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Thrush of the Hour
--Mon PM & Tues AM, Sept 11/12 2023--
On Monday evening it’s clear as a bell over Tyrone, the temperature is dropping, and there’s a breeze. I sit on the balcony 22 years on with my traditional cigar; smoke carries away the memories, as always.
An Osprey circles on flat wings high over the towers, among Turkey Vultures. Later, it’s joined by another. A Ruby-throated Hummingbird buzzes by the feeder and off into the blue, not gone yet. A Cooper’s Hawk catches the breeze over Bald Eagle Mountain and flaps off northward.
Nighttime temperatures dip into the low 50s, silencing the loudest insects after midnight. At 5:30 AM on Tuesday, a dense fogs wraps Tyrone, but we climb out of it in the Hollow, finding the field bathed in light from planets, stars, the Moon, and not a few artificial satellites.
As I step out of the car, I hear Swainson’s Thrushes, and as I reach the sit spot, Eastern Screech-Owls and Barred Owls begin a wild screaming contest across the ridges.
From a quarter ‘til to a quarter after six, the crisp air reverberates with hundreds, if not thousands, of thrush calls, interspersed with Rose-breasted Grosbeaks and a few other species at the lower registers, including at least one Red-headed Woodpecker. Swainson’s outnumber Veeries five to one or more, and at the peak, about 6:05 to 6:10, there are at least five calls per second. A few Wood Thrushes descend as well, and possibly a Gray-cheeked Thrush, though the latter’s peak (in much smaller numbers) is a few weeks off. Here’s what the thrushes look like around 6:10 AM, with one-second increments on the X-axis:
Here is a close-up of some Swainson’s Thrushes (X-axis labels are tenths of a second):
The classic calls to the right are not by any means the only NFCs the SWTHs make; they can be distinguished from calling spring peepers (of which we have at least one right now, though not on this recording) by the tremolo at the end and other characteristics. However, because you can’t actually see the thrushes going over and dropping down—or at least, I haven’t been able to—I suspect that the vast majority of folks simply assume this September peeping chorus is frogs.
Here’s what the snippets above are from:
If you listen carefully, you can also hear a Whip-poor-will, some warbler NFCs, and the first clucks of a Wood Thrush on the ground near the end.
How Many Thrushes?
When I look at the full recordings later, I can see it will be a long slog through many hours of thrushes, though not by any means at the call density of the last minutes of the descent. Figuring out how many are going over is a bit problematic. If you look closely, you can see that some calls appear to be repeated, so there are clearly two or three times as many vocalizations as there are birds (assuming all or most birds call). Nevertheless, the half-hour period doubtless had hundreds of Swainson’s alone pass over.
The peak night in 2022 was September 21st, with similar weather conditions. During the 4o minutes after 5:50 AM, I estimated a Pennsylvania record 2,000 Swainson’s Thrushes, with 50 Gray-cheeked Thrushes (also the state record) and 40 Veeries mixed in. Veeries had already reached their peak on September 2 (state record of 396), while Hermit Thrushes peaked on October 24th, with an estimated 420 (state record), mostly in the 20 minutes before 7 AM.
Today, a fair portion of the descent happened right into the trees and bushes on Sapsucker Ridge mere yards from me. The calls of the first Eastern Towhees at 6:17 came right after the end of the descent, but scattered thrush NFCs continued, several of which were on the ground nearby, interspersed with other calls (but no songs from any thrush species). Around 6:23, at least a dozen Swainson’s were calling all through the tangles, and flying about, together with Gray Catbirds, towhees, a couple Veeries, a Hermit Thrush, and Northern Cardinals. The Swainson’s at the top of this post responded to pishing a bit later on and perched up in the black cherries. The Hermit Thrush seems to be a longer-term resident from molt-migration; Hermits will have their day in October, the last of the Catharus thrushes to come through in numbers, and the only one that leaves a few behind.
I suspect the thrushes are coming for the cherries; they most likely have memories of this feeding spot in their mental maps of the voyage south.
There is a seamless transition to insectivore and frugivore insanity, a familiar experience that makes this part of September seem the most tropical of any time during the year. With the first sunlight, a huge mixed flock of warblers, vireos, flycatchers, tanagers, grosbeaks, and waxwings comes pouring down out of the sunlit canopy to work the black locusts, goldenrod, and lower grape tangles among low-hanging black cherries, to the left of the powerline. This goes on for a sold hour, and for the first time I approach the edge of panic as I can’t possibly ID or even see everything.
Today’s main warbler is the Black-throated Green, getting worked up enough that some are even attempting to sing. A few of the numerous Tennessees and Nashvilles try some songs as well, but mostly, other than the singing Hooded Warblers it’s just a staccato chorus of chips and ticks from hundreds of individual birds, only a few of which I am able to tally before they head on. A bonus from the warbler catalpa is three Wilson’s Warblers, though the Connecticut is nowhere to be seen. As usual, Cape Mays and Magnolias are also in high numbers and quite tame.
Flycatchers at this point are mostly the ubiquitous Eastern Wood-Pewees, somewhat down in numbers but still vocal and active. Too many bugs here to pass up, I guess. Otherwise, the Empids dominate, with a Least Flycatcher holding on and the maddeningly silent “Traill’s” in probably much higher numbers than the three I see.
Given my limited time on a work day, I pass up numerous photos, including the second curious Philadelphia Vireo of the day a few feet away in the denuded field-corner catalpa.
By not long after 8 it’s a wrap, as American Goldfinches in all plumages twitter about the field, wires, and black walnuts. The day’s count stands at 62 species even without any common birds of town. I’m hoping for a north wind today to add some raptors and get the September trifecta of thrush descent, migrant passerine flocks, and Broad-winged Hawk kettles all in the same day.
The odd mimicry from down near the deer exposure revealed itself as a Blue Jay today, something I’ve been suspecting for a couple days. Throughout the day, every time I step outside to check raptor conditions, I hear Blue Jays. I think they may already be migrating, though it seems to be a couple weeks early for them.
Around 12:30, the clouds look promising, so I move my work station to the porch to brave the fierce sun in hopes of catching a kettle. Right off the bat, a Peregrine Falcon rushes out of the Gap into town. I have to think some pigeon chaos ensued, but my vantage point was blocked.
Half a heat stroke later, all I have to show is single purposeful Bald Eagle; the rest of the raptors are Turkey Vultures at the towers. Maybe tomorrow.
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