Opportunistic Evidence of the Impact of Bacterial Infections on Social Integration in Vampire Bats

Abstract Social integration can affect an individual’s susceptibility to infectious disease. Conversely, infectious disease can reduce an individual’s social activity. Yet, it remains unclear to what extent short-term infections can inhibit social integration and the formation of new relationships. During a previous study on relationship formation, we captured 21 female common vampire bats ( Desmodus rotundus ) from different wild populations and housed them together in captivity. Upon introduction, we observed an unplanned outbreak of bacterial infections that caused cutaneous lesions. After treating infected bats with an antibiotic, five bats recovered, but four others suffered lasting injuries. Given that observations of how natural infections alter relationship formation are rare, we analyzed how allogrooming rates changed over time among familiar and new dyads consisting of the nine infected and 12 asymptomatic bats. We found that (1) infected bats demonstrated reduced activity and social behavior, (2) more severely infected bats gave and received less allogrooming than asymptomatic bats, (3) the effect of infection was larger for new dyads relative to familiar dyads, and (4) this effect decreased as infected bats recovered and new dyads became more familiar. These opportunistic observations were consistent with the hypothesis that short-term infections can impact the formation of new relationships.