Spatiotemporal dynamics in habitat suitability of a large Arctic herbivore: Environmental heterogeneity is key to a sedentary lifestyle

Abstract

Quantifying spatial and temporal variation in habitat suitability is crucial to understand changes in animal distribution and to inform conservation and management initiatives, especially for species occupying regions profoundly impacted by climatic and environmental change. A detailed understanding of the environmental conditions shaping seasonal habitat suitability of free-ranging muskoxen (Ovibos moschatus), a key species in the Arctic tundra ecosystem, is currently lacking. We applied the maximum entropy modelling algorithm (MaxEnt) to build seasonal species distribution models (SDMs) over four years to quantify variation in habitat suitability in time and space. Suitable habitat was predicted based on location data from 27 GPS-collared adult female muskoxen in northeast Greenland and the spatial distribution of topographic variables and landcover within the study area. Overall, our results highlight distinct seasonal differences in both the spatial extent and distribution of suitable muskox habitat. Suitable space was smallest and spatially most clustered during autumn, and increased in extent and dispersion throughout the snow-covered period until peaking in summer. Nonetheless, the importance of environmental variables influencing habitat suitability was consistent across inter-annual and seasonal scales as habitat suitability was consistently predicted to be highest in vegetated, flat to moderately rugged terrain at low to medium elevation (<500–600 m.a.s.l.) close to the coast (<5–10 km). One year with extraordinary large amounts of snow differed from the general pattern, exhibiting markedly smaller areas of suitable habitat and higher spatial clustering. The results support the notion that adult female muskoxen are able to lead a relatively sedentary lifestyle due to the close proximity of suitable habitats across all seasons. However, above-average snow depths appear to be a potential bottleneck limiting access to suitable habitat, with consequences even beyond the snow-covered season. Our study provides the foundation for assessing potential future changes in habitat suitability and distribution of this key Arctic herbivore. Keywords: Species distribution modelling, Habitat suitability, Seasonality, Climate, Ungulate, Muskox