The Ages of Non-breeding Kangaroos

Abstract

In central Australia, anoestrous red kangaroos and males with reduced interstitium were, in general,the younger adults. Anoestrous females suckling young throughout drought were among the oldest in the population. The weights of non-breeding animals were lower than those of reproductive counterparts of the same tooth class. No similar relationship was found for aspermous males, their distribution being random in the population, supporting the idea that the condition is induced by high ambient temperatures. As red kangaroos are not known to have dominance hierarchies in the wild but rather are nomadic, gregarious and promiscuous, it is suggested that the experience of older animals plus the social benefits of larger size may gain them nutritional advantage during drought.