Crucial importance of pack size in the African wild dog Lycaon pictus
Courchamp F., Macdonald DW.
Although the massive organized slaughter of African wild dogs, Lycaon pictus, largely ended several decades ago, this endangered canid continues to decline and faces extinction. Several lines of evidence suggest that this arises from obligate cooperative breeding, which makes Lycaon more sensitive to anthropogenic mortality. A number of behaviours in this species are characterized by a reliance on helpers. These include cooperative hunting, defence from kleptoparasitism, pup feeding and baby-sitting. As a result, there are strong, positive relationships between pack size and the production and survival of pups, and pairs of wild dogs are often unsuccessful at raising offspring without the assistance of helpers. Consequently, a pack in which membership drops below a critical size may be caught in a positive feedback loop: poor reproduction and low survival further reduce pack size, culminating in failure of the whole pack. Here, we review the literature to reveal the importance of pack size in the African wild dog. Most importantly, we argue that there is a critical minimum threshold, below which packs face an increasing probability of extinction - an Allee effect with consequences for the conservation of this species, and of other obligate cooperators.