Some (Don't) Like it Hot : Investigations of wolverine (Gulo gulo) activity patterns across seasons

Increasing temperatures due to ongoing climate change have varying impacts on environments and the species that inhabit them. For this reason, it is important to understand how species are affected or may adapt to higher temperatures, to evaluate species vulnerabilities and future distributions. This is of particular relevance for the wolverine (Gulo gulo), a cold adapted species inhabiting the northern hemisphere. In Sweden, a national management plan influences the growth of the wolverine population; currently, because of ongoing predator conflicts in reindeer husbandry areas in northern Sweden, the population is shifting their distribution south. This may create long-term problems for population persistence if wolverines cannot adapt to the warmer southern temperatures in the new regions they are colonising. This study aims to investigate wolverine activity patterns during the winter and summer season to gain a deeper understanding of their behaviour, ecology, and possible future distributions in relation to temperature. GPS and accelerometer data from 12 individuals from the southern wolverine population were used along with actual temperature data from the area collected between 2018 and 2024. The activity patterns were analysed in R, using overlap plots and Generalised Additive Models (GAMs), to visually inspect activity and movement patterns across seasons and temperatures during different periods of the day. The results reveal that the wolverines were more active and moved longer distances during midday in winter compared to summer. When less activity and movement were observed during midday in summer, they instead appeared to shift this to the period between sunset and sunrise. Furthermore, the analysis, which included ambient temperature in the area showed that wolverines were less active during midday as ambient temperatures increased in the summer season. This was the opposite pattern to what was observed around midnight in summer. In the winter season, wolverines were generally more active as temperatures increased and their activity levels were either stable or increasing as temperatures increased. These results indicate that higher temperatures have an impact on wolverines’ behaviours, where they adjust their activity and movement depending on the season and ambient temperature, which may help them to thermoregulate. These findings are of importance considering future conservation methods, as they show how wolverines behaviourally adapt to warmer temperatures. However, there are likely multiple factors influencing wolverine activity, for instance, predator-prey interactions, which needs to be investigated further in future studies.