On Wednesday of this week I was looking at the weather forecast for the weekend and began getting that restless feeling of anticipation that comes every autumn. The first real cold front of the fall is here and with it will come thousands of tiny migrants heading south. The stars of the early season fall land bird migration are the warblers; that large family known for brilliant spring finery.
But not so much in the fall. Fresh breeding plumages of adults have become so worn or molted away that it can be a challenge to identify some, even for experienced birders. The change is so marked that Roger Tory Peterson coined the collective term “confusing fall warblers” in his groundbreaking field guides.
The warblers are also more of a challenge to locate. The distinctive songs of the males as they pass through in the spring are largely silenced now. A few weak remnants may be whispered out, as if the birds have forgotten the full song and are clinging to fading memories.
By far most of the migrants are immatures, those individuals fledged within the previous couple of months, that won’t even get the urge to sing until next spring. More prominent are various chip, zeet, and tsup calls as migrant flocks forage through foliage.
A very few species retain their spring patterns. American redstart and black-throated blue warbler males look the same. Other species like the blackburnian warbler retain the general patterns of earlier plumages but the color is not nearly as intense.
The brilliant orange face, throat and upper breast are now more yellow or cream. Experienced birders should be able to correctly identify them but perhaps not before a prolonged look is achieved.
And then there are those warblers that look totally different from in the spring. If you have a field guide take a look at adult male spring chestnut-sided warbler, bay-breasted warbler, or blackpoll. Then take a look at each’s fall or winter plumage. Previous spring plumage patterns are of no help with these guys. Birders just have to memorize the differences.
Birders from all across both Carolinas will be afield this weekend. Hopefully next week I will be able to compare this weekend’s area sightings with the previous week’s.
Taylor Piephoff is a naturalist with an interest in the birds and wildlife of the southern Piedmont: PiephoffT@aol.com. Check out his blog at piedmontbirding.blogspot.com