A stochastic modelling framework to accommodate the inter-annual variability of habitat conditions for Peary caribou (Rangifer tarandus pearyi) populations

摘要

Climate variability and a wide range of anthropogenic disturbances in the Canadian Arctic Archipelago (CAA) have a negative impact on Peary caribou (Rangifer tarandus pearyi) populations by encumbering seasonal migration patterns, forage accessibility, and calving processes. Increasing Arctic temperatures and precipitation along with the higher frequency of extreme weather events (winter cyclones, rain-on-snow) are responsible for spatiotemporal shifts in floral and faunal phenology, changes in species overlap, and functional alterations of trophic relationships. Building upon empirical estimates of the Peary caribou population rates of change on the Canadian Arctic Archipelago, we introduce a two-pronged approach aiming to characterize year-to-year variability of habitat conditions across the Canadian Arctic Archipelago from 2000 to 2013. Our explanatory variables are based on meteorological (surface snow melt, precipitation, temperature, wind speed) variables, landscape features (fraction of rockland), and resource competition with muskoxen (Ovibos moschatus). These habitat suitability estimates form the basis of a stochastic algorithm to recreate the population growth rates and identify locations, where Peary caribou could experience >10%, 25%, or 50% decrease relative to the population levels at the beginning of our study period. Our analysis identifies the Boothia island complex as a high-risk area, where the low Peary caribou population size is suggestive of their increased susceptibility to extirpation after episodic weather-related events, disease outbreaks, or even elevated incidental predation. In Banks island complex, we provide evidence that the volunteered curtailment of hunting, achieved through co-management between Indigenous communities and regional biologists, moderated (and possibly reversed) the declining trends as established during the pre-2000 period. Our random-walk search also suggests that the prevailing habitat conditions in Melville and Bathurst island complexes were generally favorable and could partly explain the recent Peary caribou population increase. We conclude by identifying unaccounted factors that are critical for building an empirical modelling framework with quasi-mechanistic foundation in order to evaluate the impact of climate change on the integrity of Peary caribou populations within any location of the Canadian Arctic.