A dicey situation: capture behaviours in free-ranging dice snakes

Abstract

When captured by a predator, the prey’s options for escape decrease dramatically; however, some species, such as dice snakes, display a wide variety of behaviours in order to escape. We explored how factors such as locality, body temperature, body size, sex, reproductive status (i.e. gravid vs. non-gravid), presence and state of injuries, and the presence of food affect the occurrence of behavioural displays in a capture situation within and among four free-ranging populations of dice snakes, Natrix tessellata (Colubridae). Our study shows that dice snakes regularly hiss, discharge their cloacal glands, and coat themselves in musk when captured, while other behaviours were displayed only occasionally. Our study corroborates previous findings of local differentiation in snake behaviour, especially the case of supposed Batesian mimicry in dice snakes. In three of four localities where the dice snake lives in proximity or in sympatry with nose-horned vipers, they display fake striking, with additional head flattening as opposed to the viper-free locality. Larger snakes exhibit a wider array of antipredator behaviours, which commonly include musking and hissing. Expectedly, warmer snakes were more likely to display vigorous antipredator behaviours such as struggling and striking. Injured snakes (a possible measure of a previous exposure to predation) displayed fewer behaviours and musked and hissed less. We call into question the analysis of isolated antipredator behavioural displays, and encourage using entire behavioural sequences in order to understand the complexity of antipredator behaviour.