Appearance

Nightjars are nocturnal birds with plumage that is cryptically patterned, and is dominated by shades of brown. They have long wings, short tarsi, very wide but short bills, and prominent rictal bristles. Dusky Nightjar is a medium sized species with dark plumage, heavily spotted with cinnamon rufous; these spots are larger on females. It has a buff throat, and wings that are entirely dark, with no white band on the primaries. The sexes differ in the tail pattern: the male has broad white tips to the outer rectrices, but these tips are smaller and are buff in females.

Eastern Whip-poor-will (Antrostomus vociferus) is a rare nonbreeding migrant to Costa Rica and Panama, present from approximately mid November to mid March. The whip-poor-will is a larger than Dusky Nightjar, with more grayish plumage, and a white throat. Both Rufous Nightjar (Antrostomus rufus) and Chuck-will's-widow (Antrostomus carolinensis), which is another nonbreeding migrant to Costa Rica and Panama, are much larger than Dusky Nightjar, and are more uniformly cinnamon rufous. Common Pauraque (Nyctidromus albicollis) usually occurs at lower elevations, has a much longer tail, paler plumage overall with contrasting rufuous auriculars, and has white or buff bands on the outer primaries.

The following description is based on Wetmore (1968); see also Ridgway (1914) and Cleere (1998):

Adult male: Upperparts sooty black, rather finely spotted with cinnamon rufous, which tend to merge to form narrow, irregular bars. Lores cinnamon rufous. Central rectrices with indistinct cinnamon rufous barsl the three outermost pairs of rectrices broadly tipped with white, with less rufous barring. Remiges blackish, outer webs of primaries spotted, and secondaries barred, with cinnamon rufous. Lower throat with an indistinct, partially concealed, narrow band of white and buff. Rest of throat and breast like back, but with a few scattered white spots. Lower breast and belly cinnamon buff to buff, narrowly barred with black. Undertail coverts buff, with few black bars. Underwing coverts black, with a very few cinnamon buff spots.

Adult female: Similar to male, but cinnamon buff markings larger, so the plumage overall appears more uniformly this color. Pale tips to outer rectrices narrower and buff, not white.

Juvenile: Similar to adults, but paler and more rufous (Carriker 1910, Cleere 1998).

There is no information available on molts of Dusky Nightjar; presumably this species follows the complex basic molt strategy.

Iris: dark brown

Bill: black

Tarsi and toes: dull black, the scutes outlined in dull white

Bare parts color data from Wetmore (1968).

Total length: 21-22.5 cm (Wetmore 1968), 21-25 cm (Cleere 1998), 23 cm (Stiles and Skutch 1989)

Linear measurements (from Wetmore 1968):

male (n = 14)

wing length: mean 153.9 mm (range 149.5-159 mm)

tail length: mean 112.4 mm (range 100.1-119.8 mm)

tarsus length: mean 15.2 mm (range 14.0-17.1 mm)

female (n = 11)

wing length: mean 153.9 mm (range 149.3-159.0 mm)

tail length: mean 113.1 mm (range 104.4-120.5 mm)

tarsus length: mean 16.0 mm (range 15.2-16.5 mm)

Mass: male, 52.9 g (n = 1; Cleere 1998); female, 51 g (n = 1; Cleere 1998)