Moanalo

The Moa Nalo
Moa-Nalo—Many species of the giant, flightless ducks known as moa-nalo once inhabited the Hawaiian Islands. (Renata Cunha)

Scientific name: Several species Scientific classification: Phylum: Chordata Class: Aves Order: Anseriformes Family: Anatidae When did they become extinct? These birds became extinct around 1,000 years ago. Where did they live? Their remains have been found on all the larger Hawaiian islands.

The island chain of Hawaii, located around 3,700 km from the U.S. mainland, is the most remote archipelago on the planet. The islands that make up Hawaii appeared from beneath the waves and are effectively the tops of submarine volcanoes that increase in height and area as they disgorge their very runny lava. Following their appearance, these landmasses were quickly colonized by living things. Bacteria, plants, fungi, and small animals can be dispersed on the wind, and the waves deposit other pioneers.

Birds, with their power of flight, are probably the first large animals to reach uncolonized islands, and one group of these animals, which reached Hawaii, evolved into bizarre creatures. These were the moa-nalo, and they were a group of flightless, gooselike birds that lived on all the main Hawaiian Islands. The word moa means "fowl" and nalo means "lost," so their Hawaiian name can be translated as "lost fowl." The remains of these birds have been found in sand dune blowouts, where the wind has uncovered their bones, and in sinkholes and lava tubes, both of which probably act as natural traps. These bones show that these birds were about the same weight as a swan, but much stockier, with a robust pelvis and powerful, thick legs. Moa-nalo also had very large bills that have been likened to the horny jaws of the giant tortoises that inhabit the Galápagos Islands and some of the islands in the Indian Ocean.

The moa-nalo may have been equipped with powerful bills and sturdy legs, but their wings were tiny structures that were of no use whatsoever for flight. Like the moa of New Zealand, the dodo of Mauritius, and the elephant bird of Madagascar, the moa-nalo had no need of flight as there were no large predators on the Hawaiian Islands. In this predator-free environment, the birds gave up flight and became large, ground-dwelling creatures.

What did these peculiar birds eat? The numerous remains that have been found of the moa-nalo include coprolites (fossilized droppings). These droppings have been studied, and it seems that the moa-nalo were specialist plant eaters. They probably waddled around the lush Hawaiian Islands nibbling a variety of low-growing plants. The beaks of some species of moa-nalo are even equipped with serrations that functioned like teeth, enabling them to take beakfuls of tough vegetation. The contents of plant cells are nutritious, but they are bound in a tough wall of cellulose that animals cannot digest because they lack the ability to produce the enzyme known as cellulase. To get at the goodness inside plant cells, any plant-feeding animal has to enlist the help of bacteria, and moa-nalo were no exception. Like horses and rabbits, the moa-nalo were hind-gut fermenters. The rear portion of their digestive tract was where the soup of mashed up plant matter and digestive fluids were brought into contact with the symbiotic, cellulase producing micro-organisms. More evidence for moa-nalo as plant eaters is the observation that many types of native Hawaiian plant are well protected with thorns and prickles. Such protection seems an extravagance on an island where there are no large native herbivores, but these defenses are probably reminders of the time when these plants were at the mercy of these plant-nibbling birds that roamed all over Hawaii.

Following the discovery of moa-nola remains, it was a mystery exactly what type of bird they were. In general size and proportion, they were gooselike, but the bones of the moa-nalo had more in common with ducks. Today, it is possible to extract DNA from long-dead bones and compare this to DNA taken from living species to build a family tree and to tell us how long a species has been around. Ancient DNA cannot give us 100 percent accurate results, but it can give us plausible estimates and scenarios. The DNA extracted from moa-nalo bones showed that these birds were indeed more closely related to the ducks and that their ancestor reached the Hawaiian Islands about 3.6 million years ago. What was their ancestor? It is difficult to know for sure, but some experts believe that the very widespread Pacific black duck (Anas superciliosa) or a now extinct similar species are likely candidates. The Hawaiian Islands, 3.6 million years ago, were a lush paradise without any large browsing animals, so the ancestors of the moa-nalo spread between the islands and evolved to fill this gap.

Like the numerous other flightless birds that have become extinct in the last couple of millennia, we can be almost certain that humans caused the extinction of the moa-nalo. The time of arrival of humans in Hawaii is a bone of contention among anthropologists, but Polynesians have been there since at least a.d. 800. Like the dodo, the moa-nalo was very easy to hunt. They had never seen a human and so had no innate fear of our very dangerous species. Moa-nalo were large birds (4 to 7 kg) and probably highly prized by Polynesian hunters. As the moa-nalo had evolved in the absence of predators, there was no need to reproduce quickly to balance out the mortality rate. They were probably very long-lived, slow-growing birds with a low rate of reproduction. The other big problem that humans brought with them to Hawaii was a menagerie of nonnative animals (dogs, cats, sheep, goats, pigs, etc.). These competed with the moa-nalo for food, disturbed their nests, and even ate their eggs. Even though they had lived, unmolested, on the Hawaiian Islands for more than 3 million years, the moa-nalo were probably hammered into extinction in as little as 200 years after the first humans reached this volcanic archipelago.

♦ Hawaii is so distant from other landmasses that a huge variety of unique creatures evolved there. The birds were especially diverse, and a few ancestral colonists that reached these remote islands from distant shores gave rise to a myriad of species, many of which are now sadly extinct.

♦ It is thought these original colonists were represented by 15 species, and over a short period of geological time, they evolved into around 78 species, although this number is far higher if we include those species, such as the moa-nalo, that are known only from bones.

♦ Since humans colonized Hawaii, more than 56 species of bird have become extinct, and many of the remaining native species are severely endangered. The demise of some of these species is thought to have been caused by avian malaria, which was introduced to the islands by nonnative birds brought by humans.

Further Reading: James, H. F., and D. A. Burney. "The Diet and Ecology of Hawaii's Extinct Flightless Waterfowl: Evidence from Coprolites." Biological Journal of the Linnaean Society 62 (1997): 279-97; Sorenson, M. D., A. Cooper, E. E. Paxinos, T. W. Quinn, H. F. James, S. L. Olson, and R. C. Fleischer. "Relationships of the Extinct Moa-Nalos, Flightless Hawaiian Waterfowl, Based on Ancient DNA." Proceedings of the Royal Society of London, B: Biological Sciences 266 (1999): 2187-93; Slikas, B. "Hawaiian Birds: Lessons from a Rediscovered Avifauna." Auk 120 (2003): 953-60.

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