Moa-nalo

The moa-nalo are a group of now extinct aberrant, goose-like ducks (or duck-like goose) that once lived on some the larger Hawaiian Islands in the Pacific Ocean. They were the major herbivores on most of these islands until they became extinct after human settlement, a fate that it shared with the dodo (Raphus cucullatus).

The moa-nalo (the name literally means 'lost fowl' in the local language) were long unknown to science, having been wiped out before the arrival of James Cook in 1778, thus they were the victim of Polynesians that visited the island earlier.

Like island taxa from Mauritius, New Zealand and Polynesia, the moa-nalo were unused to mammals and were easily predated on by hunters or the animals that were introduced and became feral, such as domestic pigs or rats.

In the early 1980s, their fossil remains were discovered in sand dunes on the islands of Molokaʻi and Kauaʻi. Subsequently, bones were found on Maui, Oʻahu, and Lānaʻi, in lava tubes, lake beds, and sinkholes.

They represent four species in three genera so far:
- turtle-jawed moa-nalo (Chelychelynechen quassus) on Kauaʻi
- small-billed moa-nalo (Ptaiochen pau) on Maui
- O'ahu moa-nalo (Thambetochen xanion) on Oʻahu
- Maui Nui large-billed moa-nalo (Thambetochen chauliodous) on the prehistoric island of Maui Nui, which is composed of four modern islands: Maui, Molokaʻi, Lānaʻi, and Kahoʻolawe.

This also means that the moa-nalo isn't (yet) found on the main island.

Chelychelynechen ('turtle-jawed goose') had a large, heavy bill a bit like that of a tortoise, while the other two genera, Thambetochen and Ptaiochen, both had serrations in their bills known as pseudoteeth. All species were flightless and large, with an average mass of 4 to 7.5 kilograms.

Some moa-nalo fossils have been found to contain traces of mitochondrial DNA which were compared to living duck species in order to establish their place in the duck family, Anatidae. The result was that the moa-nalo were not related to the large geese (Anserinae), but instead to the genus Anas, which includes the mallard or wild duck (Anas platyrhynchos). At present, the DNA analysis' resolution is not high enough to precisely determine their relationships to different species of Anas, but biogeography strongly suggests that their closest living relative is the widespread Pacific black duck (Anas superciliosa).

The unusual bill shape and size of the moa-nalo can be attributed to their role in the ecology of prehistoric Hawaiʻi. A study of coprolites (fossilized dung) of the Maui Nui large-billed moa-nalo, found in Puʻu Naio Cave on lowland Maui, has shown they were folivorous ('leaf eaters'), eating particularly fronds from ferns. This conclusion is backed up by the shapes of their beaks. This indicates they were the principal browsers on the island.

The presence of prominent spines on the leaves and soft young stems of several Hawaiian lobelioids in the genus Cyanea suggests that they evolved these thornlike prickles on new growth because they would protect against browsing by the moa-nalo. Spines are unusual in an island flora where such defenses are frequently lost.

The moa-nalo themselves filled the niche of herbivore usually filled by mammals such as goats, or the giant tortoises of Galápagos and other archipelagoes. This has implications for the ecology of Hawaiian Islands today, as a major group of species have been lost.