Male-Male Competition and Infanticide Among the Langurs <i>(Presbytis Entellus) </i>of Abu, Rajasthan

TLDR

Infanticide by male langurs during leadership changes is a documented phenomenon, often linked to intense female competition and the brief tenure of new males. The study compared infanticide events in Abu troops with similar reports from Dharwar and Jodhpur to identify patterns. Infanticide consistently occurs when outsider males take over, prompting females to mate with the new leader and, in most cases, to conceive within eight months, thereby enhancing the new male’s reproductive success.

Abstract

Leadership changes accompanied by infanticide are described for two langur troops at Abu, Rajasthan. These events are compared with similar reports from Dharwar and Jodhpur. In each of seven cases, infanticide occurred when males entered the troop from outside it. Females whose infants were killed subsequently exhibited estrous behavior and copulated with the new leader. In three troops at Dharwar and Abu, seventy percent of females who lost infants gave birth within eight months. In these cases, infanticide appears on average to increase the reproductive success of the incoming male. Confronted with a male reproductive strategy disadvantageous for them, females respond to usurping males with various counter-strategies. From a comparison with other mammals, infant-killing by males may be advantageous (1) when there is intense competition for females; and (2) when frequent take-overs potentially curtail the tenure of an incoming leader.