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Hoatzin

Opisthocomus hoazin · hard

The hoatzin is a bird that digests like a cow. It eats leaves — a poor diet no other bird has committed to in the same way — and ferments them in a greatly enlarged crop full of bacteria that break down cellulose before the material reaches the stomach. The arrangement works, and it produces a strong manure-like odour that has earned the bird the name stinkbird and largely protected it from being hunted.

The fermentation chamber occupies so much of the chest that it displaces the flight muscles, and hoatzins fly poorly and reluctantly, clambering through riverside vegetation instead.

Their chicks are stranger still. A hoatzin nestling has two functional claws on each wing. Threatened, it drops from the nest into the water below, swims, and then uses those claws to haul itself back up through the branches — after which the claws are lost. The behaviour was once taken as evidence of a direct link to Archaeopteryx; it is now understood as a separate solution to the same problem.

Hoatzins are common along Amazon and Orinoco waterways. Where they sit on the bird family tree has resisted resolution for over a century, and they are usually placed in an order of their own.

Where it lives

Worml lists the hoatzin as native to 8 countries — Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru, Suriname and Venezuela. Its habitat is riverside and swamp forest.

Ranges here are reduced to whole countries for playability and exclude introduced populations — see about the data for what that simplification leaves out.

In the game

Hoatzin is rated hard. To solve the round you need to find any 4 of its 8 listed countries. How scoring works →

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