By day, these bark-colored owls melt into their surroundings as they perch on  a cottonwood limb or peer out of a nest cavity. At night, when they swoop over meadows and streams snaring small rodents, birds, and crayfish, they’re more often heard than seen. Their two primary calls, a sustained trill and a horse-like wail or whinny, have enlivened dozens of horror and suspense movies.

Eastern screech-owls favor mixed deciduous woods bordering streams or wetlands. In Boulder County they nest in riparian woodlands and in shady urban neighborhoods. Nesting densities along sections of Boulder and St. Vrain Creeks average about one pair per linear mile.

The female lays three to seven eggs in a woodpecker hole, usually in a deciduous tree, in March or April. Young fledge in June or early July. Vocal activity peaks during the courtship period, November through February, and just after the young fledge. The adults may grow nearly silent while incubating eggs and brooding young.

These small owls adapt well to urbanization. Several pairs nest in Denver urban parks. In a Texas study, pairs nesting in towns were more successful than pairs nesting in rural areas.

Vocalizations: A high, horse-like whinny; a monotonic  trill, like the sound of a Ping-Pong ball bouncing on a hollow table; hoots, whistles, barks, and screeches.

Nesting: March-July in riparian woodlands and shady urban areas, mostly plains.

Where to listen and look: South Mesa Trail trailhead, near Eldorado Springs; Centennial Trail; Chautauqua Park; Boulder Creek at Sawhill Ponds; St. Vrain Creek west of Longmont.