If it looks like a duck and flies like a duck, it’s definitely not a subfossil Hawaiian duck

It’s pretty hard to find a body of water without finding ducks. They’re found on every continent except for Antarctica, and have made their way to a number of oceanic islands. This, of course, has led to the evolution of some downright daffy species.

Compared to common barnyard ducks, the extinct ducks of Hawaii were short-beaked, pot-bellied, and even less graceful. They were Hawaii’s own version of another famous flightless island-dweller, the dodo: descended from ancestors who could fly, they evolved to fill the niche as the island’s main herbivores. Unfortunately, the fate of Hawaii’s ducks followed that of the dodo. Shortly after the arrival of humans, these wonderfully bizarre birds vanished from their island paradise.

Moa-nalos: the turtle-jawed and stumbling pot-bellied ducks

The biggest of the Hawaiian ducks were the moa-nalos, a name formed from the Hawaiian words moa (“fowl”) and nalo (“lost”). (James & Olson, 1991)The word moa will appear familiar to those interested in extinct island birds, as the huge ratites of New Zealand shared this name. And, like the moas of New Zealand, these birds were equipped for a life on the ground.

Various species of Hawaiian ducks and geese, both extinct and extant. Top row, left to right: greater Hawaiian goose Branta sp. (extinct), Thambetochen chauliodous (extinct), T. xanion (extinct). Bottom row, left to right: Chelychelynechen quassus (extinct), greater Hawaiian goose B. hylobadistes (extinct), Ptaiochen pau (extinct). In the center is the nene B. sandvicensis the only surviving species of this group. Artwork by Julian Hume.

The moa-nalos displayed extremely robust legs and hips, as well as wings and keels reduced beyond use. With the exception of one species, moa-nalos also sported large, tooth-like ridges in their bills, perfect for grinding vegetation. All species probably lacked webbing on their feet, allowing them to lead a life on land with greater ease. Four species, consisting of three genera, have been discovered thus far.

The nearly-unpronounceable Chelychelynechen quassus, found on Kauai, translates to “broken turtle-jawed goose,” in reference to its extremely shortened bill and the locality of the original fossils: in the middle of a jeep trail. The remains were found in a shattered state due to the passing of cars overhead. C. quassus is the aforementioned token species which lacks the toothy ridges present in other species. This is likely due to the age of Kauai: older than the other Hawaiian islands, C. quassus had more time to adapt to a strictly herbivorous diet. Perhaps, had the other species endured, they would have developed similar adaptations.

C. quassus, the turtle-jawed goose of Kauai. Reconstruction by Carl Buell.

The two species of Thambetochen are surprisingly similar given their geographic distribution. Although they are found on two entirely difference islands, the distinction between the two species appears to be in general size. T. chauliodous is the larger of the two species, and also possesses a shorter, more curved bill than T. xanion of Oahu; the latter species also displays prominent comb-like ridges in its bill. Though T. chauliodous was present on both Maui and Molokai, there is no obvious variation between the two populations.

T. chauliodous shared the island of Maui with the unfortunately-named “stumbling goose,” Ptaiochen pau. P. pau was named for “the propensity of the species to fall into holes,” a reference to the environment in which the fossils were found, mostly in caves and valleys. The remains of P. pau are much more common at higher elevations than those of T. chauliodous; likewise, T. chauliodous is more common in the lowlands. This difference in range, even on the same small island, explains how the two species were able to avoid competition. (James & Olson, 1991)*

P. pau, a denizen of the highland rainforests of Maui. The toothlike ridges which allowed the moa-nalos to process tough plant matter can clearly be seen in the bills of these two birds. Reconstruction by Julian Hume.

DNA analysis of the moa-nalos indicates that, despite their goose-like appearance, they evolved from the same common ancestor as the most common family of ducks, the dabblers. (Cooper et. al, 1999) These include recognizable species such as mallards and wood ducks. Despite the weirdness of the “lost fowl,” there was one Hawaiian duck even stranger still.

*The vast majority of the information in this section comes from this text. It provides fantastic detail, comments, and visuals about the moa-nalos and many more extinct Hawaiian species. The references to this text are too numerous for me to add without being a nuisance. Hence, this footnote.

Check back soon for the jaw-dropping, hair-raising second part of this post.