Tepui Swift is a medium sized swift (but is one of the smallest species of Streptoprocne), with long, relatively broad wings and a long tail with a deep central notch. The plumage generally is blackish brown, but Tepui Swift has a broad, orange chestnut collar that extends onto the sides of the head, and down onto the lower breast. Females are similar in pattern to males, but the collar is paler in color, and may be mixed with brown on the throat and breast. The tail fork is shallower in immatures, and the feathers of the underparts of immatures have prominent pale fringes.
Tepui Swift is similar is size to swifts of the genus Cypseloides. White-chinned Swift (Cypseloides cryptus) occurs in the pantepui region, but has a shorter tail with little or no notch. White-chinned Swift also lacks the orange chestnut collar of Tepui Swift. Tepui Swift is most similar to Chestnut-collared Swift (Streptoprocne rutila). These species usually do not overlap, as Chestnut-collared is not reported from the pantepui region; but Tepui Swift is a vagrant or rare disperser to the range of Chestnut-collared in the coastal cordilleras of northern Venezuela. The most noticeable difference between the two is the shape of the tail: Chestnut-collared has a shorter, less deeply notched tail. Other differences (which may be more difficult to perceive under field conditions, but are readily apparent in the hand) are: Chestnut-collared Swift is browner, less blackish; has shorter wings; its collar is deeper chestnut (less orangey, as in Tepui); the collar is reduced or absent on female Chestnut-collared; and the collar of Chestnut-collared does not extend onto the chin and upper throat, as it does on Tepui Swift. These two species also have different Vocalizations.
The following description is based on Collins (1972):
Adult male: Generally sooty black, except for a broad orange chestnut collar that encompasses the nape, sides of the head up to the eyes, chin, throat, and upper breast. Some individuals have a few (three to six) white feathers on the breast, at the lower border of the chestnut collar. Suprocular streak white. Tail deeply forked; shafts of rectrices not stiffened, nor projecting beyond the vanes of the feathers.
Adult female: Similar to the male, but on some individuals the breast is paler, and is mixed with brown.
Immature: The feathers of the underparts, including the chin, are edged with paler gray (Dickerman and Phelps 1982).
Little information. Two specimens collected in July are in the early stages of wing molt (Collins 1972); whereas three specimens collected in February showed no molt (Barrowclough et al. 1997).
Iris: brown, dark brown
Tarsi and toes: purplish gray, pinkish brown to black
Bare parts color data from Collins (1972) and Willard et al. (1991).
Total length: 14-16 cm (Hilty 2003), 16.5 cm (Chantler 2000)
Linear measurements (from Collins 1972):
male (n = 12)
wing length (flat): mean 136.92 mm ± 0.61 mm (range 133-140.5 mm)
tail length: mean 61.31 mm ± 0.81 mm (range 56.5-66 mm)
depth of tail fork: mean 9.61 mm ± 0.45 mm (range 7.0-11.5 mm)
bill length (culmen from nostril): mean 4.18 mm ± 0.06 mm (range 4.0-4.5 mm)
tarsus length: mean 13.76 mm ± 0.13 mm (range 12.7-14.5 mm)
female (n = 18)
wing length (flat): mean 133.92 mm ± 0.64 mm (range 129.5-138 mm)
tail length: mean 58.87 mm ± 0.36 mm (range 56.5-61.5 mm)
depth of tail fork: mean 9.71 mm ± 0.48 mm (range 5.5-13.0 mm)
bill length (culmen from nostril): mean 4.21 mm ± 0.06 mm (range 3.7-4.5 mm)
tarsus length: mean 13.60 mm ± 0.11 mm (range 12.7-14.3 mm)
male: mean 22.6 g (n = 4, range 20-24.3 g; Dickerman and Phelps 1982, Willard et al. 1991)
female: mean 20.8 g (n = 3, range 17.9-24.0 g; Willard et al. 1991); mean 20.7 g (n = 3, range 19-23 g; Dickerman and Phelps 1982)