A Case of Offspring Adoption in Free-ranging Polar Bears (Ursus Maritimus)

S.N. Atkinson, M.R.L. Cattet, S.C. Polischuk, M.A. Ramsay


During a study of the reproductive ecology of polar bears (Ursus maritimus) in western Hudson Bay (Canada), we documented a case of litter adoption. In an eight-month period, a ten-year-old adult female lost a litter of two cubs-of-the-year and adopted three other cubs-of-the-year. This is the first reported case of natural offspring adoption in polar bears, and its significance as a reproductive strategy is unknown. Nevertheless, the observation raised questions regarding the social circumstances under which adoption may occur and the benefits or costs to maternal fitness in a solitary mammal such as the polar bear.

Key words: polar bear, Ursus maritimus, litter adoption, maternal fitness


Animal behaviour; Animal reproduction; Polar bears; Churchill, Cape, Manitoba

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DOI: https://doi.org/10.14430/arctic1187

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