Linking energetics of individuals to bear populations

• Author / Creator

  López Alfaro, Claudia Viviana

• Dynamics in wildlife populations emerge from the interactions between individuals and their environment. Constraints between individual nutrition and food availability are therefore fundamental to understanding how species adapt to environmental variability and to identify mechanisms controlling population-level processes. Brown bears (Ursus arctos) exhibit a wide variety of life history traits across its distribution that may be a consequence of differences in their diet. Amount and quality of nutritional resources influence individual energy storage and this plays a central role in female reproductive success. Using energetic simulations models I integrated existing knowledge of energetics and nutrition to explore how the interactions among the ecology and physiology of brown bears, and the nutritional quality of the bear’s habitat influence body mass and thus reproductive success. The model simulates the transfer of energy and protein from the environment to the individual, accounting for allocation in maintenance, growth and reproduction. Results reveal that: lean tissue and high protein foods play a fundamental role in reproductive success of bears. The relationship between protein available early in the season and energy available late in the season determine the allocation of nutrients in growth and reproduction and thus influence life history traits such as body size. Minimum levels of fat reserves necessary to support reproduction during hibernation varied from 19% to 33% of the total body mass depending on the number of cubs and length of lactation. However, when nutritional environments are poor (resource limiting) lactating bears require higher levels of denning body fat to support lactation after den emergence. Interactions between the digestive tract capacity of bears and food resource quality limit mass gain in bears and thus female reproductive success. Results reveal that brown bear populations in Alberta are restricted by the nutritional quality of its environment. This has two management consequences for Alberta’s threatened population: (1) it limits the carrying capacity of bears resulting in small population sizes; and (2) rate of population recovery will be slower than what has been observed in other populations such as the Greater Yellowstone Ecosystem. This study provides insight into how nutritional factors control reproductive success in brown bears how this ultimately affects population processes.

• Subjects / Keywords

  • Bear
  • Wildlife nutrition
  • Ursus
  • Energetics

• Graduation date

  Spring 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R39092

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.