Tyto alba
(Common Barn-owl)

Physical Description:
14-20" (36-51 cm). Medium-sized owl. White, heart-shaped face ringed with tan with dark eyes and light bill; no ear tufts. White below, sparsely spotted black; golden tan back with fine pearl gray streaks; spotted black and white on crown, back, and wings.

Similar Species- Short-eared Owl, immature Snowy Owl

Song:
A loud, almost blood-curdling, rasping hiss.

Distribution:
Resident from southern Canada and northern U.S., south to South America. Northern populations are partially migratory.

Diet:
Eats mainly small mammals. In many areas (including southern Idaho), voles are principal prey. Pocket gophers, ground squirrels, pocket mice, kangaroo rats, and deer mice are locally important.

Ecology:
Nests in cavity in standing snag, cliff, or building. Breeding density depends on availability of nest sites and food supply. Young disperse widely from natal area (up to hundreds or 1900 km has been documented). Home ranges may overlap considerably where nest sites and prey are abundant. Individual remains solitary or paired when not breeding. Hunts mostly at night, from about 1 hr after sunset to about 1 hr before sunrise. May forage up to a few km from nesting or roosting site. Hunts mainly by quartering flights 1.5-4.5 m above ground. In northern winter, often roosts in dense conifers; also roosts in nest boxes, barns, and silos. Susceptible to starvation during prolonged low temperatures and snow cover. In Utah study, most adults survived only 1 breeding season. Great Horned Owl is principal predator in North America. Long-term study of breeding density and foraging ecology continues in Idaho Birds of Prey Area.

Breeds throughout year in Texas (as many as 3 broods/year); some California birds attempt 2 broods/year. Average clutch size is 4-6 eggs. Female incubates eggs (21-24 days for single egg, 29-34 days for full clutch). Female broods and feeds young, male brings food. In Utah study, mean fledging time was 64 days. Male may care for fledged young as female begins second clutch. Most individuals apparently breed at 1 yr. Pair are typically monogamous with life-long pair bond; polygyny sometimes occurs.

Conservation:

Element Code:	ABNSA01010
Status:	Protected nongame species
Global Rank:	G5
State Rank:	S3
National Rank:	N5

Important State References:
Marti, C.D. 1988. A long-term study of food-niche dynamics in the common barn- owl: comparisons within and between populations. Can. J. Zool. 66:1803-1812.