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Population, individual and behavioural approaches to understanding the implications of habitat change for arctic ground squirrels Open Access


Other title
Climate change
Arctic ground squirrel
Population biology
Shrub encroachment
Type of item
Degree grantor
University of Alberta
Author or creator
Wheeler, Helen Claire
Supervisor and department
Hik, David (Biological Sciences)
Examining committee member and department
Tierney, Keith (Biological Sciences)
King-Jones, Kirst (Biological Sciences)
St. Clair, Colleen (Biological Sciences)
Lewis, Mark (Bioloical Sciences)
Foote, Lee (Renewable Resources)
Fryxell, John (Integrative Biology, University of Guelph)
Department of Biological Sciences
Date accepted
Graduation date
Doctor of Philosophy
Degree level
The ecological niche describes the entire set of resources and environmental conditions suitable for species to occur and persist. In northern ecosystems, rapid climate change appears to be altering these conditions and increasing the likelihood of shifts in distribution and abundance of species, with unknown consequences for resilience of ecosystem processes. Arctic ground squirrels are a widespread northern species, acting as agents of community disturbance and prey for many northern predators. Understanding the effects of habitat characteristics on occurrence and population persistence of arctic ground squirrels will improve projections of how habitat change may affect their ecosystem role. I compared arctic ground squirrels inhabiting an alpine ecotone extending across shrub, shrub-tundra and tundra habitats in southwest Yukon, and considered a variety of ecological factors determining distribution, population dynamics and individual behaviour. Populations in high suitability habitats (tundra) have greater viability and persisted at higher density with greater survival compared with low suitability habitats (more shrubs), possibly driven by a reduced risk of predation associated with lack of visual obstruction. Surprisingly, intermediate levels of shrub cover appeared to support the lowest densities and lowest survival in adult females. The apparent low suitability of shrub-tundra was also characterized by temporary habitat associations by non-resident individuals.   Trends in behaviour and individual condition between habitats were inconsistent with those observed at the population level. These patterns resulted from either differences in individual state between habitats, or possibly maladaptive behaviours in transitional shrub-tundra habitat. Specifically, giving-up densities, which indicate costs of foraging and individual condition, were not consistent with predictions based on the observed population processes. Individuals in shrub habitat had higher giving-up-densities, lower adult female mass, and lower juvenile growth rates compared with shrub-tundra. Other factors showed no clear association with density or apparent habitat suitability, including reproductive output and juvenile coccidial parasite load. In general, the increasing occurrence of dense shrub in the Arctic is likely to reduce the density and restrict the distribution of arctic ground squirrels. If these low suitability habitats become more isolated, the potential for local extinction of arctic ground squirrel populations may increase.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Wheeler, H. C. and Hik, D. S. 2012. Arctic ground squirrels (Urocitellus parryii) as drivers and indicators of change in northern ecosystems. Mammal Review, In press.

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