Site fidelity of black brant wintering and spring staging in the strait of Georgia, British Columbia

Abstract

Site fidelity has important implications for population genetics and dynamics. In birds, most studies have dealt with breeding ground fidelity, ignoring the fact that waterfowl mainly pair in winter or early spring. We used multiple observation data from a mark-resight study of Black Brant (Branta bernicla nigricans) to estimate fidelity to wintering and spring staging areas in Boundary Bay and Parksville-Qualicum, British Columbia. Site fidelity was low for winter residents but still indicated that Brant were faithful to Boundary Bay. Birds seen twice or more during any given winter had significantly higher site fidelity rates than those seen only once. The models for the spring period showed the presence of transients in both Boundary Bay and Qualicum. Birds seen for the first time in an area had a lower probability of returning to that area than birds seen in more than one year. Survival probability was significantly higher for Qualicum birds than for Boundary Bay birds. We concluded that prior knowledge of an area was an important determinant of site fidelity, and that low site fidelity levels were unlikely to lead to genetic substructuring of the population.