Thursday, January 6, 2011

Barred Owl

This widespread woodland owl dozes by day on a well-hidden perch but seldom relies on its good camouflage to avoid harm. Instead, it flies away at the least disturbance, seldom tolerating close approach. But where foot traffic is heavy, such as along boardwalks in southern swamps, the barred owl may sit tight and provide good views at close range. It hunts mainly from a perch but will also hunt on the wing, preying on small mammals, birds, amphibians, reptiles, and invertebrates. It prefers to nest in a natural tree hollow, but it will also use an abandoned stick nest of another species. Polytypic (4 ssp.; 3 in North America). Length21" (53 cm); wingspan 43" (109 cm).

Identification Flight is heavy and direct, with slow, methodical wingbeats; occasionally makes long, direct glides. Adult: chunky, dark brown barring on its ruff-like upper breast; rest of underparts are whitish with bold, elongated dark brown streaks; lacks ear tufts. Central tail feathers expose 3–5 pale bars between their tips and the tips of the uppertail coverts. Sexes alike in plumage; female larger. Chiefly nocturnal. Juvenile: by about September, young birds acquire a complete set of fresh flight feathers; may be variably worn on adults. Central tail feathers expose 4–6 pale bars.

Geographic Variation Weak to moderate; clinal where ranges meet. The southeastern subspecies, georgica, is darker brown than the widespread nominate subspecies, varia. Subspecies helveola of southeast Texas is paler.

Similar Species The underparts of the slightly smaller spotted owl are spotted overall, not barred and streaked. Hybridization has occurred where ranges overlap; the hybrids’ plumages, voices, and sizes were intermediate between the two species.

Voice Highly vocal, with a wide range of calls. Much more likely than other owls to be heard in the daytime. Its most common vocalization is a rhythmic series of loud hoot or whoo notes: who-cooks-for-you, who-cooks-for-you-all. Also often heard is a loud, drawn-out hoo-waaah that gradually fades away; it is sometimes preceded by an ascending agitated barking. Often a chorus of two or more owls will call back and forth with these and other calls; the female’s voice is higher pitched.

Status and Distribution Common in eastern North America. Has expanded its range north and west through Canada’s boreal forest and then southward into Montana, Idaho, and California. Year-round: resident in mature mixed deciduous and uniform coniferous forests, often in river bottom­lands and swamps; also in upland forests. Breeding: probably in southeastern Alaska. Migration: More northerly populations may drift south during late autumn if prey are scarce. Accidental on Bermuda.

Population Stable to increasing in North America.

—From the National Geographic book Complete Birds of North America, 2006