Ecological consequences of nest site fidelity in Black Brant

Empirical tests of ecological advantages of site fidelity in birds are few because consequences of dispersal are rarely measured. We examined the relationship between dispersal distance between consecutive nesting attempts and age, nest success, reproductive performance, and spring environment for female Black Brant (Branta bernicla nigricans) nesting colonially at the Tutakoke River, Alaska, 1987-1993. We found little evidence of fidelity to natal sites. Young brant moved towards a peripheral area of the colony. Successfully breeding brant dispersed shorter distances than those failing to nest successfully. Brant that initiated nests early dispersed farther than brant that initiated nests late. Neither nest success nor initiation date in year t + 1 were related to dispersal distance (year t to year t + 1), but clutch size declined with dispersal distance, Although generally not significant, annual variation (interaction) in the relationship between dispersal distance and measures of reproductive performance (i.e., initiation date and clutch size) suggest that this relationship may be influenced by spring weather conditions. Evidence for the advantages of site fidelity in brant was equivocal. Dispersal distance explained little variation associated with reproductive performance. Variation in individual bird quality, environmental conditions, and demographic status may be more important determinants of breeding performance in brant than potential benefits of site fidelity.