Among leopards whose cubs are regularly killed by lions, hyenas and even male leopards knowing where to find safe den sites can mean the difference between life and death. Secure den sites such as rock crevices and caves, or tunnels beneath tangled tree roots, are vitally important refuges for young, which must be left alone for many hours while their mothers hunt. Young females learn the location of these safe dens while they are growing up and often give birth in den sites where they themselves were born. For all the interest in leopards, Waser thinks philopatry may turn out to be more common in species such as beavers, wood rats and kangaroo rats animals in which females make large investments in their ranges. Kangaroo rats live in large mounds that take months to build and may contain up to six kilograms of stored seed.
Juveniles often inherit a mound from their mother.
Waser believes these female kin groups provide insight into socialization. When you try to imagine how social groups evolved, the first step was probably the retention of adult young, he says. The next step would be a set of circumstances that would favor the formation of groups, such as increased hunting efficiency or improved survival of young. These advantages are probably at the root of cooperative behavior in wolf packs, mongoose packs, hyena clans and lion prides. In the case of solitary leopards, clusters of closely related females can be viewed as a sort of exploded pride, where neighboring leopard females are as related as lionesses in a pride.