Non-offspring nursing in social carnivores: minimizing the costs

We compare the nursing behavior of two species, African lions(PanfheraLeo) and spotted hyenas(Crocuta Craig Packer crocuta), and showthat non-offspring nursing is much less common in hyenas thanlions. Hyenas spend less time with their cubs, are more alertduring the suckling attempts of cubs, and more frequently resistthe attempts of non-offspring. Vigilance against milk theftmay therefore influence the distribution of non-offspring nursingacross species. Our detailed study of non-offspring nursingin lions shows that females preferentially nurse their own offspringand that cubs are more surreptitious when attempting to sucklefrom other females. Non-offspring nursing in lions is most commonwhen the costs are lowest. First, non-offspring nursing is morecommon among close kin. Second, females with small litters,and presumably more milk to spare, give a higher proportionof their nursing to non-offspring. Third, females give a higherproportion of their nursing to non-offspring as their own cubsgrow older and need less milk. Cubs reared in créchesdo not appear to gain more milk that cubs raised alone, andfemales do not show any evidence of reciprocity in nursing oneanother's offspring. We suggest that non-offspring nursing inlions occurs as a by-product of the females' communal defenseof their cubs against infanticide.