Cross-seasonal effects on reproductive performance of Pacific black brant

Abstract

We used re-sightings of Pacific Black Brant from San Quintin Bay, Ojo de Lieber Lagoon, and San Ignacio Lagoon, Baja California and Boundary Bay, British Columbia, to examine winter population structure, variation in structural size and the importance of winter location to individual reproductive performance at the Tutakoke River colony. Sexes of adults and juveniles were distributed equally among winter locations. Adult structural size and mean age were similar among winter locations. A higher proportion of juveniles over-wintered in San Quinton Bay and Ojo de Liebre Lagoon. Individuals wintering at Ojo de Liebre and San Ignacio lagoons were less likely to breed and initiated clutches later than those that wintered in Boundary Bay or San Quinton Bay. Maternal mass did not vary, although clutch size was slightly larger in individuals that wintered in southern areas. Variation in winter location and habitat quality could influence individual reproductive performance and population dynamics.