The Volcano Hummingbird is restricted to the Costa Rica and Panama Highlands Endemic Bird Area, where it is generally common in highland pastures and open grassland with scrub, usually above 2000 m elevation. This tiny hummingbird is mainly green above, with a brilliant wine-colored gorget in the male (replaced by dark spotting in the female), a white breast band, and greenish (males) or pale rufous (females) over the rest of the underparts. The tail is slightly forked in both sexes, more noticeably so in males. Three subspecies have been named, and these principally differ in the color of the gorget, being purplish gray to brilliant green in the southernmost form. In the non-breeding season, both sexes may defend territories around certain patches of small flowers.