Monday, September 1, 2008

Confusing Fall Flycatchers

Jerene and I spent most of yesterday out birding in Philadelphia. We spent the morning at Carpenter's Woods and the afternoon at Morris Arboretum. One of the surprises of this August has been the discovery that there are a number of migrating warblers, and other migrants, around at this time of year. I'd read that some shorebirds actually start their southern migration as early as late June, but I didn't realize until this year that warblers were also on their way by mid-August or earlier.

So I've seen a number of warblers over the last few weeks, most of them at Carpenter's Woods. They include: Blue-Winged, Canada, Black and White, American Redstart, and Common Yellowthroat. Yesterday we added Magnolia, Black-Throated Blue, and Chestnut-Sided at Carpenter's Woods. Despite the famous line about "confusing fall warblers", probably from Peterson's Field Guide to the Birds, we haven't really run into that many difficult fall warblers.

Over the last few weeks though, we have run into plenty of confusing fall flycatchers. The main problem is that many of them are neither singing nor calling. No 'peeaweees', 'che-BEK!s', 'PIZZZa!s' or 'FEEBEES' to give a clue. For the most part the birds are silent. When the view is only from behind, as it was for a flycatcher at Carpenter's Woods last week, is the bird an Eastern Wood-Pewee or an Acadian Flycatcher? Or yesterday at Morris Arboretum, what were the many flycatchers? The huge eye-ring of one, combined with color and tail-flicking, determined it to be a Least Flycatcher. But we didn't hear the familiar 'CheBEK' that used to waken us at Shenandoah National Park. Fortunately the other clues were enough for identification. But what about the other flycatchers we saw: strong white throat, light vest, yellow, lower bill and fine, narrow eye-ring? We finally narrowed it down to Willow/Alder. According to David Sibley first year winter Alder's have a 'distinct but narrow eye-ring'. These two birds both did but were they first year winter birds? I leaned toward calling them Alders due to their fine eye-ring but finally had to just call them Willow/Alder. If only one of them would have called.

As for the back view of the Pewee/Acadian I finally decided on Acadian, due to the somewhat oval eye-ring. The next day I came upon another flycatcher at Carpenter's Woods, this time a grayer bird with noticeably longer primary projection. He also flew back to the same perch, like Eastern Wood-Pewees often do. So I decided he was an Eastern Wood Pewee. Then, in an unusual occurrence for August flycatchers, he sang his plaintive 'pawee'. I was thankful to finally have some aural confirmation for my identifications.

All in all it has some very challenging birding, necessitating the weighing of many clues to make a final, but often tentative identification. So I stand with my headline: 'Confusing Fall Flycatchers.'

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