Tactile stimuli induce deimatic antipredator displays in ringneck snakes

Abstract

Adaptations for predator defense are often complex traits with integrated display components spanning multiple signaling modalities. For antipredator coloration like deimatic or startle coloration, behavioral variation controlling dynamic color displays is an important but poorly understood component of the predator defense in most taxa. We studied antipredator behavior in North American ringneck snakes (Diadophis punctatus), which possess a brightly colored (red to yellow) ventral surface of the body and the tail compared to the mostly gray dorsal coloration. We sought to (a) characterize intraspecific variation in antipredator behaviors in ringneck snakes and (b) test which stimuli can induce antipredator displays. First, we assessed antipredator displays in the field and during routine handling during data collection by comparing categorical classifications of all displayed behavior across 25 individuals. Second, we performed experimental assays with tactile and visual stimuli to determine the cues that can elicit an antipredator display in ringneck snakes. We found that antipredator displays include ventral displays and tail‐coiling and that these components were induced by tactile cues in the field and the lab, but not visual cues. Our work is the first to show that a snake species with bright ventral coloration uses this behavior in response to tactile cues from a potential predator, but only in response to relatively strong stimuli (i.e., handling). This experimental evidence that tactile stimuli can induce a behavior revealing bright ventral coloration highlights the importance of correlated evolution of antipredator coloration and behavior.

Body size and predator cues structure variation in defensive displays of Neotropical calico snakes (Oxyrhopus spp.)

“…However, experiments in other systems have also found the strongest defensive responses in trials that had the highest perceived risk (de Albuquerque & de Araujo Lira, 2021), indicating that this may be a more important form of context dependence than the specific identity of the predator. To disentangle the relative contributions of predator type and predation risk intensity to anti‐predator behavioral responses, future studies could leverage more realistic predator models, such as taxidermied mounts, while simultaneously varying the frequency of tactile contact (Cox et al., 2021).…”

“…However, many organisms also vary their behavioral responses according to life stage and sex differences, as sensitive life stages may experience increased or even novel selection pressures (such as leaf rolling by larval caterpillars but not by adult butterflies, Loeffler, 1996; see also Glaudas et al., 2006; York & Bartol, 2016). The relative impact of each of these factors ‐ predator type, age, and sex ‐ on shaping behavioral responses is often unknown, as these effects are only easy to isolate when tested under experimental conditions rather than opportunistically observed in nature (Abom & Schwarzkopf, 2016; Cox et al., 2021; Gove & Burghardt, 1983; Shine et al., 2000).…”

“…by larval caterpillars but not by adult butterflies, Loeffler, 1996; see also Glaudas et al, 2006;York & Bartol, 2016). The relative impact of each of these factors -predator type, age, and sex -on shaping behavioral responses is often unknown, as these effects are only easy to isolate when tested under experimental conditions rather than opportunistically observed in nature (Abom & Schwarzkopf, 2016;Cox et al, 2021;Gove & Burghardt, 1983;Shine et al, 2000).…”

Defensive tail displays in dice snakes (Natrix tessellata) are influenced by colour morph and sex

“…For example, ringneck snakes (Diadophis punctatus) have extremely bright and contrasting colour on the ventral side of the body, including the tail, compared to the cryptic dorsal colour. These snakes display brightly coloured ventral scales, including undersides of tails, during handling, probably as a startle effect (i.e., deimatic coloration; Cox et al, 2021). Brightly colored tail tips are present in a wide variety of snake species and are thought to serve the same purpose (Greene, 1973).…”