Dispersal is a critical life-history component; it determines gene flow and has profound effects on population structure, demography, social systems, and population viability. To add to our knowledge of dispersal and, in particular, our understanding of the relationship between dispersal and inbreeding, I studied three aspects of the biology of the red-cockaded woodpecker: dispersal of breeding females; the costs, benefits, and frequency of inbreeding; and the effect of inbreeding on natal dispersal.

Dispersal of breeding female red-cockaded woodpeckers is strongly associated with inbreeding avoidance and mate choice, weakly associated with site choice, and not found to be associated with social constraints. Estimates of mortality for non-dispersing and dispersing breeding females were 24 and 59 percent per year, respectively-rare evidence of the cost of breeding dispersal.

Significant costs of close inbreeding were found. Closely related pairs (kinship coefficient greater than 0.1) had lower hatching success as well as lower survival and recruitment of fledglings than unrelated pairs. Moderately related pairs (kinship coefficient between 0 and 0.1) and moderately inbred individuals had increased hatching success, but did not produce more young.

Despite documented costs of close inbreeding and a predictable spatial distribution of closely related males near the natal territory, female fledglings disperse a median of only two territories and a modal distance of one territory. Natal dispersal of females is affected by closely related males on the natal site but unaffected by closely related males or moderately related males that are off the natal site.