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Kererū

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Kererū
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Aves
Order:
Columbiformes
Family:
Columbidae
Genus:
Hemiphaga

Bonaparte, 1854
Species:
H. novaeseelandiae
Binomial name
Hemiphaga novaeseelandiae

The kererū or New Zealand Pigeon (Hemiphaga novaeseelandiae) is a bird endemic to New Zealand. The Māori name is Kererū in the South Island and much of the North Island. Other Māori names for the bird are kūkupa (in parts of the North Island) and kūkū (Northland). New Zealand pigeons are commonly called wood pigeons, though they are not the same as the Wood Pigeon (Columba palumbus) which is a member of a different genus.

The kererū belongs to the family Columbidae, and the subfamily Treroninae, which is found throughout Southeast Asia, Malaya, Africa and New Zealand. The members of this subfamily feed largely on fruits mainly drupes.[1] New Zealand pigeons are members of the pigeon genus Hemiphaga (Bonaparte, 1854, this is a monotypic genus endemic to the New Zealand archipelago and Norfolk Island, however recently a Hemiphaga bone was found on Raoul Island.[2] The Chatham Island Pigeon, formerly considered a subspecies of the Kererū, has been elevated to a full species.

Description

The New Zealand pigeon is a large (550 to 850 g) arboreal (lives in trees) fruit-pigeon[3] found in forests from Northland to Stewart Island, ranging in habitats from coastal to montane.[4] The general morphology is that of a typical pigeon, in that it has a relatively small head, a straight soft-based bill and loosely attached feathers. It also displays typical pigeon behaviour, which includes drinking by suction, a wing-threat display, hitting with the wing when threatened, a diving display flight, a ‘bowing’ display, ritualised preening and ‘billing’ during courtship. New Zealand pigeons build flimsy, shallow, twiggy nests and feed crop milk to hatchlings.[1] [5]

The New Zealand pigeons are the second largest members of the family Columbidae. Kererū grows to some 51 cm (20 inches) in length and 650 g in weight on the mainland, and parea 55 cm (22 in) and 800 g on the Chatham Islands. The head, throat and wings are generally a shiny green-purple colour, but with a bronze tinge to the feathers on the mainland and an ashy-grey wash on the Chathams. The breast is typically white and the bill red with an orange-ish tip. The feet and eye are red. Juveniles have a similar colouration but are generally paler with dull colours for the beak, eyes and feet and a shorter tail.

The New Zealand pigeons make occasional soft coo sounds (hence the onomatopoeic names), and the wings make a very distinctive whooshing sound as they fly. The bird's flight is also very distinctive - birds will often ascend slowly before making impressively steep parabolic dives, this thought to be often associated with nesting, or nest failure.

Diet

The New Zealand pigeons are commonly known as frugivorous, primarily eating fruits from native trees. They play an important ecological role, as they are the only birds capable of eating the largest (smallest diameter greater than 1cm) native fruits and drupes and thus spreading the seeds intact. While fruit comprises the major part of their diets, the New Zealand pigeon also browses on leaves and buds, especially nitrogen rich foliage during breeding. One of their favorite leaves to eat is from an introduced plant the common plum tree. The diet changes seasonally as the availabiltiy of fruit changes, and leaves can comprise the major part of the diet at certain times of the year, such as when there is little fruit around.[6]

Breeding

Breeding generally depends on the occurrence of ripe fruit, which varies seasonally, annually (good years and bad years), and by location. New Zealand pigeons, like other frugivorous pigeons, feed on many species with tropical affinities, including the Lauraceae and Arecaceae [7][8][9][10] but live in the temperate forest of New Zealand and also feed on podocarp species, thought to be elements of Gondwana, such as miro (Prumnopitys ferruginea) and Kahikatea (Dacrycarpus dacrydioides). [8][9][11][10] A complete list of fruits taken by kererū can be found below. The more tropical tree species are restricted to the warmer norther half of the North Island, and in these regions pigeons can nest nearly all year round provided enough fruit is available. Further south many tropical tree species are missing and in these areas breeding usually occurs between October (early spring) and April (late summer/early autumn), again depending on fruit availability.

New Zealand pigeons nest in trees, laying a single egg, in a flimsy nest constructed of a few twigs thrown together. The egg is incubated for 28 days. The young bird then takes another 36 days to fledge. In seasons of plentiful fruit the pigeons can successfully nest more than once.

Distribution and conservation

The population of the Kererū dropped considerably since the arrival of humans in New Zealand, and this decline continues, especially in the North Island, but is still relatively common in the west of the South Island and in coastal Otago. They are commonly found in native forests (lowlands in particular), scrub, rural and city gardens and parks.

The introduced Australian common brushtail possum (Trichosurus vulpecula) and introduced species of rats - mainly the ship or black rat (Rattus rattus) but also the kiore or Polynesian rat (Rattus exulans) and brown rat (Rattus norvegicus)) have significantly reduced the amount of fruit available for pigeons and other native birds and also prey upon eggs and nestlings.

Pigeon populations are under also threat from hunting, habitat degradation and poor reproductive success.[12][13][14] Pigeons were very numerous until about the 1860s and large flocks used to congregate in fruiting trees to feed.[15] Restrictions on the shooting of pigeons were necessary as early as 1864, with total protection since 1921,[1] although the enforcement against hunting was not consistent [2].

Subspecies

There are two subspecies of New Zealand pigeon, H. n. novaseelandiae of mainland New Zealand is the most numerous. The other subspecies was the H.n. spadicea of Norfolk Island, which is now extinct. The subspecies differ in their plumage colour and physical morphology.[5]

Formerly considered a subspecies, H. n. chathamensis or parea on the Chatham Islands is distinct enough to have been raised to full species status.[16]

See also

Wikimedia Commons has media related to Hemiphaga novaeseelandiae.

References

  1. ^ a b c Falla, R. A., R. B. Sibson, and E. G. Turbott (1979). The new guide to the birds of New Zealand and outlying islands. Collins, Auckland.
  2. ^ Worthy, T. H., and R. Brassey. (2000). New Zealand pigeon (Hemiphaga novaeseelandiae) on Raoul Island, Kermadec Group. Notornis 47
  3. ^ Clout, M. (1990). The Kereru and its forests. Birds International 2:10-19.
  4. ^ Clout, M. N., P. D. Gaze, J. R. Hay, and B. J. Karl. (1986) Habitat use and spring movements of New Zealand pigeons at Lake Rotoroa, Nelson Lakes National Park. Notornis 33:37-44.
  5. ^ a b James, R. E. (1995). Breeding ecology of the New Zealand pigeon at Wenderholm Regional Park. p93. School of Environmental and Marine Science. University of Auckland, Auckland.
  6. ^ O'Donnel, C & P. Dilks (1994) "Foods and foraging of forest birds in temperate rainforest, South Westland, New Zealand" New Zealand Journal of Ecology 18(2): 87-107. [1]
  7. ^ Bell, R. (1996). Seed dispersal by kereru (Hemiphaga novaseelandiae) at Wenderholm Regional Park. p87. School of Biological Sciences. University of Auckland, Auckland.
  8. ^ a b Clout, M. N., and J. R. Hay. (1989) The importance of birds as browsers, pollinators and seed dispersers in New Zealand forests. New Zealand Journal of Ecology 12:27-33.
  9. ^ a b Clout, M. N., B. J. Karl, and P. D. Gaze. (1991). Seasonal movements of New Zealand pigeons from a lowland forest reserve. Notornis 38:37-47.
  10. ^ a b McEwen, W. M. 1978. The food of the New Zealand pigeon (Hemiphaga novaeseelandiae). New Zealand Journal of Ecology 1:99-108.
  11. ^ Clout, M. N., and J. A. V. Tilley. (1992) Germination of miro (Prumnopitys ferruginea) seeds after consumption by New Zealand pigeons (Hemiphaga novaeseelandiae). New Zealand Journal of Ecology 30:25-28.
  12. ^ Clout, M. N., K. Denyer, R. E. James, and I. G. Mcfadden. (1995) Breeding success of New Zealand pigeons (Hemiphaga novaeseelandiae) in relation to control of introduced mammals. New Zealand Journal of Ecology:209-212.
  13. ^ Clout, M. N., B. J. Karl, R. J. Pierce, and H. A. Robertson. (1995) Breeding and survival of New-Zealand pigeons Hemiphaga novaeseelandiae. Ibis 137:264-271.
  14. ^ Clout, M. N., and A. J. Saunders. (1995) Conservation and ecological restoration in New Zealand. Pacific Conservation Biology 2:91-98.
  15. ^ Best, E. (1977). Forest lore of the Maori. E.C. Keating Government Printer, Wellington, New Zealand.
  16. ^ Millener, P. R., and R. G. Powlesland. (2001). The Chatham Island pigeon (Parea) deserves full species status; Hemiphaga chathamensis (Rothschild 1891); Aves: Columbidae. Journal of the Royal Society of New Zealand 31:365-383.
  • Template:IUCN2006 Database entry includes a range map and a brief justification of why this species is near threatened
  • Hugh Robertson and Barrie Heather - The Hand Guide to the Birds of New Zealand, Penguin Books (1999) ISBN 014028835-X
  • Dijkgraaf, A. C. 2002. Phenology and frugivory of large-fruited species in northern New Zealand and the impacts of introduced mammals. PhD Thesis, School of Biological Sciences. University of Auckland, Auckland. 413Pages.
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