Yesterday morning’s fallout of hundreds of nocturnally migrating birds was followed overnight by the influx of one hundred or more new arrivals atop Second Mountain in Lebanon County, Pennsylvania. Visitors to the forest clearing used as a hawk watch lookout were treated to the antics of these colorful Neotropical species and more…
These night-flying warblers, vireos, and flycatchers did again provide a thrilling show during the hours after sunrise, but today’s rarity passed through among the hundreds of migrating diurnal raptors—the tropics-bound Broad-winged Hawks—that made their way down the ridges of the lower Susquehanna valley this afternoon.
A “kettle” of Broad-winged Hawks climbing on a thermal updraft above Second Mountain Hawk Watch.After gaining altitude, Broad-winged Hawks glide away toward the southwest in search of the next thermal updraft upon which they will rise to continue their journey to Texas, Mexico, and beyond. Over three hundred of these raptors were counted as they passed the Second Mountain lookout today.Another “kettling” flock of migrating Broad-winged Hawks above Second Mountain.A closer look reveals something unusual. While the Broad-winged Hawk at the bottom center of the image displays the typical light-morph plumage, the bird in the upper left appears to be a dark-morph Broad-winged Hawk, a rarity in the eastern United States.A zoomed-in view of the probable dark-morph Broad-winged Hawk seen over Second Mountain this afternoon. Populations of these variants nest in areas of central and western Canada.
The peak of the autumn Broad-winged Hawk migration will likely occur during the coming two weeks with many counting stations tallying more than one thousand birds on the best of days. Visit one of these prominent lookout points so that you too can witness this amazing spectacle. Click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab at the top of this page to find a hawk watch near you!
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…
A Black-throated Green Warbler.The Black-throated Green Warbler was perhaps the most frequently identified treetop warbler during the most recent four mornings.A Black-throated Green Warbler with a unique variation in the crown plumage.The Blackburnian Warbler was another plentiful species.Cape May Warblers have an affinity for conifers like this Eastern White Pine.But when traveling in mixed flocks with other migrants, Cape May Warblers can also be found feeding in the crown foliage of deciduous trees.This adult Tennessee Warbler appears to be adorned in a very worn set of plumage……and its traveling companion looks like it’s overdue for a new set of feathers as well.Like the Tennessee Warbler, the Nashville Warbler was common among mixed flocks.A Nashville Warbler atop a Black Cherry.This Chestnut-sided Warbler was one of several found among the more common species of migrants.A Chestnut-sided Warbler.We were lucky enough to spot this male Chestnut-sided Warbler sporting his namesake flank feathers.A Black-and-white Warbler uses its nuthatch-like feeding behavior to search the tree bark for edible invertebrates.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.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.Here we found a perky little House Wren.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.An Eastern Wood-Pewee fiercely defending its hunting perch.An Eastern Wood-Pewee.The numbers of migrating Least Flycatchers and other members of the genus Empidonax may be reaching their seasonal peak this week.Scarlet Tanagers are currently a common find following nocturnal flights.A Scarlet Tanager peers down from the top of a Red Maple.Did you hear a loud squeak in the treetops? It could be a southbound Rose-breasted Grosbeak stopping by for the day.A Rose-breasted Grosbeak in a dead tree snag.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.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……several hungry Yellow-throated Vireos arriving after nocturnal flights,……and a Philadelphia Vireo (Vireo philadelphicus) at the hawkwatch at Rocky Ridge County Park in York County.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 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.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.A juvenile Red-headed Woodpecker during a brief pit stop.The flights of roving bands of masked Cedar Waxwings continue. Their numbers appear to be an improvement over those of 2023.At regional hawk-counting stations, observers are seeing more Broad-winged Hawks and other species beginning to move through.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.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.
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)
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.
Migrating Caspian Terns and an Osprey take a break on a lower Susquehanna valley gravel bar.
As August draws to a close, these early birds are being joined by widespread nocturnal flights of Neotropical migrants—those species, primarily songbirds, on their way to wintering grounds which lie exclusively south of the continental United States.
To catch a glimpse of these night-flying avians, your best bet may be to position yourself on the crest of a ridge or along a linear break in the forest such as a utility right-of-way where waves of warblers, vireos, flycatchers, and other Neotropical passerines sometimes feed on invertebrates after making landfall at daybreak. Pick a place where the trees are bathed in the warm light of the rising sun and be there by 7 A.M. E.D.T. The activity can be tremendous, but it usually ends between 8 and 9.
One of more than half a dozen Red-eyed Vireos seen during a daybreak fallout at Second Mountain Hawkwatch in Lebanon County earlier this week.During sunrise, a just-arrived Blackburnian Warbler checks the foliage of a ridgetop Red Maple for insects.A Least Flycatcher quietly searches the shrubby growth along the forest edge for a morning meal.A Black-and-white Warbler in the first hour of sunlight after a big nocturnal flight.A Scarlet Tanager having a look around. This individual and other migrating birds may be here for a few days before moving on.A Black-throated Green Warbler in a treetop glowing with the light of sunrise.A hungry Chestnut-sided Warbler inspects limbs, leaves, and twigs looking for nourishment after an all-night flight.
Diurnal migrants, birds that make their movements during the daylight hours, are ramping up their flights now as well. Broad-winged Hawks, Bald Eagles, and falcons are currently being tallied at hawk-counting stations throughout the northeast. Many of those lookouts are seeing Ruby-throated Hummingbirds, swallows, and other daytime migrants too.
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.Many American Kestrels transit our area in August and early September, a time coinciding with flights of migratory dragonflies, insects upon which they and another falcon, the Merlin, frequently prey.Chimney Swifts are fast-flying diurnal migrants. They are beginning to congregate into larger groups in preparation for their departure. Some are already on the move.Cedar Waxwings are currently being seen in roving flocks throughout the region. Their migration is less of a point-to-point flight and more of a continuous wandering in search of berries and other wild foods.Not everyone is yet ready to go. American Goldfinches are still in the midst of their nesting cycle and won’t begin leaving until the young are on their own and colorful adult males like this one are beginning to molt into their drab winter plumage.
Autumn migration flights are an ever-changing process, with different species peaking at different times throughout the season. In these months just after the nesting season, each of these species is more numerous than at any other time of the year. And of course, the more often we as observers get out and have a look, the more of them we’ll see.
Be certain to click the “Birds” tab at the top of this page for a photo guide to the species you’re likely to see passing through the lower Susquehanna valley this fall. Nearly four months of autumn hawk migration flights lie ahead, so don’t forget to click the “Hawkwatcher’s Helper: Identifying Bald Eagles and other Diurnal Raptors” tab to find a hawk-counting station near you, then stop by for a visit or two. See you there!
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)
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.
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.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.
The Yellow-throated Vireo nests, feeds, and spends the majority of its time feeding among canopy foliage.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.The Northern Parula nests in mature forests along rivers and on mountainsides, particularly where mature trees are draped with thick vines.The Hooded Warbler (Setophaga citrina) is found among thick understory growth on forested slopes.The Ovenbird builds a domed, oven-like nest on the ground and forages in the canopy.The Kentucky Warbler (Geothlypis formosa) nests in woodland undergrowth, often near steep, forested slopes.The Worm-eating Warbler (Helmitheros vermivorum) nests among woody understory growth on forested hillsides.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 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.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.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.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.
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.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.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.Adapt and Reuse- A Red-eyed Vireo visits an Eastern Tent Caterpillar nest……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.
Our Lucky Break- This Scarlet Tanager descended from the treetops to feed on spiders in a small forest clearing.
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.
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!
Along woodland edges, in thickets, and in gardens, Gray Catbirds were everywhere today. We heard and/or saw hundreds of them.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 Vireos are difficult to see but easily heard in forested areas throughout the Lower Susquehanna River Watershed.If the oriole isn’t the showiest of the Neotropical migrants, then the Scarlet Tanager is certainly a contender…Listen for their burry, robin-like song in the treetops of mature upland forests.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.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 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.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.The Yellow Warbler likes streamside thickets too. You can also find them along lakes, ponds, and wetlands, especially among shrubby willows and alders.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.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.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……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 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!
“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 hungry Blackburnian Warbler feeding on insects.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.One of the scores of Tennessee Warblers seen on Second Mountain early this morning.Cape May Warblers were still common today, but not moving through in the numbers seen yesterday.A male Black-throated Blue Warbler.Compared to yesterday’s flight, lesser numbers of Magnolia Warblers were seen today.An adult male Wilson’s Warbler was a good find among the hundreds of birds swarming the ridgetop.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 numbers were higher than yesterday.This Warbling Vireo was found peering from the cover of the shady forest.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.Three Least Flycatchers were heard calling and seen chasing one another through a stand of dead timber on the south slope below the lookout.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.
Neotropical birds are presently migrating south from breeding habitats in the United States and Canada to wintering grounds in Central and South America. Among them are more than two dozen species of warblers—colorful little passerines that can often be seen darting from branch to branch in the treetops as they feed on insects during stopovers in the Lower Susquehanna River Watershed.
Being nocturnal migrants, warblers are best seen first thing in the morning among sunlit foliage, often high in the forest canopy. After a night of flying, they stop to feed and rest. Warblers frequently join resident chickadees, titmice, and nuthatches to form a foraging flock that can contain dozens of songbirds. Migratory flycatchers, vireos, tanagers, and grosbeaks often accompany southbound warblers during early morning “fallouts”. Usually, the best way to find these early fall migrants is to visit a forest edge or thicket, particularly along a stream, a utility right-of-way, or on a ridge top. Then too, warblers and other Neotropical migrants are notorious for showing up in groves of mature trees in urban parks and residential neighborhoods—so look up!
A Black-and-white Warbler descends into the tangles of the forest understory to search for a morning meal of insects or creepy-crawlies.Success! Looks like a cranefly (Tipulidae).A Black-throated Green Warbler high in the treetops.Warblers often travel and feed in the company of other Neotropical species like this Red-eyed Vireo.Get out and look for those Neotropical migrants now because, like this Canada Warbler, in just a few weeks they’ll be gone.
Be sure to visit the Birds of Conewago Falls page by clicking the “Birds” tab at the top of this page. There, you’ll find photographs of the birds, including warblers and other Neotropical migrants, that you’re likely to encounter at locations throughout the Lower Susquehanna River Watershed.
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
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.
Birds on radar last evening. A dense liftoff of nocturnal migrants is indicated at radar sites across the northeastern United States. Rain showers can be seen in Virginia. (NOAA/National Weather Service image)
Today’s arrivals—Neotropical migrants found in a streamside thicket in the Lower Susquehanna River Watershed this morning…
Red-eyed Vireos nest in forests throughout the lower Susquehanna valley.The Northern Waterthrush is a regularly occurring migrant that can be found in vegetated wetlands and along the backwaters of streams and rivers. Despite its drab appearance, it is classified as one of our Neotropical warbler species.The adult male American Redstart is unlike any other eastern warbler. It is easily recognized. Along the lower Susquehanna, redstarts nest in the dense understory of damp forests.The first-spring male American Redstart is similar to the female, but usually shows black markings beginning to develop on the breast and face. It is an energetic singer.In its strikingly colorful plumage, the Magnolia Warbler is a classic Neotropical bird. Locally, it is a regular migrant.The Wilson’s Warbler (Cardellina pusilla) forages in lowland thickets during its migratory stopovers. Riparian buffers along streams can provide critical habitat for this and other transient species.Baltimore Orioles continue to trickle in, creating squabbles when they enter nesting territories established by birds that arrived earlier in the month.
A couple of inches of rain this week caused a small increase in the flow of the river, just a burp, nothing major. This higher water coincided with some breezy days that kicked up some chop on the open waters of the Susquehanna upstream of Conewago Falls. Apparently it was just enough turbulence to uproot some aquatic plants and send them floating into the falls.
Piled against and upon the upstream side of many of the Pothole Rocks were thousands of two to three feet-long flat ribbon-like opaque green leaves of Tapegrass, also called Wild Celery, but better known as American Eelgrass (Vallisneria americana). Some leaves were still attached to a short set of clustered roots. It appears that most of the plants broke free from creeping rootstock along the edge of one of this species’ spreading masses which happened to thrive during the second half of the summer. You’ll recall that persistent high water through much of the growing season kept aquatic plants beneath a blanket of muddy current. The American Eelgrass colonies from which these specimens originated must have grown vigorously during the favorable conditions in the month of August. A few plants bore the long thread-like pistillate flower stems with a fruit cluster still intact. During the recent few weeks, there have been mats of American Eelgrass visible, the tops of their leaves floating on the shallow river surface, near the east and west shorelines of the Susquehanna where it begins its pass through the Gettysburg Basin near the Pennsylvania Turnpike bridge at Highspire. This location is a probable source of the plants found in the falls today.
Uprooted American Eelgrass floating into the Pothole Rocks under the power of a north wind. Note the white thread-like pistillate flower stem to the left and the small rooted specimen to the upper right. The latter is likely a plant from the creeping rootstock on the edge of a colony. As a native aquatic species, American Eelgrass is a critical link in the Susquehanna River and Chesapeake Bay food chain. Its decimation by pollution during the twentieth century led to migration pattern alterations and severe population losses for the Canvasback (Aythya valisineria) duck.American Eelgrass, a very small specimen, found growing in a low-lying Pothole Rock alongside the accumulations of freshly arriving material from upstream. Note that the creeping rootstock has leaves growing from at least three nodes on this plant. Eelgrass dislocations are regular occurrences which sometimes begin new colonies, like the small one seen here in this Diabase Pothole Rock Microhabitat.
The cool breeze from the north was a perfect fit for today’s migration count. Nocturnal migrants settling down for the day in the Riparian Woodlands at sunrise included more than a dozen warblers and some Gray Catbirds (Dumetella carolinensis). Diurnal migration was underway shortly thereafter.
A moderate flight of nocturnal migrants is indicated around NEXRAD sites in the northeastern states at 3:18 AM EDT. The outer rain bands of Hurricane Irma can be seen approaching the Florida Keys as the storm closes in on the peninsula. (NOAA/National Weather Service image)
Four Bald Eagles were counted as migrants this morning. Based on plumage, two were first-year eagles (Juvenile) seen up high and flying the river downstream, one was a second-year bird (Basic I) with a jagged-looking wing molt, and a third was probably a fourth year (Basic III) eagle looking much like an adult with the exception of a black terminal band on the tail. These birds were the only ones which could safely be differentiated from the seven or more Bald Eagles of varying ages found within the past few weeks to be lingering at Conewago Falls. There were as many as a dozen eagles which appeared to be moving through the falls area that may have been migrating, but the four counted were the only ones readily separable from the locals.
Red-tailed Hawks (Buteo jamaicensis) were observed riding the wind to journey not on a course following the river, but flying across it and riding the updraft on the York Haven Diabase ridge from northeast to southwest.
Bank Swallows (Riparia riparia) seem to have moved on. None were discovered among the swarms of other species today.
Ruby-throated Hummingbirds, Caspian Terns, Cedar Waxwings (Bombycilla cedrorum), and Chimney Swifts (Chaetura pelagica) were migrating today, as were Monarch butterflies.
Not migrating, but always fun to have around, all four wise guys were here today. I’m referring to the four members of the Corvid family regularly found in the Mid-Atlantic states: Blue Jay (Cyanocitta cristata), American Crow (Corvus brachyrhynchos), Fish Crow (Corvus ossifragus), and Common Raven (Corvus corax).
It looks like a big Blue Jay, but it’s not. This Belted Kingfisher (Megaceryle alcyon) takes a break after flying around the falls trying to shake a marauding Ruby-throated Hummingbird off its tail.CLICK ON THE LOGO FOR TODAY’S MIGRATION COUNT TOTALS
SOURCES
Klots, Elsie B. 1966. The New Field Book of Freshwater Life. G. P. Putnam’s Sons. New York, NY.
A Baltimore Oriole (Icterus galbula) glowed in the first sunlight of the day as it began illuminating the treetops. I’m not certain of the cause, but I often have the urge to dig into a bowl of orange sherbet after seeing one these magnificent blackbirds. That’s right, in the Americas, orioles and blackbirds are members of the same family, Icteridae. Look at blackbirds more carefully, you might see the resemblance.
Sunshine at dawn and migrating warblers were again active in the foliage. Eight species were identified today. Off to the tropics they go. To the land of palm and citrus, yes citrus…limes, lemons, grapefruits, and oranges.
The Ruby-throated Hummingbirds (Archilochus colubris) are on the way toward the gulf states, then on to Central and South America. Five dashed by the rocky lookout in the falls this morning. Remember, keep your feeders clean, wash and rinse all the parts, and refill them with a fresh batch of “nectar”, four or five parts water to one part sugar. Repeating this process daily during hot weather should keep contamination from overtaking your feeder. It’s not a bad idea to rotate two feeders. Have one cleaned, rinsed, and air drying while the second is filled and in use at your feeding station, then just swap them around. Your equipment will be just as clean as it is at the sanitary dairy…you know, where they make sherbet.
The first of the season Caspian Terns (Hydroprogne caspia), giant freshwater versions of the terns you see at the seashore, passed through the falls late this morning. Their bills are blood-red, not orange like the more familiar terns on the coast. They’re stunning.
Ring-billed Gulls (Larus delawarensis) have been at the falls for several weeks. Total numbers and the composition of the age groups in the flock change over the days, so birds appear to be trickling through and are then replaced by others coming south. The big push of southbound migrants for this and many other species that winter locally in the Mid-Atlantic region and in the southern United States is still more than a month away. There are still plenty more birds to come after the hours of daylight are reduced and the temperatures take a dip.
A Ring-billed Gull on the lookout for a morning snack. They’ll eat almost anything and do a good job of keeping the river picked clean of the remains of animals that have met misfortune. They’ll linger around landfills, hydroelectric dams, and fast-food restaurant parking lots through the winter.Turkey Vultures (Cathartes aura) are common around the falls due to the abundance of carrion in the vicinity and because of the strong thermal updrafts of air over the sun-heated Pothole Rocks. These rising currents provide lift for circling vultures. We would expect migrating birds of a number of species will also take advantage of these thermals to gain altitude and extend the distance of their glides.
Some migrating butterflies were counted today. Cloudless Sulphurs, more of a vagrant than a migrant, and, of course, Monarchs. I’ll bet you know the Monarch, it’s black and orange. How can you miss them, colored orange.
That’s it, that’s all for now, I bid you adieu…I’m going to have a dip of orange sherbet, or two.
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Rain from the remnants of Hurricane/Tropical Storm Harvey ended just after daybreak this morning. Locally, the precipitation was mostly absorbed into the soil. There was little runoff and no flooding. The river level at Conewago Falls is presently as low as it has been all summer. Among the pools and rapids of the Pothole Rocks, numbers of migrating birds are building.
Mist and a low cloud ceiling created poor visibility while trying to see early morning birds, but they’re here. The warblers are moving south and a small wave of them was filtering through the foliage on the edge of the Riparian Woodlands. One must bend backwards to have a look, and most could not be identified due to the poor lighting in the crowns of the trees where they were zipping about. Five species of warblers and two species of vireos were discerned.
There are increasing concentrations of swallows feeding on insects over the falls. Hundreds were here today, mostly Tree Swallows (Tachycineta bicolor). Bank Swallows (Stelgidopteryx riparia) numbered in the hundreds, far below the thousands, often 10,000, which staged here for migration and peaked during the first week of September annually during the 1980s and 1990s. Their numbers have been falling steadily. Loss of nesting locations in embankments near water may be impacting the entire population. A reduction in the abundance of late-summer flying insects here on the lower Susquehanna River may be cause for them to abandon this area as a migration staging point.
Bank and Tree Swallows by the hundreds were feeding upon flying insects above the waters of Conewago Falls today. Lesser numbers of Northern Rough-winged Swallows (Stelgidopteryx serripennis) and Barn Swallows (Hirundo rustica) joined the swarm.
Clear weather in the coming nights and days may get the migrants up and flying in large numbers. For those species headed to the tropics for winter, the time to get moving has arrived.
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