Here’s an amazing bird unlike any other. Found in the Amazon and Orinoco Basins of South America, the pheasant-like hoatzin (pronounced Watson, Opisthocomus hoazin) eats leaves as 82% of its diet.
Leaves are really hard to digest so the bird has a huge crop that ferments the leaves and makes adult hoatzins smell like manure. The breath of mammal ruminants — cattle, sheep, goats, deer — may smell sweet. Not so with the hoatzin!
The hoatzin’s huge crop allows little room for flight muscles, so the bird is barely able to fly but that doesn’t matter. No one eats a bird that smells this bad.
Hoatzin nestlings don’t smell bad yet so they have to escape predators. During development in the egg, the young birds retain vestigial wing claws that all other birds lose during gestation. Before they can fly, hoatzin nestlings can climb back into their nests!
Read more about hoatzins and see video of a nestling crawling back into the nest at this vintage blog post: Watson, I Presume.
(photos from Wikimedia Commons; click on the captions to see the originals)