Great Maui crake

The great Maui rail or great Maui crake ("Porzana" severnsi) is an extinct bird species from Maui, Hawaiian Islands, known only from subfossil bones. The holotype (USNM collection numbers 378344 to 378363) are the bones of one almost-complete skeleton, found in Auwahi Cave on the lower southern slope of Haleakalā at 1,145 m AMSL.

Great Maui crake
Conservation status
Extinct (early 12th century)  (IUCN 3.1)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Gruiformes
Family:	Rallidae
Genus:	Porzana
Species:	†P. severnsi
Binomial name
†Porzana severnsi (Olson, 1973)
Island of Maui

This was the larger of two flightless rails which survived on Maui until people arrived in 150 C.E. Traditionally placed in the "wastebin genus" Porzana, it almost certainly does not belong there, but while its placement in subfamily Himanthornithinae is generally agreed upon, its precise affiliations are disputed. Its scientific name refers R. Michael Severns, in honour of his pioneering discoveries of lava caves with remains of extinct animals on Maui.

Description and ecology

The great Maui crake was the larger of two species of rail found on the island of Maui, roughly the size of a Ash-throated crake or half again as large as the Hawaiian rail, about 20-25 cm (8-10 in) altogether and weighing about 100 grams (3.5 oz), with a beak some 2 cm (slightly less than 1 inch) long. It was flightless due to its small wings – the entire arm, from fingertips to shoulder joint, was only about 5.5 cm (some 2 in) long, and the humerus was about 10% smaller in all dimensions than in the Great Oʻahu crake which was similarly-sized and also flightless. In the holotype, the sternum was even partially unossified despite the bird being fully grown, and had 6 large holes which would have prevented the development of anything but vestigial flight muscles. The legs, on the other hand, were at least as well-developed as in the Oʻahu species, with the tarsometatarsus measuring 36 mm on average.

The species' plumage is unattested, but most likely it had a brownish-greyish cryptic coloration – possibly almost blackish, or with some dark or pale spotting on the upperside – and perhaps with white-and-black vertical barring on the body between legs and tail like its presumed relatives.

Its ecology is largely unknown, but not likely to have differed much from the still-extant, slightly smaller, and probably fairly closely related Henderson crake. It was probably omnivorous, feeding mostly on invertebrates, seeds, and perhaps some fruit, bird eggs, and carrion. The great Maui crake's remains have so far been found only on the drier parts of Haleakalā, but below the almost desert-like upper slopes, in a region which even before human settlement and associated deforestation was mostly covered in shrubland and open koa/ʻōhiʻa lehua forest and at least seasonally arid.

Other than in Auwahi Cave, remains of this species have also been found in other lava caves on the southern slope of Haleakalā, as well as in the Lower Waihoi Valley Cave at 300 m AMSL about halfway between Hana and Kīpahulu near the eastern tip of the island. Whether it inhabited other parts of Maui – such as the tropical rainforest on the northeastern slope of Haleakalā –, or whether it was restricted to the semi-arid woodland habitat where its remains were found, is not yet known.

Extinction

Before human settlement, this species was apparently far more plentiful than the smaller Maui crake, as it is attested by abundant remains. While these were not found in a cultural context such as a village hearth or midden, it is very likely that the great Maui crake was hunted for food by Polynesian settlers. It may have also have been predated by Polynesian rats that were introduced by those settlers. In addition, the region where its remains were discovered is one of the most long-standing areas of dryland taro cultivation on Maui, and was extensively deforested starting about 1400 CE. By November 26 1778, when Maui was discovered by Europeans, the species was apparently entirely extinct already.

External links

• BirdLife International (2004). "Porzana ralphorum". IUCN Red List of Threatened Species. 2004. Retrieved 9 November 2006.old-form url Database entry includes justification for why this species is extinct