Pup recognition in Mus musculus: parental discrimination between their own and alien young.

The responses of male and female mice each presented with a sequence of 4 pups from their own litter, a pup from another litter but of the same age and strain, and finally their own pup were noted. Both sexes spent longer sniffing the alien pup than the preceding own pup regardless of the age of pups at testing, and more time licking the alien pup on some test days. Young pups (Days 0-3; birth = Day 0) emitted fewer ultrasounds in the presence of a male than a female, but there was no quantitative difference in the vocalizations of own and alien pups. These data indicate that adult mice are able to discriminate between their own and alien offspring; this discrimination appears to be based upon olfactory and possibly gustatory cues rather than auditory ones.