Do less or eat more: strategies to cope with costs of parental care in a pair-living monkey

Abstract

Infant care is costly, and strategies to deal with its energetic demands may involve increasing feeding time or reducing activity levels or social time. In mammals, the most energetically expensive form of infant care is lactation, followed by infant carrying in species where young are transported over long distances. In titi monkeys, infants are carried primarily by males, which allows us to tease apart the effects of lactation and infant carrying. We analysed activity budgets and diet composition in adult males and females in seven free-ranging groups of red titi monkeys, Plecturocebus cupreus, in the Peruvian Amazon over 14 months. Females fed more, consumed more arthropods and rested less after infant birth than before, and males fed less, consumed fewer arthropods and rested more. Lactating females increased feeding time at the expense of mainly resting and, to a lesser degree, social time. Despite the general decrease in social time, females conserved grooming time within pairs. Our results suggest that females and males use opposing strategies to cope with the costs of parental care and indicate the importance of pair bond maintenance for females.