Pathogens can affect host behaviour in ways that influence disease transmission as well as survival andfitness for both host and pathogen. Hibernating bats with white-nose syndrome (WNS) show a numberof unusual behaviours including increased frequency of arousal from torpor, altered roosting behaviourand premature emergence. However, mechanisms underlying these patterns are not understood, and thebehaviour of bats with WNS has not been examined systematically. Three hypotheses could explainincreased arousal frequency. Bats may arouse to (1) groom in response to skin infection, (2) drink tooffset dehydration or (3) increase activity, possibly in an attempt to access resources, avoid a source ofinfection or limit the risk of infecting relatives. We tested these hypotheses with captive little brown bats,Myotis lucifugus, inoculated with Pseudogymnoascus destructans, the fungus that causes WNS. In contrastto predictions of all three hypotheses, bats inoculated with the fungus tended to be less active thancontrols during arousals from torpor and did not increase grooming or visits to the water source in theirenclosures. However, bats showed a dramatic reduction in clustering behaviour as infection progressed.Reduced activity and clustering could represent adaptive, maladaptive or pathological responses.Reduced activity could be an energy-saving mechanism or a pathological consequence of infection whilereduced clustering could have beneficial or detrimental consequences for transmission, energetics, waterbalance and survival. Our results highlight the need for studies of host behaviour to understand dynamics of wildlife infectious diseases.