Appearance

Sheartails (Doricha) are two species of small hummingbird, with relatively long, decurved bills; the males of both species also have long, deeply forked tails. The male Mexican Sheartail is green above. It has a glittering rose pink gorget; the belly is whitish, but the flanks are mottled with bronzy green. The female has a much shorter tail, which is only moderately forked (notched); the outer rectrices are mostly rufous, with a black subterminal band and white tips. The underparts of the female are whitish, washed with buffy cinnamon on the flanks and undertail coverts.

Mexican Sheartail is similar to several other species of small hummingbird, but is allopatric to any species with which it might be confused in the field. Male Slender Sheartail (Doricha enicura), of southern Mexico, has an even longer tail than Mexican Sheartail, and a more purplish gorget. female Slender Sheartail is more deeply colored below than female Mexican Sheartail. The two species of Calothorax (Lucifer Hummingbird Calothorax lucifer and Beautiful Hummingbird Calothorax pulcher) occur only in the interior of Mexico, and have slightly shorter, less decurved bills.

The following description is based on Ridgway (1911):

Adult male: Upperparts metallic bronze or bronze green, duller on the crown; forecrown sometimes dull brownish gray. Tail deeply forked (see Measurements). The three outer pairs of rectrices are purplish bronzy black, the inner web of the second and third pair broadly edged with light cinnamon. Remiges deep brownish gray, very faintly glossed with purplish. Gorget on chin and throat bright metallic pinkish purple, tinged with violet towards the sides and the bottom of the gorget. Breast white, center of belly and undertail coverts dull white, undertail coverts (and sometimes the belly) tinged with cinnamon buff. Flanks broadly metallic bronze or bronze green. Tibial tufts white.

Adult female: Upperparts as in male. Three outer pairs of rectrices basally light cinnamon rufous; the two outermost pairs broadly tipped white, with a broad black subterminal band, and the third pair with the terminal half black (sometimes with a narrow white tip). Also, the second and third pair have metallic bronze green between the cinnamon rufous base and the subterminal black band. Underparts dull grayish white, more or less tinged with brownish buffy, especially on the flanks and undertail coverts. Flanks broadly glossed with metallic bronze or bronze green.

Immature male: Similar to the adult female, but the throat is flecked with pink, and the tail has a broader black subterminal band (Howell and Webb 1995).

Undescribed.

Birds in female plumage often greatly outnumber adult males (Paynter 1955, Howell and Webb 1995), at least in the Yucatan population, perhaps indicating that this species has delayed plumage maturation (Peterson 1999). The ratio between birds in female and adult male plumages was 1:1 in surveys in Veracruz, however (Ortíz-Pulido et al. 2002).

Iris: dark brown

Bill: black

Toes: dusky

Bare parts color data from Ridgway (1911).

Total length: male 8.6-9.7 cm, female 8.2-8.5 cm (Ridgway 1911); 9.5-10 cm (Howell and Webb 1995)

Linear measurements (Ridgway 1911):

male (n = 7)

wing length, mean 35.5 mm (range 34.5-36.5 mm)

tail length (outer rectrices), mean 37.1 mm (range 35.5-38 mm)

tail length (central rectrices), mean 11 mm (range 10-12.5 mm)

bill length (exposed culmen), mean 21.3 mm (range 20.5-22.5 mm)

female (n = 4)

wing length, mean 38.7 mm (range 37.5-40 mm)

tail length (outer rectrices), mean 24.4 mm (range 23-25 mm)

tail length (central rectrices), mean 20.8 mm (range 19.5-23 mm)

bill length (exposed culmen), mean 22.4 mm (range 22-23 mm)

Mass: male, 2.3 g (n = 1; Paynter 1955); female, mean 2.6 g (range 2.5-2.7 g, n = 3; Paynter 1955)