Black-chinned hummingbirds are small birds that occupy a broad range of habitats in North America. Adults are metallic green above and white below with green flanks. Their bill is long, straight and very slender. The adult male has a black face and chin, a glossy purple throat band and a dark forked tail. The female has a dark rounded tail with white tips and no throat patch; they are similar to female ruby-throated hummingbirds. Juvenile plumage is similar to that of adult females, but with buff margins on the dorsal feathers. Juvenile males may also possess purple feathers on their throats.
Black-chinned hummingbirds are found in most of the western United States, reaching north into Canada in Alberta and British Columbia, east to Oklahoma, and as far south as Mexico. They are migratory, spending winter as far south as Mexico. These birds can be found in mountains, woodlands, orchards, meadows, and chaparral habitats. Their breeding habitat is open, semiarid areas, usually near water.
Black-chinned hummingbirds are diurnal birds; they spend the day in search of plant nectar which they extract using a long extendable tongue or catch insects on the wing. Black-chinned hummingbirds are solitary and territorial. The males and females use different habitats from one another for breeding territories. Black-chinned hummingbirds can exhibit territorial behavior around feeders as well as at other small feeding sites, and become more defensive during the breeding season. Unlike most passerines, the agonistic call of the Black-chinned hummingbird is acoustically complex, with notes ordered in non-random patterns, and is even more complex than their songs. These birds also use diving displays performing dives up to 12-18 m (40-60 ft) for territory defense as well as courtship, producing a variety of tones as air passes through their feathers during the plunge.
Black-chinned hummingbirds are polygynous; they don't form long-lasting pair bonds and males mate with more than one female during the breeding season. Black-chinned hummingbirds breed in April-September and may raise 2-3 broods per year. The female builds a well-camouflaged nest in a protected location in a shrub or tree using plant fibre, spider webs, and lichens. Black-chinned hummingbirds prefer to nest 6-12 ft (1.8-3.7 m) above the ground, often on exposed horizontal branches below the canopy. The female lays 2 small white eggs at a time and incubates them for a period of 12-16 days. The chicks hatch altricial; they are almost featherless but obtain a complete set of feathers within 3 weeks of hatching. The female feeds her young and protects them until they fledge and are able to leave the nest; this occurs around 21 days after hatching.
There are no major threats to the Black-chinned hummingbird at present.
According to the All About Birds resource the total breeding population size of the Black-chinned hummingbird is 5 million individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are increasing.
Black-chinned hummingbirds play an important role in their ecosystem. While collecting nectar, they fly from flower to flower and transfer the pollen, thus assisting in plant pollination.