The Nene Goose (Branta sandvicensis), also known as nēnē and Hawaiian goose, is a species of bird endemic to the Hawaiian Islands. The official bird of the state of Hawaiʻi, the nene is exclusively found in the wild on the islands of Oahu, Maui, Kauaʻi, Molokai, and Hawaiʻi.
The Hawaiian name nēnē comes from its soft call. The specific name sandvicensis refers to the Sandwich Islands, a former name for the Hawaiian Islands.
It is thought that the nene evolved from the Canada goose (Branta canadensis), which most likely arrived on the Hawaiian Islands about 500,000 years ago, shortly after the island of Hawaiʻi was formed. This ancestor is the progenitor of the nene as well as the prehistoric giant Hawaiʻi goose (Branta rhuax) and nēnē-nui (Branta hylobadistes). The nēnē-nui was larger than the nene, varied from flightless to flighted depending on the individual, and inhabited the island of Maui. Similar fossil geese found on Oʻahu and Kauaʻi may be of the same species. The giant Hawaiʻi goose was restricted to the island of Hawaiʻi and measured 1.2 m (3.9 ft) in length with a mass of 8.6 kg (19 lb), making it more than four times larger than the nene. It is believed that the herbivorous giant Hawaiʻi goose occupied the same ecological niche as the goose-like ducks known as moa-nalo, which were not present on the Big Island. Based on mitochondrial DNA found in fossils, all Hawaiian geese, living and dead, are closely related to the giant Canada goose (B. c. maxima) and dusky Canada goose (B. c. occidentalis).
The Nene is a medium-sized goose at 41 cm (16 in) tall. Although they spend most of their time on the ground, they are capable of flight, with some individuals flying daily between nesting and feeding areas. Aside from being smaller, the female Nene is similar to the male in coloration. The adult's bill, legs and feet are black. It has soft feathers under its chin. Goslings resemble the male but are a duller brown and with less demarcation between the colors of the head and neck and striping and barring effects are much reduced.
The nene is an inhabitant of shrubland, grassland, coastal dunes, and lava plains, and related anthropogenic habitats such as pasture and golf courses from sea level to as much as 2,400 m (7,900 ft).
The Nene is a herbivore that will either graze or browse, depending on the availability of vegetation. Food items include the leaves, seeds, fruit, and flowers of grasses and shrubs.
The Nene population stands at 2,500 birds, making it the world's rarest goose. It is believed that it was once common, with approximately 25,000 Hawaiian geese living in Hawaiʻi when Captain James Cook arrived in 1778. Hunting and introduced predators, such as small Asian mongooses, pigs, and cats, reduced the population to 30 birds by 1952. The species breeds well in captivity, and has been successfully re-introduced. In 2004, it was estimated that there were 800 birds in the wild, as well as 1,000 in wildfowl collections and zoos. There is concern about inbreeding due to the small initial population of birds.