Appearance

Leucippus are medium sized hummingbirds with drab plumage and little or no sexual dimorphism. The upperparts are green, and the underparts are white or buffy, with no glittering gorget. Leucippus have bills that are relatively long, are straight or only gently curved, and are black. The tails of all Leucippus are of medium length, and are blunt tipped. Tumbes Hummingbird is a medium sized member of the genus. Its underparts are off white or very pale gray, with no speckles or spots on the throat.

Tumbes Hummingbird is similar to Spot-throated Hummingbird (Leucippus taczanowskii), which also occurs in northwestern Peru, but usually is found at higher elevations in the region where both species occur; these two species generally replace each other elevationally, and are not syntopic. Spot-throated Hummingbird is larger than Tumbes, and, as the name suggests, its throat is densely marked with small green speckles.

The following description is based on Weller (1999):

Adult: Sexes similar. Upperparts pale golden green. Small white postocular spot. Rectrices pale green, the inner rectrices with bronzy tips, and the outer rectrices with a dusky gray subterminal band and narrow whitish tips (more grayish in the female). Underparts pale grayish, becoming white on the belly.

Juvenile: Undescribed.

Undescribed.

Iris: very dark

Bill: black

Tarsi and toes: black

Bare parts color data from specimens in the Louisiana State University Museum of Natural Science.

Total length: 8 cm (Ridgely and Greenfield 2001b), 9-10 cm (Weller 1999), 11 cm (Schulenberg et al. 2010)

Linear measurements:

bill length, male: 20.8 mm (n = 1; Colwell 2000)

bill length, female: 19.3 mm (n = 1; Colwell 2000)

sexes combined: 19 mm (Schulenberg et al. 2010), 20 mm (Ridgely and Greenfield 2001b)

Mass: mean 4.5 g (range 4.2-5 g, n = 3, sexes combined; Dunning 2008)