Social organization of sea otters in Prince William Sound, Alaska.

Abstract

Enhydra lutris were spatially segregated into predominantly (97%) male areas at the front of the expanding population and breeding areas with fewer (up to 33%) males. Mating occurred year-round, but peaked in September and October. Females first bred at 4 yr old and were capable of pupping annually; they generally separated from their pup before mating. Males established breeding territories that enabled prolonged precopulatory interactions that may have prompted female-pup separation and post-copulatory interactions that precluded females from mating with other males. Male mating success was related to age, weight, territory quality, and length of time they maintained their territory. After the breeding season, territorial males returned to male areas where food was more abundant. Young, dispersing males also entered male areas and remained there until attaining breeding age. In male areas, otters commonly rested in groups of >50 individuals. Gregariousness promoted social interactions and likely enhanced food finding and (historically) predator protection. As food diminished, males moved into adjacent, unoccupied regions; females then occupied former males areas. -from Authors