Cinereous Mourner Chicks Pretend to Be Poisonous Caterpillars


Santiago David Rivera (left) // Wendy Valencia (right)

This strange baby bird may look like pretty flashy, but its plumage keeps it safer than you would think. 

The jungle is a rough place for the young, and nestlings often fall victim to predators like snakes, birds, and mammals. Each animal needs a special way to stay out of harm's way, or else risk extinction. The cinereous mourner chick lives in a high-kill area, but lacks the colors to camouflage or the ability to fly. So, according to a new study published in the the January 2015 issue of The American Naturalist, vulnerable chicks have evolved the ability to hide in plain sight.

During an ecological study in the fall of 2012, researchers found a cinereous mourner nest in southeastern Peru (only the second such nest ever described) and noted that although the adults have smooth black feathers, the chicks are covered in downy orange feathers tipped with black and white. When the researchers took measurements of the nest, the tiny birds began to bob their heads slowly back and forth, not unlike a caterpillar. After some investigating, the scientists found a poisonous caterpillar in the area with similar coloring that made similar movements, and theorized that the tiny birds mimicked the poisonous caterpillars to discourage potential predators from eating them. 

So what exactly are these birds mimicking? It's a horrifyingly large orange caterpillar that's 12 centimeters long, or about one chick size. The fuzzy bug's hairs contain a toxin that irritates the skin (not that you would want to touch it anyway). The exact species has yet to be described, but you can watch the creepy-crawlie move around: 

The fluffy chicks' behavior is an example of Batesian mimicry, a survival technique where a harmless animal has evolved to imitate a more threatening species with which it shares a common predator. Batesian mimicry is often seen in insects, but rarely in vertebrates; it's the first time it has ever been found in birds. With such a remarkable hiding technique, it's no wonder they've stayed hidden for so long.