Steven H Ferguson

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Phylogenetic comparative methods are often improved by complete phylogenies with meaningful branch lengths (e.g., divergence dates). This study presents a dated molecular supertree for all 34 world pinniped species derived from a weighted matrix representation with parsimony (MRP) supertree analysis of 50 gene trees, each determined under a maximum(More)
We review seven Arctic and four subarctic marine mammal species, their habitat requirements, and evidence for biological and demographic responses to climate change. We then describe a pan-Arctic quantitative index of species sensitivity to climate change based on population size, geographic range, habitat specificity, diet diversity, migration, site(More)
We investigated the influence of ice conditions on activity and movement patterns of polar bears in the CanadianWest Greenland Arctic. We used radiotelemetry data gathered over 11 years (1989–99) from 160 adult female polar bears to test for differences in movement and activity of bears inhabiting active ice and consolidated ice. Bears inhabiting active ice(More)
Many hypotheses for larger body size with increasing latitude invoke environmental explanations, such as decreasing temperature. We propose a novel explanation that links environmental selection pressures and body size with spacing behaviour. We test for causal pathways between (1) environment (snow, latitude, primary productivity, seasonality, and(More)
BACKGROUND Killer whales (Orcinus orca) are the most widely distributed cetacean, occurring in all oceans worldwide, and within ocean regions different ecotypes are defined based on prey preferences. Prey items are largely unknown in the eastern Canadian Arctic and therefore we conducted a survey of Inuit Traditional Ecological Knowledge (TEK) to provide(More)
Predation can regulate prey numbers but predator behaviour in multiple-prey systems can complicate understanding of control mechanisms. We investigate killer whale (Orcinus orca) predation in an ocean system where multiple marine mammal prey coexist. Using stochastic models with Monte-Carlo simulations, we test the most likely outcome of predator selection(More)
Classification of animal vocalizations is often done by a human observer using aural and visual analysis but more efficient, automated methods have also been utilized to reduce bias and increase reproducibility. Beluga whale, Delphinapterus leucas, calls were described from recordings collected in the summers of 2006-2008, in the Churchill River, Manitoba.(More)
Animals store lipids, which are 13C-depleted, in their tissues that often must be extracted to correctly interpret δ13C data. However, chemical lipid extraction (CLE) can alter δ15N values and lipid normalization (LN) models are not consistent across fauna. We determined whether lipids should be extracted by assessing effects of CLE and validating LN models(More)
We developed a conceptual model of spatial organization in vertebrates based upon changes in home range overlap with habitat quality. We tested the model using estimates of annual home ranges of adult females and densities for 30 populations of brown bears (Ursus arctos) in North America. We used seasonality as a surrogate of habitat quality, measured as(More)
Killer whales (Orcinus orca) are major predators that may reshape marine ecosystems via top-down forcing. Climate change models predict major reductions in sea ice with the subsequent expectation for readjustments of species' distribution and abundance. Here, we measure changes in killer whale distribution in the Hudson Bay region with decreasing sea ice as(More)