Authors: Andrew E Derocher Magnus Andersen Øystein Wiig Jon Aars
Publish Date: 2010/02/20
Volume: 64, Issue: 6, Pages: 939-946
Abstract
We assessed the role of size mass and age in mating and nonmating polar bears Ursus maritimus at Svalbard Norway during the spring breeding season The ratio of male to female mass in malefemale pairs ranged from 100 to 302 overline x = 199 indicating that mating males were larger than mating females but with substantial variation Paired males were older than unpaired males and male mass was related to age However males paired with females were not significantly different in body mass from those males caught alone Wounds and scars resulting from fights between males began at about 6 years of age and peaked at about 17 and 20 years of age respectively The frequency of broken canines in males presumably due to increased malemale conflicts increased with age but showed little increase in females The wide range of male size in malefemale pairs and the agerelated signs of injury suggest that male polar bears engage in both scramble competition and contest competition for access to breeding females The mating system of polar bears is variable but is best described as female defense polygyny or serial monogamyAssistance in logistics was kindly provided by the Governor of Svalbard We are grateful for the help of the Hopen Radio staff who provided an excellent base for operations The Norwegian Polar Institute funded this study with assistance from the Norwegian Research Council and the World Wildlife Fund Ages of bears were determined by D Andriashek and C Spencer of the Canadian Wildlife Service Environment Canada Edmonton Animal handling methods were approved by the National Animal Research Authority PO Box 8147 Dep N0033 Oslo Norway and complied with Norwegian law S Amstrup kindly provided helpful comments on an earlier draft of this paper
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