Behavioral interactions between harbor seals (Phoca vitulina) and gray seals (Halichoerus grypus) on Cape Cod, Massachusetts

• Language: unknown
• Subjects: harbor seal; Phoca vitulina
• Online Access: http://hdl.handle.net/2047/d10016624

Behavioral interactions between harbor seals and gray seals in Chatham Harbor were surveyed over two seasons. Harbor seal occurrence on Cape Cod brackets the breeding season of the gray seal. As this season approaches, gray seals become highly organized, forming large groups. High intensity interactions increased among gray seals prior to the breeding months. Harbor seals are affected more by adjacent seals than are gray seals. Domination of shared sites and haul-out site distribution were biased toward gray seals. The majority of interactions were intraspecific, with a strong correlation between frequency of interactions and on-site seal abundance. In the presence of gray seals, harbor seals were interacting at a higher frequency with conspecifics. The presence of gray seals may not directly impact haul-out behavior of harbor seals. However, it influences onshore aggregation patterns of harbor seals hauled-out through the winter months.