Stygian Owl - Asio stygius

Originally described as Nyctalops

The first published description of Stygian Owl was made in 1832 by Johann Georg Wagler. The adjective Stygian comes from the Styx, the river in the underworld which the souls of the dead had to cross in Greek mythology. Thus, attributes of this owl's name are related to hell and darkness.

[For help with terms used in the description, see parts of an owl. For general characteristics common to most owl species, see owl physiology.]

Description: It is a medium to large dark owl with long and erectile ear tufts. The Stygian Owl has fuscous face, yellow eyes and blackish bill. It has almost bare toes, although the legs are feathered. On the back, it is almost sooty black, with dull white and buff barring and mottling. The front is rich buff, marked in a very close, herring-bone pattern of black streaks and cross bars. Wings are long and tail relatively short.

Size: Length 38-46 cm (15-18"). Wings 29.2-34.9 cm (11½ - 13¾"). Weight 632-675 g (22⅓ - 23¾ oz). Females heavier than males.

Habits: Essentially nocturnal. It roosts during daytime in dense vegetation, but seems to be active mostly in more open vegetation. When alarmed, its ear tufts stand erectile, but when relaxed they are almost invisible. Stygian owls fly with fairly slow wing beats, occasionally glides over some distance.

Voice: A deep "whuof" with a descending inflection is repeated at intervals of several seconds by the male. The female occasionally utters a shrill call "miah", in response to the male. Both sexes vocalize "wak-wak-wak" when excited. Females and young produce a "cheet" when begging for food.

Hunting & Food: It is said to feed on bats. It was also reported the consumption of birds such as doves and secondarily small mammals and insects. Populations from south-east Brazil appear to prey mostly on small gregarious birds as grassquits and other Passerines. Birds are taken at their night time perches, detected by their own involuntarily sounds when touching  the foliage. Stygian Owls normally hunt from a perch. Bats are captured on the wing.

Breeding: Virtually unknown. It seems to be able to nest both in trees and on the ground. This owl was observed using abandoned nests of other birds in trees. During the courtship period, male claps wings under body in flight. Female lays two eggs and incubates them alone. Both parents feed the young. Juveniles appear to have a deep blue pupil.

Mortality: Human persecution is probably the major cause of unnatural deaths. Stygian Owl characteristics such as long ears tufts, dark coloration and particularly the brilliant red reflection of the eyes when illuminated by lamps have been associated with the Devil. As an example, its vernacular name in Brazil is "coruja-diabo", or "devil's owl"!

Habitat: It is said to be a forest owl, commonly found high in the mountains. It also occurs in humid and semi-arid forests, in fully developed tropical rain forest and in low, thorny bush country from about 700m up to 3,000m above sea level. Usually absent from lowlands. On the other hand, field observations in south-east Brazil and Belize showed Stygian owls hunting mostly in savannah-like habitats. Thus, forests may be mostly used as roosting sites during daytime.

Distribution: It is found in parts of north-west and east Mexico, parts of Belize and Guatemala, in Cuba and the Isle of Pines, Hispaniola, Colombia, Ecuador, north-west and south Venezuela, south and central Brazil, all over Paraguay and north Argentina.

Distribution of the Stygian Owl Asio stygius

Status: Uncertain

Original Description: Wagler, Johann Georg. 1832. Isis, oder Encyclopaedische Zeitung, von Oken 25 (1817-1848 Jena): Col. 1221.

Subspecies: A. s. stygius, A. s. barberoi, A. s. lambi, A. s. noctipetens, A. s. robustus, A. s. siguapa

References:

Page Information:

Text and Range Map by José Carlos Motta-Junior & Adriana de Arruda Bueno
The text above was a combination of literature reviewing and personal field experiences by the authors. Page last updated 2012-07-30

OwlPages.com Owl Species ID: 280.020.000