Consistency of individual differences in anti-predator behaviour and colour pattern in the garter snake, Thamnophis ordinoides

Abstract

Abstract. The importance of individual variation in behaviour as both an ingredient and a consequence of natural selection has only recently received much attention from empirical researchers. The manner in which individual differences change ontogenetically and how such changes may affect an individual's fitness are still largely unknown. This study investigates the development of anti-predator behaviour and colour pattern in the northwestern garter snake, Thamnophis ordinoides, during the first 2 years of life under laboratory conditions and in the wild. Several aspects of escape behaviour were examined, including the maximum sprint speed, the distance crawled until an anti-predator display was performed (stamina), and the tendency to perform stereotypical evasive manoeuvres during flight (reversals). These aspects of escape behaviour and the stripedness of colour pattern showed significant changes during this time, although the specific changes varied between laboratory and field conditions. Many of the developmental changes were associated with growth. Traits generally showed strong positive correlations across ages, both in the laboratory and in the field. Individual differences in anti-predator behaviour and colour pattern in this species of snake appear to be relatively consistent throughout the first 2 years of life. Using neonate trait values to estimate selection during this time will provide accurate representations of the form of selection because the ontogenetic trajectories of individuals are parallel.