Evidence of ‘sickness behaviour’ in bats with white-nose syndrome

Many animals exhibit distinct behavioural changes in response to pathogenic infections and these changes can be useful for understanding disease mechanisms. White-nose Syndrome (WNS) is a fungal disease causing rapid declines of hibernating North American bats. Cutaneous infection with the fungus Pseudogymnoascus destructans causes bats to arouse from torpor more frequently than normal, contributing to potential starvation. Mechanisms underlying increased arousal frequency are not fully understood but fungal invasion of the wings could trigger increased thirst and drinking to relieve fluid loss, or increased arousal for grooming to relieve skin irritation. Alternatively, bats might exhibit so-called ‘sickness behaviour’, a suite of responses to infection that reduce energetic demand. To test these hypotheses, we analysed video recordings of arousals by healthy and experimentally inoculated captive little brown bats (Myotis lucifugus), and scored behaviours that could reflect active (i