Hawaiian Goose

Branta sandvicensis

Description

The Hawaiian goose—Branta (=Nesochen) sandvicensis or nene—ranges from 22-40 in (55.9-101.6 cm) in length, about the size of the common Canada goose. It has a blunt, triangular black bill and a black face, cap, and hindneck. The side of the neck is buff and darkly furrowed. The gray-brown body and wings are heavily barred. The nene is the state bird of Hawaii.

Behavior

The nene typically reaches sexual maturity after two years. Nesting season is from October through February. Geese tend to nest in the same area year after year, often in a kipuka (an island of vegetation surrounded by barren lava). Average clutch size is four eggs, which are incubated for 30 days. If a first attempt fails, geese will not usually renest that season. During the breeding season, nonbreeding birds form loose flocks within the nesting areas.

Young nene, being flightless, are extremely vulnerable to predators for about 11-14 weeks after hatching. Family groups flock soon after young are able to fly and remain in the breeding grounds for about a month. They then wander freely in search of foraging areas. Nene feed on green vegetation and berries of native plants such as ohelo (Vaccinium ssp.), kukaenene (Coprosma ernodeoides ), pukiawe (Styphelia tameiameiae ), and ulei (Osteomeles anthyllidifolia ).

Habitat

The Hawaiian goose nests in areas of rugged lava flow among upland scrub, grasses, and herbs. Unlike other geese, it does not require open water but will swim where water is available close to the nests. During the nonbreeding season the nene feeds in pastures dominated by introduced grasses.

Distribution

Before the European discovery of Hawaii in 1778 by Captain James Cook, an estimated 25,000 Hawaiian geese inhabited the islands. The population began to decline around 1800, and the bird was soon extirpated from lowland areas. A population on Maui became extinct before 1890. By 1944 most remaining birds were concentrated at higher elevations in the Hualalai-Puuwaawaa region on the island of Hawaii. By 1952 the total population had plummeted to a low of about 30 birds.

The nene survives on Hawaii on the upper slopes of Mauna Loa at elevations above 5,000 ft (1,524 m) and on Kilauea at slightly lower altitudes. On Maui, a reestablished population is found above 7,000 ft (2,133.6 m) near the center of the island. As of 1982 a total of 1,800 captive-reared geese had been released on both Hawaii and Maui. Although the propagation and release program has failed to establish self-sustaining colonies, it has enabled the wild nene population to hold steady, even increasing slightly. By 1994 an estimated 400-600 free-flying nene remained on the islands of Hawaii, Maui, and Kauai.

Threats

Hunting, egg collecting, and predation have contributed to the historic decline of the nene. Reduction of habitat and a scarcity of native food plants are probably the main reasons for its continued difficulties. Poor reproduction in the wild has kept the nene from replacing its losses. Only about 50% of adult geese breed each year, and gosling mortality is high.

Conservation and Recovery

Since 1949 the state of Hawaii has operated a propagation program to release geese into the wild from stocks raised in captivity at Pohakuloa on the island of Hawaii. In the early 1950s, the Severn Wildfowl Trust in England began rearing the birds and distributing them to zoos and aviaries; the trust has also released captive-bred geese on Maui.

In 1972 the U. S. Fish and Wildlife Service initiated a nest enclosure project at the Hawaiian Volcanoes National Park on Hawaii. The parks maintain captive nene pairs in open-topped pens within wilderness thresholds to serve as foster parents for young birds. These young are donated by state brooders or are hatched by captive pairs. The off-spring are then permitted to leave the pens to occupy adjacent habitat, which has been rehabilitated and replanted with native food plants. At Haleakala National Park on Maui, a similar program is under way.

Since the species' decline, nene populations have been sustained by intensive husbandry. Along with the captive breeding facilities at Haleakala and Hawaii volcanoes, the state operates an advanced breeding facility on Maui and donates some goslings to the parks for release in the wild. Wild nene also produce some young, but not enough to sustain the population.

Park management emphasizes enhancing back-country feeding areas for the nene by regularly mowing large plots of senescent alien grasses to produce palatable sprouts. Managers also plan to 1) develop more efficient predator control methods, 2) enlarge and improve conditions inside the open-topped backcountry release pens, and 3) make road corridors safer for nene. A main goal is to achieve a self-sustaining, free-flying population in an environment with manipulated refuges. Scientists from the United Kingdom Wetlands and Wildfowl Trust are advising the parks in the nene management and habitat enhancement effort.

Contacts

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N.E. 11th Ave.
Portland, Oregon 97232-4181
(503) 231-6121
http://pacific.fws.gov/

Pacific Remote Islands Ecological Services Field Office
300 Ala Moana Blvd., Room 3-122
P.O. Box 50088
Honolulu, Hawaii 96850
Telephone: (808) 541-1201
Fax: (808) 541-1216

References

Kear, J., and A. J. Berger. 1980. The Hawaiian Goose: An Experiment in Conservation. Buteo Books, Vermillion, South Dakota.

U. S. Fish and Wildlife Service. 1983. "The Nene Recovery Plan." U. S. Fish and Wildlife Service, Portland.