The Campbell Teal, a small, flightless, nocturnal species of dabbling duck, was once endemic to the Campbell Island group of New Zealand, but was driven to extinction by the introduction of Norway Rats. It was thought to be completely extinct for 150 years till 1975 when around 20 of them were rediscovered on the Dent Island, a tiny rock islet near Campbell that was rat-free.
As the population was very small it was apprehended that even a single unwanted event could be sufficient to sweep it to complete extinction. In an attempt to save the species from the ultimate end, eleven of them were captured to be rehabilitated by the Pukaha Mount Bruce National Wildlife Centre, equipped with a captive breeding facility, located in a protected forest area, 2.30 km north of Masterton, a large town in the Greater Wellington Region of New Zealand. By the time the rest of the species surviving on the Dent Island followed their preceding mates in 1990, the International Union for Conservation of Nature and Natural Resources (IUCN) enlisted the Campbell Teal in the category of the endangered species in 1979.
As the captive breeding programme ensured, 24 birds were released onto Codfish Island, located to the west of Stewart Island/Rakiura in southern New Zealand, and after the eradication of rats from Campbell Island in 2001, captive-bred and Codfish Island-bred teals numbering 150 were released onto Campbell Island, the last stop before Antarctica, in 2004-2006. However, the captive-breeding programme proved to be a difficult process as it took years to produce a successful result, and in the end, only one of the captivated wild females called Daisy accepted a mate and produced offspring.
Today, the entire captive-bred population is descended from that female, and the Campbell Island teals are found to have the lowest level of genetic variation among any wild bird population.
The tough little flightless dabbling ducks that are only found on two cold, wet and windswept Sub-Antarctic islands are an anomaly of the isolated evolution of New Zealand ecology. Also called Campbell Island Teal, and sometimes considered conspecific with brown teal, its natural habitat is tussock grassland dominated by Poa tussock, ferns, and megaherbs. Detailed activity, habit, and behavior of the Campbell Island teal are mostly unknown as they are rarely seen as they are nocturnal. In addition, it is also difficult to study them in the wild due to the inaccessibility of their inhabits, covered with dense vegetation and their furtive nature. While on Codfish Island, a small flock sometimes gathers at the mouth of Sealers Creek, on Campbell Island, they are rarely seen active during the day or venture far from their protective cover. However, at night they have been observed feeding on the tidal flats at the head of the Perseverance Harbour, Campbell Island, and scrabbling around along the rocky shoreline of the inlet.
However, the diet of Campbell Island teals in the wild is actually unknown. It is considered that probably they are omnivorous with a preference for amphipods, found in almost all aquatic environments, and invertebrates like insects, earthworms, mollusks, spiders, snails, and the like.
While they have been observed stripping seeds from seedheads along a stream edge on Codfish Island, with a limited food supply on Dent Island, seabird guano, the accumulated excrement of seabirds, with exceptionally high content of nitrogen, became a part of their diet.
The smallest of the three brown-plumaged teals endemic to New Zealand, the plumage of the Campbell Island teals is similar to that of the Auckland teals, dark sepia with the head and back tinged with green indecency, a chestnut breast, and a conspicuous white patch at the tail base of the male, with the females are dark brown all over. Both the males and females have a conspicuous white eye-ring, dark-grey bill, legs and feet, and dark brown eye. Their wings are very short, with the main wing feathers extending only about halfway along the back. They cannot fly, but they can run very fast and escape at the first sign of any possible danger. While the calls of the males are like soft whistling or piping, given in alarm at the apprehension of any possible danger, the females have a rasping growl and a high-pitched and rapid quack.
Campbell Island teals are probably monogamous and strongly territorial. There, incubated nests containing clutches of 4 and 5 eggs have been found from mid-November to mid-December. Although the fledging period in the wild is unknown, in captivity, ducklings reach adult weight in 50-60 days.