RESPONSES BY RAT PUPS TO THEIR OWN NEST VERSUS A STRANGE CONSPECIFIC NEST

In a two-choice preference test, Norway rat pups discriminated between bedding from their own nest versus bedding from the nest of a strange conspecific dam whose pups were the same age (±1 day) as the subjects. Twelve-day old pups preferred their own bedding (p<0.02), 16-day old pups were indifferent to the two types of bedding, and 20-day old pups preferred the strange bedding (p<0.05). Among mammals, few naturally occurring preferences exhibit such a striking reversal of polarity over so brief a time span. The cues mediating the preferences stem from some endogenous characteristic that is peculiar to each dam and her litter. Such cues are likely to involve one or more of the chemical senses. © 1979.