WIDE-RANGING BY NESTING PEREGRINE FALCONS (FALCO-PEREGRINUS) DETERMINED BY RADIOTELEMETRY

In 1994, 2 adult male and 3 adult female Peregrine Falcons (Falco pere grinus) were radio-tracked during hunting flights in the nesting seaso n in Colorado. Based as many as 319 locations per bird, 95% harmonic m ean contour home ranges varied from 358-1508 km(2). All estimated rang es overlapped even though the most distant nests were separated by 28 km. About 60% of the locations were less than 8 km from nest sites, bu t about 20% of locations for females exceeded 23 km. Searches from air craft verified that several hunting flights were as far as 20-43 km fr om nest sites and were much greater than previously reported. One fema le flew at least 79 km on one flight and, during another flight, the s ame bird flew over 19 km in 10 min, averaging 115 km/hr. Peregrine Fal cons in Colorado apparently obtained prey in widely separated places w ith no apparent dependence on any certain area.