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Glaucidium peruanum

Peruvian Pygmy-Owl

  • Order: Strigiformes
  • Family: Strigidae
  • Monotypic

Authors: Schulenberg, Thomas S., and Hope Batcheller

Identification

Summary

Pygmy-owls (Glaucidium) are very small owls, with a large rounded head, a pair of prominent black marks (false "eye spots") on the nape, and a relatively long tail. Peruvian Pygmy-Owl is a relatively larges species of Glaucidium. The upperparts usually are brown or gray, but less commonly are rufous; the underparts are white, marked with broad streaks that are the same color as the upperparts. The crown also has fine white streaks. Peruvian Pygmy-Owl overall is very similar to the brown and gray morphs of the Ferruginous Pygmy-Owl (Glaucidium brasilianum).

Similar Species

All species of pygmy-owls are superficially similar in appearance, and often are distinguished most easily by voice (see Vocalizations), elevational preferences, and habitat. Fortunately the distribution of Peruvian Pygmy-Owl has little or no overlap with other species of pygmy-owl. In the Andes, Peruvian Pygmy-Owl also overlaps geographically with Andean Pygmy-Owl (G. jardinii) and Yungas Pygmy-Owl (G. bolivianum), both of which also are similar in size and shape to Peruvian, and both of which have a rufous morph. Both species typically occur in more humid and more closed forest. Adults of both species have small pale spots on the crown, but the crown of juveniles may be streaked, thus replicating the crown pattern of Ferruginous Pygmy-Owl. These juveniles are best distinguished from Peruvian by voice, habitat, and elevation.

Peruvian Pygmy-Owl is very similar as well to Ferruginous Pygmy-Owl (G. brasilianum) of the lowlands of eastern Ecuador and Peru, although the rufous morph, which is frequent in Ferruginous Pygmy-Owl, is uncommon in Peruvian. These two species are allopatric, however, and so will not be confused in the field; otherwise they best are distinguished by voice.

Vocalizations

The song of Peruvian Pygmy-Owl is described as "a series of rapidly delivered notes, given at a rate much faster than that of Ferruginous [Pygmy-Owl Glaucidium brasilianum] (too fast for most people to effectively whistle it, continued for 10 to upward of 30-34 seconds" (Ridgely and Greenfield 2001b) and as "a rapid (about 4 notes/sec or faster) of rising hoots: poop'poop'poop'poop...." (Lane, in Schulenberg et al. 2007). 

When excited, the song can end in more of a chatter (Ridgely and Greenfield 2001b). Calls "include chirping and thin warbling notes" (Lane, in Schulenberg et al. 2007).

Additional recordings of vocalizations of Peruvian Pygmy-Owl can be heard at Macaulay Library and at xeno-canto.

Nonvocal Sounds

None reported; probably can make a snapping sound with the bill, as does Ferruginous Pygmy-Owl (Glaucidium brasilianum).

Detailed Description (appearance)

Very similar to Ferruginous Pygmy-Owl (Glaucidium brasilianum). The following description is based on König and Weick (2008).

Adult: Sexes similar, but occurs in several plumage morphs; gray and brown morphs are more frequent than is the rufous morph. 

In the gray morph, upperparts generally are grayish brown. The forecrown hasnarrow longitudinal buff streaks, which may become spots on the crown and nape. There is a broken white collar across the nape; the tips of the feathers on either side of the midline are tipped black, forming an oval black spot ("false eye"), enclosed by white, on each side of the nape. Mantle and back with whitish spots; outer webs of scapulars largely whitish. Remiges incompletely barred light and dark. Tail grayish brown with 6-7 transverse broken whitish bars. Lores and supercilium whitish. Throat white. Sides of breast grayish brown, almost meeting across the center. Belly white or whitish, broadly streaked with rufous. In other morphs, the general tone of the upperparts is dark brown or reddish brown. In the rufous morph, the pale transverse bars on the rectrices are pale rusty brown or orange-buff; and the pattern on the underparts is less distinct than in the gray or brown morphs. 

Juvenile: Similar to adult, but crown unstreaked.

Bare Parts

Iris: lemon yellow

Bill: yellow-green

Tarsi and toes: yellow-green

Bare part color data from specimens in the Louisiana State University Museum of Natural Science.

Measurements

Total length: 15-17 cm (König and Weick 2008), 16-16.5 cm (Ridgely and Greenfield 2001b).

Linear measurements: 

wing length, male: 98 mm (n = 1, holotype; König 1991)

                     female: mean 102.3 mm (range 101-104 mm, n = 3; König 1991)

tail length, male: 67.5 mm (n = 1, holotype; König 1991)

                   female: mean 72.2 mm (range 69-72.5 mm, n = 3; König 1991)

Mass: male, mean 60.5 g (range 58-62 g, n = 3; König 1991)

            female, 64.5 g (n = 1; König 1991)

Molts

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Geographic Variation

Monotypic; there is no described geographic variation. König and Weick (2008) suggest that there are vocal differences between populations of the coast and those of the Río Marañón drainage in southeastern Ecuador and north central Peru, but Lane (in Schulenberg et al. 2007) describes the vocalizations of the Marañón population as similar to those of the Pacific slope.

Systematics

Until recently, the populations of Glaucidium in the lowlands of northwestern South America were classified as part of Glaucidium brasilianum brasilianum, a subspecies of the very widespread Ferruginous Pygmy-Owl that otherwise occurs only east of the Andes. After it became known that these Pacific slope pygmy-owls differ vocally from all populations of brasilianum, they were described as a distinct species, Glaucidium peruanum (Peruvian Pygmy-Owl) by König (1991). The type locality of peruanum is Ninabamba, Apurímac, Peru, and the holotype is in the (British) Museum of Natural History. Although the distribution of peruanum primarily is on the Pacific slope, the type locality is from a semiarid intermontane valley.

Recommended Citation

Schulenberg, Thomas S., and Hope Batcheller. 2012. Peruvian Pygmy-Owl (Glaucidium peruanum), 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=%0A%09%09%09%09212376