Wide ranging by nesting Peregrine Falcons (Falco peregrinus) determined by radiotelemetry

In 1994, 2 adult male and 3 adult female Peregrine Falcons (Falco peregrinus) were radio-tracked during hunting flights in the nesting season in Colorado. Based as many as 319 locations per bird, 95% harmonic mean contour home ranges varied from 358-1508 km(2). All estimated ranges 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, but about 20% of locations for females exceeded 23 km. Searches from aircraft verified that several hunting flights were as far as 20-43 km from nest sites and were much greater than previously reported. One female flew at least 79 km on one flight and, during another flight, the same bird flew over 19 km in 10 min, averaging 115 km/hr. Peregrine Falcons in Colorado apparently obtained prey in widely separated places with no apparent dependence on any certain area.