I looked out my window the other morning and noticed a small warbler with bright green upper parts and crown, gray underside, prominent eye ring, and a tail cocked at a jaunty angle. Superficially it resembled perhaps an oddly plumaged, short-tailed blue-gray gnatcatcher. Thanks to experience I immediately recognized it as a fall plumaged chestnut-sided warbler. The casual observer or less experienced birder likely would have struggled with the identification, however.
Fall migration is well underway, and warbler identification just got trickier. Gone are the bright colors and bold patterns of the northbound spring birds. Southbound birds usually wear muted and washed-out colors; and some, like the chestnut-sided warbler, look totally different from the spring adults.
Sure, there are some warblers that really don’t change too much from spring to fall. Pine warblers, waterthrushes, ovenbirds, worm-eating warblers, black-throated blue warblers, black and white warblers, American redstarts, and a few others are species that look the same. If the casual observer can identify them in the spring, then they should be able to identify them now.
Then there are those that retain some semblance of spring plumage. With a good look and a good field guide, they can be figured out, but not always. I’m talking about the blackburnian warblers, black-throated green warblers, Northern parulas, Cape May warblers and magnolia warblers, to name a few. Experience helps greatly, too.
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Finally, there are those species that look nothing like what they did in the spring; chestnut-sided warblers, bay-breasted warblers, blackpoll warblers and Tennessee warblers. And don’t count on any of these fall birds singing to help you out with the ID. The most you might get out of them are a few chips or thin flight notes.
But it is the challenge these warblers present that makes fall birding so great. With the immatures moving south, the number of migrants is greater than in the spring. Sometimes the action can be so fast that I must break into a slow jog to keep up with small bands of warblers foraging through the trees and brush.
I expect those conditions this week as markedly cooler temperatures move in via the northerly component of the prevailing winds. It looks like those conditions will stay with us for a pretty good while. If they do, it will make for a great September of fall birding.
Taylor Piephoff is a naturalist with an interest in the birds and wildlife of the southern Piedmont: PiephoffT@aol.com.