Spatial and temporal patterns of territory use of male California sea lions (Zalophus californianus) in the Gulf of California, Mexico

Little is known about the spatial distribution patterns of territory use throughout the breeding season and the potential influence of these patterns on male behavior and fitness for California sea lions (Zalophus californianus (Lesson, 1828)). We used empirical data from behavioral observations to document the distribution of 1271 territories during the 2004-2006 breeding seasons at three breeding colonies in the Gulf of California, Mexico. Territories were depicted as circular objects and overlaid over one another in ArcINFO (R), separated by island and year. Areas with consistent overlap in territory use were identified among years. Territory boundaries and locations were spatially distinct within breeding seasons and at each of the breeding colonies. Males occurring in these areas were partially influenced by island, year, territory size, number of females, aggressive interactions, and distance to nearest neighbor (best fitting modela- AIC = 1273.09, omega(i) = 0.99). However, the best model only accounted for 30% of the variation, indicating that other variables are needed to explain the occurrence of these hot spots. Territory site selection, therefore, may be influenced by extrinsic factors under which female choice may be operating resembling a lek-like mating system.