Author(s): SA WICH, PR ASSINK, FBECHER, EHM STERCK
A number of studies on birds and mammals have shown that individuals respond differently to neighbour and stranger call playbacks. This response is generally thought to be adaptive, because differentiating calls from neighbours and strangers can prevent the costs of unnecessary contests. In addition, it has recently been suggested that female lions use call recognition to avoid infanticidal males. In this paper we show that Thomas langur (Presbytis thomasi) males react more vigorously towards calls from strange than neighbouring males. It is hypothesised that, although differentiating between calls from different males can be useful to reduce unnecessary contests between the males, discriminating between individual calls is important because it might reduce the risk of infanticide.