Bay-breasted Warbler. Photo courtesy of Craig Millard. (click to see the larger version)

I don’t think anyone had high expectations for October 2. BirdCast and radar didn’t indicate a strong movement overnight, and the last few days have been flat for migrants at Montrose. Early October is usually an excellent time for warblers and sparrows, but the number of Bay-breasted Warblers exceeded anything I’ve experienced before. They were the most common warbler and at times seemed to be everywhere, including on the ground feeding. My final Bay-breasted count was 16. Not surprisingly, eBird wanted details as this is a big number for a bird that isn’t abundant in Chicago. We also had large numbers of Tennessee and Black-throated Green Warblers. I’m not sure what caused this incursion of Boreal forest breeding warblers, as we’ve been experiencing unseasonably mild weather and few cold fronts, which are usually the impetus for birds to move in the fall. Link to my eBird checklist for the day below.

eBird Checklist
October 2, 2021