Wednesday, October 14, 2009

Confusing Fall Warbler Clinic

We had quite a warbler show last weekend. Despite the now over-whelming preponderance of Yellow-rumped Warblers in the species mix passing through, all the following species, plus several others, can be found through the end of October at least, of course some more easily than others. All the following photos were taken on Saturday, October 10 2009 - in the same tree (!) in Cape May Point. One general suggestion on fall warblers - virtually all will show at least a muted version of their spring patterns, so if you know them in spring, look for that in fall. That being said, the following species can be a little tricky.

[Know thy common birds. Yellow-rumped Warblers can seem variable, but in the fall they all are quite brown loooking - not green, not yellow, not even gray, really. The are biggish for a warbler, with stout (for warblers) black bills . They sport a dark cheek, white eye-arcs, and coarse streaking on the breast. Some fall birds show the yellow spots on the sides of the breast found on all spring birds, but some do not. Of course, they all have a bright yellow rump, if you can see it. When they fly off you often catch flashes of white from their tail corners, making for a bright going-away view between that and the yellow rump. Yellow-rumpeds call more than other warbler species, and mix their tiup call note with their rising seep flight note. Photo by Don Freiday, click to enlarge.]

[Ah, there we are, a better view of the rump. But beware, other species can show yellowish rumps, including the next one. Photo by Don Freiday, click to enlarge.]

[Get good at this one, too. Another biggish warbler, with breast sometimes gray-brown, sometimes yellow (eastern breeding birds are yellow, though we get more gray ones overall). The signature is of course the yellow undertail coverts, that and the constantly pumping tail. If it's on the ground, especially in the dunes, it's probably a Palm Warbler. This one is obviously in a tree, demonstrating something typical of the later warblers - they are adaptable, feeding in multiple locations and often switching from insects to berries or tree sap. We saw several warblers picking bugs from spider webs. Photograph by Don Freiday, click to enlarge.]

[Believe it or not, this Pine Warbler is a fairly bright individual for fall. Note the yellowish eye-arcs, nearly forming an eye-ring, the murky streaking on the sides of the breast, and the very prominent wing bars. Fall female Pines can be completely without yellow coloration, and have been called Empidonax flycatchers by the unwary who relied on colors without considering shape and behavior. As warblers go, Pines are built like, and tend to move like, musclebound bodybuilders. Photo by Don Freiday.]

[In this photo we can see one thing Pine Warblers don't have, and that is definite streaks on the back, which is helpful information, because with their underparts yellowish towards the front and white towards the back, they can be confused with the next species. . .]

[. . .which is much longer of wing and more athletic than Pine (note the primary projection) and does have those back streaks. This Blackpoll Warbler is showing the yellow legs and feet that separate it from similar Bay-breasted, but a more visible feature to separate Bay-breasted and Blackpoll is the very white undertail coverts on Blackpoll, which tend to buffy on Bay-breasted. Blackpolls do always have yellow soles to their feet, but not all have legs this bright - time for the very best optics you can get your hands on. Photo by Don Freiday.]

[Fall warblers separate the birders from the bird watchers, at least some of them do. This acrobatic little thing (that it is acrobatic and little are both field marks, separating it from some warblers and all vireos) has a short tail, a white eyebrow and dark eyeline, white-undertail coverts, and a distinctly, and distinctively green back: Tennessee Warbler, photo by Don Freiday. Click to enlarge.]

[Grand finale - Vince Elia called this one a "birder's bird." Field conditions view, we see a short tail, a fine bill, and a yellowish breast with obvious streaking all the way across.]

[Look how mouse-gray the back and crown are - the color is distinctive on fall female Cape May Warblers, the warbler we perhaps get asked most about, since, after all, it is Cape May. Note the bit of green on the rump, which on brighter Cape Mays is yellow. Photo by Don Freiday, click to enlarge.]

[Our Cape May again, front-on. Cape May Warbler bills are very pointy and slightly decurved - compare it with, say, the Yellow-rumped's. Photo by Don Freiday, click to enlarge.]

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