Master of Science (MSc)
Faculty of Science
Frances E.C. Stewart
The Arctic and Sub-Arctic ecosystems are seeing accelerated changes in temperature, landcover, and consequently species abundance and distributions. Reliable distributions, and associated population density estimates, are essential for effective conservation and management efforts. Growing concerns from northern communities regarding the relationship between muskox and declining caribou populations strengthens the need for updated information on muskox populations within mainland Northwest Territories (NWT). The first objective for my research was to quantify and map updated winter estimates of abundance, density, and distribution of muskoxen within three recent survey regions located in mainland NWT, using a multiple covariate distance sampling method (MCDS), paired with density surface modelling (DSM). My second objective was to explore spatial and social predictors of muskox habitat associations to help infer the extent and potential causes of their contemporary southward expansion across mainland NWT. I tested two competing hypotheses that drive ungulate distributions generally across large spatial and temporal scales of high habitat heterogeneity, as encompassed by the study regions investigated here; muskox density and distribution may be driven by the nutritional landscape where environmental covariates representing high forage quality best predict muskox occurrence. Alternatively, muskox density and distribution may be driven by a predatory landscape, where environmental covariates that support antipredator grouping behaviours best predict muskox occurrence. Through my analyses I infer muskox populations are stable in northern regions (the Sahtú and Beaufort Delta regions) and growing in southern regions (the East Arm region) of mainland NWT; range expansion of muskoxen appears to be continuing southward beyond their historical boundary. I showed varying support for both hypotheses. Muskox density was best predicted by nutritionally important environmental covariates but muskox distribution did not uphold my nutritional hypothesis, while group size was often correlated with land cover that supports antipredator grouping behaviours. However, weak, and inconsistent results across all regions suggest that unmeasured environmental conditions that occur similarly in all regions may also influence muskox occurrence and grouping behaviours. Snow depth and predator occurrence may be important considerations for future investigation. I suggest continued and expanded aerial survey efforts and additional environmental data collected at finer spatial grains may help to inform future muskox density and distribution analyses across mainland NWT.
Rentmeister, Charlotte, "Variation in mainland Northwest Territories late-winter muskox (Ovibos moschatus) density estimations and habitat associations above and below treeline." (2024). Theses and Dissertations (Comprehensive). 2610.