Number, speeds, and approach paths of predators affect escape behavior by the Balearic Lizard, Podarcis lilfordi

The number of simultaneously attacking simulated predators and their approach speeds and angles affected escape trajectories and flight initiation distance in Balearic Lizards (Podarcis lilfordi). Our findings confirmed predictions prey flee in directions maximizing distance from predator(s). During slow approaches, escape angle was 45° when approached by two predators at right angles and 90° when approached from opposite directions. Escape at close to 45° by lizards approached at slower speed by a single predator supports the hypothesis that prey use escape trajectories allowing them to visually monitor predators. Flight angles were closer to being straight away from a predator during faster approaches, suggesting that distance maximization may be more important than monitoring predator position when risk is great. When predators approached from opposite directions, flight angle shifted away from the faster predator, suggesting that lizards may have equalized risk from both predators based on positions and speeds. Flight initiation distance was greater for approach by predators side by side than by one only during faster approaches, suggesting that risk is a joint function of predator number and speed. Flight initiation distance was greater when predators approached at right angles than side by side, perhaps because of difficulty of monitoring multiple predators in different locations. Distance fled did not differ among treatments and may have been affected by distance to refuge. Thus, Balearic Lizards adjusted flight initiation distance and escape trajectories in ways that enhanced their abilities to avoid predation during simultaneous approaches by two predators.