Ruby-crowned Kinglet

First fall immature, Central Park, Oct 8th.
These birds are hyperactive, so most of my images of Ruby-crowned have a dubious level of blur about them. It's a borderline nemesis bird for that reason, especially for a relatively common species. Golden-crowned Kinglet and Wilson's Warbler have the same challenges - they never pause, especially in migration when they are looking for food after flying all night. The odds were enhanced in this case by it being a sunny day, so a higher shutter speed helped. And also a large amount of luck.