Long-Eared Owl
Asio otus

During spring of 1887 naturalist Denis Gale collected eggs from 11 long-eared owl nests in Boulder County. Twenty years later, University of Colorado Museum curator Junius Henderson classified this species as a “common resident of the mountains and plains.” By the mid-1980s, long-eared owls were nesting at only two known sites in the county: a cliff near White Rocks and a grove of Douglas-firs in Skunk Canyon. During the 1990s, no nests were reported.

During the 2000s, a half dozen newly-documented nest sites cropped up, suggesting a modest recovery. These sites include ponderosa pine woodlands on Shanahan Ridge and at  Heil Ranch Open Space, dense shelterbelts on the plains, and an urban park in Louisville.

The local long-term decline in numbers of breeding long-eared owls has coincided with an increase in nesting populations of great horned owls. The adaptability of great horned owls may give them a competitive advantage over long-ears in our urbanizing environment.

Gale found nests with eggs (3 to 5) between April 10 and May 20. Young fledged in late June or July. The owls typically used magpie or crow nests in box elders or willows on the plains, and in Douglas-firs in the foothills. Long-eared owls often nest near meadows, where the adults hunt mice and voles. During the 1990s, a pair in Rocky Mountain National Park nested in spruce-fir forest at 10,700 feet.

Long-eared Owl

Vocalizations: Loud hoots given singly; barks, wails, moans, and squeals.

Nesting: Dense riparian thickets and dense Douglas-fir stands, plains and foothills, March-July.

Where to listen and look: Search for winter roosts and rare nests in shelterbelts and dense conifers, plains and mesas.

Cornell McCaulay Library reference