A Costa's Hummingbird at my window

I think that female hummingbirds are an under-appreciated identification challenge. Throw in all the immatures at this time of year and it can be quite confusing. Allen's or Rufous? Broad-tailed or Calliope? Anna's or Costa's? Ruby-throated or Black-chinned?

Up until this past month I've only seen Anna's at my feeder. But then, what's that? Is that bird smaller? Oh, look! The breast is whitish, not green. That eliminates Anna's--it's something else. The flanks are grayish, not buffy, that eliminates Allen's, Rufous, Calliope, and Broad-tailed. The tail is very short tail with wings extending well past the end. That eliminated Black-chinned and Ruby-throated. That leaves Costa's, and the white eyebrow separating the crown from the ear coverts and the short slightly curved bill confirms it.

Costa's Hummingbird. Escondido, California. August 12, 2016. Greg Gillson.

This bird may be diminutive, but it is spunky. It chases away the much bigger Anna's from the window feeder. She has been hanging out now for over two weeks. Last week I noted a juvenile male a couple of times with a spot of dark feathers growing on the throat. I also noted an adult male Black-chinned Hummingbird twice last week at this "hidden" window feeder. The more exposed hanging feeder in the back yard is carefully guarded by an Anna's Hummingbird.

Costa's Hummingbirds follow the flowers--out in the desert during the winter and breeding in early spring, then westward into the coastal lowlands with all the non-native flowers (and hummingbird feeders!) in residential areas for the summer. So, even though this hummingbird is an uncommon resident throughout the year within San Diego County, it moves around.

Thank you for gracing the window just outside my desk!