Black-billed streamertail

The International Ornithological Committee (IOC), BirdLife International's Handbook of the Birds of the World, and the Clements taxonomy treat the black-billed streamertail and red-billed streamertail (Trochilus polytmus) as separate species. However, the North American Classification Committee of the American Ornithological Society treats them as subspecies of the "streamertail" under the binomial T. polytmus.[4][5][6] The two species (or subspecies) interbreed in their narrow contact zone.[7][8]

The species as defined by the IOC is monotypic: no subspecies are recognised.[4]

The male black-billed streamertail is 22 to 24 cm (8.7 to 9.4 in) long including the 10 to 13 cm (3.9 to 5.1 in) tail streamers and weighs 4.0 to 5.8 g (0.14 to 0.20 oz). The female is about 10.5 cm (4.1 in) long and weighs 3.5 to 5.5 g (0.12 to 0.19 oz). Both sexes have a black bill. The male has a dull black to blue-black crown; it and the nape form a deep velvety black crest. The rest of its upperparts are bright grass green. Its tail is black with a green to bronzy green gloss. The next to outermost pair of tail feathers is very long, giving the species its English name. The male's face and most of its underparts are metallic green; the undertail coverts are blue-black or black with a bluish gloss. The adult female's upperparts are metallic bronze green to greenish bronze that is duller on the crown. Its tail lacks the male's streamers. Its central pair of feathers are bright bronze green and the rest black with some bronze green gloss, and the outermost two pairs have wide white tips. Its underparts are white with metallic bronze green spots on the breast and flanks. Immature males are similar to the adult but lack the tail streamers; its tail feathers have bronze green tips.[8]

The black-billed streamertail is found in far eastern Jamaica; its range slightly overlaps that of the red-billed which is found throughout the rest of the island. It inhabits evergreen montane forest, lowland tropical forest, and secondary forest. It shuns mangroves and arid highlands. In elevation it ranges from sea level to 1,500 m (4,900 ft); it is considered fairly common in the lowlands and common at middle and higher elevations.[8]

The IUCN has assessed the black-billed streamertail as being of Least Concern, though it has a restricted range and its population size and trend are not known. No immediate threats have been identified.[1] "The ready occupation of man-made habitats suggests that habitat loss is unlikely to be a problem."[8]