| Whitehead | |
|---|---|
 | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Family: | Mohouidae |
| Genus: | Mohoua |
| Species: | M. albicilla |
| Binomial name | |
| Mohoua albicilla (Lesson, 1830) | |
Thewhitehead (Mohoua albicilla;Māori:pōpokotea) is a small species (15 cm in length, 18.5/14.5 g.[2]) ofpasserine birdendemic to New Zealand. It is classified in the familyMohouidae. The male whitehead's upperparts, wings and tail are a pale brown in colour, while the head and underparts are white – in the case of the male an almost pure white in colour. Females and juveniles have similar colouration except that thenape and crown (top of the head) are shaded brown.[2][3] The blackbeak and eyes contrast with the white head and the feet are bluish black in colouration.
Formerly quite common and widespread in native forests in theNorth Island, the whitehead has suffered a marked decline in the past two centuries since European colonisation and today it is restricted to a fraction of its former range. Historically,deforestation has destroyed large areas of habitat for this species but today the greatest threat is from predation byinvasive mammalian species such asrats andstoats. It has been the subject of an active conservation campaign and has been successfully reintroduced into reserves nearAuckland andWellington respectively. In the past whiteheads held a special place in Māori culture. As well as the species appearing in many legends, whiteheads were viewed by Māori to have roles as messengers of the gods and as fortune tellers orseers – and because of these beliefs, live birds were caught and used in several different kinds of ceremonial rites.
Therange of this species has always been restricted to theNorth Island of New Zealand, as well as several offshore islands surrounding it, includingLittle Barrier Island (where it is the most common forest bird),[4]Great Barrier Island andKapiti Island.[5] It has however, contracted markedly since the 19th century due to a number of human induced factors (see the Conservation section below). The distributions of the whitehead and its close relative, the yellowhead areallopatric, with the range of the yellowhead being restricted to theSouth Island. Whiteheads are generally restricted to the larger tracts of older scrub and native forest that remain in the North Island but have proven their adaptability by establishing populations in a number of exotic pine plantations, particularly on theNorth Island Volcanic Plateau.[2][3]
When encountered whiteheads often displayflocking behaviour. The flocks generally consist of small family groups.[2]
The diet of whiteheads is primarilyinsectivorous in nature – they are classified asarboreal insectivores.[7] Their main prey are spiders, moths, caterpillars and beetles[2] which aregleaned from tree trunks, leaves and branches in thecanopy andsubcanopy. They rarely feed on the forest floor.[3][5] They will supplement their predominantly insectivorous diet with the fruits of native plants such asmāhoe and matipo and like theyellowhead, they frequently hang upside down from branches or twigs while feeding. Whiteheads will often formmixed-species feeding flocks withsaddlebacks,kākāriki orsilvereyes 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 2–4eggs of variable colouration are laid, theincubation 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, thelong-tailed cuckoo frequently acts as abrood parasite for 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 withinMāori culture among the forest birds of New Zealand. They featured not only inMāori folklore and legends but also in a number of rites for which live individuals were captured.[10] Flocks of whiteheads form part of thehākuturi, a multitude of small birds sometimes calledTe Tini o te Hākuturi – "The myriads of Hākuturi", the spirit guardians of the forest. In aNgāti Mahuta story, the culture heroRata went into the forest and cut down a tree to make a canoe, but failed to perform the proper placatory rites toTāne, god of the forest. Whiteheads andriflemen 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 byMāui to accompany him in his (ultimately unsuccessful and fatal) quest to abolish death by killingHine-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 ofWhaitiri, goddess of thunder, as they pass her house, thus causing her to go blind.[10]
The whitehead, as a messenger between man and the gods, was a verytapu (sacred) bird.[10] This status was reflected in its role in the tohi rite, a ritual performed over an infant. This entailed atohunga touching the head of an infant with a live whitehead and reciting akarakia (incantation) firstly to cause themana (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 newpā (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 amatakite, 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 theWhanganui 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 ofrodents andmustelids. Suchintroduced 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 fromNorthland in the 1870s and from the greaterAuckland area in the 1880s.[2] They also disappeared fromGreat 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.
| Release location | Birds sourced from | Number of whiteheads released | Date(s) of release | Population successfully established? |
|---|---|---|---|---|
| Mana Island[12] | Kapiti Island | 38 | 20 July 2010 | Uncertain |
| Waitākere Ranges[13] | Tiritiri Matangi Island | 55 | August 2004 | Uncertain |
| Hunua Ranges[14] | Tiritiri Matangi Island | 40 | April 2003 | Yes |
| Karori Wildlife Sanctuary | Kapiti Island | 63 | 2001–2002 | Yes |
| Tiritiri Matangi Island[15] | Little Barrier Island | 80 | 1989–1990 | Yes |
Due to the northern North Island local extinctions, whiteheads were, until recently, extinct on the mainland of the North Island north of aboutHamilton. However, this situation has been rectified by three 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 anAuckland 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 NGOForest and Bird.
