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'' <br />1 <br /> <br /> <br />HABITAT FOR THREATENED OR ENDANGERED WILDLIFE IN COLORADO <br />S ep ties: American Peregrine Falcon, Falco peregrinus anatum <br />Status: Federal and State Classified as Endangered <br />Habitat Requirements and Limiting Factors: Habitat requirements for nesting <br />peregrine falcons in the Central Rocky Mountain Region appear to <br />be quite variable from site to site: Efforts are underway to <br />delineate common factors which are essential to occupancy of all <br />nesting sites. In general, the sites require two components: <br />1) adequate nesting habitat, and 2) extensive hunting habitat <br />with sufficient prey to support the breeding falcons and their <br />offspring. <br /> Nesting sites (eyries) are located on precipitous cliffs ranging <br /> in height from 40 to 2100 feet, .but cliffs averaging between <br /> 200 and 400 feet are most frequently preferred. Several ledges, <br /> potholes or small caves must be present in the cliff face to <br />' serve as suitable nest sites. A breeding pair will frequently <br /> alternate their nesting activities to different ledges on a <br /> cliff face and they will often relocate on adjacent cliff faces, <br /> (it appears that at least one pair of Colorado peregrines shifted <br /> to a cliff one mile distant from the previous nesting cliff). <br /> So, protective measures will have to be addressed to an entire <br /> cliff complex rather than a single cliff. At higher elevations, <br />' cliffs with southerly exposures are preferred. Most peregrine <br /> nests are located at elevations of less than 9;000 feet above <br /> sea level (one site was recently confirmed at 10,500 feet <br /> elevation). Nesting peregrine falcons will not tolerate exces- <br /> sive human encroachment or prolonged disturbance in the vicinity <br /> of the nesting cliff. Any activity or development above the <br /> nesting cliff will very likely cause abandonment. Breeding <br />' peregrines become extremely agitated and may abandon the site <br /> if disturbance occurs during the courtship period prior to <br /> initiation of egg laying. One explanation as to why some sites <br />were occupied in spite <br />of excessive human activity in the vicin- <br /> , <br />ity below the nesting cliff is that the falcons occupied the <br /> site early in the season prior to the human activity buildup and <br />' had eggs or young when the distrubance occurred. Thus, they were <br /> attached to the site and would not abandon it at that time. In <br /> Colorado, peregrines generally return to the nesting cliffs in <br /> late February or early March and initiate courtship activities <br />' which continue through to mid or late April when the eggs are <br /> laid. The young hatch from mid to late May and fledge from the <br /> eyrie in mid to late June. The young and adults remain in the <br /> vicinity of the nesting cliff up to several months after fledging <br /> (young were observed in the immediate vicinity of one eyrie <br /> through mid September). <br />' <br /> -40- <br /> <br />I~ <br />r <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br /> <br />