Chatham Island merganser
The Chatham Island merganser is an extinct species of merganser duck from New Zealand.
Taxonomy
The binomial name refers to Dr. Philip Millener, a former curator of fossil birds at New Zealand's national museum, to recognize his work in collecting material on the species.
Description
The Chatham merganser is known only from subfossils, so not much is known about the bird. It was the smallest of all Mergus species. It had a smaller skull and beak than the Auckland Island merganser, but had larger salt glands. Most bones of the species were 3-6% smaller than those of the Auckland Island merganser. They had a lesser flying ability compared to most other Mergus species but were still capable of flight.
Distribution and habitat
Fossil records indicate it was widespread on Chatham Island but either not found, or not abundant, on the smaller nearby islands. Suitable habitat on Chatham Island would have included small lakes, slow peat-stained rivers, and a lagoon.
Behaviour
Nesting
Remains of adults, eggs, and nestlings have been found in a small cave on the shoreline of the Te Whanga Lagoon, indicating that this cave was used as a popular nesting site.
History
The species was described formally in 2014, the species was previously considered to be the same species as the Auckland Island merganser.
Extinction
One of the causes of extinction for the species was likely human hunting, indicated by the presence of its bones in prehistoric human food middens. Other possible causes of its extinction include habitat destruction and introduced predators like the Polynesian rat and Polynesian dog.