Effective dispersal of peregrine falcons (Falco peregrinus) in the Midwest, U.S.A.

Abstract

Dispersal is a significant life-history trait of vagile species that affects the distribution and genetic structure of populations. Natal dispersal in birds is the movement of an individual from its hatch site to a new location where its first reproductive effort occurs. To examine the ongoing recovery of the Peregrine Falcon (Falco peregrinus) in the upper Midwest, U.S.A., we assessed the influence of sex, hack-status (hacked or wild-fledged), and hatch site (cliff or human-made) on natal dispersal distance, and we evaluated directional trends of dispersal in the midwestern Peregrine Falcon subpopulation. We found that mean dispersal distance of female peregrines was >2 times farther than that of males. Dispersal distance did not differ between hacked females and wild-fledged females; however, hacked males dispersed significantly farther than wild-fledged males. Dispersal distance among urban-hatched females and cliff-hatched females did not differ, nor did dispersal distance of urban-hatched males and cliff-hatched males, probably because the sample size for cliff-hatched birds was small. As a whole, the direction of dispersal in midwestern peregrines was nonuniformly distributed and skewed to the northwest and southeast. This report may benefit future studies of peregrine demographics and population viability analyses by providing wildlife managers with information about the patterns and natal movements of Peregrine Falcons in the midwestern U.S. © 2013 The Raptor Research Foundation, Inc.