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!

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