How to Design Experiments in Animal Behaviour

Abstract

There are many examples of perfectly palatable animals resembling related unpalatable species and, thereby, avoiding attack by predators who have learnt or evolved to avoid the unpalatable species. To facilitate recognition by predators, unpalatable species often have warning colourations, which is what is mimicked by the palatable species. This form of mimicry is known as Batesian mimicry. While there are many well-documented examples of Batesian mimicry among butterflies and other arthropods, there are somewhat fewer examples amongst vertebrates, and even these examples are often debated. The coral snake mimicry system in North America, where non-venomous kingsnakes and milksnakes mimic venomous coral snakes, is one of the best-studied vertebrate examples of Batesian mimicry. However, it has also been debated for over a century. In this article, I will describe three experiments using plasticine replicas of the mimics designed to understand the effectiveness of their mimicry. These field experiments were performed in the natural habitats of the mimics, the models and their predators, by David W. Pfennig and his students and collaborators, in the states of Florida, North Carolina, South Carolina, and Arizona in the USA. The simple, clever, and low-cost experiments have significantly strengthened the hypothesis of Batesian mimicry in this system. They have also provided an unexpected new understanding of how mimics might evolve from cryptic ancestors through a process of gradual natural selection.