birds gathered in weedy meadows and alfalfa fields for the week.
A Bobolink sheltering in a field of Sweet Vernal Grass (Anthoxanthum odoratum) during the rain on Friday, May 8th.
Two of seven Solitary Sandpipers (Tringa solitaria) in a wet field on Friday, May 8.  Not-so-solitary after all.
Grounded by inclement weather, Rose-breasted Grosbeaks (Pheucticus ludovicianus) made visits to suburban bird feeders in the lower Susquehanna valley.  (Charles A. Fox image)

Freeze warnings were issued for five of the next six mornings.  The nocturnal flights of migrating birds, most of them consisting of Neotropical species by now, appeared to be impacted.  Even on clear moonlit nights, these birds wisely remained grounded.  Unlike the more hardy species that moved north during the preceding weeks, Neotropical birds rely heavily on insects as a food source.  For them, burning excessive energy by flying through cold air into areas that may be void of food upon arrival could be a death sentence.  So they wait.

A freeze warning was issued for Saturday morning, May 9, in the counties colored dark blue on the map.  (NOAA/National Weather Service image)
This radar image from 3:28 A.M. Saturday morning, May 9, indicates a minor movement of birds in the Great Plains, but there are no notable returns shown around weather radar sites in the freeze area, including the lower Susquehanna valley.  (NOAA/National Weather Service image)
To avoid the cold wind on Saturday, May 9, this Veery was staying low to the ground within a thicket of shrubs in the forest.
This Black-throated Blue Warbler avoided the treetops and spent time in the woodland understory.  He sang not a note.  With birds conserving energy for the cold night(s) ahead, it was uncharacteristically quiet for the second Saturday in May.
A secretive Northern Waterthrush (Parkesia noveboracensis) remained in a wetland thicket.
A Scarlet Tanager (Piranga olivacea) tucks his bill beneath a wing and fluffs-up to fight off the cold during a brief May 9th snow flurry.
In open country, gusty winds kept Eastern Kingbirds, a species of flycatcher, near the ground in search of the insects they need to sustain them.
Horned Larks are one of the few birds that attempt to scratch out an existence in cultivated fields.  The application of herbicides and the use of systemic insecticides (including neonicotinoids) eliminates nearly all weed seeds and insects in land subjected to high-intensity farming.  For most birds, including Neotropical migrants, cropland in the lower Susquehanna valley has become a dead zone.  Birds and other animals might visit, but they really don’t “live” there anymore.
Unable to find flying insects over upland fields during the cold snap, swallows concentrated over bodies of water to feed.  Some Tree Swallows may have abandoned their nests to survive this week’s cold.  Fragmentation of habitats in the lower Susquehanna valley reduces the abundance and diversity of natural food sources for wildlife.  For birds like swallows, events like late-season freezes, heat waves, or droughts can easily disrupt their limited food supply and cause brood failure.
For this Barn Swallow, attempting to hunt insects above the warm pavement of a roadway had fatal consequences.
Another freeze warning was issued for Sunday morning, May 10, in the counties colored dark blue on this map.  (NOAA/National Weather Service image)
This radar image from 4:58 A.M. Sunday morning, May 10, again indicates the absence of a flight of migrating birds in the area subjected to freezing temperatures.  Unlike migrants earlier in the season, the Neotropical species that move north during the May exodus appear unwilling to resume their trek during freezing weather.  (NOAA/National Weather Service image)
On Sunday evening, May 10, a liftoff of nocturnal migrants is indicated around radar sites along the Atlantic Coastal Plain and, to a lesser degree, in central Pennsylvania.  The approaching rain and yet another cold front quickly grounded this flight.
After a one day respite, yet another freeze warning was issued for Tuesday morning, May 12.  (NOAA/National Weather Service image)
And again, no flight in the freeze area.  (NOAA/National Weather Service image)
The freeze warning for Wednesday morning, May 13.  (NOAA/National Weather Service image)
And the nocturnal flight: heavy in the Mississippi valley and minimal in the freeze area.  (NOAA/National Weather Service image)
The freeze on Thursday morning, May 14.  (NOAA/National Weather Service image)
At 3:08 A.M. on May 14th, a flight is indicated streaming north through central Texas and dispersing into the eastern half of the United States, but not progressing into New England.  (NOAA/National Weather Service image)
The flight at eight minutes after midnight this morning.  Note the stormy cold front diving southeast across the upper Mississippi valley.  As is often the case, the concentration of migrating birds is densest in the warm air ahead of the front.  (NOAA/National Weather Service image)

Today throughout the lower Susquehanna region, bird songs again fill the air and it seems to be mid-May as we remember it.  The flights have resumed.

Indigo Bunting numbers are increasing as breeding populations arrive and migrants continue through.  Look for them in thickets along utility and railroad right-of-ways.
Common Yellowthroats and other colorful warblers are among the May migrants currently resuming their northward flights.
The echoes of the songs of tropical birds are beginning to fill the forests of the lower Susquehanna watershed.  The flute-like harmonies of the Wood Thrush are among the most impressive.
Ovenbirds are ground-nesting warblers with a surprisingly explosive song for their size.  Many arrived within the last two days to stake out a territory for breeding.  Listen for “teacher-teacher-teacher” emanating from a woodland near you.