How a Bird Came to Look Like a Caterpillar

BirdNote^® 
How a Bird Came to Look Like a Caterpillar 
Written by Bob Sundstrom

This is BirdNote.

         [Amazon nature ambient]

In nature, one way to avoid being eaten is to look like something you’re not—ideally, something that tastes really awful — or that might even kill you.

Science calls this Batesian mimicry, named for a 19th century naturalist. Bates found that some perfectly edible butterflies had evolved color patterns that mimic those of toxic butterflies, which predators avoid.

Well, these butterflies are not alone.

The Cinereous Mourner is a small, ashy-gray bird that lives in the forest understory of the Amazon Basin. And it’s taking mimicry to the next level: its chick looks like a poisonous caterpillar!

         [Cinereous Mourner call]

The chick is covered in vivid orange feathers punctuated with black dots. Lying alone in its cup-shaped nest, it’s a near match to a highly toxic caterpillar — one that snakes and monkeys won’t eat. The chick even waves its head like a caterpillar, increasing the illusion.

Cinereous Mourners live in an area where many birds’ nestlings are routinely lost to predators—and this may explain how a bird wound up dressed as a deadly caterpillar.

         [Cinereous Mourner call]

For BirdNote, I’m Michael Stein.

This episode is brought to you by Wild Delight Bird Food, which aims to support wild bird populations with clean, nutritious ingredients in every blend. Available at Chewy.com.

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Senior Producer: Mark Bramhill
Producer: Sam Johnson
Managing Producer: Jazzi Johnson
Managing Producer: Ariana Remmel
Content Director: Jonese Franklin

Bird sounds provided by The Macaulay Library of Natural Sounds at the Cornell Lab of Ornithology, Ithaca, New York. Recorded by ML 225024 B. Oshea and ML 98606 D Finch.
BirdNote’s theme music composed and played by Nancy Rumbel and John Kessler.
© 2019 BirdNote    March 2019/2026 & October 2023    
Narrator: Michael Stein

ID# LANHYP-01-2019-3-13    LANHYP-01

References: 
https://www.ncbi.nlm.nih.gov/pubmed/25560558 
https://www.newscientist.com/article/dn26689-zoologger-the-bird-that-mimics-a-toxic-caterpillar/