Long-tailed Sylph

The male long-tailed sylphs are 16 to 19 cm (6.3 to 7.5 in) long including the 12 cm (4.7 in) outer tail feathers, and weigh 5 to 6 g (0.18 to 0.21 oz). Females are 9.7 to 11.7 cm (3.8 to 4.6 in) long and weigh 4.5 to 4.7 g (0.16 to 0.17 oz). All subspecies have a short black bill. Males of the nominate subspecies A. k. kingii have a shining emerald green crown, metallic bronzy green upperparts, duller green underparts with an olive cast, and a blue or violet throat. The inner tail feathers are very short and the outer ones very long. (Despite the species' English name, its tail is not noticeably longer than those of the other sylphs.) The tail's upper surface is iridescent blue, green, and violet and the underside bluish black. Nominate females' upperparts are similar to the males'. Their tail is short and somewhat forked, with dark blue outer feathers broadly tipped with white. The head is metallic green with a white malar stripe and a white to buffy throat with green speckles. The underparts are cinnamon. Males of subspecies A. k. margarethae have paler green upperparts than the nominate; females are similar to the nominate. A. k. caudatus does not have the nominate's blue throat and its females are also similar to the nominate. A. k. emmae has a somewhat longer bill than the nominate. …

The subspecies of long-tailed sylph are found thus:

A. k. margarethae, north central and coastal Venezuela A. k. caudatus, in western Venezuela's Serranía del Perijá and the Andes into northern Colombia A. k. emmae, the northern Central and southern Western Andes of Colombia south into northwestern Ecuador A. k. kingii, the Eastern Andes of Colombia A. k. mocoa, the southern Central Andes of Colombia through Ecuador into northern Peru A. k. smaragdinus, the eastern Andes of Peru south into west-central Bolivia The long-tailed sylph inhabits generally open landscapes like scrublands, clearings and edges of forest, gardens, secondary forest, and high-elevation grassland. In elevation it ranges between 900 and 3,000 m (3,000 and 9,800 ft).

The long-tailed sylph's diet is nectar and insects. It feeds on nectar in several ways. It uses trap-lining around a circuit of flowering plants but also will defend specific feeding territories. It usually hovers at flowers to feed but sometimes clings to them and also "robs" nectar by piercing the base of a flower. It catches insects by hawking from a perch. At lower elevations it feeds mostly in the treetops, and lower to the ground at elfin forest and high-elevation grassland.