Green tails in lizards of the genus Podarcis: Do they influence the intensity of predation?

Abstract

Juveniles of a variety of lizard species exhibit bright tail colors that contrast clearly to the cryptically colored body. The 'predator escape' hypothesis suggests that bright tail colors deflect the attack of a predator towards the lizard's tail, which can be autotomised, and hence increase the probability of surviving a predatory attack. Although this hypothesis is widely accepted, surprisingly few empirical data exist to support it. Here, we examined the relative frequencies of predatory attack on plasticine replicas of juvenile lizards in the genus Podarcis with either green or brown tails in nine areas of Spain. Replicas with bright green tail color experienced, over a one-week period, the same rates of attack by birds and other predators as replicas with cryptic brown tails. However, the proportion of replicas that showed bill markings on the tail only was highest for the green-tailed replicas. In contrast, the frequency of predatory attacks towards the head or body was similar in the two groups of replicas. Our experiment appears to support the classical prediction of the adaptive value of a green autotomic tail in lizards. However, lizard species with multiple tail colors may also represent alternative anti-predator strategies that may have arisen by different selective pressures between habitats. We also suggest that the evolution of bright tail coloration in juveniles of Podarcis as an antipredator mechanism may be favored by the correlated evolution of morphological, physiological, and behavioral characteristics.