Northern Pygmy-Owl
Glaucidium gnoma
On cold March evenings the dove-like whistles of courting pygmy-owls float through foothills ponderosa pine forests. These little owls call for only a few weeks while establishing and defending nesting territories. Too much vocalizing would attract northern goshawks, great horned owls, and other predators. In late April or May the female lays three to five eggs in a woodpecker hole or tree crevice. The young hatch about four weeks later.
Adults make a soft twittering sound around the nest as they shuttle birds, small rodents, and insects to their hungry young. They will dive-bomb magpies, squirrels, and humans that approach too close to the nest. They can kill rock doves, robins, and other birds much larger than themselves. They also hunt small rodents, lizards, and insects.
In Boulder County, northern pygmy-owls nest primarily in coniferous forests, from 5,500 to 10,000 feet. During winter they migrate vertically, sometimes concentrating in canyons at the base of the foothills. Partially diurnal, they perch on exposed branches, attracting mobs of chickadees, juncos, and other songbirds. False eye spots on the back of the owls’ heads may discourage attacks by songbirds and hawks.
Vocalizations: A series of breathy whistles, 1-2 per second, slightly syncopated (“toot-toot, toot, toot-toot”); a soft, creeper-like twitter around the nest; a wailing whistle when alarmed.
Nesting: Tree cavity in conifer or aspen, foothills to 10,000 feet, March-June. Only four nests have been documented in Boulder County.
Where to listen and look: Enchanted Mesa (Boulder Mountain Park), Sunshine and Left Hand Canyons, Hall Ranch Open Space.