EXPERIMENTAL STUDIES OF CORAL SNAKE MIMICRY - GENERALIZED AVOIDANCE OF RINGED SNAKE PATTERNS BY FREE-RANGING AVIAN PREDATORS

1. Plasticine snake replicas were used to demonstrate that free-rangin g avian predators generalize avoidance of Coral Snake ringed patterns to similar patterns, supporting the argument that the convergence on r inged and banded patterns among neotropical snakes is a result of the mimetic advantage of resembling venomous Coral Snakes. 2. The study wa s conducted at a tropical dry forest site in Costa Rica, where only on e species of Coral Snake occurs. The Coral Snake has a tricolour (red- yellow-black-yellow-red) ringed pattern and no snakes at the site have bicolour (red-black) ringed patterns. Neither tricolour nor bicolour ringed replicas were attacked by birds, whereas an unmarked brown repl ica was. 3. The avoidance of the bicolour ringed pattern is attributab le to generalized avoidance of Coral Snake-like patterns. No red-and-b lack ringed prey have been observed at the site, so birds could not ha ve learned specific avoidance of the bicolour pattern. Historical biog eographical evidence suggests that the avifauna at the site did not ev olve in the presence of red-and-black ringed snakes, so it is unlikely that birds evolved a specific innate avoidance of the bicolour ringed pattern.