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Home > New Zealand ecology > Native ducks > Auckland Island merganser   


The Auckland Island merganser Mergus australis, sometimes known as Southern merganser, is an extinct member of the Anatidae family and Anseriformes order of swans, geese and ducks.  The Mergus genus is in the Anatinae subfamily of the Anatidae family.

M. australis was endemic to New Zealand, and found only on the Auckland Islands during the nineteenth century.

The first recorded sighting was by the explorer Jules d'Urville during his 1840 subantarctic voyage.  In the years following d'Urville's sighting, 26 birds were killed for collections.

The last known pair were shot at Carnley's Harbour in 1902 by the Earl of Ranfurly when he was Governor of New Zealand.  Searches in 1909 and 1972/73 confirmed that it was extinct.

The last Auckland Island merganser were shot for museum collections when the population was unknown, and it must have been apparent that there were very few birds.

Fossils of a closely related species, possibly a subspecies, have been found in the Chatham Islands.  McCormack reported "merganser" in the Campbell Islands in 1842, however, this record is vague and it may have been a reference to Campbell Island teal.

Merganser were more widespread before human settlement.  Bones have been identified from coastal dunes and Maori middens in the South Island and on Stewart Island.

Mainland decline and eventual extinction occurred with Maori introduction of kiore (Polynesian rat), extensive burning, and hunting.

Above: An Auckland Island merganser Mergus australis family.  Image: Permission and Copyright © Peter Schouten

Following extinction on the mainland, merganser survived on the bleak but beautiful Auckland Islands.  The population must have started to decline after pigs were introduced to the Auckland Islands in 1807, and cats in 1820.

The failed settlement at Port Ross in 1849-1851 probably had an impact on the demise of merganser.  It is quite likely that disillusioned settlers who had extreme difficulty obtaining food in the harsh conditions, hunted duck.

The flightless Auckland Island teal Anas aucklandicus has survived on Ross, Enderby, Ewing and Dundas Islands off the northeast tip of the Auckland Islands because those islands have remained free of introduced rats.

At latitude 50.5°South, the Auckland Islands are the world's third most southern duck location, behind the Campbell Islands (latitude 52.5°South), and Tierra del Fuego (latitude 54.9°South).

The world's five Mergus species

The Auckland Island merganser could be one of a small number of New Zealand birds that have been exceptional colonisations from the Northern Hemisphere.  Mergus australis has its closest relative in Mergus squamatus of China (Kear & Scarlett 1970).

There are four living species of the Mergus genus worldwide.  The only other species of the southern hemisphere is the Brazilian merganser M. octosetaceus which is listed as 'critically endangered' on the IUCN Red List of Threatened Species.

Three species in the northern hemisphere include the red-breasted merganser M. serrator, and common merganser M. merganser which are both migratory and listed as 'least concern'; and the very striking looking scaly-sided merganser M. squamatus of Asia which is 'endangered'.

The Auckland Island merganser was the smallest of all Mergus species, weighing less than a kilogramme, and with a torso length of (20.5 inches).

A reluctant flier .....

Auckland Island merganser showed signs of reduced power of flight and the beginning of flightlessness. It's wings were small, but it could still fly.  Hunters found it difficult to flush.  When disturbed, it preferred to hide instead of taking flight.

The tameness of merganser, reluctance to fly, and a small clutch size is consistent with many New Zealand indigenous birds, and most probably contributed to its' decline.

It was mainly a freshwater species, foraging in inland creeks and streams, but it also inhabited estuaries and was sometimes found in sheltered bays.

Merganser had a long, narrow bill with a hooked tip that turned down. The edges of the upper and lower mandibles were serrated, suited to catching its principal food of small fish. Shellfish and marine worms were also part of the diet.

Merganser have some morphological characteristics of diving ducks, with large webbed feet set back on the body providing strong paddling power.

The Merganser name comes from the latin words "mergus" which referred to diving waterfowl, and "anser" which means goose.


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