A Rufous Hummingbird (Selasphorous rufous) is visiting a feeder in Hollis, NH. This is a very unusual hummingbird for here. One was last reported in NH in 2007. The Rufous Hummingbird is a western species whose breeding range goes as far up as Alaska. Increasingly, Rufous Hummingbirds are showing up in fall in the eastern half of the country. This hummingbird was banded over the weekend and the bander has reported it as a hatching year Rufous Hummingbird, sex could not be determined. Identification of female and immature hummingbirds can be tricky, especially telling Rufous from Allen's Hummingbirds. Sometimes only banders, holding them in hand, can tell them apart by subtle differences in the shape of the tail feathers and even then sometimes it is not possible to definitively tell their sex. The above photo shows the extensive rufous on the sides and rufous on the tail feathers.
The throat has lines of small marks, with a number of larger marks (looking dark because the sun is not hitting them) concentrated in the center and going out to the sides of the throat. Usually the immature female rufous has smaller and fewer throat marks, occasionally with a few larger iridescent marks confined to the center of throat.
The back shows little rufous coloring on this bird. Some immature male Rufous Hummingbirds can show more rufous back coloring, especially later in winter. Adult male Rufous Hummingbirds often have extensive rufous on their backs and their throats, here's a photo, from video I took in the past.
If you live in the Northeast, and have a late hummingbird visiting your feeders in October, look closely at the sides to see if they are rufous. You may have a Rufous Hummingbird visitor, or in really rare circumstances, an Allen's Hummingbird.
Update: On Oct. 26th there was a report of a Selasphorous hummingbird in Scituate, Mass.