Puerto Rican Screech-Owl is a mid-sized screech-owl (ca 23-25 cm in length, and ca 140 g) with an obviously rounded head and no ear-tufts. There are two color morphs, brown and rufous. This owl also has been known as Cuckoo Bird or Puerto Rican Bare-legged Owl. The sexes are similar in appearance, but females usually are a few grams heavier than males. Puerto Rican Screech Owl originally was described by the French ornithologist F.M. Daudin in the 1800s. The legs are completely bare, which is rare for most owls in the Strigidae family. There are two common color morphs (brown and rufous) and a rare color morph (gray) that appears in dry forested areas.
Puerto Rican Screech-Owl is similar to North American screech-owls, such as Eastern Screech Owl (Megascops asio), but does not have "ear" tufts or feathered tarsi. Confusion with other species in the field is mostly unlikely, as Puerto Rican Screech-Owl is the only species of small owl in its range.
The following description is based on Ridgway (1914) and König and Weick (2008), and refers to nominate nudipes; see also Geographic Variation:
Adult: Sexes similar. Overall plumage color variable; most frequent is a brown morph (described first), but there also is a rufous morph (see below). Upperparts generally brown, more or less distinctly with irregular bars or vermiculations of paler brown; forecrown, back and scapulars sometimes with dusky shaft streaks. Rectrices vermiculated, occasionally with indistinct and interrupted bars of paler brown. Wing coversts similar to back, but the outermost coverts usually with a few irregular whitish spots. Secondaries finely vermiculated, but sometimes with indistinct narrow bands of pale brown. Primaries spotted on outer webs with pale brown and whitish. Lacks "ear" tufts. "Eyebrows" (supercilium) and lores white, the feathers with dusky shafts. Facial disks narrowly barred with light and dark brown. Underparts mostly white, with broad dusky central streaks and numerous trasnverse vermiculations or narrow bars of brown. Belly and undertail coverts white, and often unmarked. Tarsus mostly bare; feathers of tibia and upper tarsus pale brown or whitish, narrowly barred with darker brown. Rufous morph: Similar, but plumage generally pale rufous brown or ochre buff.
Little information; may have similar molts to North American screech-owls.
Bill: horn (paler at tip), greenish yellow
Tarsi and toes: pale brown, grayish yellow
Bare parts color data from Ridgway (1914) and König and Weick (2008).
Total length: 20-23 cm (König and Weick 2008), 23-25 cm (Raffaele et al. 1993)
Linear measurements (mm) (from Arendt et al. 2004):
Mass: mean 142.76 g (s.d. 11.57, range 102.9-169 g, n = 187; sexes combined; Arendt et al. 2004)
male, mean 130.69 g (s.d. 12.58, range 103-146 g, n = 9; Arendt et al. 2004)
female, mean 144.13 g (s.d. 10.66, range 102.9-169 g, n = 14; Arendt et al. 2004)