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.

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!

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.