Personality and foraging behaviour of Namaqua rock mice (Micaelamys namaquensis)

Abstract

Although there is a growing body of literature on animal personality (consistent interindividual differences in behavioural responses over time and space) and behavioural syndromes (correlation between personality axes found within a population or species), several aspects are still unexplored or misunderstood. Animal personality contributes to the understanding of individual variation in fitness and population trends and may explain sub-optimal foraging behaviour in individuals. To date, the studies of animal personality have been taxonomically and geographically biased, with most studies focussed on Passeriformes and in the Northern hemisphere. In addition, most studies concentrated on either endogenous (physiological state) or exogenous (environmental) factors, but not both. An animal is faced with multiple decisions daily that affect its fitness, most of which involve the gain of energy and nutrients. Both endogenous and exogenous factors influence these decisions by affecting where and when to forage, based on hunger motivation and perceived risks. In this study, I aimed to determine whether wild-caught Namaqua rock mice (Micaelamys namaquensis), rodents widely distributed throughout southern Africa, exhibit animal personality and a behavioural syndrome. In addition, I investigated whether animal personality was temporally consistent over extended periods or affected by habituation. Furthermore, I examined whether personality, as well as other endogenous (i.e., sex and satiation) and exogenous (i.e., conspecific and predator cues) factors, affected the foraging behaviour of rock mice. I measured exploration, aggressiveness, and boldness using an open-field, aggressive response, and a boldness test, respectively. I also investigated the foraging behaviour of M. namaquensis using a Y-maze. Results showed that animal personality was present in the study species and there was a behavioural syndrome between aggression and boldness, but exploration was not correlated with either of these. Comparisons between assessments before and after laboratory habituation revealed no temporal stability, however, the subsequent assessments post habituation was stable over time. Two of the three endogenous factors influenced the foraging behaviour. Despite the presence of a behavioural syndrome, only boldness affected the foraging behaviour of M. vi namaquensis, bolder individuals entered the maze and arms faster and remained in the arms for longer. Sex had no significant effect on foraging behaviour, while food-deprived individuals spent significantly more time foraging compared to satiated individuals. Predator odour was the only exogenous factor that resulted in avoidance behaviours. Thus, assessments of personality were affected by habituation in M. namaquensis and although it exhibited a behavioural syndrome, personality had only limited effects on their foraging behaviour. The lack of effect of sex was potentially due to the sexually monomorphic nature of M. namaquensis. Food-deprived individuals were more motivated to feed and behaved bolder to gain energy. The difference in response to conspecific and predator cues may be attributed to a disparity in the perception of danger. My study emphasises the importance of including both endogenous and exogenous factors along with their interactions to have a better comprehension of the degree to which they influence an animal’s behaviour. In the current study, the biggest influences appeared to be satiation and predation cues, and this might be applicable to other prey species.