Natal dispersal and population structure in a migratory songbird, the indigo bunting

Abstract

Male and female Passerina cyanea were equally likely to return and breed in their natal areas. Variation in distance within the natal area was affected by date of birth. The local distribution of dispersal distances approximated a neutral model with a decreasing probability of settling with distance from the natal site. A population inbreeding coefficient ΔF of 0.01 was estimated from known genealogies and matings. The proportion of nestlings recaptured in a later year on their natal area was 1.65% of 1212 nestlings at the George Reserve and 8.78% of 1332 nestlings at Niles. Locally born birds comprised 1.6% and 13.0% of the breeding population in areas of 10 and 4 km2. Most buntings settle and breed more than 2 km from their natal site. Results are consistent with a model of neutral dispersal within a genetically open population. -from Author