Predator-elicited foot shakes in wall lizards (Podarcis muralis): Evidence for a pursuit-deterrent function.

Abstract

Under certain circumstances, prey may inform potential predators of their unprofitability by means of pursuit-deterrent signals. The evidence for pursuit-deterrent signaling in reptiles is scant and taxonomically biased. Wall lizards, Podarcis muralis (Squamata: Lacertidae) produce several distinct types of stereotyped foot shake displays, of which one, performed in antipredator contexts, is a likely candidate for a pursuit-deterrent function. We investigated this possibility by recording the responses of lizards in the field to a slowly approaching human acting as a surrogate predator. In addition to starting and flight initiation distances, we measured the presence of foot shakes, the leg that was shaken, and the distance from the observer at which the display was performed (display distance). Of a total of 484 approaches, 109 (22.5%) elicited foot shake displays. Roughly half the lizards displayed from the location where they were first sighted, while the other half moved a short distance, then displayed. There was no left-right preference in the leg used to display, but most lizards displayed with the leg closer to the approaching predator. Juveniles and subadults had smaller flight initiation distances than adult lizards. There were no sex-related differences in starting or flight initiation distances, but females, for a given distance, were more likely to display than males. Foot shake display frequency declined abruptly at 1 m. If lizards waited until the surrogate predator was this close, they mostly fled without displaying. Our results show that antipredator foot shaking in P. muralis is consistent with expectations from pursuit-deterrent theory.

Sex- and performance-based escape behaviour in an Asian agamid lizard, Phrynocephalus vlangalii

“…However, a very low percentage of individuals tail-waved during our predatory approaches, and as such, the tail display is only likely to be used in social signalling. While it is possible that some aspect of our approach failed to elicit tail waving, this protocol has been used to successfully test pursuit-deterrent signals in lizards in the past (Font et al 2012). Cooper (2001) suggested that the lizard Callisaurus draconoides tail-waved based on predator approach distance, with fewer individuals signalling at longer or shorter distances.…”

“…One way to reduce these costs is to communicate with predators using pursuit-deterrent displays (Dial 1986;Cooper 2001). For example, Anolis cristatellus use push-up displays to convey information about their endurance to a predator (Leal 1999) and wall lizards Podarcis muralis communicate with predators using foot shake displays (Font et al 2012). Alternatively, animals may freeze or make escape decisions through risk assessment.…”

The Asian grass lizard (Takydromus sexlineatus) does not respond to the scent of a native mammalian predator

“…During a time period of 10 min, which began shortly after the lizard was placed in the centre of the test arena, the following behaviours were scored: the time spent Walking, Not‐moving, Basking, Nudging and Standing up‐right against one of the test arena's walls, and the amount of Tongue flicks (indicative of chemical sampling; Graves & Halpern, ), Labial licks, Head rubs (the lizard rubs its head sideways over the substrate), Tail vibrations, Startles and Foot shakes. The latter three are considered to be indicative of stress or linked to predator‐escape strategies in lizards (Font, Carazo, Pérez i de Lanuza, & Kramer, ; Mori, ; Van Damme & Quick, ). See Thoen et al () and Monks et al () for a detailed description of all aforementioned behaviours.…”

“…During a time period of 10 min, which began shortly after the lizard was placed in the centre of the test arena, the following be- shakes. The latter three are considered to be indicative of stress or linked to predator-escape strategies in lizards (Font, Carazo, Pérez i de Lanuza, & Kramer, 2012;Mori, 1990;Van Damme & Quick, 2001).…”

Sexual dimorphism in conspicuousness and ornamentation in the enigmatic leaf-nosed lizardCeratophora tennentiifrom Sri Lanka

“…A separate class of conspicuous signals function in an anti‐predator context and may be aposematic or function as a pursuit‐deterrent signal. Classical pursuit‐deterrent signals are used at a distance early in an encounter with a predator, to dissuade a potential predator from a costly or fruitless pursuit (Leal & Rodriguez‐Robles, ; Font et al ., ). A less well known class of signals are deimatic displays that are concealed and only exposed late in an encounter with a predator, often during subjugation, and are highly conspicuous signals that startle a predator (Umbers, Lehtonen & Mappes, ).…”