Never seen before in a Zoo - The Auckland merganser from New Zealand

The newest arrival in the Lost Zoo is a pair of Auckland mergansers which were kept never before in a zoo. Mergansers are fish-eating ducks in the seaduck subfamily (Merginae). All mergansers have serrated edges on their long and thin beaks to help them to grip their prey. Because of this characteristic they are often known as "sawbills”. Besides mergansers are classifi ed as "divers", because they go completely under-water in looking for food. In addition to fish, they take a wide range of other aquatic prey like mollusks, crustaceans, worms, insect larvae and amphibians.

Auckland Island Merganser Mergus australis collected Jun 1902, Auckland Islands,New Zealand. © Te Papa CC BY-NC-ND licence. Te Papa (OR.001357)
(Click to view larger image).

Depending on the sometimes different zoological system all the mergansers of the genus Mergus contain 5 or 7 species. Mergansers are closely related with the diving ducks of the genus Bucephala and also hybridization between mergansers and the Common goldeneyes (Bucephala clangula) and Buffleheads (Bucephala albeola) can be observed in nature.
Although the mergansers are seaducks, most of them prefer riverine habitats. Only the Red-breasted merganser (M. serrator) is common at sea. Most species live in the northern hemisphere, except the Brazilian merganser (M. octosetaceus) from Eastern South America and the Auckland merganser (M. australis) from New Zealand.

The Auckland merganser was similar in size to the Japanese Red-breasted merganser, but had a longer beak,even longer than all other merganser species have. Adult males had a dark reddishbrown head, crest and neck, a bluish black mantle and tail and slate grey wings.The females were slightly smaller with a shorter crest. They mainly fed on smaller fish like Broad-fi nned galaxias and aquatic invertebrates. The Auckland merganser was an excellent diver, but because of its short wings he could not fly very well and preferred to hide between rocks when pursued. The pairs of the Auckland merganser lived probably the whole year together. The breeding season was between November and December and normally five eggs were laid.

Fossil bones certify that in former times the Auckland merganser lived not only on the Auckland Islands but also on the Main Northern and Southern Islands of New Zealand as well as on Stewart Island. The species became extinct in the beginning of the 20th century. But the population of the Auckland merganser declined already, when the Maoris settled on the islands and hunted the merganser intensively.
There fore the Auckland merganser was already extinct in most parts of New Zealand, when the first Europeans arrived in the 19th century. Already in that time, the Auckland merganser could be found only on the Sub-Antarctic Auckland Islands.
When in 1806 domestic pigs were imported to the Auckland Islands, the Auckland merganser’s population was diminished intensively. In 1840, the Auckland merganser was collected for the first time by the Dumont d’Urville expedition and in 1841, the species was described scientifically.
The change of the habitats and the import of larger mammals like pigs, cattle and cats after 1850 and at the end also the collection of 25 birds for museum collections caused the Auckland merganser’s extinction. The last collected pair of Auckland mergansers was shot for the British Museum in January 1902. Since that time the species has never been seen again and is therefore declared to be extinct.

Today all Natural History Museums worldwide have in their collection only 23 skins of adult and immature Auckland mergansers. Four of them are mounted female birds. The other 19 skins are comprised of 11 males and 8 females. Keeping these few numbers in mind, it is an even bigger surprise that our Lost Zoo keeps these Auckland mergansers now. Of course we are proud that our Lost Zoo is one of the few institutions in the world which exhibits this colorful rare merganser species.

Executive Curator
JURGEN LANGE