On the firing line – interactions between hunting frogs and Odonata

Abstract

Frogs are important predators of Odonata. We investigated frogs catching Odonata prey by means of slow-motion filming in the field in order to understand the prey–predator interactions. In particular, we aimed to analyse kinematics of captures, and of Odonata fleeing, through evaluation of frame-by-frame filming; 122 (20%) of 613 events were analysed. While dragonflies were ovipositing, frogs were sitting and waiting motionless, or they sneaked slowly towards the intended prey. The speed of the lashing tongue was much higher than the start and flight velocities of Odonata during escape attempts. The reaction time of Odonata was around 45×10–3 s, and it was not correlated to capture rate. The fleeing behaviour of Odonata cannot be considered to be stereotypical. The usual fleeing measure was to evade sideways to the jump direction of the frog, with the individual turning their body to one side and flying away from the frog. Perched odonates escaped by overturning to one side, sometimes falling into the water, or by flying in a loop. To escape, individuals were observed flying backward with the head down, in two cases. From the video clips, capture rates were counted. Large Anisoptera escaped more often than small Zygoptera. Anax imperator females mostly escaped after capture by fighting with strong wing beats, even when pulled under water by the frog.