Branta sandvicensis
Hawaiian goose
(Also: nene)

The Hawaiian Goose, or nene, is endemic to the Hawaiian Islands. ("Nene or Hawaiian Goose", 2005; Banko, Black, and Banko, 1999; National Audubon Society, 2002)

Nenes inhabit a variety of habitats, including grasslands, scrub forests, and sparsely vegetated volcanic slopes. ("Nene or Hawaiian Goose", 2005; Banko, Black, and Banko, 1999)

Adult nenes are either sepia or dark brown, with no difference in plumage between males and females. The face and crown are black, while the cheeks are cream-colored and the neck is buff with black streaks. The body is brown to grey, the wings are brown to gray, with white tips and the bottom side of the tail is black. The eyes, beak, and feet are black as well. Nenes have longer legs and less toe webbing than other geese, adaptations which aid walking on lava flows. ("Nene or Hawaiian Goose", 2005; Banko, Black, and Banko, 1999; National Audubon Society, 2002)

Annual mortality varies greatly from study to study, depending on whether the animal is wild or in captivity, locality, elevation, etc. The range is from 0 to 87% annual mortality, with slightly lower mortality rates for males than females. In the wild the main causes of mortality include exposure (from low temperatures in high nesting locations), predation (from several indigenous and introduced raptor species, as well as rats, pigs, dogs and mongoose), competition with other species (due to an overlap in diet with game birds and grazing mammals), and starvation or dehydration due to drought. In captivity, 84% of deaths resulted from parasites and diseases while the remaining 16% resulted from trauma. Males die evenly throughout the year. Female mortality occurs mainly in the breeding season when they are most vulnerable to exposure, trauma, and stress from egg laying and predation. (Banko, Black, and Banko, 1999)

Having longer and stronger legs, as well as less webbed feet than other geese, Nenes walk and run very swiftly on volcanic lava flows. Alternatively, since their wings are 16% smaller than their closest relative, the Canada Geese, they are not the best fliers. However, they can fly from island to island, usually taking off from land. They can also swim, usually in ponds and lakes. Similar to other water fowl, they also use their beak to spread oil from their oil gland along their feathers for water proofing.

Nenes are diurnal and sleep on the ground with feet beneath their bodies. The most tight nit social unit is the immediate family (mating pair and children). Nenes also live in flocks of up to 30 birds, some of which are more loosely constructed than others. Nesting ranges from as close as 45 meters to very far away. Dominance ranks come from the size of the family unit. Large families are dominant to small ones which are dominant to pairs which are dominant to individuals. Males defend the territory immediately surrounding nests and families from other Nenes.

Threat displays are numerous. The most common display is the bent-neck threat, which includes facing rivals with head and neck pointed downward, while the neck feathers vibrate. The most intense display is the forward threat, in which neck feathers are erect, the mouth is open and the bird is calling loudly, and the head and neck are up facing the opponent. This is often followed by charging of one bird towards another, in which case the subordinate usually runs off. Physical confrontation rarely occurs, and involve grabbing the neck of an opponent with one's beak, pulling, and beating the opponent with the wing. ("Nene or Hawaiian Goose", 2005; Banko, Black, and Banko, 1999)

Home Range

Nene home ranges are roughly 200 square kilometers in size. ("Nene or Hawaiian Goose", 2005; Banko, Black, and Banko, 1999)

Other than threat and mating displays and sounds described previously, vocalizations are used to communicate with family members, solidify territory, send alarm calls, and threaten predators. Nenes also murmur when foraging as a way of maintaining foraging distance between family members. Chicks can send pleasure calls, distress calls, sleepy calls and greeting calls. Calls are louder during and close to breeding season.

In addition to auditory cues, vision is key in foraging and recognizing family members, predators, and opponents. ("Nene or Hawaiian Goose", 2005; Banko, Black, and Banko, 1999)

Nenes are herbivores and forage solely on land. They eat leaves, grasses, flowers, berries, flowers, and seeds. Nenes usually eat the more nutrient rich bottom part of grasses, and grab and pull food with their beaks. Several important grasses on the Hawaiian islands that are eaten by nenes include Digitaria violascens, Andropogon virginicus, Sporobolus africanus, Carex wahuensis and some others. ("Nene or Hawaiian Goose", 2005; Banko, Black, and Banko, 1999; National Audubon Society, 2002)

Males defend their brood and nest most often, while females also engage in defense sometimes. Threat displays such as the bent neck and forward threat are used to scare off predators. When defending themselves from aerial attack, nenes produce alarm calls, huddle in groups and spread wings, or they simply fly away. Chicks usually hide behind parents, leaving defense to them. ("Nene or Hawaiian Goose", 2005; National Audubon Society, 2002)

Nenes are important at spreading seeds for many of the plants on which they feed. They are also important food sources for many of the predators mentioned in the previous predation section. ("Nene or Hawaiian Goose", 2005; Banko, Black, and Banko, 1999)

Since they fly low, nenes often collide with fences and automobiles. Otherwise, there are no known adverse effects of nens on humans. (Banko, Black, and Banko, 1999)

Nenes are the state bird of Hawaii and are thus a state symbol. ("Nene or Hawaiian Goose", 2005)

Early Hawaiian settlers used nenes as a food source and hunted the birds to near extinction. In 1907, a hunting ban was placed on these birds, but still approached extinction by 1940 due to predation by introduced species as well as degradation of habitat and other human related destruction. In 1957, nenes were named the state bird in Hawaii and efforts to rescue the almost extinct population, including breeding in captivity and protecting nesting areas began. Though early programs for reintroducing birds into the wild failed, later ones have been very successful and the wild nene population is recovering at around 800 individuals. Currently the greatest threat to nenes is predation of eggs by introduced Indian mongooses (Herpestes javanicus). ("Nene or Hawaiian Goose", 2005; Banko, Black, and Banko, 1999; National Audubon Society, 2002)