Barn Owl
Tyto alba
Though locally uncommon, barn owls nest in a variety of sites on the plains, including embankments, tree cavities, old barns, and radio towers. A cliff pothole at the White Rocks, along Boulder Creek, was the first documented nesting site in the county in 1943. Recently active sites include a historic barn on N. 63rd St, heart-shaped cavities in dying cottonwoods on St. Vrain and Plateau roads, burrows on the banks of Coal Creek, a water tower on Gunbarrel Hill, a wood duck nest box at Valmont Reservoir, and a grain silo in Lafayette.
Boulder County lies near the northern edge of this cosmopolitan owl’s central North American breeding range. Barn owls also inhabit most of Latin America and Australia and much of Eurasia and Africa.
When alarmed, barn owls sway their heart-shaped heads from side to side or walk backwards into the shadows. Two calls, a beak-clapping rattle and an ear-piercing hiss-scream, suggest a ghostly presence. Snowy feathers and buoyant, silent flight enhance this effect.
Our barn owls begin nesting as early as March and fledge young as late as November. Pairs may raise two broods. The female lays 2 to 11 eggs. Incubation requires about 30 days. The adults bring in up to 30 rodents (mostly mice, voles, and shrews) per night. Using their acute hearing, barn owls can capture rodents in total darkness.
Vocalizations: A loud hiss-scream similar to a locomotive venting steam; a prolonged rattle; slurps, clicks, and squeaks.
Nesting: Burrows, rock crevices, caves, tree hollows, barns and other structures; plains, March -November.
Where to listen and look: Embankments, cottonwood trunk cavities, and old barns on the plains.