Social grooming in the common vampire bat, Desmodus rotundus

Abstract

Grooming patterns among 65 common vampire bats in hollow tree day roosts were studied by behavioural sampling techniques during a 15-month period. Self-grooming occurred more than social grooming in response to ectoparasites since the proportion of time spent self-grooming and the amount of ectoparasite infestation covaried positively among tree roosts while the time spent grooming others was independent of roots and ectoparasite level. Rates of social grooming were not independent of the sex of participants due to infrequent social grooming by adult males. Two variables, the level of relatedness and a measure of roosting association, which previously were shown to predict food sharing by regurgitation, correlated positively with the rate of social grooming. Since social grooming occurred more often than expected before a regurgitation and correlated with regurgitation frequency, it is suggested that this behaviour facilitates identification of food sharing partners by enabling a grooming bat to monitor other animals' potential for giving or receiving blood.