Lehigh Valley bird sightings for September 24

Philadelphia Vireo

While birders were scanning the skies last week for hawks, eagles and falcons, an extraordinary number of sightings of Philadelphia Vireos were reported throughout the Lehigh Valley region.

The Philadelphia Vireo is a migratory bird often mistaken at first glance by its common relative, the Red-eyed Vireo. The two species live in the same kind of habitat: deciduous trees such as aspen, willow, alder, ash and maple. But they don't get along very well. They've been known to fight for territory.

Despite its name, the Philadelphia Vireo is almost never seen in the Lehigh Valley except for an occasional sighting during migration in the spring and fall. The bird migrates mostly at night. It spends its days refueling for the flight across the Gulf of Mexico to wintering grounds in Central America, where it is found from the Yucatan Peninsula to Panama.

The Philadelphia Vireo breeds in Canada north of the Great Lakes, with the greatest concentrations found between Quebec and Saskatchewan. It nests in trees. The female produces three to five eggs. Both parents incubate the eggs, which hatch in about 14 days. The young leave the nest 12 to 14 days after hatching.

A comparison: Red-eyed Vireo

Adults are mainly olive-brown on the upper parts with yellow underparts and a gray crown. They have no wing bars and no eye ring but display dark eyes through the dark eyes and a white stripe just above them. 

The diet consists of mostly of caterpillars, moths, beetles, wasps, bees, ants, bugs and some spiders. It is a berry-eater in late summer and fall, when bayberry and dogwood fruit are available. The bird forages mostly in deciduous trees, flitting from branch to branch looking for insects. It often will hover from foliage or hang upside down to feast on insects located underneath twigs.

So where did the Philadelphia Vireo get its name? Other than migration time, the bird is rarely seen in the City of Brotherly Love. It turns out that ornithologist John Cassin collected a specimen of the bird in Philadelphia during the 1851 migration, hence the name. Birders of the era sometimes called it the Brotherly-love Vireo, according to Tennessee's Watchable Wildlife.

Populations of the Philadelphia Vireo appear to have increased between 1966 and 2014, the North American Breeding Survey reports.

Philadelphia Vireo

Regional sightings of the Philadelphia Vireo appear in Dave DeReamus's report for the Eastern PA Birdline, which is sponsored by the Lehigh Valley Audubon Society. The list covers the week ended September 24.

Pen Argyl, Northampton County
Gray-cheeked Thrush: 1 on September 20.

Jacobsburg State Park, Northampton County
Philadelphia Vireo: 2 on September 16 and 1 on September 22.

Williams Township, Northampton County
Connecticut Warbler: 1 on September 23.

Monocacy Nature Center, Northampton County
Philadelphia Vireo, 1 on September 22.

Little Gap, Northampton County
Ruffed Grouse, 1 on September 18.
Philadelphia Vireo, 1 on September 16.

Little Gap, Carbon County
(at the Blue Mountain Ski Resort)
Philadelphia Vireo, 1 on September 18.

Bake Oven Knob, Lehigh County
Osprey, 34 on September 17.
Bald Eagle, 12 on September 17 and 10 on September 20.
Broad-winged Hawk, 1,901 on September 20 and 519 on September 22.
Peregrine Falcon, 2 on September 20 and September 22.
Philadelphia Vireo, 1 on September 16 and September 23.

Long Swamp Township, Berks County
Mississippi Kite, 1 on September 22 (fly-by).

Green Lane Reservoir, Montgomery County
(at the Church Road area)
Black-crowned Night Heron, 1 on September 19.
Snowy Egret, 1 from September 19 through September 22.
American Golden-Plover, 2 on September 22.
Stilt Sandpiper, 1 on September 17 and 2 from September 19 to September 21.
Sanderling, 2 on September 19 and 1 on September 20.

Peace Valley Park, Bucks County
Lesser Black-backed Gull, approximately 50 on September 17.
Forster's Tern, 2 on September 16.
Philadelphia Vireo, 1 on September 17.
Gray-cheeked Thrush, 1 on September 17.

Red-breasted Nuthatches continue to be reported from several sites last week.

To report bird sightings to Dave DeReamus, send an e-mail to becard.com with the word "Birdline" in the subject heading.

Philadelphia Vireos top list of Lehigh Valley bird sightings

Philadelphia Vireo

A profusion of sightings of migrating Philadelphia Vireos were reported during the week that ended on September 18. The unusual thing about these sightings is that the bird is seen infrequently in the Lehigh Valley even during migration, according to Birds of the Lehigh Valley and Vicinity.

Despite their name, the species is rarely are seen in Philadelphia except during migration. John Cassin, the American ornithologist, gave the bird its name upon observing one in Philadelphia in September 1842.

The Philadelphia Vireo is one of the most northerly breeding species of vireo. It spends its summers in northern New England and southern Canada from the maritime provinces west as far as Saskatchewan. It winters in the Yucatan Peninsula and Central America.

The species breeds in the treetops of second-growth aspens, birches, alders and ashes in woodlands and parklands. The birds forage for insects in trees, sometimes hovering or flying as they pick off their prey. They've even been known to hang upside down to catch insects at the tips of twigs. Their favorite meals are caterpillars, moths, beetles, wasps, bees and ants. They also eat the berries of bayberry and dogwood when the fruit becomes abundant in late summer and early fall.

Philadelphia Vireo

The Philadelphia Vireo is fairly small, less than 5 inches long and about 8.5 inches from wingtip to wingtip. Their appearance is similar to that of other species. For instance, the Philadelphia Vireo and the Warbling Vireo both lack wing bars, but the former has a strong yellowish cast across its breast and a more distinct white eyebrow. The Philadelphia Vireo's bill is stouter than that of a Tennessee Warbler. The vireo's back is grayish green; the warbler's is a brighter green.

Within the past week, Philadelphia Vireos have been seen in Northampton, Lehigh, Carbon and Bucks counties, according to reports compiled by Dave DeReamus of the Eastern PA Birdline, which is sponsored by the Lehigh Valley Audubon Society. 

Upper Mount Bethel Township, Northampton County
(along National Park Drive)
Philadelphia Vireo, 1 on September 15; 4 on September 18.
Gray-cheeked Thrush, 1 on September 18.
(along Institute Road)
Philadelphia Vireo, 1 on September 13.

Martins Creek Environmental Preserve, Northampton County
(Tekening area)
Philadelphia Vireo, 1 on September 17.

Albert Road Ponds, Northampton County
Caspian Tern, 1 on September 12.

Jacobsburg State Park, Northampton County
Philadelphia Vireo, 1 on September 11; 2 on September 12; and 1 on September 16.

Williams Township, Northampton County
Blue Grosbeak, 1 on September 14.
Also seen: Cerulean Warbler.

Little Gap, Carbon County
Bald Eagle, 5 on September 17.
Broad-winged Hawk, 832 on September 17.

Little Gap village, Carbon County
Connecticut Warbler, 1 on September 17.

Beltzville State Park, Carbon County
Yellow-bellied Flycatcher, 1 on September 13.
Philadelphia Vireo, 1 on September 15.
Connecticut Warbler, 1 on September 12.

Leaser Lake, Lehigh County
Connecticut Warbler, 1 on September 13.

Bake Oven Knob, Lehigh County
Bald Eagle, 6 on September 11; 23 on September 13; and 7 on September 14 and September 18.
Northern Goshawk, 1 on September 12.
Broad-winged Hawk, 678 on September 16; 1,237 on September 17; and 1,026 on September 18.
Merlin, 4 on September 13 and 5 on September 14.
Peregrine Falcon, 1 on September 13 and September 16.
Philadelphia Vireo, 1 on September 13 and September 17; and 2 on September 16.
Other species reported in addition to Dave DeReamus's report:
Warbler species: Magnolia, Black-throated Blue, Black-throated Green, Black-and-white, Chestnut-sided, Blackpoll and Blackburnian.
Other species: Northern Parula, Common Raven, Red-eyed and Warbling Vireos, Common Nighthawk and Eastern Wood-pewee.

Trexler Park, Lehigh County
Olive-sided Flycatcher, 1 on September 11.

Green Lane Reservoir, Montgomery County.
(at the Church Road area)
Northern Pintail, 1 from August 27 to at least September 12.
Snowy Egret, 1 from September 12 to at least September 17.
Little Blue Heron, 1 on September 13.
Stilt Sandpiper, 1 on September 11 and 3 on September 12.
Sanderling, 1 on September 12.
Red-necked Phalarope, 1 on September 13.

Peace Valley Park, Bucks County
Glossy Ibis, 1 on September 12 (a fly-by).
Lesser Black-backed Gull, 13 during the past week.
Philadelphia Vireo, 1 on September 15.

Merrill Creek Reservoir in New Jersey
(at Scotts Mountain Hawkwatch)
Bald Eagle, 12 on September 14.
Broad-winged Hawk, 449 on September 13; 647 on September 16; 1,025 on September 17; and 406 on September 18.
Merlin, 3 on September 16.
Peregrine Falcon, 1 on September 16.
Red-headed Woodpecker, 1 on September 11 and September 17.

To report bird sightings to Dave DeReamus, send an e-mail to becard@rcn.com with the word "Birdline" in the subject heading.