Reduced body size and cub recruitment in polar bears associated with sea ice decline

Ecological Applications
By: , and 



Rates of reproduction and survival are dependent upon adequate body size and condition of individuals. Declines in size and condition have provided early indicators of population decline in polar bears (Ursus maritimus) near the southern extreme of their range. We tested whether patterns in body size, condition, and cub recruitment of polar bears in the southern Beaufort Sea of Alaska were related to the availability of preferred sea ice habitats and whether these measures and habitat availability exhibited trends over time, between 1982 and 2006. The mean skull size and body length of all polar bears over three years of age declined over time, corresponding with long‐term declines in the spatial and temporal availability of sea ice habitat. Body size of young, growing bears declined over time and was smaller after years when sea ice availability was reduced. Reduced litter mass and numbers of yearlings per female following years with lower availability of optimal sea ice habitat, suggest reduced reproductive output and juvenile survival. These results, based on analysis of a long‐term data set, suggest that declining sea ice is associated with nutritional limitations that reduced body size and reproduction in this population.

Publication type Article
Publication Subtype Journal Article
Title Reduced body size and cub recruitment in polar bears associated with sea ice decline
Series title Ecological Applications
DOI 10.1890/08-1036.1
Volume 20
Issue 3
Year Published 2010
Language English
Publisher Ecological Society of America
Description 15 p.
First page 768
Last page 782
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