Mus spretus Lataste: a hygienic house mouse?

Abstract

Mus spretus, an aboriginal species of house mouse, appears to show a pattern of behaviour not reported in other rodents. Faeces are picked up and carried short distances in the mouth or rolled along the ground with the tip of the snout, often repeatedly. Two experiments using wild-caught subjects held temporarily in captivity investigated the potential function of this behaviour. Provided with a choice of faeces up to 12 h old from different donors in an arena, mice showed a strong preference for manipulating their own fresh faeces deposited during the trial, especially those in corners. A second experiment, using single fresh faecal samples encountered in a tunnel, confirmed that mice manipulated their own faeces (in 56% of trials) more frequently than those from conspecifics (26% of trials). Manipulation was not affected by the presence of tapeworm eggs in faeces, although this stimulated increased investigation from the donor. In both experiments, differences in investigation suggested that mice could discriminate between the faeces of conspecifics according to the sex and familiarity of a donor, preferring samples from familiar animals of the opposite sex (caught within 25 m of the subject). They showed no bias in manipulating samples from different conspecifics. Given the frequency with which moist fresh faeces stuck to mice as they passed, the results suggest that manipulation is a hygienic response to move sticky faeces away from pathways and resting sites. However, faeces are likely to play an important role in providing social information in M. spretus populations.