ID of this female is based on the male that she is constantly with. See http://www.inaturalist.org/observations/1707366.
OK, I cropped out the feeder, I didn't really get a random flight shot.
26 Jun 2011.
Calvert, Cecil Co, MD.
Adult female or juvenile.
The Ruby-throated Hummingbird (Archilochus colubris) is a species of hummingbird.