A baby bird in the Amazon rain forest has downy feathers with long, orange barbs and white tips that make it look like a poisonous hairy caterpillar, researchers are reporting.
The disguise helps the young birds, with the poetic name cinereous mourner, avoid the clutches of hungry snakes and monkeys, said Gustavo Londoño, an ecologist at Icesi University in Cali, Colombia, and an author of a new paper about them in The American Naturalist.
The birds are rarely seen by humans and, as a result, hard to study. “They are very shy and quiet and their vocalization is a very low whistle,” Dr. Londoño said. “They stay in heavily forested areas in the Amazonian.”
So when the researchers happened upon a nest with two eggs in Peru, they set up a camera to monitor them before and after hatching.
Only one egg hatched, and when the researchers took measurements of the baby, it started moving its head very slowly from side to side, much like the hairy caterpillar it resembles.
The nestling made the same cautionary movement when its parents arrived with food.
“It was only when the parents started making a particular vocalization that the bird opened its mouth and asked for food,” Dr. Londoño said.
After about 14 days, the bird no longer looked so much like a caterpillar, but by then it had the strength to jump out of the nest if a predator arrived.
The researchers hope to study more cinereous mourners, along with sister species that have the same plumage.
“Right now the sample size is only one,” Dr. Londoño said. “We need to find more of these nests to know what is really going on.” SINDYA N. BHANOO