Long-term consequences of early development on personality traits: a study in European rabbits

Early-life parameters such as litter size and growth are frequently associated with an animal's behavioral performance or motor skills as well as with its stress responsiveness. All these traits can be involved in the ontogeny of behavioral phenotypes, and therefore, we wanted to know whether features such as early growth also show long-term correlations with the animals' behavioral responses to challenges around maturity. We collected data on the early postnatal development of individually marked European rabbits living in a field enclosure and conducted 2 standardized behavioral tests shortly before the animals matured. In small enclosures, we experimentally tested their behavioral responses 1) in this novel environment and 2) to the confrontation with predator odor. Animals, which were more exploratory during the novel environment test, showed lower behavioral signs of anxiety during the predator test. Both responses were correlated with individual pup body mass, with subjects with higher body mass being more exploratory in the first test and showing lower levels of anxiety in the second. The animals' current body mass or age when being tested were not correlated with any of their responses. First, the correlated responses of the animals during the different contexts of the applied tests strongly suggest the existence of behavioral phenotypes in European rabbits. Second, and most importantly, our study provides evidence that an animal's early development can exert long-term effects on its personality type, although it is not clear whether body mass per se or some correlated physiological features drive the observed relationships. Copyright 2011, Oxford University Press.