Spatial and Temporal Patterns of Territory use in California Sea Lions (Zalophus californianus californianus)

Robertson, K; Runcorn, C.; Young, J. K.; and Gerber, L. R.
School of Life Sciences, Arizona State University

Territorial behavior is known to influence male reproductive success and population dynamics in polygynous mammals. In California sea lions (Zalophus californianus californianus) a small fraction of males defend terrestrial and aquatic territories during the mating season. Little is known about the spatial distribution of territories at different spatial and temporal scales and the potential influence of these patterns on male behavior and fitness. We used GIS analyses to examine spatial variation and temporal patterns of male California sea lion territory use at three sea lion colonies in the Gulf of California during the 2004-2006 breeding seasons. Comparisons were made within and between breeding seasons. Preliminary results indicate that territory size is lowest and spatial clustering is highest at the peak of the breeding season. The relative position and number of territories remain stable and evenly spaced across years. This stability suggests that territory site selection may be integral to male reproductive success.