Appearance

Aeronautes are slender swifts with relatively long tails with a slight notch at the tip, and black and white piebald plumage patterns. White-tipped Swift is mostly blackish, with a contrasting white throat and flank patches. White-tipped Swift resembles the partly sympatric Andean Swift (Aeronautes andecolus), but has much less white below and generally is found in more forested habitat at slightly lower elevations.

Andean Swift (Aeronautes andecolus) is sympatric with White-tipped Swift from Peru south to Argentina. These species rarely are syntopic, however, as Andean Swift usually forages over more xeric, open habitats, and its elevational distribution extends higher than that of White-tipped Swift. Andean Swift has a white belly and a white band across the rump. The rump of White-tipped Swift is black (although perhaps from certain angles its white flanks could be mistaken for a white rump), and a dark belly, with white confined to the throat and upper breast. There is no geographic overlap with the third species of Aeronautes, White-throated Swift (Aeronautes saxatilis) of North America, which has a white belly, larger white flank patches, and a whitish face.

Lesser Swallow-tailed Swift (Panyptila cayennensis) occurs at lower elevations, is smaller, has a much longer, more pointed tail, and its white flank patches do not meet across the vent.

The following description is based on Chantler (2000), and refers to nominate montivagus; see also Geographic Variation:

Adult male: Crown and patch around eye blackish brown; lores, forecrown, line over eye paler gray brownl auriculars gray brown. Upperparts blackish brown, concolor with crown. Rectrices black brown, feathers wtih broad white tips, individually variable in extent, and more prominent on the upper surface of the rectrices. Remiges blackish brown, secondaries with white fringes. Greater coverts blackish brown; median and lesser coverts, and alula, blacker. Throat white, the white extending laterally on the sides of the neck behind the auriculars, and distally onto the upper breast. Underparts otherwise mostly blackish brown, slightly paler than the upperparts. White patches around legs, often joining across the vent. ,Overall appearance can be slightly mottled when worn.

Adult female: Plumage often browner than male; lower back and rump can be paler than the upper back. White on underparts is duller than in male. Reduced or no white tips to rectrices.

Juvenile: Similar to adults, but with more pale fringes on body feathers and on the tips of the rectrices.

Body and wing molt is reported from two females specimens from Colombia in December (Donegan et al. 2007). This was interpreted as a "pre-breeding molt, given that the species supposedly breeds in April-July" (Donegan et al. 2007), although in swifts it would be expected that the complete molt would be the pre-basic molt, which usually occurs following breeding.

Iris: dark brown

Bill: black

Toes/tarsus: black

Bare parts color data from specimens in The Field Museum.

Total length: 12 cm (Ridgely and Greenfield 2001b), 12.7 cm (Hilty 2003), 13 cm (Chantler 2000)

Linear measurements:

montivagus: wing length mean 117.7 mm (range 116-1119, n = 3; Chantler 2000)

tatei: wing length 112 mm; tail length 44 mm; bill length (exposed culmen 5 mm); tarsus length 8 mm (n = 1, male, holotype; Chapman 1929)

Mass: mean 19.62 ± 1.33 g (range 17.2-22.9 g, n = 26, Ecuador, Marín et al. 1992).

male: 20 g, 21.1 g (n = 2; Beebe 1949, Willard et al. 1991)

female: 21 g, 23 g (Dickerman and Phelps 1982, Willard et al. 1991)