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Megascops nudipes

Puerto Rican Screech-Owl

  • Order: Strigiformes
  • Family: Strigidae
  • Polytypic 2 Subspecies

Authors: Goodson, Chloe

Identification

Summary

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.

Similar Species

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.

Vocalizations

The territorial song (or "A-song") of Puerto Rican Screech-Owl is "a short, relatively deep, somewhat guttural, toad-like quavering trill of c. 3-5 seconds' duration, rrurrrrrrr" (König and Weick 2008).

The "B-song" is used in duets between male and female (König and Weick 2008), and perhaps in other contexts (aggression?).

Other vocalizations of Puerto Rican Screech-Owl include "a soft cackling gu-gu", which may be a contact call (König and Weick 2008), and "a loud coo-coo" (König and Weick 2008). The latter call gave rise to the local English name, "Cuckoo Bird".

Additional audio recordings of vocalizations of Puerto Rican Screech-Owl can be heard at Macaulay Library, at xeno-canto, and at Internet Bird Collection.

Nonvocal Sounds

None reported.

Detailed Description (appearance)

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.

Bare Parts

Iris: brown

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).

Measurements

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)

Molts

Little information; may have similar molts to North American screech-owls.

Geographic Variation

Two subspecies recognized:

nudipes, described as Strix nudipes (Daudin 1800); type locality Puerto Rico

Occurs throughout Puerto Rico. 

See Detailed Description.

newtoni, described as Gymnoglaux Newtoni (Lawrence 1860); type locality St. Croix, Virgin Islands

Similar to nominate nudipes, but "color of upper parts lighter and more grayish brown and under parts more sparsely and less heavily streaked and vermiculated" (Ridgway 1914). This taxon may not be valid, "as the name was assigned based on only slight plumage color differences" (Moreno 1998).

Formerly occurred in the Virgin Islands (Ridgway 1914, Raffaele 1989); probably now extinct (Moreno 1998; see Distribution).  One record from Vieques, where probably now extinct. Possibly also occurs on Culebra (Raffaele 1989).

Systematics

Phylogenetic relationships within the genus Megascops remain poorly known. The few studies published to date include only a small number of species of Megascops, and have not included nudipes (e.g. Wink et al. 2008). König and Weick (2008) consider the territorial song (A-song) of Megascops guatemalae (Vermiculated Screech-Owl) to be similar to that of nudipes, but it is not clear if they mean to imply a phylogenetic relationship between these two species.

Recommended Citation

Goodson, Chloe. 2014. Puerto Rican Screech-Owl (Megascops nudipes), Neotropical Birds Online (T. S. Schulenberg, Editor). Ithaca: Cornell Lab of Ornithology; retrieved from Neotropical Birds Online: http://neotropical.birds.cornell.edu/portal/species/overview?p_p_spp=209016