Walking in Their Footsteps: New Approaches to Identify Behavioural Processes and Define Home Ranges Using Animal Movement Data

• Author / Creator

  Auger-Méthé, Marie

• Animal movement and space-use patterns influence the distribution and abundance of species, predator-prey interactions, and many other ecological processes. Different approaches are used to study individual's space-use strategies and each approach suffers from unique challenges. The mechanistic underpinning of some movement models have led many to confuse patterns with process, while coarse space-use analyses have led many to miss critical aspects of animal behaviour. In this thesis, I address these challenges by refining models of animal search strategies and developing new methods to incorporate drift in home range analyses. Understanding how animals find resources with incomplete information is a topic of interest and controversy in ecology. Two search strategies have become prominent: the Lévy walk and area-restricted search (ARS). Although the processes underlying these strategies differ, they can produce similar movement patterns and current methods cannot reliably differentiate between them. I present a method that can simultaneously assess the strength of evidence for these two strategies, and assess the empirical support for the use of each strategy by a range of species: woodland caribou (Rangifer tarandus caribou), grizzly bears (Ursus arctos), and polar bears (U. maritimus). Although previous methods would have found evidence for the Lévy strategy, my method shows greater support for the ARS strategy. My results also show that species and individuals vary in their search strategies. While the ARS was sufficient to explain the movement of some caribou and grizzly bears, none of the models examined adequately explained the movement of polar bears. These results demonstrate the usefulness of this method when evaluating the evidence for the Lévy and ARS strategies, and highlight the need for additional mechanistic search strategy models. A home range represents the area an animal use to perform the majority of the activities required for survival and reproduction. As such, measuring home range size has been an important tool to quantity the amount of habitat an animal requires. However, in moving habitats, traditional home range estimates may be ill-suited to this task. I present a new approach to estimate the amount ice habitat encountered by polar bears. These estimates showed that the traditional geographic home range underestimates both the movement of bears and the amount of ice habitat that they encounter. The results also indicated that bears living on highly mobile ice might be exposed to higher energetic costs, and potentially larger energetic gains, than bears inhabiting more stable ice. By improving methods to identify search strategies and developing new approaches to investigate the effects of drift on animal home ranges, I provide ecologists a set of new tools to study animal space use and contribute to the flourishing field of movement ecology.

• Subjects / Keywords

  • Area-restricted search
  • Lévy walk
  • Home range
  • Sea ice
  • Animal Movement
  • Drift
  • Polar bears
  • Grizzly bears
  • Caribou

• Graduation date

  Fall 2014

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3F18SR52

• 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.