Turnover and dispersal of prairie falcons in southwestern Idaho

We studied Prairie Falcon (Falco mexicanus) breeding dispersal, natal dispersal, and turnover
at nesting areas in the Snake River Birds of Prey National Conservation Area (NCA) from 1971-
95. Of 61 nesting areas where falcons identified one year were known to be present or absent the following year, 57% had a different falcon. This turnover rate was 2-3 times higher than that reported elsewhere for large falcons, and may have been related to high nesting densities in the NCA. Turnover at nesting areas was independent of nesting success in the previous year, but was significantly higher for females nesting on large cliffs. Mean distance between natal and breeding locations for 26 falcons banded as nestlings and later encountered as nesting adults was 8.9 km. Natal dispersal distances were similar for males and females, but more than twice as many males marked as nestlings were later encountered nesting in the NCA. Fourteen adult falcons found on different nesting areas in successive years moved an average of 1.5 km between nesting areas; males dispersed significantly farther than females. Natal and breeding dispersal distances in the NCA were lower than those reported for Prairie Falcons in other study areas. Only four falcons banded as nestlings were found outside NCA boundaries
during the breeding period, and only one of these birds was known to be occupying a nesting
area. We encountered no falcons banded outside the NCA occupying nesting areas in the NCA during this study.