Antipredatory behaviour of a mountain lizard towards the chemical cues of its predatory snakes

The ability to early detect a potential predator is essential for survival. The potential of Iberolacerta cyreni lizards to discriminate between chemical cues of their two predatory snakes Coronella austriaca (a non-venomous active-hunter saurophagous specialist) and Vipera latastei (a venomous sit-and-wait generalist) was evaluated herein. A third snake species, Natrix maura, which does not prey on lizards, was used as a pungent control. Thus, the behaviour of I. cyreni was studied regarding four treatments: (1) C. austriaca scent, (2) V. latastei scent, (3) N. maura scent and (4) odourless control. Lizards showed antipredator behaviour (such as slow-motion and tail waving) to C. austriaca and V. latastei chemicals. The antipredatory response was similar for both predators. This ability to react with an intensive behavioural pattern to the chemical cues of their predatory snakes may prevent lizards from being detected, and, if detected, dissuade the predator from beginning a pursuit.

Predator or prey? The dive response to aerial and aquatic predators of Arafura filesnakes

In air-breathing aquatic animals, predation is a strong selection pressure that may be reduced by modification to diving patterns. The risk of predation increases with time spent at the surface, thus shorter, more frequent surfacing events or longer, less frequent surfacing events would decrease predation risk. A reduction in time spent on the surface can be achieved by use of bimodal respiration, which is an ability to extend dive duration using dissolved oxygen to supplement aerially acquired oxygen. Air is a more efficient respiratory medium; however, under predation pressure, the cost of surfacing increases and the reliance on aquatic gas exchange should therefore increase. We tested whether the bimodally respiring filesnake (Acrochordus arafurae) changed its diving behaviour under simulated aerial (model bird) and aquatic (large fish) predation. Aerial predation did not alter dive or surface duration, percentage time surfacing or activity. However, a greater number of longer dives were observed with fewer long surface intervals, suggesting an increase in the use of aquatic gas exchange. The diel diving patterns (short night dives, long day dives) may provide an in-built antipredatory response to aerial predation. The threat of aquatic predation produced atypical antipredator behaviour, with longer surface intervals, shorter dives and increased activity, indicating that piscivorous filesnakes may have identified the predatory fish as prey rather than a predator.