Exploratory and defensive behaviours change with sex and body size in eastern garter snakes (Thamnophis sirtalis)

Phenotypic traits are important to consider when examining behaviour because they can help explain behavioural trait variation. Behaviours such as exploration, boldness, and defense may vary between individuals because different intensities of a behaviour may be advantageous for males versus females, or at different body sizes. We tested the hypothesis that exploration, boldness, and defensive behaviours are related to body size, sex, and reproductive status in eastern garter snakes, Thamnophis sirtalis. We also tested whether the measured behavioural traits were consistent through time (i.e., whether eastern garter snakes could have personalities) and whether the measured behavioural traits were related to one another (i.e., whether behavioural syndromes could be present in eastern garter snakes). Males and non-gravid females were more likely to flee than gravid females when faced with an attack. Males and non-gravid females were also more active after the attack than before the attack, whereas gravid females were more active before the attack. Furthermore, longer females explored less than smaller females, with a more precipitous decline of exploration as a function of size in gravid females than in non-gravid females. In contrast, longer males explored more than smaller males. Although we did not detect behavioural syndromes, within individuals the measured behavioural traits were repeatable through time, suggesting that eastern garter snakes could have personalities.