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New Zealand grebe

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New Zealand grebe

Nationally Increasing (NZ TCS)[2]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Podicipediformes
Family: Podicipedidae
Genus: Poliocephalus
Species:
P. rufopectus
Binomial name
Poliocephalus rufopectus
(Gray, 1843)

The New Zealand grebe (Poliocephalus rufopectus), also known as the New Zealand dabchick or weweia, is a member of the grebe family endemic to New Zealand.

Taxonomy

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Poliocephalus rufopectus is an aquatic diving bird in the grebe order.[3]

Poliocephalus rufopectus (G.R.Gray) was originally described by the English ornithologist George Robert Gray as Podiceps rufopectus G.R.Gray, 1843 (in subgenus Poliocephalus).[4] The type specimen was collected by British botanist and scientific collector Andrew Sinclair in New Zealand.[4][5] P. rufopectus is one of two species in the genus Poliocephalus, with the other being the hoary-headed grebe (Poliocephalus poliocephalus) which is native to Australia.[6][7]

Description

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The New Zealand grebe has dark brown plumage, a small black head with fine silver feathers, a black pointed bill and characteristic yellow eyes.[8][3] It grows to about 29 cm (11 in), and weighs about 250 g (8.8 oz).[9] Non-breeding individuals have a paler plumage and females tend to be a bit lighter, smaller and have a slightly shorter bill than males.[8][10]

Distribution and habitat

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This grebe species inhabits mainly shallow freshwater lakes, ponds and sheltered inlets.[3] Currently it is found mainly in the North Island, where it is well distributed on the coastal lakes of the West coast from North Cape to Pukekohe and from Taranaki to Paraparaumu, as well as on ponds of the Volcanic Plateau, Gisborne, Hawkes Bay and the Wairarapa.[8][9][11] Formerly this species was also present in the lowland lakes of the South Island,[12] but underwent a rapid decline, for unknown reasons, in the 19th century – the last regular breeding record in the South Island was in 1941.[9] In 2012 a pair bred near Takaka for the first time in recent history.[1][13]

Behaviour

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These freshwater diving birds usually fly only at night, whilst during the day, they are always found in the water, swimming on the surface and frequently diving to feed. Thus, if they are in danger or get disturbed at daytime they do not flee by flying, but swimming or diving away. During autumn and winter, they are found forming flocks, while during the breeding season they are mostly seen in monogamous pairs. They show aggressive territorial behaviour towards intruders [8][3] and the otherwise silent species give short calls throughout the breeding season and when in danger.[3][14]

Diet

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Adult grebe with insect

Their diet consists mostly of aquatic insects and their larvae, as well as small molluscs such as freshwater snails.[12] Bigger prey such as fish and freshwater crayfish are sometimes eaten too.[9] Thus, their bill, being short and pointed, is adapted to their mainly invertebrate diet. They catch their prey during dives and feeding underwater or pick it from the water surface.[8][3]

Breeding

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Adult with young chick
Adult and chick at Queen Elizabeth Park, Kāpiti Coast District

The breeding season is from June to March. On average 2–3 eggs are laid and incubated 22–23 days by both female and male, in a nest. The nest is mostly made out of surrounding vegetation, including floating plant material. Hatched chicks are precocial, although being flightless for the first few weeks they can swim and dive.[8] Both parents assist in rearing and feeding their young for up to 70 days after hatching. Until the adult plumage develops, the chick has irregular striped markings on head and neck and the bill is black.[3]

Conservation

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This species is endemic to New Zealand and is nowadays only found in the North Island. In 1994, the IUCN classified the New Zealand grebe as Endangered, but due to conservation actions including habitat management, its population has recently increased to around 1,900–2,000 birds and was reclassified as Near Threatened in 2016, and to least concern in 2022.[1] Human activity currently has a net benefit as artificial habitat, including farm dams and ponds formed for stock water supplies, increases the area of occupation for the grebes.[8][3][15] So, although the population is still quite small it is thought not to be in decline anymore.[16]

References

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  1. ^ a b c BirdLife International (2022). "Poliocephalus rufopectus". IUCN Red List of Threatened Species. 2022: e.T22696592A209544697. Retrieved 26 July 2022.
  2. ^ "Poliocephalus rufopectus. NZTCS". nztcs.org.nz. Retrieved 17 December 2024.
  3. ^ a b c d e f g h "New Zealand dabchick". New Zealand Birds Online. Retrieved 23 Mar 2024.
  4. ^ a b Gray, George Robert (1843-01-01). "Fauna of New Zealand. List of the Birds hitertho recorded as found in New Zealand, Chatham, and Auckland Islands, with their synonyma". Travels in New Zealand with contributions to the geography, geology, botany, and natural history of that country: 186–201.
  5. ^ Watola, George (2011). "New Zealand dabchick". The Discovery of New Zealand’s Birds (PDF) (Updated and amended text supplied by George Watola, October, 2011. 3rd ed.). Orewa, New Zealand: Arun Books. p. 38.
  6. ^ Fjeldsa, Jon (1983-09-01). "Social Behaviour and Displays of the Hoary-Headed Grebe Poliocephalus Poliocephalus". Emu. 83 (3): 129–140. doi:10.1071/MU9830129.
  7. ^ Storer, Robert W. (1987-09-01). "Morphology and Relationships of the Hoary-headed Grebe and the New Zealand Dabchick". Emu. 87 (3): 150–157. doi:10.1071/MU9870150.
  8. ^ a b c d e f g Robertson, Hugh; Heather, Barrie (1999). The Hand Guide to the Birds of New Zealand. Penguin.
  9. ^ a b c d Barrie Heather and Hugh Robertson, "The Field Guide to the Birds of New Zealand (revised edition)", Viking, 2005
  10. ^ Marchant, S.; Higgins, P.J. (Eds.) (1990). Handbook of Australian, New Zealand & Antarctic Birds. Volume 1, Ratites to ducks; Part A, Ratites to petrels. Melbourne: Oxford University Press. p. 107.
  11. ^ commoncopper (April 2022). "New Zealand Dabchick (Poliocephalus rufopectus)". iNaturalist NZ. Retrieved 2022-04-22.
  12. ^ a b Andrew Crowe, "Which New Zealand Bird?", Penguin, 2001
  13. ^ Petyt, Chris (2013-01-01). "First recent recorded breeding of the New Zealand dabchick (Poliocephalus rufopectus) in the South Island". Notornis. 60: 322–323.
  14. ^ Chambers, S. (2009). Birds of New Zealand - Locality Guide (3rd ed.). Orewa, New Zealand: Arun Books.
  15. ^ Bright, A.; Waas, J.; Innes, J. (2004-01-01). "Correlations between human-made structures, boat-pass frequency and the number of New Zealand dabchicks (Poliocephalus rufopectus) on the Rotorua Lakes, New Zealand". New Zealand Journal of Ecology. 28 (1): 137–142.
  16. ^ "New Zealand Grebe (Poliocephalus rufopectus) - BirdLife species factsheet". datazone.birdlife.org. Retrieved 12 April 2017.
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