WonderDigestive biology fact

The leaf-eating hoatzin relies on microbes in an enlarged foregut to ferment tough vegetation, an unusual digestive strategy among birds.

Hoatzin

The story behind the card

The hoatzin lives in swampy forests along rivers in the Amazon and Orinoco basins of South America. It is the only bird known to digest leaves mainly by fermentation at the front of its gut, much as a cow does in its rumen. Bacteria in its huge crop and lower oesophagus break down tough plant fibre before food reaches the stomach. The fermenting crop gives the bird a manure-like smell, which earned it the English nickname 'stinkbird' and means it is seldom hunted for food. The oversized crop also leaves little room for flight muscles, so hoatzins are clumsy fliers. Chicks have two claws on each wing, which help them climb back into the branches after dropping into the water to escape a predator.

Türkçe oku

Yaprakla beslenen hoatzin, sert bitkileri sindirmek için iri kursağındaki mikroplardan yararlanır. Yiyeceği bu şekilde mayalandırarak sindirmek kuşlar arasında çok ender görülür.

Hoatzin, Güney Amerika'da Amazon ve Orinoco havzalarında, nehir kıyılarındaki bataklık ormanlarında yaşar. Yaprakları ağırlıklı olarak sindirim kanalının ön kısmında mayalandırarak sindiren bilinen tek kuştur; inek de işkembesinde buna benzer bir şey yapar. Kocaman kursağındaki ve yemek borusunun alt kısmındaki bakteriler, sert bitki liflerini daha mideye ulaşmadan parçalar. Mayalanan kursak kuşa ahır gübresini andıran bir koku verir; bu yüzden İngilizcede “kokan kuş” (stinkbird) diye anılır ve pek avlanmaz. İri kursak uçuş kaslarına da az yer bırakır, bu yüzden hoatzin beceriksiz bir uçucudur. Yavruların her kanadında iki pençe bulunur; bir yırtıcıdan kaçmak için suya atladıklarında bu pençelerle dallara geri tırmanırlar.

Sources and further reading

Background reading: Hoatzin

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The leaf-eating hoatzin relies on microbes in an enlarged foregut to ferment tough vegetation, an unusual digestive strategy among birds.

The story behind the card

Sources and further reading

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