Burrowing Owl
Athene cunicularia
These spindly-legged cuties once nested by the dozens in eastern Boulder County. Now they have diminished to scattered pairs that fledge far too few young to sustain a healthy local breeding population.
What has become of our burrowing owls? Banding studies of some North American populations suggest a high rate of winter mortality, possibly caused by ingestion of pesticides in Mexico. Automobiles kill hundreds each year. Loss of nesting habitat (particularly prairie dog colonies) also has threatened populations. In Boulder County, where many prairie dog colonies remain, fragmentation of nesting habitat by farms, highways, and subdivisions may lead to increased predation on these owls by great horned owls, red foxes, and dogs.
Burrowing owl pairs arrive in eastern Colorado in April. The female typically lays 6 to 11 eggs in an abandoned rodent burrow. Once the eggs hatch in May or June, the adults take turns bringing in insects and small rodents. The whole family flies south to Arizona, New Mexico, Texas, or Mexico in September.
Burrowing owls will abandon nests if grass grows tall enough to obstruct their view of terrestrial predators. They sometimes fight with, but rarely prey on prairie dogs.
Vocalizations: A soft coo-cooo or cackle;young make a rattlesnake-like hiss when begging for food.
Nesting: May-July in prairie dog colonies on the plains.
Where to look: Rock Creek Farm open space, prairie dog colonies around Boulder Reservoir, and other prairie dog colonies throughout the county. Several dozen pairs nest in prairie dog colonies near Barr Lake State Park and at Rocky Mountain Arsenal National Wildlife Refuge.