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.
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).A Blackpoll Warbler.The Bay-breasted Warbler, another common species found among the fallout flock.The Tennessee Warbler was today’s most abundant migrant with at least 200 birds seen moving among the other species.A newly arrived Tennessee Warbler at sunrise.A Tennessee Warbler snatches breakfast.The Magnolia Warbler was another common find among today’s migrants.A Magnolia Warbler.A Nashville Warbler among tangles of Mile-a-minute Weed.A Nashville Warbler.Black-throated Blue Warbler.An adult male Black-throated Blue Warbler.An acrobatic Northern Parula.Blackburnian Warblers continue their southerly trek.An American Redstart.A Chestnut-sided Warbler feeding on Mile-a-minute Weed berries.A Cape May Warbler.A handsome adult male Cape May Warbler.A Swainson’s Thrush.Scarlet Tanagers continue to work their way south through the Lower Susquehanna River Watershed.A composite image of an uncommon find, a large-headed Olive-sided Flycatcher seen perched atop a dead tree snag.A brief encounter with a Philadelphia Vireo, another uncommon species.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.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)
Here’s a native plant you don’t see very often, but Ruby-throated Hummingbirds have a knack for finding and adoring it within the limited habitat where it still exists.
Allegheny Vine (Adlumia fungosa), also known as Climbing Fumitory or Mountain Fringe, is a seldom-found biennial herbaceous plant in the poppy family (Papaveraceae). Both its divided leaves and drooping clusters of flowers might remind the observer of a more familiar member of the poppy family, the spring-blooming Dutchman’s Breeches. But unlike the low-growing Dutchman’s Breeches, Allegheny Vine ascends nearby shrubs and small trees with trailing stems that add a garland-like pizzazz to the summertime foliage.Seen here creeping atop a small Sassafras (Sassafras albidum) tree, Allegheny Vine seldom escapes notice by the Ruby-throated Hummingbird, a primary pollinator of the plant.Allegheny Vine grows on moist, rocky slopes and blooms in late summer, just in time to refuel migrating Ruby-throated Hummingbirds.
Not likely to thrive in deep forest cover, Allegheny Vine is a denizen of edge habitat. The species is dependent on some type of disturbance to maintain suitable growing conditions. The plants seen here were found flowering in an area that had experienced a fire prior to last year’s growing season. It is therefore quite possible that the fire completed the stratification process and triggered long-dormant seeds to germinate last spring or summer to develop a basal plant which matured and flowered during this second summer of the biennial’s growth. On a forested slope opposite this site, a first-ever prescribed burn was conducted in March of this year to eliminate accumulated fuel and replicate a natural fire cycle. With a little luck, this forest management approach may prompt additional long-dormant Allegheny Vine seeds to germinate and form basal plants this year for maturation in 2025. Without man-made disturbances, Allegheny Vine may remain viable as a species by enduring seed dormancy periods of 40-100 years or more between fires, lightning strikes, wind storms, ice accumulations, and other events which clear the canopy and encourage growth.
Many years in the making, Allegheny Vine nectar must be delectable because the hummers can’t leave it alone. And another plus, with a little help from prescribed fire, this native creeping plant seems to be holding its own while in direct competition with invasive Mile-a-minute Weed (leaves in lower right).
“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.
Earlier today, these migrants were found feeding on berries along the edge of a forest clearing in northern Lebanon County, Pennsylvania. Can you find the three Hermit Thrushes among the early successional growth seen here? For extra credit, identify the three species of berry-producing pioneer plants that are shown. For additional credit, which one of these plants is a non-native invasive species? Click the image to see how you did.
Thoughts of October in the Lower Susquehanna River Watershed bring to mind scenes of brilliant fall foliage adorning wooded hillsides and stream courses, frosty mornings bringing an end to the growing season, and geese and other birds flying south for the winter.
The autumn migration of birds spans a period equaling nearly half the calendar year. Shorebirds and Neotropical perching birds begin moving through as early as late July, just as daylight hours begin decreasing during the weeks following their peak at summer solstice in late June. During the darkest days of the year, those surrounding winter solstice in late December, the last of the southbound migrants, including some hawks, eagles, waterfowl, and gulls, may still be on the move.
The Rough-legged Hawk (Buteo lagopus), a rodent-eating raptor of tundra, grassland, and marsh, is rare as a migrant and winter resident in the lower Susquehanna valley. It may arrive as late as January, if at all.
During October, there is a distinct change in the list of species an observer might find migrating through the lower Susquehanna valley. Reduced hours of daylight and plunges in temperatures—particularly frost and freeze events—impact the food sources available to birds. It is during October that we say goodbye to the Neotropical migrants and hello to those more hardy species that spend their winters in temperate climates like ours.
During several of the first days of October, two hundred Chimney Swifts remained in this roost until temperatures warmed from the low forties at daybreak to the upper fifties at mid-morning; then, at last, the flock ventured out in search of flying insects. When a population of birds loses its food supply or is unable to access it, that population must relocate or perish. Like other insectivorous birds, these swifts must move to warmer climes to be assured a sustained supply of the flying bugs they need to survive. Due to their specialized food source, they can be considered “specialist” feeders in comparison to species with more varied diets, the “generalists”. After returning to this chimney every evening for nearly two months, the swifts departed this roost on October 5 and did not return.A Northern Parula lingers as an October migrant along the Susquehanna. This and other specialist feeders that survive almost entirely on insects found in the forest canopy are largely south of the Susquehanna watershed by the second week of October.The Blackpoll Warbler is among the last of the insectivorous Neotropical warblers to pass through the riparian forests of the lower Susquehanna valley each fall. Through at least mid-October, it is regularly seen searching for crawling insects and larvae among the foliage and bark of Northern Hackberry (Celtis occidentalis) trees near Conewago Falls. Most other warblers, particularly those that feed largely upon flying insects, are, by then, already gone.The Blue-headed Vireo, another insectivore, is the last of the vireo species to pass through the valley. They linger only as long as there are leaves on the trees in which they feed.Brown Creepers begin arriving in early October. They are specialist feeders, well-adapted to finding insect larvae and other invertebrates among the ridges and peeling bark of trees like this hackberry, even through the winter months.Ruby-crowned Kinglets can be abundant migrants in October. They will often behave like cute little flycatchers, but quickly transition to picking insects and other invertebrates from foliage and bark as the weather turns frosty. Some may spend the winter here, particularly in the vicinity of stands of pines, which provide cover and some thermal protection during storms and bitter cold.Beginning in early October, Golden-crowned Kinglets can be seen searching the forest wood for tiny invertebrates. They are the most commonly encountered kinglet in winter.The Yellow-bellied Sapsucker, a woodpecker, is an October migrant that specializes in attracting small insects to tiny seeps of sap it creates by punching horizontal rows of shallow holes through the tree bark. Some remain for winter.The Yellow-rumped Warbler arrives in force during October. It is the most likely of the warblers to be found here in winter. Yellow-rumped Warblers are generalists, feeding upon insects during the warmer months, but able to survive on berries and other foods in late fall and winter. Wild foods like these Poison Ivy berries are crucial for the survival of this and many other generalists.American Robins are most familiar as hunters of earthworms on the suburban lawn, but they are generalist feeders that rely upon fruits like these Eastern Red Cedar (Juniperus virginiana) berries during their southbound migration in late October and early November each year. Robins remain for the winter in areas of the lower Susquehanna valley with ample berries for food and groves of mature pines for roosting.Like other brown woodland thrushes, the Hermit Thrush (Catharus guttatus) is commonly seen scratching through organic matter on the moist forest floor in search of invertebrates. Unlike the other species, it is a cold-hardy generalist feeder, often seen eating berries during the southbound October migration. Small numbers of Hermit Thrushes spend the winter in the lower Susquehanna valley, particularly in habitats with a mix of wild foods.Due to their feeding behavior, Cedar Waxwings can easily be mistaken for flycatchers during the nesting season, but by October they’ve transitioned to voracious consumers of small wild fruits. During the remainder of the year, flocks of waxwings wander widely in search of foods like this Fox Grape (Vitis labrusca). An abundance of cedar, holly, Poison Ivy, hackberry, bittersweet , hawthorn, wild grape, and other berries is essential to their survival during the colder months.Red-breasted Nuthatches have moved south in large numbers during the fall of 2020. They were particularly common in the lower Susquehanna region during mid-October. Red-breasted Nuthatches can feed on invertebrates during warm weather, but get forced south from Canada in droves when the cone crops on coniferous trees fail to provide an adequate supply of seeds for the colder fall and winter seasons. In the absence of wild foods, these generalists will visit feeding stations stocked with suet and other provisions.Purple Finches (Haemorhous purpureus) were unusually common as October migrants in 2020. They are often considered seed eaters during cold weather, but will readily consume small fruits like these berries on an invasive Mile-a-minute Weed (Persicaria perfoliata) vine. Purple Finches are quite fond of sunflower seeds at feeding stations, but often shy away if aggressive House Sparrows or House Finches are present.
The need for food and cover is critical for the survival of wildlife during the colder months. If you are a property steward, think about providing places for wildlife in the landscape. Mow less. Plant trees, particularly evergreens. Thickets are good—plant or protect fruit-bearing vines and shrubs, and allow herbaceous native plants to flower and produce seed. And if you’re putting out provisions for songbirds, keep the feeders clean. Remember, even small yards and gardens can provide a life-saving oasis for migrating and wintering birds. With a larger parcel of land, you can do even more.
GOT BERRIES? Common Winterbery (Ilex verticillata) is a native deciduous holly that looks its best in the winter, especially with snow on the ground. It’s slow-growing, and never needs pruning. Birds including bluebirds love the berries and you can plant it in wet ground, even along a stream, in a stormwater basin, or in a rain garden where your downspouts discharge. Because it’s a holly, you’ll need to plant a male and a female to get the berries. Full sun produces the best crop. Fall is a great time to plant, and many garden centers that sell holiday greenery still have winterberry shrubs for sale in November and December. Put a clump of these beauties in your landscape. Gorgeous!
