Maternal behavior of wild and domestic Rattus norvegicus recorded continuously in dual-chambered cages.

Continuous measurements of maternal behavior--the amount of time the mother was in contact with the litter and quality of nest--indicated no differences between these 2 stocks of rats. A decrease in both measures was found for both stocks over the 22 days of postnatal observation. The data indicated that the mother was with the litter more during the light portion of the 24-hr light-dark cycle and that wild rat mothers were in contact with their litters more than domestic mothers in the period around light offset.