Description 3 1/2-4 1/4" (9.5-11 cm). Iridescent green above and below, with deep chestnut wings, tail, and rump. Belly chestnut in male only; female belly grayish. Base of lower mandible red.

Voice Song a series of repeated buzzy twitters, dzzzir or dzzzzrrt.

Habitat Oak and pine woodlands and edges, oak scrub and clearings, plantations; in U.S., forested canyons of desert mountains.

Nesting 2 eggs in nest of plant down and fibers, lichen and spider web, placed on thin branch of deciduous tree or shrub. Has bred in southeastern Arizona.

Range Endemic of southern and western Mexican foothills and highlands; seen in southeastern Arizona as a stray, occasionally breeds.

Discussion The Berylline is among the rarer of southeastern Arizona's hummingbird strays, and is much sought after by visiting birders. Most likely to be seen at hummingbird feeders in wooded mountain canyons, such as Madera Canyon or in the Huachuca or Chiricahua mountains.