Habitat Relationships of Sciurids in the Continental Taiga

Simpson, Holly

Taiga Biological Station, Department of Zoology, University of Manitoba, Winnipeg, Manitoba R3T 2N2




Simpson, H., 2000. Habitat Relationships of Sciurids in the Continental Taiga. Trent University, Hons. BSc. Thesis:44 pp.



Literature on the habitat preferences of Northern Flying Squirrel (Glaucomys sabrinus), Red Squirrel (Tamiasciurus hudsonicus) and Least Chipmunk (Tamias minimus) is inconsistent. The present study was conducted in the continental taiga of southeastern Manitoba. The landscape matrix included bog and upland plant communities which were disturbed by an extensive fire in 1980. The purpose of the study was to elucidate some relationships between these three species and the ever-changing environment of the boreal taiga, and to see if these relationships were consistent at different spatial scales. Squirrels were live-trapped during May and June of 1999 (1136 trap sessions) and habitat variables were measured within sites representing old and young bog, and upland plant communities. Density of overstory species and snags by diameter at breast height (dbh) classes were quantified to represent species composition of habitats, while percent cover of coarse woody debris (CWD) and percent cover of vegetation at four strata were estimated within nested microsites of 4m radius around each trap. Patterns of structural and compositional features of the habitat in association with each species were viewed on two scales by combining the data from the microsites into larger units. Results of Canonical Correspondence Analysis (CCA) showed that Glaucomys sabrinus was highly associated with the canopy, mature birch trees (dbh>10cm) at both scales, while habitat relationships for the other two species of Sciuridae are scale-dependent. Tamiasciurus hudsonicus exhibited strong association with mature jack pine (dbh>10cm) at the small scale, and a weaker association with young aspen (dbh<10cm) at the level of the site. Habitat relationships for Tamias minimus were not as apparent, but seem to suggest a preference for disturbed areas. Logistic regression models, based on Principal Components Analysis of the environmental variables, showed significant predictive ability for the occurrence of the two squirrels, but were unreliable for the chipmunk.



This page created August 1, 2001.




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