Identification

Perching: Medium-sized raptor with short beak, pale brown back, white breast streaked with brown, and prominent brown "teardrop" below eye. Sexes similar in plumage.

Flying: Pointed wings, rapid wing beats, long banded tail, distinctive dark axillaries ("armpits") and dark bar on wing lining (front part of underwing).

Nesting Habitat

Cliffs in open country such as grasslands, deserts, and shrublands, usually below 3000 m. They lay their eggs directly onto the rock of a ledge, pothole, or crevice, or occasionally in a used hawk or eagle nest. Nest sites are prominently marked by excrement ("whitewash"), and screaming of adults is audible from 1-2 km. In the Flatirons near Boulder they typically nest in south-facing potholes; in the Pawnee Buttes, they nest on cliff ledges. Adults compete with peregrine falcons for nest sites, although these two species can nests successfully in close proximity.

Nesting Dates

Courtship: late March to early June

Incubation: late April to mid-July

Dependent nestlings: late May to late July

Clutch sizes range from 2-6 eggs. Incubation period is about 30 days; young fledge about 40 days after hatching.

Statewide Distribution and Population

Only about 5000 pairs nest in all of North America. About 300-500 pairs probably nest throughout Colorado, with highest nesting densities in the Front Range foothillsand the north central mountains. Nesting populations have declined near urban areas, particularly in the area between Denver and Colorado Springs and from Pueblo south to New Mexico.

State and Federal Status

Colorado State Wildlife Action Plan Tier 2 species.

Search and Nest Monitoring Protocol

Beginning early April, search potential nesting habitat (cliffs) for whitewash, then observe potential nesting and perching sites for 2-3 hours every week from a fixed observation point located at least 800 m away. Once nesting is confirmed, monitor nests on weekends to enforce climbing and recreational closures. Continue monitoring until late July or until all young have fledged.

Recommended Nest Buffer Areas

CPW recommends no surface occupancy (beyond that which historically occurred in the area) within 800 m of the nest site and no human encroachment or disturbance within 800 m of the nest site from 15 March through 15 July.

References

Bent, A. C. 1937. Life histories of North American birds of prey, part 1. U.S. National Museum Bulletin 167, Washington, D.C.

Craighead, J. J., and F. C. Craighead. 1956. Hawks, owls, and wildlife. Stackpole Books, Harrisburg, PA.

Enderson, J. H. 1964. A study of the Prairie Falcon in the central Rocky Mountain region. Auk 71: 16-35.

Johnsgard, P. A. 1990. Hawks, eagles, and falcons of North America. Smithsonian Institution press, Washington, D.C.

Kingery, H. E., ed. 1998. Colorado breeding bird atlas. Colorado Bird Atlas Partnership, Denver.