Peruvian Screech-Owl Megascops roboratus Scientific name definitions

Both red and gray morphs of the Peruvian Screech-Owl are known. The species ranges from southwestern Ecuador to northwestern Peru, and two moderately distinctive subspecies have been described, although they do not differ in vocalizations. Mostly found below 1200 m, this screech-owl ranges locally to 2100 m in Peru, and is often common dry deciduous woodland (the larger and darker-crowned Megascops roboratus roboratus) or arid coastal scrub with many cacti (Megascops roboratus pacificus). Morphologically, this species (especially the nominate race) is most similar to the Tropical Screech-Owl (Megascops choliba), but there is no geographical overlap between them, while the Koepcke’s Screech-Owl (Megascops koepckeae) is found solely at higher elevations. The latter’s song is much more similar to that of Tropical Screech-Owl than to the present species. Comparatively few biological data have been published for this Megascops, which fact is true for many South American congeners.

20–22 cm (1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ), 144–162 g (roboratus); 18–19 cm (1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ), 70–90 g (pacificus). Small to medium-sized screech-owl that occurs in grey and rufous morphs. Facial disc greyish, narrowly barred dusky, with black border; small ear tufts greyish-white and warm brown; crown blackish-brown, giving capped effect, contrasting strongly with white eyebrows; distinct pale nuchal collar; upper­parts grey-brown, slightly barred dark, with blackish shaft streaks; inner wing with narrow cinnamon-brown bars and dusky speckles; scapulars with black-edged whitish outer webs; flight-feathers barred buffy-white; underparts whitish, faintly vermiculated, with variable but often fine dark shaft streaks with lateral bars, central belly often clear white; tarsus fully feathered; irides pale yellow to golden yellow; cere and bill greyish-olive; toes greyish-olive to brownish (1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ). Rufous morph pale rufous with dark brown markings. Juvenile densely barred, irides pale yellow. Race <em>pacificus</em> smaller (wing length 139–150 mm versus 165–175 mm in nominate (1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ) ), less heavy, averages paler and greyer but much overlap; rufous morph commoner than in nominate.

Editor's Note: This article requires further editing work to merge existing content into the appropriate Subspecies sections. Please bear with us while this update takes place.

Has been treated as conspecific with M. choliba, but vocalizations distinct. Smaller race pacificus (originally described as subspecies of M. guatemalae) recently treated as separate species in major works (2 König, C. (2000). Owl-vocalizations as interspecific-differentiation patterns and their taxonomical value as ethological isolating mechanisms between various taxa. Pp. 781–794 in: Chancellor, R.D. & Meyburg, B.U. eds. (2000). Raptors at Risk. Proceedings of the V World Conference on Birds of Prey and Owls, Midrand, Johannesburg, 4–11 August 1998. WWGBP & Hancock House, Berlin & Blaine, Washington. Close , 1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ), hence also in subsequent regional guide (3 Restall, R.L., Rodner, C. and Lentino, M. (2006). Birds of Northern South America: an Identification Guide. Vols. 1 and 2. Christopher Helm, London. Close ), on basis of “morphology and vocalisations”, but songs appear identical to those of roboratus (this supported by material on xeno-canto and contra some published statements (2 König, C. (2000). Owl-vocalizations as interspecific-differentiation patterns and their taxonomical value as ethological isolating mechanisms between various taxa. Pp. 781–794 in: Chancellor, R.D. & Meyburg, B.U. eds. (2000). Raptors at Risk. Proceedings of the V World Conference on Birds of Prey and Owls, Midrand, Johannesburg, 4–11 August 1998. WWGBP & Hancock House, Berlin & Blaine, Washington. Close ) ) and morphological differences involve much smaller size (based on published data), with effect size for weight of males 5.45 (score 3), and “averaging slightly grayer, especially dorsally” (1). Nevertheless, size difference unusual and further study, including confirmation of vocal similarities, appropriate. Two subspecies recognized.

Editor's Note: Additional distribution information for this taxon can be found in the 'Subspecies' article above. In the future we will develop a range-wide distribution article.

Dry deciduous woodland with scattered bushes on mountain slopes and in hilly country, mostly at 500–1200 m, but occasionally as high as 1800 m in Ecuador and 2100 m in Peru (4 Freile, J.F., Bonaccorso, E.A. and Santander, T. (2003). First nesting report of the West Peruvian Screech-Owl (Otus roboratus). Ornitología Neotropical. 14(1): 107-111. Close , 5 Schulenberg, T. S., D. F. Stotz, D. F. Lane, J. P. O’Neill, and T. A. Parker (2007). Birds of Peru. Princeton University Press, Princeton, NJ, USA. Close ). Race pacificus inhabits arid coastal plains and foothills, generally below 500 m; habitats range from open, dry scrub of various shrubs, cacti, mesquite and various short trees, to dry deciduous forest of small to medium-sized trees and columnar cactus (Cereus); other typical species include Capparis, Acacia, Prosopis and Bombax.

Presumably resident (1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ).

Poorly studied. Probably largely insectivorous (1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ), perhaps almost exclusively so; known to take caterpillars, cockroaches, grasshoppers, crickets, and beetles and their larvae. So far as is known, strictly nocturnal.

Typical song of nominate race a trill of equally spaced notes  increasing in volume toward the end (1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ), lasting c. 2·5 seconds; pacificus said to give a similar trill  that rises in volume and drops slightly in pitch at toward the end, lasting 1·5–2 seconds (1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ); in aggression, gives short upward-inflected yelps  .

Nominate race reported to nest in tree cavity and perhaps in old nests of the Pale-legged Hornero (Furnarius leucopus) (1 König, C., F. Weick, and J.-H. Becking (2008). Owls of the World. Second Edition. Christopher Helm, London, UK. Close ). First nest known to science for race pacificus found on 28 Apr at 520 m elevation in SW Ecuador; nest in natural cavity of Tabebuia chrysantha tree 2·7 m above ground; when nest first inspected on 2 May, a female was incubating 2 eggs (4 Freile, J.F., Bonaccorso, E.A. and Santander, T. (2003). First nesting report of the West Peruvian Screech-Owl (Otus roboratus). Ornitología Neotropical. 14(1): 107-111. Close ); no other information.

Not globally threatened (Least Concern). CITES II. Global population size and population trend unknown. Can be very common locally, but overall rare and possibly vulnerable; both N and S limits of distribution, however, uncertain. Since early 1970s, much habitat rendered unsuitable by effects of grazing by goats, and by cutting of trees and shrubs for firewood and for charcoal production; although able to occupy very sparse woodland and scrub, at least for foraging, and probably to lesser extent for roosting, species may not be able to survive in such open habitat without trees of at least moderate stature that can provide nesting cavities. Because of pastoral economy typical of region, goat browsing and firewood-gathering difficult to control; however, harvesting for charcoal could be discouraged wherever possible.