Abstract
In March 2009, we documented the death of one member of a triplet polar bear (Ursus maritimus) litter at its den site in the southern Beaufort Sea (SBS) of Alaska. We used a self-contained video camera unit to document activity between den emergence and departure. All three cubs showed low activity levels relative to other cubs observed, and one died within one week of den emergence. Necropsy confirmed that the dead cub had a low body weight and was malnourished. Capture later confirmed that the two surviving cubs were also undersized. Polar bear cub survival is influenced by many factors including litter size and sea ice conditions. Triplet litters are often smaller and suffer higher mortality rates than singletons and twins. This cub was not only a triplet but also born following 2 years of record minimum sea ice extent, both of which may have played a role in this cub’s demise.
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Acknowledgments
We thank S. C. Amstrup and G. Durner for invaluable assistance in writing this document as well as A. Derocher, T. DeBruyn, and K. Rode for their initial reviews. We thank W. J. Streever, D. Sanzone, and Tatyana Venegas of BP for their support and assistance. N. Hermon and R. Murray of Alaska Clean Seas and K. Thomas-Ford and D. Heebner of BP Environmental provided valuable assistance at the BP Milne Point facility. W. Dawley, B. Collver, and T. Cummings were helpful at the BP PBOC facility. We also thank B. Cardon, R. Minatra, J. Allen, D. Kruger, J. Michaels, and Fire Chiefs Ski and Vic, plus a number of mechanics and other personnel at both the PBOC and Milne facilities for their support and assistance in keeping our project on track and gear operational. Polar Bears International played a crucial role in supporting this work. Funding for this work was provided, in part by the Brigham Young University, the U.S. Fish and Wildlife Service, the National Fish and Wildlife Foundation, the U.S. Geological Survey, BP, the Columbus Zoo, and Polar Bears International.
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Robinson, R., Smith, T.S., Kirschhoffer, B. et al. Polar bear (Ursus maritimus) cub mortality at a den site in northern Alaska. Polar Biol 35, 139–142 (2012). https://doi.org/10.1007/s00300-011-1013-2
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DOI: https://doi.org/10.1007/s00300-011-1013-2