Small hummingbird of tropical lowlands, favoring forest edge and semi-open areas, often in relatively dry habitats. Usually feeds rather low, and often inconspicuous. Both sexes habitually pump their forked tail while hovering, unlike most other hummingbirds found in the same areas. Solidly emerald-green male is distinctive. Combination of small size, rather short straight bill, face pattern (whitish eyestripe and broad dark mask), and tail wagging behavior help ID the female. Also note the dry chattering call, which may suggest the call of Ruby-crowned Kinglet.