The Ringed Seal: Behavioral Adaptations to Seasonal Ice and Snow Cover

Behavioral adaptations for maintaining breathing holes in sea ice and lairs in the overlying snow cover allow ringed seals to occupy sea ice environments from which other marine mammals are excluded for much of the year. The broad distribution of ringed seals in the ice-covered seas of the northern hemisphere created a niche for an apex predator, and polar bears have evolved as specialists preying on ringed seals. The earliest occupation of the Arctic by people, likewise, depended heavily on the year-round availability of ringed seals. Reliance on breathing holes limits ringed seal movements for as much as 9 months of the year, with implications for foraging and reproductive behaviors as well as for predator avoidance. Ringed seals forage throughout the year with the greatest intake during a brief foraging period between the breakup and subsequent formation of sea ice. Predator avoidance appears to explain the allocation of time better than optimal foraging, at least during ice-bound periods. The under-ice behavior of breeding adults is more consistent with mate or resource guarding than with territoriality as a mating strategy. Feeding through lactation requires a trade-off between time spent foraging and attendance of pups vulnerable to predation. Ringed seals are becoming more vulnerable to predators in the water and on the ice as refuge on ice and under snow diminishes in a warming Arctic.