Temporal consistency and behavioural variation : a long-term study of exploration and activity in Microcebus murinus

Among-individual variation and intraindividual stability of behaviours over time are considered the first criteria for establishing personality in animals. We investigated behavioural stability and determinants of variation in locomotor activity and explorative behaviour in a small primate, the grey mouse lemur, Microcebus murinus, to contribute to a better understanding of the drivers of temporal behavioural dynamics. We observed behaviours shown in captivity in an unknown, that is, potentially risky situation, an open field. Experiments were conducted over a period of 5 years, and we tested the influence of sex, age, body mass, season and previous experimental experience on interindividual and intraindividual behavioural dynamics. Behavioural repeatability decreased over time and did not differ between the sexes. Age was a major driver of behavioural dynamics between individuals, as older animals marked more and explored earlier than younger animals, suggesting a possible life-history trade-off. Body mass had significant negative effects on exploration, and animals were less active outside the reproductive season. Increasing experience led to a decrease of activity and exploration, suggesting important long-term memory effects. Individual behavioural variability differed partly between the sexes and correlated positively with exploration and locomotor activity, suggesting that more explorative and active mouse lemurs are also more flexible, which may be advantageous under changing environments in the wild. An association between activity and exploration suggests a potential behavioural syndrome in mouse lemurs. Our findings highlight the importance of activity- and exploration-related behaviours as components of mouse lemur personality. Taken together, long-term behavioural dynamics of this ecological generalist can be best explained by age-, condition- and experience-dependent behavioural changes that individuals undergo over the course of their lifetime. In particular, they may be of evolutionary relevance for these small solitary foragers in adapting to an always-changing environment.