Appearance

Swallow-tailed Nightjars are the smaller of the two species of Uropsalis nightjars. They are cryptically patterned, like most nightjars; overall they are dark brown, spotted with tawny, and with tawny buff barring on the belly and flanks. The English name describes the distinctive tail of the males, which have extremely long outer tail feathers edged in white; females have a shorter, much less graduated tail.

Lyre-tailed Nightjar (Uropsalis lyra) is the species most likely confused with the Swallow-tailed Nightjar, as there is broad geographic overlap between these two species. Lyre-tailed Nightjar is larger, paler, and more patterned than Swallow-tailed Nightjar, with a more conspicuous rufous nuchal collar. Swallow-tailed Nightjar occupies more open habitat and usually occurs at higher elevations than Lyre-tailed, but locally they may occur together.

Scissor-tailed Nightjar (Hydropsalis torquata) is larger and more patterned, with a lighter color overall, a nuchal collar, and buff along the scapulars and a relatively shorter tail. This species also occurs at lower elevations and in less humid habitats than Swallow-tailed Nightjar.

Long-trained Nightjar (Macropsalis forcipata) of southeastern Brazil does not overlap with Swallowtailed. It also is distinguished by having a tawny nuchal collar, buff scapulars, and more white in the tail of males.

The following description is based in Cleere (1998), and refers to nominate segmentata; see also Geographic Variation:

Adult male: Upperparts dark brown, heavily spotted with tawny; no nuchal collar. Rectrices brown. The outer pair of rectrices are greatly elongated; the outer webs are very narrow and whitish (basally edged with buff), and the inner webs are dark brown. The shafts of the outer rectrices are broad and white. The inner rectrices are barred and spotted with tawny. Scapulars dark brown, barred and spotted with tawny. The wing coverts are dark brown, spotted and barred with tawny and buff. The remiges generally are brown. The two outer primaries are edged with buff; the secondaries are narrowly tipped with grayish brown, and the inner secondaries are spotted or barred with tawny on the outer webs. The tertials are brown, spotted and barred with tawny. Lores and auriculars dark brown, heavily spotted with tawny. Chin and throat dark brown, spotted with buff; lower throat often buffish. Breast dark brown, spotted or scalloped with tawny and buff. Belly, flanks, and undertail coverts buff, barred with brown.

Adult female: Similar to male, but the outer pair of rectrices are not elongated. Also often more densely spotted with tawny.

Immature: Similar to adult, but secondaries and inner primaries broadly tipped with tawny or buff.

Downy chick: Not described.

Undescribed; presumably follows the Complex Basic molt strategy.

Iris: brown, gray brown

Bill: blackish, black

Tarsi and toes: brownish, gray brown, dark gray

Bare parts color data from Cleere (1998) and specimens in the Field Museum of Natural History.

Total length: male 66 cm (including tail streamers), female 23 cm (Hilty and Brown 1986)

Linear measurements (from Cleere 1998):

wing length, male: 162-175 mm; female: 168-170 mm

tail length, male: 500-540 mm; female: 117-126 mm

bill length, male: 15.6-18.5 mm; female: 17.2-19.7 nn

tarsus length, male: 15.1-17.5 mm; female: 15.0-17.1 mm

Mass: male, 42 g (n = 1; Weke 1972); female, mean 43.4 g (n = 2; Weske 1972)