Mother–offspring recognition in communally nesting degus, Octodon degus

Evolutionary theory predicts that mothers will direct care preferentially to their own offspring. This may be difficult when mothers nest communally, as occurs with degus, a social South American rodent. We used an olfactory habituation–discrimination technique to determine whether co-nesting mothers could discriminate among the odours of young that differed with respect to relatedness (a mother's own offspring or not), familiarity (a mother and pup did or did not occupy the same cage) or both. We tested mothers that were housed with an unrelated female and her litter (experiment I) or a sister and her litter (experiment II) and conducted tests when pups were 2 weeks old (during lactation, experiments I and II) and 6 weeks old (after weaning, experiment I). In experiment I, lactating mothers discriminated between the odours of their own pups and their co-nesting partner's pups, and between the odours of their own pups and unfamiliar pups, but not between odours of their co-nesting partner's pups and unfamiliar pups. After weaning, however, mothers discriminated between odours based on familiarity, but not kinship. In experiment II, lactating mothers discriminated between the odours of their own offspring and their co-nesting sister's pups. Thus, degu mothers could distinguish between their own offspring and those of their co-nesting partner whether mothers were related or not. Mothers could therefore potentially use olfactory cues to care discriminatively for pups they encounter in their communal nest.