The Rufous Hummingbird (Selasphorus rufus) is relatively small even for a hummingbird, but can be quite aggressive in defending a patch of flowers at which it feeds. These birds often visit red tubular flowers. This species breeds farther north than any other hummingbird, all the way up to south-central Alaska and southern Yukon. Of all the western hummingbirds, the Rufous Hummingbird shows up most often in eastern North America. Rufous Hummingbirds breed around forest edges, streamsides, and mountain meadows and winter mainly in pine-oak woods in Mexico (although some winter along the Gulf Coat in the southeastern United states and casually northward throughout much of the eastern United States). This species is closely related to the more narrowly distributed and females and immatures of the two species are nearly impossible to distinguish in the field (adult males can usually be distinguished by back color, typically solid green in Allen's and mostly rufous in Rufous). This species is closely related to Allen's Hummingbird (Selasphorus sasin), which breeds mainly in coastal California. Females and immatures of these two species are nearly impossible to distinguish in the field, but adult males can usually be distinguished by back color (typically solid green in Allen's and mostly rufous in Rufous).

The male's courtship display traces a steep U or vertical oval, climbing high and then diving steeply, with whining and popping sounds at the bottom of the dive. The male also buzzes back and forth in front of a perched female. A single male may mate with several females.

The nest of a Rufous Hummingbird is typically well concealed in the lower part of a coniferous tree, deciduous shrub, or vine. The nest is generally less than 5 m above the ground, although it may be as high as 10 m. The nest, built by the female alone, is a compact cup of soft materials held together with pieces of spider web and lined with plant down, The outside is camouflaged with pieces of lichen. Old nests may be repaired and re-used. The clutch of two (sometimes one, possibly rarely three or even four) white eggs is incubated by the female alone for 15 to 17 days. The female is also solely responsible for feeding the young after hatching. Age at first flight is around 21 days.

This species is widespread and abundant, although there is some evidence of recent declines

(Kaufman 1996; AOU 1998)