Whitehead (bird)

Whitehead, Mohoua albicilla[6]

The diet of whiteheads is primarily insectivorous in nature – they are classed as arboreal insectivores.[7] Their main prey are spiders, moths, caterpillars and beetles[2] which are gleaned from tree trunks, leaves and branches in the canopy and subcanopy. They rarely feed on the forest floor.[3][5] They will supplement their predominantly insectivorous diet with the fruits of native plants such as māhoe and matipo and like the yellowhead, they frequently hang upside down from branches or twigs while feeding. Whiteheads will often form mixed-species feeding flocks with saddlebacks, kākāriki or silvereyes to catch the insects these birds dislodge as they feed.[2]

Unlike the yellowhead, which nests only in the cavities of tree trunks which are generally high up in the canopy, the whitehead builds a more conventional cup shaped nest at a height between 1 and 15 metres above the ground; either in the canopy of the forest or lower down in smaller trees or shrubs.[2] Between 2–4 eggs of variable colouration are laid, the incubation period is generally around 18 days and fledging takes a further 16–19, the chicks being fed by both parents.[3] In November and December, the long-tailed cuckoo frequently acts as a brood parasite of nesting whiteheads by pushing their eggs out of the nest and laying a single egg of its own in their place[8][9]

In times past, the whitehead held a special place within Māori culture among the forest birds of New Zealand. They featured not only in Māori folklore and legends but also in a number of rites for which live individuals were captured.[10] Flocks of whiteheads form part of the hākuturi, a multitude of small birds sometimes called Te Tini o te Hākuturi – "The myriads of Hākuturi", the spirit guardians of the forest. In a Ngāti Mahuta story, the culture hero Rata went into the forest and cut down a tree to make a canoe, but failed to perform the proper placatory rites to Tāne, god of the forest. Whiteheads and riflemen whistled shrilly at him in admonishment and gathered together the pieces of the tree until it stood whole again. This happened several times until Rata showed remorse and the birds felled the tree and made the canoe for him.[10] In some stories, the whitehead was one of several small birds chosen by Māui to accompany him in his (ultimately unsuccessful and fatal) quest to abolish death by killing Hine-nui-te-pō, the goddess of night and death.[10] The mobbing behaviour sometimes seen in whiteheads is reflected in one legend which tells of swarms of whiteheads scratching out the eyes of Whaitiri, goddess of thunder, as they pass her house, thus causing her to go blind.[10]

Whitehead on Tiritiri Matangi Island

The whitehead, as a messenger between man and the gods, was a very tapu (sacred) bird.[10] This status was reflected in its role in the tohi rite, a ritual performed over an infant. This entailed a tohunga touching the head of an infant with a live whitehead and reciting a karakia (incantation) firstly to cause the mana (power and prestige) of the gods to descend on the child from the gods and secondly to open the child's eyes and ears to the knowledge of the ancestors.[10] After the karakia was complete the bird was freed to demonstrate that the mana received would return to the gods when the child died. The whitehead also held this role as a messenger to the gods when a new pā (fortified village) was dedicated. Once the ceremonies were complete a single whitehead was released unharmed, the pā became free of tapu, and could be safely entered. The purpose of this rite was to bring prosperity and vitality to the pā and its people in times of war and peace.[10] When a candidate was applying to a senior tohunga to become a matakite, or seer, he had first to catch a small bird such as a whitehead. After more ritual the applicant was shut in a hut to sleep with the bird for a night. Next morning he opened the door and if the bird flew away of its own accord, his suitability to be a seer, as indeed the whitehead was regarded to be, was confirmed.[10] In the past, the appearance of a flock of whiteheads was interpreted by Māori from the upper regions of the Whanganui River as a sign that kēhua (ghosts) were nearby[9]

19th-century forestry workers (bushmen) regarded the whitehead as a useful forecaster of the weather: "They kept up a lively chirping some hours before an approaching storm. It was a warning which the bushmen never allowed to pass unnoticed".[11] Colonists called this bird "Joey whitehead" for its distinctive head colouration.[10] This is the origin of the English-language name of the bird.

Subfossil remains of whiteheads have been found on the North Island[2] and the species was still very widespread when European settlement of New Zealand began in the 1840s.[2] However, soon after, they began to decline as a result of both the widespread clearance of lowland forests for agriculture[2] and the predation by several species of mammalian predators introduced by Europeans, including several species of rodents and mustelids. Such introduced species remain a problem for many whitehead populations today, as they both compete with them for food and prey upon the birds themselves. As a result, the species has experienced local extinctions of many of its populations throughout the North Island, particularly in its northern regions; whiteheads disappeared from Northland in the 1870s and from the greater Auckland area in the 1880s.[2] They also disappeared from Great Barrier Island in the 1950s.

In an effort to restore this species to its former range, a number of conservation reintroductions have been carried out in the last twenty years. All these reintroductions were carried out as part of wider efforts towards eco-restoration at each of the native forest sites concerned.

Due to the northern North Island local extinctions, whiteheads were, until recently, extinct on the mainland of the North Island north of about Hamilton. However, this situation has been rectified by 3 of the above releases in the Hunua Ranges, Waitākere Ranges and on Tiritiri Matangi Island. The Karori and Tiritiri Matangi reintroductions were done independently while the Hunua reintroduction was an Auckland Regional Council initiative. The Auckland Regional Council also played a part in the Waitākere Ranges "Ark in the Park" project release – the project is a joint effort being a joint effort between this local government body and the NZ conservation not for profit NGO Forest and Bird.