Cross-species fostering affects meat preferences of wild house mice

Wild-strain male house mice were fostered at birth onto conspecifics, deer mice, or domestic Norway rats. In adulthood, their flesh-eating preferences were tested by allowing them to feed from freshly asphyxiated conspecifics and either deer mice or rats. The mice ate significantly more conspecific flesh than contraspecific flesh, except when the flesh offered was that of the contraspecies upon which the mouse had been fostered at birth. The failure of cross-species-fostered mice to discriminate between their own species and their foster species in flesh-preference tests is attributed to their having learned early in life to respond to the foster species in the same way they normally respond to conspecifics, that is, by approaching them, investigating them, and, when finding them dead, feeding upon them.