Seeing through the lizard’s trick: do avian predators avoid autotomous tails?

Abstract

Counter-adaptations of predators towards their prey are a far less investigated phenomenon in predator-prey interactions. Caudal autotomy is generally considered an effective last-resort mechanism for evading predators. However, in victim-exploiter relationships, the efficacy of a strategy will obviously depend on the antagonist’s ability to counter it. In the logic of the predator-prey arms race, one would expect predators to develop attack strategies that minimize the chance of autotomy of the prey and damage on the predator. We tested whether avian predators preferred grasping lizards by their head. We constructed plasticine models of the Italian wall lizard (Podarcis sicula) and placed them in natural habitat of the species. Judging from counts of beak marks on the models, birds preferentially attack the head and might also avoid the tail and limb regions. While a preference for the head might not necessarily demonstrate tail and limb avoidance, this topic needs further exploration because it suggests that even unspecialised avian predators may see through the lizard’s trick-of-the-tail. This result may have implications for our understanding of the evolution of this peculiar defensive system and the loss or decreased tendency to shed the tail on island systems with the absence of terrestrial predators.

Deceived by stripes: conspicuous patterning on vital anterior body parts can redirect predatory strikes to expendable posterior organs

“…As the size of the receptive field involved in processing early motion signals in vertebrates is small, it is possible that the accuracy of attacks is affected by the eye gaze being directed to an apparently immobile anterior part of the prey containing striped patterns rather than global prey movement [ 40 ]. Moreover, it is known that predators target vital body parts such as the head or trunk to thwart prey escape [ 41 ], particularly in the case of lizards [ 27 , 28 , 42 ]. This was approximated in our experiments by instructing the volunteers to attack the anterior half of the moving prey.…”

The island syndrome hypothesis is only partially validated in two rodent species in an inland–island system

“…Caudal autotomy has been little studied in rodents, in comparison with lizards (Cooper et al 2004, Bateman and Fleming 2009). In some lizard species, studies have shown that some predator species do not catch their prey by the tail, but focus on other body parts such as the area around the head in a context of predator–prey arms race (Vervust et al 2011). This could also be the case for predators of deer mice and red‐backed voles.…”

A different kind of ecological modelling: the use of clay model organisms to explore predator–prey interactions in vertebrates

“…A relatively simple experiment with undifferentiated clay models of the lizard Podarcis sicula (Lacertidae) on small islets in the Mediterranean revealed the predatory behaviour of the primary predators, yellow‐legged gulls Larus michahellis , for these sites (Vervust, Van Loy & Van Damme, ). The authors recorded more attacks aimed at the heads of their models (Vervust et al ., ), which would translate to potentially fatal attacks in live lizards.…”

“…A relatively simple experiment with undifferentiated clay models of the lizard Podarcis sicula (Lacertidae) on small islets in the Mediterranean revealed the predatory behaviour of the primary predators, yellow‐legged gulls Larus michahellis , for these sites (Vervust, Van Loy & Van Damme, ). The authors recorded more attacks aimed at the heads of their models (Vervust et al ., ), which would translate to potentially fatal attacks in live lizards. Such behaviour by predators is likely to be the selective pressure that results in many species of lizard having brightly coloured tails (Vitt & Cooper, ; Castilla et al ., ; Bateman et al ., ) or behaviour such as tail waving (Cooper, ; Telemeco, Baird & Shine, ) that directs attacks towards autotomizable tails (Bateman & Fleming, ), and may also select for longer tails (Fleming, Valentine & Bateman, ).…”