In this study, we experimentally tested for the effects of four simulated predator cues on defensive displays in two species of South American calico snakes (genus Oxyrhopus). We found that juvenile snakes were both more likely to respond and to respond more strongly than adults and that displays were most common in response to tactile stimuli than to other treatments. However, we also found broad similarity across both simulated predator treatments and species in the components used in each snake’s defensive display, suggesting a high degree of stereotyping. This research suggests an important role for both ontogeny and intensity of predation risk in structuring variation in defensive behavior in Neotropical snakes and emphasizes the foundational importance of context dependence in conceptual frameworks for understanding predator-prey interactions. and *On January 4, 2024, “Supplementary_material.pdf” was replaced with an updated version that has slightly different versions of Figures S4 and S8 after an error in code was corrected. Within “HeatmapFigures.zip,” two code files, “IndividualHeatmaps_matrices.R” and “FigureS4_S8_averagedHeatmaps.R” were updated to correct the code error. Three additional files were added to both the “figures” and “matrices” folders within the subfolder “heatmaps.” These files represent the correlation matrices, by body part, and graphical representation of the matrices for one experimental trial that had previously been excluded due to the code error.
Animals in nature use diverse strategies to evade or deter their predators, including many vivid behavioural displays only qualitatively described from field encounters with natural predators or humans. Within venomous snake mimicry, stereotyped anti-predator displays are suggested to be a critical component of the warning signal given by toxic models and thus under strong selection for independent convergence in mimetic species. However, no studies have systematically quantified variation in snake anti-predator displays across taxonomically broad clades to test how these behaviours evolve across species within a phylogenetic comparative methods framework. Here we describe a new, high-throughput approach for collecting and scoring snake anti-predator displays in the field that demonstrates both low observer bias and infinite extension across any species. Then, we show our method's utility in quantitatively comparing the behaviour of 20 highly-divergent snake species from the Amazonian lowlands of Peru. We found that a simple experimental setup varying simulated predator cues was very successful in eliciting anti-predator displays across species and that high-speed videography captured a greater diversity of behavioural responses than described in the literature. We also found that although different display components evolve at different rates with complicated patterns of covariance, there is clear evidence of evolutionary convergence in anti-predator displays among distantly related elapid coral snakes and their colubrid mimics. We conclude that our approach significantly advances opportunity for future analyses of snake behaviour, kinematics, and the evolution of anti-predator signals more generally, especially macroevolutionary analyses across clades with similarly intractable behavioural diversity.
Alison R. Davis Rabosky, Talia Y. Moore, Ciara M. Sanchez-Paredes, Erin P. Westeen, Joanna G. Larson, Briana A. Sealey, Bailey A. Balinski (2020) Convergence and divergence in anti-predator displays: A novel approach to quantitative behavioural comparison in snakes. Biological Journal of the Linnean Society http://dx.doi.org/10.1093/biolinnean/blaa222
All animal-related procedures were approved by the University of Michigan Institutional Animal Care and Use Committee (Protocols #PRO00006234 and #PRO00008306) and the Peruvian government SERFOR (Servicio Nacional Forestal y de Fauna Silvestre. and Data were collected during five field expeditions in the Amazonian lowlands of Peru from March 2016 to December 2018.