Riding out the storm: Behavioural responses of a large herbivore to high-Arctic winds.

Extreme weather poses serious challenges to wildlife, often forcing animals to alter their behaviour with potential population-level consequences. Following contemporary climate change, the number and intensity of Arctic storms are increasing, but the responses of Arctic species to wind speed and episodic storms are poorly documented. We aimed to quantify behavioural responses (i.e. changes in movement modes and habitat selection patterns) of muskoxen (Ovibos moschatus) to wind speed and to compare estimates from before, during and after storm to hurricane-level wind events (wind speeds ≥24.5 m/s on the Beaufort scale). Hourly positions of Global Positioning System (GPS)-collared adult muskoxen (N = 61) tracked in northeast Greenland between 2013 and 2024 were georeferenced with data on wind speed, precipitation class (with or without), elevation, terrain ruggedness and vegetation type. Statistical movement modes were estimated using unsupervised hidden Markov models, and habitat selection patterns were quantified using step selection functions for summer (June-August) and winter (September-May). Results showed that wind speed influenced the allocation of time between movement modes. Increasing wind speed reduced the amount of time spent in states characterized by intermediate step lengths and turning angles, suggesting a decrease in foraging activity. Changes in state-time budgets were most pronounced under wet conditions during summer, likely due to reduced fur insulation and increased thermoregulatory behaviour. Habitat selection patterns during calm conditions (e.g. selection for dense vegetation) were reinforced at increasing wind speeds. State-time budgets of muskoxen affected and unaffected by storms were comparable between days before and after episodic storm events. During storms, however, the allocation of time among movement modes shifted more towards states indicative of resting at the expense of states indicative of foraging and relocating, which differed from muskoxen unaffected by storms. Muskoxen adopt a simple energy conservation strategy of bedding down in dense vegetation habitat to buffer against negative impacts of high wind speed, without actively compensating for potential lost foraging opportunities during episodic storm events. However, as the Arctic climate continues to change, the energetic implications of increasing wind speed and frequency of storms on individual fitness and population performance represent a valuable area for future research.