Appearance

Potoos are nocturnal birds with a cryptically patterned plumage dominated by shades of brown and gray. They have long wings, short tarsi, dorsally compressed but short bills with a very wide gape, and conspicuous rictal bristles. Long-tailed Potoo is a large and long tailed species that is brownish in color. The upperparts are mottled and spotted brown and buff with blackish brown spots and streaks. Both sexes are similar and lack white patches on the wings, as well as any white on the long, graduated tail.

Long-tailed Potoo is most similar to Great Potoo (Nyctibius grandis) and the brown phase of Common Potoo (Nyctibius griseus). Great Potoo is much bulkier, with a shorter tail, and is paler and grayer, than Long-tailed Potoo; Common Potoo is smaller and shorter tailed. Compared to other potoo species, Long-tailed Potoo has a proportionately longer tail, is tawnier overall, and often has a conspicuous pale shoulder patch. Another field mark for separating Long-tailed Potoo from other potoos is the presence of upturned feather tips of the wing coverts and scapulars (Dingain 2010). This feature is caused "by the rachis bending outwards and the barbs curving inwards near the tip" of the feather (Dingain 2010). This feature is present on both N. a. aethereus (Atlantic Forest) and N. a. longicaudatus (Amazonia), but appears to be more prominent on the nominante subspecies (Dingain 2010). There are no data on whether these upturned feather tips are present in the subspecies of western Colombia (chocoensis).

The following description is adapted from Cleere (1998), and refers to nominate aethereus; see also Geographic Variation.

Adult: Sexes similar. Forecrown, crown, and nape tawny brown, speckled and spotted with buff, with bold blackish brown streaks or spots. No collar is present around hindneck. The mantle, back, and rump are tawny brown, mottled with brown and buff, and streaked with blackish brown with upturned feather tips on greater coverts. Uppertail coverts tawny or tawny brown, boldy vermiculated with brown. Strongly graduated tail brown, the rectrices broadly barred with tawny buff bars and streaked or vermiculated with brown; central pair (R1) with pointed tips. Primary coverts are brown or faintly barred with tawny. Upper and outer rows of lesser coverts blackish brown, rest of lesser coverts buff, pale buff, or whitish, forming a distinctive pale panel across shoulders. Rest of wing coverts brown, densely mottled with pale buff, buff, and tawny. Scapulars tawny brown, mottled with buff, tawny and brown, streaked with blackish brown. Primaries and secondaries brown, broadly barred with pale tawny. Tertials tawny-brown, mottled brown, tawny and buff. Lores and auriculars tawny, speckled with brown. Bold buffish submoustachial stripe, becoming broader along the sides of the throat. Chin and throat grayish buff, speckled with brown. Breast, upper belly, and flanks brown or grayish brown, speckled with buff, streaked with blackish brown, and boldy spotted with buff and blackish brown. Lower belly and undertail coverts buff, streaked and vermiculated brown. Underwing coverts brown barred buff.

Immature and Juvenile: Similar to adult but paler and "often tinged pale cinnamon?".

Chick: Covered in white down.

Very little is known. It is possible that the primaries are molted descendantly (Cleere 1998).

Iris: yellowish, greenish-chestnut?, or bluish-gray?

Bill: blackish

Tarsi and toes: brownish

Bare parts color data from Cleere (1998), and are for N. a. aetherus.

Total length: 42-56 cm (Cleere 1998), 46-58 cm (Cohn-Haft 1999), 48-53.5 cm (Ridgely and Greenfield 2001b)

Mass: 280-447 g (Cohn-Haft 1999), 434.0-447.0 g (n = ?, Brazil; Sick 1993)

Linear measurements (from Cleere 1998):

N. a. aethereus 

Mass: no data

male (n = 1):

wing length, 338 mm

tail length, 328 mm

bill length, 32.0 mm

tarsus length, 18.7 mm

female (n = 1):

wing length, 345 mm

tail length, 310 mm

bill length, 35.5 mm

tarsus length, 19.2 mm

unsexed (n not specified, but a minimum of 5):

wing length, 325-342 mm

tail length, 281-315 mm

N. a. chocoensis

Mass: no data

male (n = 1):

wing length, 305 mm

tail length, 271 mm

female (n = 1):

wing length, 305 mm

tail length, 265 mm

N. a. longicaudatus

total length: 42-49 cm

unsexed (n not specified, but a minimum of 5):

wing length, 305-312 mm

tail length, 269-285 mm

female (n not specified, but a minimum of 5):

wing length, 283-303 mm

tail length, 245-283 mm

mass (n = 1), 300 g