ML642890703

觀察細節

Banded and released. Medium-short primary projection (not long like Acadian). Smaller billed than Acadian. Shorter wing length than Acadian. Least Fly ruled out by lack of strong emargination on P6, wing length minus tail length fits Yellow belly (13mm) but is longer than expected for Least, lack of contrasting pale throat, yellowish eye ring that is also more extensive posteriorly, producing a slight "tear drop" look. The uneven spacing between folded primaries also points away from Least and towards Yellow-belly (per A Field Guide to North American Flycatchers: Empidonax and Pewees, 2023). The eBird checklist from the following week (October 3) has photos of an Acadian to compare. The only issue with this ID is the darker lower mandible.