Behavioral response of moose Alces alces to summer heat stress

Minnesota moose are heat‐stressed during summers, which is adversely impacting their survival. We used both movement and activity data to explore the behavioral responses of Minnesota moose experiencing heat stress, termed ‘hot moose events' or HMEs, to understand how both ambient temperature and available habitat contribute to the ability of these moose to thermoregulate. Hot moose (≥ 39.17°C, as determined by internal biologgers that continuously recorded body temperature), failed to adopt the behavioral switch to foraging habitats during nocturnal activity displayed by moose maintaining normal body temperatures (i.e. normal moose), which might improve their overall fitness and survival. Hot moose also selected habitats differently than normal moose, including using open canopies that offer little mid‐day protection from solar radiation (e.g. ash swamp, meadow marsh bog), whereas normal moose had a stronger selection for thermal refugia. We further investigated the behaviors of moose prone to repeated HMEs within a summer season. Members of this group were majority male, experienced 5× the daily rate of HMEs compared to other hot moose, and were more likely to die. Our findings suggest some moose are making behavioral choices that appear to undermine their ability to thermoregulate on hot summer days, adversely impacting their survival. Individual drivers are likely complex and include both moose health factors and the availability or arrangement of quality forage and cover types. Although we were unable to pinpoint a difference in overall landscape composition between the choices hot and normal moose make, it is likely that fine‐scale differences in habitat features, such as patch size, forest structure, and distance to cover, play a key role. Future forest management efforts supporting both thermal and forage needs of moose will help mitigate summer heat stress in populations threatened by climate change.