Page 137 - Atlas Of The World's Strangest Animals

HOATZIN 137

coarse call. However, these beautiful birds have another
Hoatzin habitats
name – just as descriptive as their scientific and common
names – but not nearly as flattering.They’re known as
stink birds!
The reason they’ve earned such an appalling appellation
is due to their strange digestive system. For birds, digestion
starts at the bill.This specialist tool is used for breaking
open and grinding up food, and it eliminates the need for
teeth. Once food has been cracked and crushed, it travels
down to the crop, which is a muscular pouch in the
throat. Most birds have a crop and it’s used both to soften
food and to regulate how quickly it moves on to the
gizzard.This enables birds to gorge themselves when food
is plentiful and store any ‘excess’ for later. Once food
reaches the gizzard (really a specialized stomach), muscles
grind it up. Some birds swallow stones, using them to help
this process along.
What makes hoatzins so curious is that their crop is
huge. In fact, it is so big that their flight muscles have been
reduced to make space for it. It’s here that much of the
struggling to survive as their habitats are gradually lost hoatzins’ meal is broken down, but not in the usual way.
to development. Uniquely for birds, hoatzins use bacterial fermentation,
like cattle, to digest their food. In cows, this process takes
The stink bird! place in a special chamber called the rumen (which is why
The hoatzins’ scientific name, Opisthocomus hoazin, comes cattle are called ruminants). Hoatzins don’t have this, so
from the Greek for ‘wearing long hair behind’, a reference fermentation takes place in the crop.All this produces a
to its crest.The word hoatzin is said to be an distinctive farmyard odour. Put simply, hoatzin smell
onomatopoeic attempt to mimic the bird’s distinctive, like manure!

Comparisons

Archaeopteryx lived during the Late Jurassic Period, 61–145 million
years ago, in what would be modern-day Germany.The earliest
undisputed hoatzin fossil dates from the Miocene, 23.03–5.33 million
years ago, and was found in Colombia.While hoatzins do look
strangely primitive, the two species are not related, although they
share some physical traits, such as the chicks’ wing claws and a similar
skeletal structure.

Archaeopteryx Hoatzin

(c) 2011 Marshall Cavendish. All Rights Reserved.