Jay vomiting

Monarch Butterflies (Papilio) feed mainly on milkweed plants, which gives them a taste obnoxious to birds. A single experience of a naive juvenile (left) is sufficient to discourage subsequent predation on Monarchs (right). Experienced birds will also avoid Viceroy Butterflies (Limenitis), which have a similar pattern to Monarchs, but are not distasteful. Imitation of a distasteful "model" by a tasty "mimic" is an example of Batesian mimicry. Viceroys must remain at relatively low density to obtain the advantage of mimicry, otherwise predators will not learn to avoid the pattern.