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UBC Theses and Dissertations

Status, range, and habitat of the cascade mantled ground squirrel, Spermophilus Saturatus, in British Columbia Leung, Maria Ching-Yee


In this study, I investigated three aspects pertaining to the conservation of the Cascade mantled ground squirrel (Spermophilus saturatus). These were: 1) Its taxonomic relationship to its sibling species, S. lateralis; 2) Its range and distribution in British Columbia; and 3) A preliminary description of major components in S. saturatus habitat in British Columbia. The taxonomic relationship of S. saturatus to S. lateralis was determined by comparing skull characteristics and allele frequencies of blood enzymes. The skull of S. saturatus is larger and broader than its three neighbouring S. lateralis subspecies. S. saturatus had two alleles that were absent in S. lateralis and did not show segregation in any of the loci whereas S. lateralis did show polymorphism. Some S. lateralis were more closely related to S. saturatus than they were to other S. lateralis according to standard coefficients of genetic distance (Rogers' similarity and Nei's distance), but these came from the locations furthest from S. saturatus. The taxonomic status for S. saturatus is confirmed from the morphological differences, but is mainly validated by the presence of two unique alleles, together with geographic isolation from S. lateralis. The range and distribution of S. saturatus were determined from museum records, from survey forms, by recording opportunistic observations, by conducting stationary counts/walking transects, and by live-trapping. S. saturatus were found further north and west than previously reported, but not as far east as indicated by museum records. S. saturatus also appeared to be uncommon throughout its range in British Columbia. Drainage systems that delineate its range, and displacement by invading competitor species should be examined as probable factors limiting their dispersal. Survey methods used were evaluated and I make recommendations for their application in future surveys. The percent cover of different plant genera and unvegetated categories (e.g. rocks) was visually estimated at five natural locations (no food supplemented) and four food supplemented locations where S. saturatus were present. These cover types were placed in the perceived functional components of "natural food species", "burrowing sites", "perches" and "protective cover". This grouping into functional components provides a preliminary description of S. saturatus habitat. Although this study provides information on the taxonomic status, range, distribution, and habitat of S. saturatus in British Columbia and results in a recommendation for designating S. saturatus a "vulnerable species", further research is needed on these topics throughout its full range, including Washington State. These data are necessary to determine whether S. saturatus in British Columbia are representative of the species and what efforts are needed for their conservation.

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