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Moa-nalo

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The moa-nalo were a group of large, extinct birds that lived in the Pacific. They inhabited most of the larger Hawaiian Islands, though they were not found on Hawaii itself. These birds were a unique type of waterfowl that functioned as the primary herbivores on their islands. This means they were the main animals responsible for eating plants. Because they were flightless and large, they occupied a very specific role in the island ecosystems.

Chelychelynechen quassus by Stanton F. Fink
Chelychelynechen quassus by Stanton F. Fink

Scientists have identified four distinct species belonging to three different genera. The first is Chelychelynechen quassus, known as the turtle-jawed moa-nalo, which lived on Kauai. The second genus includes Ptaiochen pau, a small-billed moa-nalo from Maui. The third genus, Thambetochen, contains two species: Thambetochen xanion from Oahu, and Thambetochen chauliodous from Maui, Lanai, and Molokai. These species are often grouped together as the Maui Nui large-billed moa-nalo. Each species possessed different physical traits suited to its environment.

Their physical features were highly specialized for their diet. The genus Chelychelynechen had a large, heavy bill similar to that of a tortoise. In contrast, the genera Thambetochen and Ptaiochen featured serrations on their bills called pseudoteeth. These pseudoteeth acted like small teeth, similar to those found on mergansers.

Thambetochen xanion (1)
Thambetochen xanion (1)

These specialized beaks allowed them to process tough plant material efficiently. Their large size and flightless nature suggest they were well-adapted to life on the ground.

Researchers discovered how these birds lived by studying fossilized remains. In the early 1980s, subfossil remains were found in sand dunes on Molokai and Kauai. Later, bones were located in lava tubes, lake beds, and sinkholes on Maui, Oahu, and Lanai.

Thambetochen xanion
Thambetochen xanion

One of the most important clues came from coprolites, which are fossilized dung. By studying coprolites from Thambetochen chauliodous in Puu Naio Cave on Maui, scientists determined they were folivorous. This means they primarily ate leaves and plant matter, such as the fronds of ferns.

The diet of the moa-nalo influenced the evolution of Hawaiian plants. Because these birds were the principal browsers, many plants developed defenses to survive being eaten. For example, several Hawaiian lobelioids in the genus Cyanea grew prominent spines on their leaves and soft stems.

Cyanea platyphylla
Cyanea platyphylla

While many island plants lose their defenses over time, the Cyanea likely evolved these thornlike prickles to protect their new growth from moa-nalo browsing. This shows a direct connection between the birds' feeding habits and the shape of the local flora.

For a long time, the exact identity of the moa-nalo was unknown to science. They were wiped out before the explorer James Cook arrived in 1778. To find their place in the family tree, scientists analyzed traces of mitochondrial DNA found in fossils.

Thambetochen xanion
Thambetochen xanion

This analysis revealed that they were not related to large geese, such as the surviving nene. Instead, they were part of the Anatidae family, specifically related to the genus Anas, which includes the mallard. Biogeography suggests their closest living relative is the widespread Pacific black duck.

In the broader history of the islands, the moa-nalo filled a niche usually held by mammals. On other lands, animals like goats, deer, or giant tortoises perform this herbivore role. The disappearance of the moa-nalo after human settlement significantly changed the ecology of the Hawaiian Islands. Like other island species in Mauritius or New Zealand, the moa-nalo were unprepared for the arrival of mammals. They were easily predated by human hunters and introduced animals, such as feral domestic pigs, which led to their extinction.

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🖼️ Images & Media (4)
File:Thambetochen xanion.jpg
Thambetochen xanion.jpg
File:Thambetochen xanion (1).jpg
Thambetochen xanion (1).jpg
File:Cyanea platyphylla.jpg
Cyanea platyphylla.jpg
File:Chelychelynechen quassus by Stanton F. Fink.jpg
Chelychelynechen quassus by Stanton F. Fink.jpg
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