Survival costs of fast exploration during juvenile life in a small mammal

Animal personality is considered to be subject to natural selection, and measuring its fitness consequences is an important step in the study of the evolution of this phenomenon. The evolutionary costs and benefits of certain personality traits are frequently assumed to fluctuate across different life history stages. However, little is still known about survival consequences of personality during juvenile life. We predicted survival costs of exploration tendency in juvenile European rabbits (Oryctolagus cuniculus), which we studied under quasi-natural conditions. In addition, consistencies between exploration and the animal's behavioral responses in other contexts were tested. Early exploratory behavior was assessed in two annual cohorts, either observationally by quantifying the time course of exploring the area around the nursery burrow shortly after emergence above ground or experimentally by conducting open-field tests shortly before emergence. In both years, the study revealed consistent results: more exploratory individuals had a lower chance of survival until the end of the vegetation period, presumably due to a higher predation risk. Fast explorers, as assessed by their exploration of the burrow environment, were also less sociable and tended to be more aggressive toward conspecifics as subadults. Sociability was repeatable across time. Furthermore, fast explorers, as assessed by their open-field behavior, were bolder in a handling test before emergence. These consistencies across context and time suggest the existence of personality. In conclusion, the results provide evidence for survival costs of fast exploration during juvenile life. The findings are in line with predictions on personality-related life history variation.