The long-tailed sylph is a species of hummingbird in the "coquettes", tribe Lesbiini of subfamily Lesbiinae. It is found in Bolivia, Colombia, Ecuador, Peru, and Venezuela. The long-tailed sylph's apparent song is "a continuous series of buzzy notes 'bzzt... bzzt... bzzt...'." Its calls include "a repeated, short, buzzy or raspy 'dzzrt'...a more drawn-out, higher-pitched 'bzzeeew' and a thin high-pitched rising twittering." Primarily found on the east slope of the Andes from Venezuela to Bolivia, in foothills and subtropical zones from 1,200–2,500 m. Occurs within cloud forest and at edges; visits feeders. Male is superficially similar to trainbearers but note different habitat.
Scientific name: Aglaiocercus kingii
Kingdom: Animalia
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).