Are plasticine models efficient to test defensive colouration of snakes?

Abstract

Plasticine models are often used to test hypotheses related to defensive colourations. However, the behaviour of natural predators is hardly ever examined in these experiments, which can lead to imperfect conclusions about the interactions. Accordingly, we ran an experiment to test whether plasticine models are an efficient tool to test Batesian mimicry, aposematism and camouflage hypotheses, using Atlantic forest snakes as a model group. We made 150 non-toxic simulacra of four snake species and two generic plasticine models. We placed cameras traps at the study sites to record the behaviour of potential predators towards the models. We classified the predator-simulacrum relations as physically interactive, interactive with no contact, or not visualised, and we examined whether mammals behaved differently from birds towards the plasticine models. We recorded 110 instances of birds or mammals approaching the plasticine models, most of them with models. Most birds presented an interaction with no contact during the day, and mammals presented physical interaction during the night. None of the model types influenced the interaction with predators, but we observed that mammals interacted significantly more with models than birds. While mammals clearly did not behave protectively when interacting with the models, some birds did behave with caution when approaching them. Our results showed that the use of plasticine models may not always result in reliable data to test predator-prey hypotheses. Keywords: Mimicry, predation, Atlantic forest, aposematic colouration, Serpentes