9508319 Wolff We propose to study the effects of immigration of unrelated individuals on the breeding success of established residents in a habitat patch. Males or females that enter unfamiliar groups often disrupt reproduction by committing infanticide on young individuals or by disturbing normal breeding patterns. This study will document breeding success, survival, and population growth of the gray-tailed vole in habitat patches differing in degree of isolation. Animal movement, survival, and numbers will be determined by live-trapping, marking, and releasing animals within experimental enclosures. This study will allow us to test the role of kinship versus unfamiliarity in the breeding success of animals in fragmented landscapes. Construction of corridors to permit movement of animals between fragments has been suggested as a mechanism for maintaining viable populations increasingly fragmented by human activity. This study will contribute to our ability to manage habitat patches by increasing our understanding of the effect of behavior on breeding success.
