The huia ( ; ; Heteralocha acutirostris) is an extinct species of New Zealand wattlebird, endemic to the North Island of New Zealand. The last confirmed sighting of a huia was in 1907, although there was another credible sighting in 1924.
It was already a rare bird before the arrival of Europeans, confined to the Ruahine, Tararua, Rimutaka and Kaimanawa mountain ranges in the south-east of the North Island. It was remarkable for its pronounced sexual dimorphism in bill shape; the female's beak was long, thin and arched downward, while the male's was short and stout, like that of a crow. Males were long, while females were larger at . The sexes were otherwise similar, with orange wattles and deep metallic, bluish-black plumage with a greenish iridescence on the upper surface, especially about the head. The tail feathers were unique among New Zealand birds in having a broad white band across the tips.
The birds lived in forests at both montane and lowland elevations – they are thought to have moved seasonally, living at higher elevations in summer and descending to lower elevations in winter. Huia were omnivorous and ate adult insects, grubs and spiders, as well as the fruits of a small number of native plants. Males and females used their beaks to feed in different ways: the male used his bill to chisel away at rotting wood, while the female's longer, more flexible bill was able to probe deeper areas. Even though the huia is frequently mentioned in biology and ornithology textbooks because of this striking dimorphism, not much is known about its biology; it was little studied before going extinct.
The huia is one of New Zealand's best-known extinct birds because of its bill shape and beauty, as well as its special place in Māori culture and oral tradition. The bird was regarded by Māori as (sacred), and the wearing of its skin or feathers was reserved for people of high status.
Taxonomy and etymology
The genus name, Heteralocha, derives from Ancient Greek ἕτερος "different" and ἄλοχος "wife". It refers to the striking difference in bill shape between male and female. The specific name, acutirostris, derives from Latin acutus, meaning "sharp pointed", and rostrum, meaning "beak", and refers to the beak of the female.
John Gould described the huia in 1836 as two species: Neomorpha acutirostris based on a female specimen, and N. crassirostris based on a male specimen—the epithet crassirostris derives from the Latin crassus, meaning "thick" or "heavy", and refers to the male's short bill. In 1840, George Robert Gray proposed the name N. gouldii, arguing that neither of Gould's names was applicable to the species.Gray 1840:15 In 1850, Jean Cabanis replaced the name Neomorpha, which had been previously used for a cuckoo genus, with Heteralocha.Cabanis 1850–1851:218, footnote In 1888 Sir Walter Buller wrote: "I have deemed it more in accordance with the accepted rules of zoological nomenclature to adopt the first of the two names applied to the species by Mr Gould; and the name Neomorpha having been previously used in ornithology, it becomes necessary to adopt that of Heteralocha, proposed by Dr Cabanis for this form."Buller 1888:8
The huia appears to be a remnant of an early expansion of passerines in the country of New Zealand and is the largest of the three members of the family Callaeidae, the New Zealand wattlebirds; the others are the saddleback and the kōkako. The only close relative to the family is the stitchbird; their taxonomic relationships with other birds remain to be determined. A molecular study of the nuclear RAG-1 and c-mos genes of the three species within the family proved inconclusive, the data providing most support for either a basally diverging kōkako or huia.
Description
The huia had black plumage with a green metallic tinge and distinctive rounded bright orange wattles at the gape. In both sexes, the eyes were brown; the beak was ivory white, greyish at the base; the legs and feet were long and bluish grey while the claws were light brown. Huia had twelveBest 2005 long glossy black tail feathers, each tipped for with a broad band of white.Barrie and Robertson 2005 Immature huia had small pale wattles, duller plumage flecked with brown, and a reddish-buff tinge to the white tips of the tail feathers. The beak of the young female was only slightly curved. Māori referred to certain huia as huia-ariki, "chiefly huia". The huia-ariki had brownish plumage streaked with grey,Buller 1888:8 and the feathers on the neck and head were darker. This variant may have been a partial albino, or perhaps such birds were simply of great age. Several true albino huia were recorded. A white specimen painted by John Gerrard Keulemans around 1900 may have been the result of progressive greying or leucism, rather than albinism; the current whereabouts of this specimen are unknown.
Although sexual dimorphism in bill shape is found in other birds, such as the riflebirds, sicklebills and other wood-excavating birds including some species of woodpecker,Jayne-Wilson 2004:76 it was most pronounced in the huia. The beak of the male was short at approximately and slightly arched downwards and robust, very similar to that of the closely related saddleback, while the female's beak was finer, longer at around , and decurved (curved downward) like that of a hummingbird or honeyeater. The difference was not only in the bone; the rhamphotheca grew way past the end of the bony maxilla and mandible to produce a pliable implement able to deeply penetrate holes made by wood-boring beetle larvae. The skulls and mandibles of the huia and saddleback are very similar, the latter essentially miniatures of the former.Holdaway, Worthy 2002:481
There are two possible explanations for the evolution of this sexual difference in bill shape. The most widely supported is that it allowed birds of different sexes to utilise different food sources. This divergence may have arisen because of a lack of competitors in these foraging niches in the North Island forest ecosystems. The other idea is that the ivory-coloured bill, which contrasted sharply with the bird's black plumage, may have been used to attract a mate. In animals that use sexually dimorphic physical traits to attract a mate, the dimorphic feature is often brightly coloured or contrasts with the rest of the body, as with the huia. It has been suggested that as the female was the main provider of food for the chicks by regurgitation, this sex evolved the longer bill to obtain the protein-rich invertebrate diet required for the chicks.
Another, less obvious aspect of the huia's sexual dimorphism was the minor size difference between the sexes. Males were long, while females were larger at . Additionally, the tail of the male was about in length and the wingspan was between , while the female's tail was and the female's wingspan was .
Distribution and habitat
Subfossil deposits and midden remains reveal that the huia was once widespread in both lowland and montane native forest throughout the North Island, extending from the northernmost tip at Cape ReingaTennyson and Martinson 2006 to Wellington and the Aorangi Range in the far south. Only a few huia are known from the extensive pitfall deposits in the karst of the Waitomo Caves area and they are also rare or absent in fossil deposits in the central North Island and Hawke's Bay; it seems to have preferred habitats that are not well sampled by the deposits known at present. The huia vanished from the northern and western North Island following Māori settlement in the 14th century, due to over-hunting, forest clearance, and introduced kiore preying on nests.Holdaway, Worthy 2002:556 By the time of European settlement in the 1840s it was only found south of a line from the Raukumara Range in the east, across the Kaimanawa Range, to the Turakina River in the Rangitikei in the west. In the south, its range extended to the Wairarapa and the Rimutaka Range east of Wellington. Reports collected by Walter Buller and a single waiata (Māori song) suggest that the huia was once also found in the Marlborough and Nelson districts of the South Island; however, it has never been identified in the rich fossil deposits south of Cook Strait,Holdaway, Worthy 2002:437 and there is no other evidence of the species' presence.Higgins et al. 2006:1014
The huia inhabited both of the two principal forest types in New Zealand. They were primarily found in broadleaf-podocarp forests where there was a dense understorey, but occasionally also in southern beech (Nothofagus) forest. The species was observed in native vegetation including mataī (Prumnopitys taxifolia), rimu (Dacrydium cupressinum), kahikatea (Dacrycarpus dacrydioides), northern rātā (Metrosideros robusta), maire (Notelaea), hinau (Elaeocarpus dentatus), tōtara (Podocarpus totara), rewarewa (Knightia excelsa), māhoe (Melicytus ramiflorus), and taraire (Beilschmiedia tarairi), and at sea level in karaka (Corynocarpus laevigatus) trees at Cape Turakirae. It was never seen in burnt forest or land cleared for farming.
Ecology and behaviour Movements
The huia's movements are little known, but it was most likely sedentary. The huia is thought to have undertaken seasonal movements, living in montane forests in the summer and moving down into lowland forests in the winter to avoid the harsher weather and cold temperatures of higher altitudes. Like the surviving New Zealand wattlebirds, the saddleback and the kōkako, the huia was a weak flier and could only fly for short distances, and seldom above tree height. More often it would use its powerful legs to propel it in long leaps and bounds through the canopy or across the forest floor, or it would cling vertically to tree trunks with its tail spread for balance.
Feeding and ecology The huia, with the previously endangered saddleback, were the two species of classic bark and wood probers in the arboreal insectivore guild in the New Zealand avifauna. Woodpeckers do not occur east of Wallace's line; their ecological niche is filled by other groups of birds that feed on wood-boring beetle larvae, albeit in rotting wood. The woodpecker-like role was taken on by two species in two different families in the New Zealand mixed-podocarp and Nothofagus forests; one was the huia and the other was the kākā.Holdaway, Worthy 2002:483
The huia foraged mainly on decaying wood. Although it was considered a specialist predator of the larvae of the nocturnal huhu beetle (Prionoplus reticularis), it also ate other insects—including wētā—insect larvae, spiders, and fruit.Higgins et al. 2006:1015
Insects and spiders were taken from decaying wood, from under bark, mosses and lichens, and from the ground. Huia foraged either alone, in pairs, or in small flocks of up to five, which were probably family groups.Higgins et al. 2006:1016 The sexual dimorphism of the bill structure gave rise to feeding strategies that differed radically between the sexes. The male used its adze-like bill to chisel and rip into the outer layers of decaying wood, while the female probed areas inaccessible to the male, such as the burrows of insect larvae in living wood. The male had well-developed cranial musculature allowing rotten wood to be chiselled and pried apart by "gaping" motions. There are corresponding differences in the structure and musculature of the head and neck between males and females. Huia had very well developed depressor jaw muscles, and an occipital crest that provided extra surface for muscle attachment, allowing the jaw to be opened with considerable force. Once the bird had secured a meal, it flew to a perch with the insect in its feet. The huia stripped its meal of any hard parts, then tossed the remainder up, caught, and swallowed it.