New Zealand Pigeon

This large and distinctively-coloured pigeon is a familiar sight to many New Zealanders. This is because the New Zealand pigeon (or kereru) has a widespread distribution through the country, being present in extensive tracts of native forest, and rural and urban habitats, including most cities. As well as allowing close approach, it often roosts conspicuously, such as on powerlines or on the tops of trees. The distinctive sound of its wing beats in flight also draws attention. Kereru also frequently feature on works of art, such as paintings and sculptures. However, even though it is widespread, like many forest birds its abundance is severely compromised by introduced mammals, particularly possums, stoats and ship rats. Only where these pests are not present (predator-free islands) or are controlled to low levels do kereru populations thrive.

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Identification

Although there is some individual variation, in general the upper parts of adult kereru are blue-green, with a purple-bronze iridescence on the neck, mantle and coverts of the wings. The underparts are white with a sharp demarcation between the white and blue-green on the upper breast. The bill colouration is quite variable, from uniformly red, but often having a paler red or even orangey tip, and feet and eyes crimson. Fledglings and juveniles have duller plumage, and often the white chest is smudgy white-grey, and the demarcation between dark and white feathering is ragged and may have a narrow border of cinnamon wash over the upper white feathers.

Voice: kereru are generally silent except for occasional ‘oos’. Brief, moderate volume ‘oos’ are given when alarmed, such as a harrier flying close by, and longer, low volume ‘oooooos’, with a rising tone towards the end given as contact calls, often repeated several times.

There is no other species in New Zealand that looks similar to the New Zealand pigeon, apart from the Chatham Island pigeon, which is confined to the Chatham Islands.

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Distribution

Kereru are widespread through the country from Northland to Stewart Island, and on some offshore islands that have suitable forest / shrubland habitats.

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Habitat

Kereru inhabit a wide variety of forest types: podocarp-broadleaf forest, beech forest, second growth native forest regenerating after logging, small forest remnants, and exotic plantations (especially those with an understorey and/or stream-sides of native shrubs and trees). They also occur in farmland shelterbelts, urban parks, and rural and suburban gardens.

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Population

Kereru are widespread through the country, and are seasonally common at some locations where they gather in moderate-sized feeding flocks (20-50 birds, and rarely over 100).

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Threats and conservation

Although a major issue for conservation of the kereru in the early 1900s, habitat loss probably has little impact on regional populations today. The main threat to kereru is predation by introduced mammalian predators, particularly feral cats, possums, stoats and ship rats, especially when nesting. Other mortality factors include collisions with fast moving vehicles, overhead power and telephone wires and windows, electrocution when perched on some power poles, and illegal hunting. Where pest populations are removed (offshore islands, exclusion fenced areas) or controlled to very low levels kereru populations have increased markedly.

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Breeding

Kereru have been recorded breeding in all months, but most eggs are laid in September-April. Pigeons in native forest have been recorded not breeding when little or no fruit was available. The nest is a platform of dead twigs, and a single egg is laid. In general, females incubate from late afternoon until mid-morning, when the male takes over. The chick is brooded constantly until it is about 10 days old and well covered with feathers. From then until fledging at about 35-40 days of age, it is left alone by day, with the occasional brief visit by a parent to feed it. When fruit is readily available, pairs are able to have overlapping nesting attempts; a large chick in one nest and an egg being incubated in another. Pairs that have failed nesting attempts (due to predators, poor nest construction or a storm) often re-nest within a week or two.

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Behaviour and ecology

During the non-breeding season, kereru can be fairly inconspicuous, feeding and then roosting under a thick canopy for sometimes hours at a time. In the breeding season, they can be just the opposite, perching on top of trees and males giving frequent display flights at the start of a nesting cycle. While not a territorial species, an individual will defend a food tree against other pigeons attempting to feed in it too. Fights involve hitting each other with their wings while flapping about in flight and moving only a metre or two. 

While some individuals can spend weeks or months living within an area of a few hectares, such periods can be interspersed with long-distance flights to reach seasonal food sources. For example, one satellite-tagged Southland pigeon travelled at least 480 km during a 100-day period, involving four crossings of Foveaux Strait. A few tagged pigeons in Taranaki flew up to 60 km to reach autumn fruit sources. Thus the species is able to travel between suburbia, remnant forest patches, extensive tracts of native forest and other habitats in their quest for seasonally available foods. Combined with the kereru’s large size (and hence large mouth-width) and diet of fruit, these landscape-scale movements make kereru the most important vector for the transfer of seeds between widely-spaced fragments of native forest.

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Food

Foods include buds, leaves, flowers and fruit from a wide variety species, both native and exotic. In addition, they have been seen feeding on the fruiting bodies of the parasitic strawberry fungus Cyttaria gunnii found in beech forest. While most foods are taken while clambering about on vines, shrubs and trees, at a few locations kereru spend time on the ground feeding on clover and possibly other herbs. While ripe fruit seems to be the preferred food, in most regions fruit is not available year round, and so kereru then feed on leaves. Important leaf sources include those of kowhai, tree lucerne, broom, willows, elms and poplars.