Campbell Island Teal - Anas aucklandica nesiotis

Coordinator: Suzy Barlow

Habitat and Distribution:

The Campbell Island teal was probably widespread on Campbell Island prior to the introduction of Norway rats in the early nineteenth century, but then disappeared from main Campbell Island once rats overtook the island. Eventually the flightless Campbell Island teal became confined to a 23 hectare islet, Dent Island, lying 1.6km off the west coast of main Campbell Island in New Zealand’s subantarctic zone. Dent Island is free of mammalian predators. The teal inhabit a dense tuccock grassland and megaherb community which overlays a peat soil.

Characteristics:

Very few wild birds have been handled; 11 teal were brought into captivity (7 males and 4 females) and a few birds were weighed and measured before being released again on Dent Island. The majority of weights and measurements have been taken from captive birds, i.e. those of wild origin and their descendants. Wild males, on capture, averaged 371g in weight and wild females, on average, weighed 302g. By comparison, adult males bred in captivity have weighed between 420g – 600g, and captive-bred adult females can weigh between 350g and 500g.

Campbell Island teal males show two distinct adult plumages each year, a colourful breeding plumage and a relatively inconspicuous eclipse (non breeding) plumage. Adult females follow a similar seasonal moult pattern which is less obvious as plumage appears virtually the same throughout the year. Adult male breeding plumage is similar to the Brown teal, with a chestnut-brown breast, a dark green irridesence to the head, finely vermiculated shoulder and flank feathering and a white posterior bar. Males resemble females when in eclipse plumage, with broad barring replacing fine vermiculations. Females remain virtually the same uniform sepia brown as immature birds. Mature females do, however, gain a small amount of green irridesence on the head, back and wing feathering.

The flightless Campbell Island teal is regarded as being predominantly crepuscular and nocturnal, although activity is not uncommon in the day.

Voice:

Adult males have a high pitched piping call, which can take the form of a territorial (rapid staccato trill) or alarm call (loud discrete notes), and a soft, repetitive hiss-like communication call.

At maturity, females develop a variety of loud broadcast ‘quaark’ calls and a quiet chattering communication call.

Male and female calls can be distinguished by about 40 to 50 days of age.

Food:

Subantarctic teal are omnivorous. Amphipods, isopods and copepods (crustaceans) make up a large part of the diet. The teal have also been observed taking terrestrial insects (including weevils and Diptera larvae), worms and small snails. Plant material in the form of seeds and aquatic weeds such as sea-lettuce may also be consumed.

Teal may forage on the ground, fossicking in grassland or on the forest floor, or dabble and upend in freshwater and shallow seawater. They may favour an ebbing tide, when rock platforms and beds of kelp are exposed. Diving has been observed on occasion; like other dabbling ducks, they use their wings for propulsion under water.

Breeding:

Breeding activity has never been observed for this species in the wild. Knowledge of their reproductive biology has been learnt from the captive population only. Campbell Island teal adult breeding plumage is complete at five months of age. Both male and female are capable of successful breeding in their first year. Of the three New Zealand teal, the female Campbell Island teal lays the largest egg in relation to body size. Clutch sizes are commonly 3-5 eggs, although one female in captivity has laid a clutch of six eggs. Eggs are a creamy buff colour with no markings. Nests are well hidden on the ground in cover. The female incubates whilst the male, with whom she will have developed a strong pair bond, defends the nest site and territory. Incubation in captivity takes around 30 days. After the hatch, the golden-brown downy ducklings are soon active in water.

Captive Program:

The captive management programme for Campbell Island teal was initiated in 1984 following the removal of three male and one female Campbell Island teal from Dent Island. A second capture expedition in 1990 boosted the captive population to a total of four females and seven males, all held at the National Wildlife Centre. The first Campbell Island teal ducklings were successfully bred in captivity in 1994. In 1998 a second breeding facility was established at Peacock Springs.

Five other institutions (Otorohanga Kiwi House, Wellington Zoo, Willowbank, Queenstown Kiwi and Bird Park, Invercargill City Council) currently hold Campbell Island teal as part of an insurance population, and for public display in order to advocate the conservation of subantarctic teal and subantarctic island ecosystems.

In 1999 12 captive-bred Campbell Island teal were released onto Whenua hou/Codfish Island. Another ….. teal were released onto this island in 2000.

By 2002 all alien mammals had been successfully removed from Campbell Island. In September 2004 21 captive bred teal from the National Wildlife Centre and 7 captive bred teal from Peacock Springs, along with 22 teal caught on Codfish Island were released back onto Campbell Island. Another release of teal onto Campbell Island will occur in 2005.

Associated Documents