Tag Archives: Chatham Island

Nestor chathamensis Wood, Mitchell, Scofield & Tennyson

Chatham Islands Kaka (Nestor chathamensis)

The family Nestoridae is endemic to the New Zealand faunal region and contains the Kaka (Nestor meridionalis Gmelin), the Kea (Nestor notabilis Gould) as well as the Kakapo (Strigops habroptila Gray); it formerly contained at least two additional species, including this one from the Chatham Islands.

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The species is known from abundant subfossil remains, which, by the way, were known since about the end of the 19th century, but had been originally assigned to the Kea. In the 1950s the remains were studied again and subsequently assigned to the New Zealand Kaka. Only in 1999 the Chatham Islands form was recognized as a distinct species, differing from both the New Zealand Kaka and the Kea. The species was finally described in 2014.

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The Chatham Islands Kaka was most closely related to the New Zeland Kaka, but was in fact a rather terrestrial species, very much like the Kea, it was on the way of becoming flightless and very likely was very tame and thus fel victim to the hunting of the first human settlers on the Chatham Islands.

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References:

[1] J. R. Wood; K. J. Mitchell; R. P. Scofield; A. J. D. Tennyson; A. E. Fidler, J. M. Wilmshurst; B. Llamas; A. Cooper: An extinct nestorid parrot (Aves, Psittaciformes, Nestoridae) from the Chatham Islands, New Zealand. Zoological Journal of the Linnean Society 172: 185–199. 2014
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edited: 16.02.2020

Anas chlorotis ssp. ‘Chatham Islands’

Chatham Islands Brown Duck (Anas chlorotis ssp.)

The Chatham Islands Brown Duck is only known from subfossil remains found on the Chatham Islands, that have not yet been described, it may have been a subspecies of the New Zealand Brown Duck (Anas chlorotisGray) (see depiction below) or even a distinct species.

The taxon was apparently already wiped out by the Moriori, the first human settlers on the Chatham Islands. [1]

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References:

[1] Trevor H. Worthy, Richard N. Holdaway: The Lost World of the Moa, Prehistoric Life of New Zealand. Indiana University Press, Bloomington 2002

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New Zealand Brown Duck (Anas chlorotis) (the two birds on the left) together with Auckland Teal (Anas aucklandica Gray)

Depiction from: ‘John C. Phillips: A Natural History of the Ducks. Boston; Houghton Mifflin Company; 1922-1926’

(public domain)

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edited: 10.11.2021

Mergus milleneri Williams & Tennyson

Chatham Island Merganser (Mergus milleneri)  

The extinct Chatham Island Merganser, which was originally described in 2014, is known only on the basis of subfossil bones which were excavated in the 1990s.  

The species was originally regarded as being identical with the Auckland Islands Merganser (Mergus australis Hombron & Jacquinot), which is likewise extinct. The two species, however, are clearly osteologically separable (by their bone structure), and, as known meanwhile, also genetically. The Chatham Island Merganser was smaller than the species from the Auckland Islands, it furthermore possessed a shorter head and somewhat downscaled wings. [1][2]  

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The Chatham Island Merganser was probably endemic to Chatham Island, where it inhabited the so called ‘Te Whanga Lagoon’, a giant salt lake that makes out a large part of Chatham Island and which represents the remainder of a former part of the sea that has become an internal water due to silting.  

The bird possessed enlarged salt glands in its skull, which it used to exude unnecessary salt.  

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References:  

[1] Trevor H. Worthy, Richard N. Holdaway: The Lost World of the Moa, Prehistoric Life of New Zealand. Indiana University Press, Bloomington 2002 
[2] Murray Williams; Alan J. D. Tennyson; Dalice Sim: Island differentiation of New Zealand’s extinct mergansers (Anatidae: Mergini), with description of a new species from Chatham Island. Wildfowl 64: 3-34. 2014  

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edited: 08.03.2017