Harbour seal grouping as an anti-predator strategy

摘要: Abstract Terrestrial grouping by western Atlantic harbour seals, Phoca vitulina concolor , was investigated to determine whether it has a functional significance and, if so, what the function might be. Two nofunctional hypotheses were tested: (1) groups arise from shortage of haul-out sites or space on sites; and (2) terrestrial are extensions formed in water for reasons not related hauling-out. Aerial surveys site use seals indicated that short supply. Observations one suggested limiting. Arrivals departures at study showed disbanded after period. The hypothesis functions increase probability predator detection tested measuring individual group vigilance relative size, simulating attacks field. Although decreased with increasing increased. Larger detected ‘attacks’ greater distances solitary seal failed detect an ‘attack’. It is proposed increases its detecting joining group.