Just keep moving? Long-term temporal stability of locomotor activity and exploratory tendencies in captive grey mouse lemurs (Microcebus murinus)

Among-individual variation and contextual intra-individual stability of behaviour over time is considered the main criterion for establishing personality in animals. Locomotor activity and exploration shown in unknown surroundings are two of five established personality traits. We investigated the behavioral stability and drivers of their temporal dynamics in captive grey mouse lemurs (M. murinus) in an experimental Large Open Field (2x2m) Paradigm over a period of five years. Behaviours were analysed for over 350 experiments conducted in seven experimental series with 72 (37 males, 35 females) individuals (age: 3 - 133 months) with known body mass. A total of 14 different behavioral variables were quantified from standardised top-view videos. In addition, a principal component analyses provided three independent components. Temporal behavioral stability was investigated over 16 time intervals ranging from 2 weeks to 50 months. As expected, repeatability decreased over time, with significant differences existing between males and females. The results showed higher short-term repeatability in males than females, but stronger behavioural changes in males than females over time. The influence of sex, age and body mass on the dynamics of mouse lemur locomotor activity and exploration was tested using generalized additive mixed models. We found significant impacts of body mass and of age on activity and explorative behaviours, while body mass and age correlated positively with each other. These findings suggest sex-dependent life history trajectories and age-dependent changes in body condition that impact locomotor activity and exploratory tendencies in this small solitary primate species from Madagascar.