Temporal changes in mother-offspring discrimination in the prairie vole (Microtus ochrogaster)

The objective of this study was to determine if mothers of a group-living rodent that often raise offspring communally exhibit temporal changes in their behaviour towards unrelated offspring. In Experiment 1, we tested the retrieval tendency and huddling behaviour of prairie vole (Microtus ochrogaster) mothers presented with one of their own and one unrelated newborn (1-2 days old). In Experiment 2, we recorded the duration of cohesive and aggressive behaviours; by mothers presented with one own or one unrelated newborn (2-4 days old) and later one own or one unrelated weanling (22-24 days old). In both experiments, mothers did not discriminate between own and unrelated newborns. In Experiment 2, mothers treated unrelated newborns the same as their own but were significantly more aggressive towards unrelated weanlings than own weanlings. Mothers were also more likely to behave cohesively with own weanlings than unrelated weanlings. Our results suggest that prairie vole mothers discriminate between unrelated weanlings but not unrelated newborns. Differences in maternal behaviour towards newborn and weanling offspring may result from differences in the costs and benefits of investment in offspring at different ages.