Many non-edible, poisonous or otherwise not pleasant-tasting butterflies have distinct colors and patterns. As a result, other more-palatable butterflies have evolved to mimic those patterns to avoid being consumed by predators. There are several types of mimicry in butterflies: Batesian mimicry, Müllerian mimicry and wasp mimicry. Birds will consume unpalatable butterflies and associate their colors and patterns with the negative experience, thus avoiding the butterflies performing mimicry. It is possible that birds even communicate their experience with other birds. Mimicry in butterflies is often described in mimicry rings like the tiger complex because there is actually a spectrum of palatability. Palatability is also relative to the birds involved, and some birds find species edible that others do not.
Batesian mimicry was established by the naturalist Henry Walter Bates in 1862. He first observed that mimicry involved a palatable butterfly resembling an unpalatable, often toxic, butterfly. This mimicry will only work when the toxic model species outnumbers the nontoxic species. He believed that mimicry was the result of edible butterflies producing mutations making them resemble their inedible cousins. This in turn resulted in the increased survival of the butterflies containing the mutation and resulted in the similarities between species. In 1879 another naturalist, Johann Friedrich Theodor Müller, observed that in some cases of mimicry both the mimic and the model are unpalatable. He considered this to be a cooperative mimicry and believed the species evolved side by side in a mutually beneficial relationship. If a bird tried to eat a member of either species, it would then avoid both. Wasp mimicry is similar to Batesian mimicry, but instead of mimicking another unpalatable butterfly species, the mimic instead resembles a wasp to avoid predators.
The tiger complex is a group of around 200 species of neotropical butterflies that are involved in the most well-known form of mimicry. It is named such because the patterns of all of the included species are black on a background of either orange or yellow, resembling a tiger. In the complex are many unpalatable species, a few toxic species and a great deal of completely edible species. Members of the tiger complex are all known for congregating in large groups that would normally be easy prey for birds. Fortunately, birds have no interest in them due to their mimicry.
The tiger complex is a mimicry ring, which is a large group of related and unrelated butterfly species that look very similar and live in the same region. Mimicry rings have both palatable and unpalatable species, Batesian mimicry, for mimicry to be successful. Other notable mimicry rings include the glasswing ring and orange ring. Butterflies that look similar, but live on opposite side of the globe, are not considered to be part of the same ring and are not examples of mimicry.