The New Neotropical Companion

butterflies that were recaptured showed wing damage

from bird attacks. Benson was even able to identify

one bird species, the Rufous- tailed Jacamar (Galbula

ruficauda; plate 11- 47; jacamars are discussed in chapter

15), by the shape of wounds it left in a butterfly’s wing

(plate 11- 48). The experiment showed that wing pattern

does confer protection once predators learn the pattern

and associate it with unpalatability (plate 11- 49).

Mimicry Systems: Look- alikes Win

Although heliconids and many other tropical butterflies

are striking in appearance, species are often difficult to

identify because different species evolve to look alike:

they mimic one another. But why?

Batesian Mimicry

Henry Walter Bates, a Victorian naturalist who explored

Amazonia in the mid- 19th century, was amazed to

discover that some unrelated species of butterflies

look alike. He suggested that a palatable species gains

protection from predators if it closely resembles a

noxious unpalatable species, a phenomenon now

termed Batesian mimicry.

The calculus of Batesian mimicry is complex. The

unpalatable species, the model, would seem to be

parasitized by the palatable species, the mimic. Because

it closely resembles an unpalatable species, the mimic

enjoys the umbrella of protection provided by the

presence of the model. For the model, the presence of

the palatable mimics makes the education of predators

more difficult. Suppose a predator encounters one or

even two palatable mimics as its first experience. It may

be subsequently more difficult for the predator to “learn”

that the noxious model is, indeed, noxious. If the mimic

were as abundant as its model, the entire system would

be relatively unprotected, because predators would

encounter palatable mimics as readily as unpalatable

models. But there is an alternative possibility. By sheer

numbers, even palatable mimics could act as mutualists

with models. If there is more overall food available to

predators because of the presence of mimics, predation

pressure on models will be relaxed.

Butterflies exhibit numerous examples of Batesian

mimicry throughout the tropics. However, they are not

the only Batesian mimics. Many other insect species

have evolved mimicry. Even in the temperate zone

Plate 11- 47. This Rufous- tailed Jacamar in the shaded forest

understory is hunting for flying insects. Photo by Gina Nichol.

Plate 11- 48. This caligo butterfly (Caligo eurilochus) shows

substantial damage along the lower edge of its wings. The

outlines of bird beaks, likely those of motmots, are clearly

visible. Photo by John Kricher.

Plate 11- 49. Heliconius doris adult on a milkweed flower.

There is little subtlety in the coloration patterns of heliconid

butterflies. Photo by John Kricher.

chapter 11 evolutionary arms races: more coevolution, more complexity 199