 |
Leiopelma frogs
Land snails
Tuatara |
| |
|
ANTIPODES ISLAND PARAKEET |
| |
|
Not all parrots live in paradise. The Antipodes Island parakeet Cyanoramphus unicolor,
also known as the green parakeet, lives only on Antipodes Island, one of New Zealand's remote,
bleak and inhospitable subantarctic islands.
The classification of C. unicolor has remained unchanged following the genetic survey
of Cyanoramphus species by Boon, Kearvell, Daugherty & Chambers (2001), which doubled the
number of species from five to ten.
It is the largest of the Cyanoramphus (kakariki) species, 31cm long which is
3cm more than the New Zealand red-crowned parakeet. The Antipodes Island parakeet is the
only member of the kakariki family with all green colouring, and without a coloured frontal
head band. |
|
C. unicolor is listed as 'vulnerable' on the 2004 IUCN
Red List of Threatened Species, and 'range restricted' on the New Zealand Threatened
Species classification.
Photo right & top right: Antipodes Island parakeet, J.L. Kendrick
1978 Crown Copyright © Department of Conservation |
 |
| |
|
The deep separation of the Antipodes Island parakeet from the other New Zealand taxa
suggest that Cyanoramphus colonisation of Antipodes Island must have occurred before the
radiation of red, yellow and orange-fronted parakeets.
Antipodes Island was colonised twice by two Cyanoramphus species. The Antipodes Island
parakeet migrated to the island about 280,000 years ago, and the ancestors of Reischek's parakeet
arrived about 30,000 years ago. The two species have co-inhabited the small island for thirty
millennium without interbreeding.
The Antipodes Island parakeet breeds very unusualy on the ground like a rabbit. Its nest is
in a well drained burrow a metre deep in the fibrous peat under tussock grass. Just two eggs
are laid for the season between November and January.
In contrast to the squawking chatter of other Cyanoramphus birds, the Antipodes
species are quiet, letting out a single note when startled. |
| |
| |
|
Antipodes Island is also the only home of Reischek's parakeet Cyanoramphus erythrotis
hochstetteri, which is now classified as the sole surviving subspecies of the extinct
Macquarie Island red-crowned parakeet C. erythrotis erythrotis (Boon et al. 2001).
C. e. erythrotis was endemic to Macquarie Island, the only subantarctic island of
the group that is in Australian territory, and the most southerly at 54.5deg south latitude.
|
|
The Macquarie Island red-crowned parakeet was originally named C. novaezelandiae
erythrotis, as a subspecies of the New Zealand red-crowned parakeet C. novaezelandiae.
As a result of research (Boon et al. 2001), it is now classified as a separate species
C. erythrotis.
Right: New Zealand red-crowned parakeet, J.L. Kendrick
1980 Crown Copyright © Dept. of Conservation |
 |
| |
|
|
Macquarie Island is infested with cats, mice and ship rats which have been
mainly responsible for the extinction of the island's parakeet.
Weka Gallirallus australis scotti were introduced from New Zealand in the
mid-1800s as food for sealers, and contributed to the extinction of the Macquarie Island
parakeet and the Pacific banded rail. Weka are no longer on the island.
Because Antipodes Island is closer to the New Zealand mainland, which is the
apparent centre of origin of Cyanoramphus parakeets, it is more likely that C.
erythrotis hochstetteri colonised Antipodes Island first, and later migrated further
south to Macquarie Island.
The sister species of the critically endangered orange-fronted parakeet C. malberbi,
is not the yellow-crowned parakeet C. auriceps, but Reischek's and the Macquarie
Island parakeet.
Reischek's parakeet has adapted to the harsh subantarctic island conditions in a similar
way to its co-inhabitant, the Antipodes Island parakeet, with the same ground feeding,
roosting and nesting habits. The two species often share the same feeding locations.
Even though there is a healthy population of Reischek's parakeet, its very limited
distribution on one island makes it vulnerable to extinction. It is listed as 'range
restricted' on the New Zealand Threatened Species classification. |
|
 |
|
 |
| |
Ground-dwelling parakeets on a cold, bleak & unforested subantarctic island ...
The Cyanoramphus parakeets have adapted to a wide range of
habitats, from tropical rainforest to subantarctic tussock.
In stark contrast with the tropical forested habitat of the New
Caledonia red-crowned parakeet C. saisetti, Antipodes Island is a cold, wind-swept
island exposed to regular storms of the rooring forties, with the principal flora limited
to two species of tussock grass, ferns and some stunted shrubs. There are no trees on the
island.
Antipodes Island is New Zealand's third most southern territory
at 49.7deg latitude south, 700 km southeast of the South Island mainland. The entire area
of 62 sq.km is designated as Nature Reserve administered by the Department of Conservation,
with very limited access.
The island is one of four in the New Zealand Subantarctic World
Heritage Site which also contains Bounty Island, the Auckland Islands, and Campbell Island.
Unlike Campbell Island to the south, which had the world's most
dense rat population before they were removed in 2001, Antipodes Island has remained rat-free.
However, it would only take one pregnant rat to get ashore from an anchored fishing boat to
set off a rat plague that could destroy both of the island's ground inhabiting parakeets.
Antipodes Island is a close second to the Auckland Islands as the
most southern Cyanoramphus parakeet location, and the world's third most southern
parrot location. The Austral parakeet Enicognathus ferrugineus of Tierra del Fuego
(54.7deg south latitude) at the bottom of Argentina and Chile, is the most southerly distributed
parrot.
The parakeets on Antipodes Islands have little fear of humans and
a strong curiosity. It is possible to approach them to within 2 metres while they are feeding
without disturbing them.
Both species of parakeet use the tussock vegetation as
a food source, for nesting, and shelter from the harsh, consistent wind and rain. Nests
are normally a tunnel in the base of a tussock.
The favourite food of both Antipodes Island parakeets is a tall dense tussock poa
litorosa, mainly because it is one of the few choices. In typiical kakariki style, they
cut off 25cm pieces, and hold them in one claw while chewing from end to end. Other seasonal food
includes seeds, flowers and berries, and the Antipodes Island parakeet occasionally supplements
its diet with meat from the carcases of dead gulls and penguins, and eggs.
Both Antipodes parakeets have had no choice but to adopt
ground-dwelling habits, and would therefore be obvious candidates to become flightless,
like so many other New Zealand birds without predators. But even without natural or
introduced predators, both species are good fliers.
Parakeets have survived on Antipodes Islands while other animals have not been able to
tolerate the inclement climate. Animals were released on subantarctic islands as a
source of food for castaways and sealing gangs. Cattle, sheep and goats were introduced
to Antipodes several times but died out.
It is remarkable that large healthy colonies of two different
parakeet species, share the same remote and limited island habitat, and that both are endemic
to the island.
The Antipodes Island parakeet and Reischek's parakeet both need
second populations on predator-free islands, to provide a complete safeguard for their
protection. |
| |
A reflection of the lifestyle of New Zealand parakeets during the last ice-age ...
The rapid adaptive radiation of the Cyanoramphus genus was
probably assisted by fluctuating glacial and interglacial intervals of the Pleistocene
(2 million to 10,000 years ago).
During the last glacial (before 14,000 years ago) and post glacial
periods, predominant grass and shrub vegetation, with patches of Nothofagus in the
central North Island, provided the habitat of Cyanoramphus parakeets on mainland
New Zealand.
The mainland vegetation before the ice retreated resembled that of
present Antipodes Island and Macquarie Island. The present lifestyle of one
of the more ancient Cyanoramphus lineages, C. unicolor, and Reischek's parakeet
C. erythrotis hochstetteri on Antipodes Island are a reflection of the New Zealand
glacial conditions.
Campbell Island is another remote island in the subantarctic group
that has a similar treeless vegetation. It is known from a bone specimen, to have been
occupied by an unidentified parakeet that has long been extinct.
Reischek's parakeet appears to come from the mainland New Zealand
stock of red-crowned parakeets, as the result of an independent colonisation event.
The extinct Macquarie Island red-crowned parakeet
also occupied habitat similar to that of Reischek's parakeet. This supports the hypothesis which
suggests that Macquarie Island may have been colonised by Ryschek's parakeet, from which the
C. e. erythrotis species evolved.
The rapid transformation of the vegetation on the mainland between
10,000 and 9,000 years ago defines the end of the glacial period, and the beginning of the
climate of today. Rimu quickly became the most predominant podocarp, and the start of a new
forested habitat for mainland and offshore island parakeets. This was not so for the
subantarctic island parakeets.
|
|
| |
|
