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PREDICTING LAIR ABANDONMENT BY RINGED SEALS BASED ON PHYSICAL PROPERTIES OF THE SNOWPACK

CONWAY, JOHN E  Davidson College.
Kelly, Brendan P  University of Alaska Southeast.
Hood, Eran  University of Alaska Southeast.

Ringed seal (Phoca hispida) populations may be responding to habitat changes associated with industrial activity and climate change in the arctic. Population assessment, however, has relied on visual surveys of the extensive sea ice habitat, and interpretation of those surveys has proven difficult. Throughout most of the year, ringed seals are not visible because they are feeding underwater or resting in lairs excavated in the snow covering the ice. They are visible on the surface only in the window between the onset of snowmelt, when lairs are abandoned, in late spring and ice breakup in summer. Surveys are meant to take place during that window, but the relationship between the onset of snowmelt and the timing of lair abandonment is not well understood. We used radio-telemetry to determine when 16 seals abandoned their lairs and compared the timing of lair abandonment with changes in cold content of the local snowpack. Snowpack cold content is the amount of energy required to raise the average temperature of a snowpack to its melting point (0ş C). Thus, cold content integrates average density, average temperature, and depth of the snowpack—all of which are directly related to the structural integrity of the snowpack. Our findings suggest that cold content is an accurate gauge of the structural integrity of ringed seal lairs. Cold content also was strongly correlated with snow temperature at the ice surface and that parameter may prove to be a more convenient predictor of lair abandonment. Predicting the timing of lair abandonment will allow for more accurate aerial surveys of ringed seal populations.


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