I don't know why this comes up as rare: it's listed in Birds of Alberta" and shows in Stokes as summering here - unless this group was late for its southward migration??

Definitely palm warblers. You've got a male house sparrow in for good measure to the left.

Thanks for the confirmation, Rangifer. I'm new to birding, so it's good to know when my deductions are correct. :o) There's also a pine siskin in the photo, between the palm warbler and the house sparrow: it's funny how so many similarly-sized birds seem to flock together even though they're different species. The chickadees usually show up in the company of sparrows, as do the pine siskins, and in the spring and summer we noticed that the cowbirds and red-winged blackbirds often "hung out" together. Safety in numbers maybe??