Esmeraldas Woodstar Chaetocercus berlepschi
Version: 1.0 — Published June 4, 2010
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The Esmeraldas Woodstar is a very small hummingbird with a straight, dark bill. The male has a white postocular stripe, glittering purple throat, white patches on the sides of the lower back, whitish underparts, shiny green upperparts, and a deeply forked tail with spiky external rectrices. The female woodstar has pale buffy underparts with a tinge of salmon-pink on the underparts (especially on the flanks), white patches on the sides of lower back, green upperparts, a white postocular stripe, and a rounded cinnamon tail with black subterminal band and green central rectrices.
The female of the species was confused with female Little Woodstar (Chaetocercus bombus) until recently. Separation of both species in the field was problematic due to sympatry and because females of C. bombus typically outnumbered female-type C. berlepshi (Ágreda 2007). Observation of feeding and sexual behaviors of female-type C. berlepschi and female-type C. bombus was recorded simultaneously in January of 2008; both defended red flower patches of Kohleria spicata and visited reproductive perches of adult males C. berlepschi (Ágreda 2008). Courtship displays and ultimately copulations between adult male C. berlepschi and female-type C. bombus were observed. Fresh studies were urgently needed to characterize and identify differences in the plumages of both species (see Ágreda 2007).
Additionally, Chaetocercus is a genus that is under-represented in museum collections; it has been little collected since the 1960’s and older specimens often have incomplete information (Freymann and Schuchmann 2005).
Differences between C. berlepschi and C. bombus
Female C. berlepschi and C. bombus differ on their overall appearance. The former shows contrasting buffy pale salmon-pink underparts with green upperparts while the latter’s ventral parts are of a richer cinnamon color. Additionally there are differences in the facial markings that are useful features to distinguish the two species. In C. berlepschi the postocular stripe characteristically is white and contrasts with a long and wide green cheek stripe, whereas in C. bombus the postocular tends to be rich cinnamon and the dusky cheek stripe is short and narrow (Harris et al. 2009). Further, the species can be separated by their distinctive tail patterns. Both species have rounded cinnamon tails with black subterminal bands. However, C. berlepschi has green central rectrices with a black subterminal band and unevenly bi-lobed, cinnamon rufous tips whereas C. bombus has a green sheen on parts of the inner webs of the central rectrices and a narrower black subterminal band (Harris et al. 2009). It is recommended to not conclusively identify C. berlepschi based on one single character but on all of the previously mentioned traits.
Male C. bombus differs from C. berlepschi by the ruby-pink rather than purple color of the gorget, the presence of a contrasting buffy pectoral collar and buffy white postocular stripe, and greenish underparts. Both species have a bronze-green crown and green upperparts, and a deeply forked tail with dark spiky external rectrices.
Adult male: Has a glittering purple gorget that extends from the chin throughout the throat to the sides of the neck. The gorget contrasts markedly with white postocular stripe and upper breast. Lower breast and belly are whitish, turning green grayish on flanks. Forehead, crown, neck and rest of upperparts, including tail, are shiny green. It presents white patches on sides of the lower back. Tail is deeply forked with long filiform external rectrices.
Adult female: Characterized by a distinctive white postocular stripe, buffy underparts with a tinge of pale salmon-pink on belly and flanks specially in adult skins, bronzy-green forehead, crown, scapulars, upper wing and tail coverts, rest of upperparts are green. It presents white patches on sides of the lower back. Tail is cinnamon with black subterminal band, except for central rectrices that are green.
No information is available.
Iris dark brown. Tarsi and bill black.
Bill straight black. Measurements of bill length are found below.
Bill length (female) 12.4 mm; (male) 12.2 mm. Wing chord (female) 26.5 mm; (male) 27.4 mm