Turning, tugging, running and reversing: survival strategies of the European pond turtle

Abstract

The European pond turtle, although mostly aquatic, still has to face a potential terrestrial predator while migrating or laying eggs. Getting stuck in vegetation is also possible, both on land and underwater, leaving the animal vulnerable to predators and exposure. We measured how animals from three populations behaved during timed test that imitate real – life situations they could face when evading a predator or freeing themselves from dense vegetation. All turtles had faster reaction times when placed on their plastron, suggesting that the upright position is safer and offers easier escape then when turtles are overturned on their carapace. On the other hand, sexes were equally fast to self-right from an overturned position, as well as to release from ‘’vegetation’’ stuck on their plastron. We found significant negative correlation between body size and efficiency of self-righting and realizing from ‘’vegetation’’. What this could imply is that smaller body size probably leads to greater agility and mating success, which is in accordance with the general hypothesis on sexual size dimorphism suggested for several other turtle species. Although females are generally the larger sex in European pond turtles, we found no effect of body size on their agility performances. Interestingly, differences in performances between sexes were much more expressed than among the three tested populations.