Pup Provisioning in the Cooperatively Breeding African Wild Dog, Lycaon pictus, is Driven by Pack Size, Social Status and Age

Abstract

Division of labour, in terms of providing for offspring, in obligate cooperatively breeding mammalian species is poorly understood. To understand offspring provisioning in a cooperatively breeding canid, we analysed a long-term dataset comprising 22 African wild dog, Lycaon pictus, denning events (nine packs over nine consecutive years). We investigated the effects of sex, age class, social status, and pack size on the likelihood and frequency of regurgitating food to pups at the den. We found that the interaction of social status and pack size affected the likelihood of regurgitation. Specifically, when in a large (≤15) pack, dominant individuals were less likely to regurgitate than subordinate individuals. However, in smaller (≤ 15) packs, dominant individuals were more likely to regurgitate than subordinate individuals. We also found that the interaction of age and pack size affected the frequency of regurgitation. Specifically, in large packs, yearlings regurgitated more frequently per observation period than adults. Contrastingly, in smaller packs, adults regurgitated more frequently. Sex did not affect pup provisioning. We suggest that these contrasting patterns of helping are best explained by a strong selection pressure for individual behaviour that results in larger pack sizes in this species. When in larger packs, costs are shared as the division of labour spreads amongst individuals. In smaller packs, a division of labour requires individuals that already experience costs (such as reproduction) to be further burdened by provisioning. Overall, our results support that the need for more helpers to care for offspring contributes to the evolutionary consequence of an inverse density dependence.