Predator mobbing by an all-male band of hanuman langurs (Presbytis entellus)

An all-male band of 15 Hanuman langurs alarm barked and mobbed a leopard in Sariska Tiger Reserve, a forest in Rajasthan, India. After initially alarm calling and barking in response to the leopard's presence five animals persistently followed and watched the leopard for about an hour. During this time they were barking and tooth grinding. Both the initial alarm calling and the following mobbing can be interpreted as altruistic behaviour. However, unlike the situation in bisexual troops, Hanuman langur males may not be related to other members of the group and the evolution of such behaviour cannot necessarily be explained by kin selection.