In response to Dave Nunnallee's posting about Townsend's Warbler flocks,
it's interesting that we see monospecific flocks of the two warblers that
winter here, Yellow-rumped and Townsend's. The two have such different
habitat preferences that I'm not surprised they don't mix, although it is
interesting that both form flocks independent of the so-called "nuclear"
species in winter flocks in this area, chickadees and golden-crowned
kinglets. I wonder why. Are their foraging techniques incompatible with
those of chickadees and kinglets? I wouldn't have thought so. I should
add that individual Townsend's Warblers do indeed join these mixed foraging
flocks.

In the tropics, where so many more warblers winter, I don't think I've ever
seen pure flocks of a single warbler species (Yellow-rumped may be an
exception, when they invade tropical areas), because most of them do forage
in mixed-species flocks. Do Townsend's flock together here just because
there aren't other species with which to flock, as there would be in
central and southern Mexico, where most of them winter. Are the Northwest
wintering Townsend's rather different birds than those that winter in
Mexico? There is some evidence that they belong to a different population,
perhaps the one that breeds in the Queen Charlottes.

Quite a few tropical wintering warblers are not flockers, instead
maintaining well-defined individual territories throughout the winter.

Here I go again with armchair birding instead of the real thing. There's
no way I'd rather be doing this than watching mixed flocks of warblers
(Black-throated Green, Townsend's, Hermit, and Golden-cheeked have been
reported from a single flock) in the southern Mexican highlands, but I'm
stuck up here in the Puget Sound lowlands where it's hard to find such
things, much less a Red Warbler or Mountain Trogon.

Dennis Paulson phone: (206) 756-3798
Slater Museum of Natural History fax: (206) 756-3352
University of Puget Sound e-mail: dpaulson at ups.edu
Tacoma, WA 98416