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The habitat ecology of the post-metamorphic coastal tailed frog (Ascaphus truei).
Alexandria L. McEwan (author)Chris Johnson (Thesis advisor)University of Northern British Columbia (Degree granting institution)
Master of Science (MSc)
Number of pages in document: 121
The coastal tailed frog (Ascaphus truei) has a biphasic life-history that includes the use of high-elevation streams and adjacent old growth forests. This species is at risk from a variety of land-use activities that result in younger and more fragmented terrestrial habitats. I investigated the fine-scale spatial ecology of post-metamorphic tailed frog populations as revealed by seasonal variation in activity and movement. I used an Information Theoretic Model Comparison approach to relate tailed frog captures in pitfall traps to sets of explanatory factors and infer habitat use by adult tailed frogs located with VHF radio transmitters. Trap data suggested that variation in the relative abundance and distribution was attributed to time of year, associated with reproductive activity seasonal trends in local climate canopy closure and distance to the larval stream. The most parsimonious logistic regression model for both years of trapping data demonstrated good' predictability (Area Under the Curve (AUC) > 0.7). Data from 24 tailed frogs with radio transmitters (8 males, 16 females) fitted to a resource selection function suggested that tailed frogs were positively associated with habitats containing decayed coarse woody debris (CWD), less light, adjacency to the larval stream, wet site types, and cool temperatures (11-12C). When compared to males, females were more selective in their choice of habitat (AUC > 0.7). Overall, the relationship between distribution and activity of tailed frogs was reflective of reproductive phenology in combination with micro-site or broader climatic conditions. Thus, habitat protections should reflect the behavior and habitat of the species as it varies across spatiotemporal scales.
Tailed frog -- Habitat -- British Columbia, Northwestern.Tailed frog -- Behavior -- British Columbia, Northwestern.