TROOP MALE MEMBERSHIP CHANGES AND INFANT KILLING IN LANGURS (PRESBYTIS-ENTELLUS)

Almost all studies of Presbytis entellus have resulted in observations of troop male membership changes. Reports from three studies indicate that in some cases troop male membership change occurs through rapid and complete adult male replacement with attendant infant mortality. Data from other investigations of P. entellus show or suggest a different pattern of troop male membership change with no infant mortality. The phenomena of infant killing and rapid male replacement are evaluated on the basis of review of data from ten P. entellus studies. While these and my own data indicate that male social instability (i.e. frequent changes in troop male membership) is species-typical for P. entellus, they do not support the hypothesis that infant killing represents part of an evolved male reproductive strategy.