Differences in patterns of pup care in Mus musculus domesticus. VIII. Effects of previous experience and parity in XLII inbred mice.

An improvement in two variables of a retrieving test has been shown in eight inbred strains of mice following the second parturition. To test the possible contribution of presence at birth and/or caregiving to a cohabitation effect, retrieval behavior was measured in four groups of XLII inbred mice: one group of biparas, and three groups of primiparas; one without any previous maternal experience, one previously exposed to parturition and caregiving by an alien female, and one exposed to a female with her newborn litter. The two variables do not discriminate between the groups in the same way. The scores on one variable (first retrieval latency) fit into an increasingly complex hierarchy of cohabitational environment with parturient females. The second variable (move away from the pups) discriminates between those primiparas who had a cohabitational experience including both birth and caregiving and those that did not. Dissimilarities between the actions of these two variables are discussed in the light of genetic and ethological mechanisms.