Violet-tailed sylph (Aglaiocercus coelestis)

Synonyms: Cynanthus coelestis
GenusAglaiocercus (1)
SizeMale length: 18 – 21 cm (2)
Female length: 9.5 – 9.7 cm (2)
Weight4.6 – 5.2 g (2)

Classified as Least Concern (LC) on the IUCN Red List (1) and listed on Appendix II of CITES (3).

A stunningly beautiful hummingbird of South America, the violet-tailed sylph is named after the striking tail of the male: an extremely long, deeply forked, metallic violet plume of feathers, tipped with blue (2). The remainder of the male’s plumage is equally as beautiful, shimmering iridescent green on the upperparts, turning slightly darker on the underside, and with patches of violet-blue feathers adorning the throat and the rump (2). Female violet-tailed sylphs are a little less striking than the males, as they have a short, unforked, bluish-green tail, with white tips to the outer tail feathers. They also differ by having a glittering blue crown, a white throat patch spotted with green that blends into a white breast, and orangey coloured underparts (2). Young violet-tailed sylphs are dull green on the upperparts and buffy-green on the underparts (2). Two subspecies of the violet-tailed sylph are recognised; Aglaiocercus coelestis athereus differs from Aglaiocercus coelestis coelestis by having a patch of green, instead of violet-blue, feathers on the throat, and a lighter scattering of green spots on the female’s throat (2).

The violet-tailed sylph is found in South America, with A. c. athereus occurring in south-western Ecuador, and A. c. coelestis inhabiting the pacific slope of the Andes in northern and central Ecuador and Colombia (2).

This striking bird inhabits cloud forest between 300 and 2,100 metres above sea level, most frequently over 900 metres (4). It favours very mossy forest, and is occasionally found at forest borders (4).

Flitting around its forest habitat, the violet-tailed sylph, like all hummingbirds, displays remarkable manoeuvrability, afforded by its unique wing structure and figure-of-eight wing-beat pattern (5). It forages near the ground, or sometimes up near the tree tops (2), hovering next to a flower to feed or clinging to the petals (2) (4). It feeds on the nectar of flowering vines, shrubs and trees (2), inserting its specialised bill into the flower to obtain the sugar-rich substance (5). On one flower, Macleania bullata the violet-tailed sylph has been observed piercing the long tube at the base of the flower to reach the nectar, leaving a conspicuous slit (6). Through this feeding, hummingbirds play an important role in the pollination of many plants in the tropics (7), but the violet-tailed sylph also feeds on insects, snatched from the air or plucked from vegetation (2).

Violet-tailed sylphs breed between October and February, when they lay a clutch of two eggs into a domed nest, built from moss and spider webs in a clump of moss and epiphytes. The female incubates these eggs for 15 to 17 days, with the young hatchlings fledging after just 26 to 30 days (2). Unusually, the violet-tailed sylph also constructs nests outside of the breeding period, in which it roosts at night. This has misled many scientists into thinking that this bird breeds year-round (2).

Male violet-tailed sylphs are known to be territorial, and will defend an area in which they feed (2) (7). The male’s dominance appears to be determined by the length of its stunning tail, with those with longer tails being dominant over those with shorter tails. Dominant males have been observed plucking feathers from the backs of subordinate males, sometimes leaving a white line down the bird’s back (7).

The forests in the region inhabited by the violet-tailed sylph are subject to a number of damaging human activities, such as intensive logging, cattle-grazing, mining, and coca and palm cultivation (8). However, this species is not currently considered to be affected by these activities to an extent that it is threatened with extinction (1), possibly aided by the fact that the violet-tailed sylph will tolerate areas of man-made habitat, provided that some patches of forest remain (2).

The violet-tailed sylph occurs in a number of protected areas, including Los Farallones National Park, La Planada Reserve and Río Nambi Reserve in Colombia (2). This provides protection from the habitat loss and degradation that is occurring in some parts of its range (2) (8).

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  1. IUCN Red List (July, 2014)