ARTICLES ON HAWAIIAN BIRDS AND BIRDWATCHING AND OTHER PACIFIC WILDLIFE

Hawai'i's State Bird - The Nene

The Nene or Hawaiian Goose (Branta sandwichensis) is the only goose species that currently breeds in the Hawaiian Islands, although other species once inhabited the islands and during the winter period, species such as Canada Goose, Brent Goose and other continental mainland geese occur as migrants and vagrants. The Nene is endemic to the main Hawaiian Islands, but today found only on Kaua'i, Maui and Hawai'i.

In the eighteenth century as many as 25,000 Hawaiian Geese inhabited the Hawaiian Islands, but mainly through excessive hunting, the numbers declined and the species came close to extinction. In 1907 the Nene became protected in the Islands, but at this time only about 50 birds remained. By 1951 the wild population was only 30 individuals. The main threats to the population were introduced species such as mongoose, cats, dogs and rats. Conservation work and captive raising of the species helped to increase numbers in captivity and soon birds were being released back into the wild, however, it became apparent that the wild population was in fact dependent on on releases of captive-bred stock to maintain its numbers in the wild. During the late 1970's and early 1980's release of birds was halted and as a result the numbers in the wild suffered a massive decline in many areas. Numbers have since recovered but only as a result of intensive trapping of predators and by supplementing the population in the wild. The Hawaiian Goose was listed as an endangered species in 1967 under the Federal Endangered Species Act.

Species Description

The Nene measures between 22 to 26 inches in length, has a black head and bill, yellow-buff cheeks, a buff neck with dark furrows, and partially webbed black feet. The reduction of webbing between their toes enables them to walk more easily on the rugged lava flows. Its loud calls are like those of the Canada Goose and when disturbed, its call resembles the “moo” of a cow.

Habitat & Behavior

Nene frequents scrubland, grassland, golf courses, sparsely vegetated slopes and on Kaua`i, in open lowland country as well as wetlands on the North Shore. The Nene's vegetarian diet consists of seeds of grasses and herbs as well as leaves, buds, flowers and fruits of various plants. The Nene does not appear to need fresh water but will use it when available. Although Nene are found mostly in the rugged lava fields of the Big Island, this is probably the only place they have survived rather than their preferred habitat. The breeding season is from November to June. Their nests are down-lined and usually well concealed under bushes. The Nene seem to prefer nesting in the same nest area, often a “kipuka” (an island of vegetation surrounded by lava). Unlike other Geese, except the Cape Barren Goose, copulation takes place on land. Two to five white eggs are usually laid and the incubation period is 30 days. Nene goslings are flightless for about 11 to 14 weeks after hatching. Family groups begin flocking soon after the young are able to fly and remain in the breeding grounds for about a month. They wander about searching for food after that. During the fledging period, the adults become flightless and flocks form for the post-breeding moult. This is a particularly dangerous time for the species, as they make easy prey for introduced predators.

Left: Hanalei Valley and National Wildlife Refuge. Twenty-four Nene were released here in 2000. By the spring of 2001 twenty-three individuals were still surviving and the first gosling was observed with it's parents during February. Although not considered the species "usual" habitat, fossil evidence shows that the Nene once were widespread in the lowland wetlands of the Islands, as well as on the barren lava flows of the uplands. The move away from the wetland and lowlands was almost certainly caused by the presence of humans.

Past & Present

Fossil records show that the Hawaiian Goose used to live on all the main Hawaiian Islands. It is believed that they were abundant (about 25,000 birds) on the Big Island before the arrival of Captain James Cook in 1778. Today, the Big Island is the only place where they are found naturally in the wild. Scientists believe that the Maui population became extinct before 1890. The decline in numbers was accelerated during the period of 1850 to 1900 due to aggressive hunting of the birds and collecting of their eggs. In 1951, the Nene population was estimated at only 30 birds.

In 1989-1990 it was estimated that between 476 and 555 Hawaiian Geese survived in the wild, although this included two feral flocks (totalling 73 birds). Between 1960 and 1990 a total of 2127 Nene had been reared in captivity and released into eight different areas on three of the main Hawaiian Islands. Most of these birds were reared at what is now known as the Olinda Endangered Species Facility (82%) with others coming from the Wildfowl and Wetlands Trust in England (9%), Volcanoes National Park (8%) and other sources (1%). During the 1960's 200 British-reared birds were released on Maui and in a survey in 1990 two of these birds were still alive and approaching 30 years of age.

Between 1960 and 1977 the general pattern of the population was one of increasing numbers, during which time 1742 Nene were released, between 1981 and 1982 a sharp decline occurred which coincided with the cessation of releasing birds. The estimated population for 1990 (Black et al.) was very similar to that estimated in 1982. Between 1982 and 1990 an average of thirty birds were released each year.

Black et al. (1990) state that numbers remaining in the different release areas vary greatly due to the survival of released birds: in four of the eight areas the current numbers were substantially lower than the number released, less than 15%. The numbers on Haleakala, Maui were sustained at a higher level (36% of releases) and the population was reported to have increased from 100-150 birds in 1980 to 180 in 1990. The two feral flocks appeared to be increasing in numbers since their initiation too, and it is of note that both these flocks inhabit lowland areas where there are no mongoose. Santos (1989) showed that 38% of 473 known releases in the dry upper elevation areas died within the first year of release and 52% died before the second year. With geese generally, mortality in the first two years of life after fledging, other than from hunting, is usually between 5% and 9%, although with some long-distance species up to 38% have been known to die within their first year. Obviously as the Nene is not a migrant species there is a real problem with survival of individuals beyond the first year. It appears from various different research papers that the individuals that usually survive longest are those which move to lower elevation grasslands shortly after birth or release. Many of today's Nene seem at least partly dependent on grasses and vegetation found in man-made locations, such as golf courses, and it may be that future planning for the species recovery will have to take into account this fact (amongst others). It may be that long-term survival of the species in today's Hawai'i will not be centred on the higher lava flow areas.

Their continued decline is attributed to the introduction of alien plants and animals. The Nene is extremely vulnerable to predation by introduced animals like rats, dogs, cats, mongooses, and pigs. In more recent studies, research shows that continuing decline of the Nene population in the wild can be attributed to low productivity, perhaps caused by the poor available nutrition in their habitat. Approximately 550 - 600 Nene exist in the wild today, of which there are about 200 on Kaua'i. The Kaua'i population appears to probably be the strongest and most rapidly expanding population in the Islands. A population exists at Kilauea Point on the north shore and evening counts at Kilauea Point National Wildlife Refuge during 1998 - 2001 would regularly reach 90 birds. Birds here also produce large numbers of young annually (between 20 and 40 goslings). Another population on the south side centered around the Kaua'i Lagoons and Kipu Kai areas is also well established and numbers in excess of 80 birds. In a "status quo" computer simulation the flock on mongoose-free Kaua'i was the only one to survive, whilst in an "optimal management" simulation, where predation was reduced and feeding opportunities enhanced the flocks on Hawai'i and Maui quickly flourished to self-sustaining levels and approached carrying capacity at 2,000 individuals. (Black and Banko 1994).

Conservation Efforts

Many public and private organizations have been actively operating and supporting propagation programs to reestablish the Nene in the wild. The State of Hawai`i reintroduced them to Kilauea Point and Hakalau Forest National Wildlife Refuges. The National Park Service has rearing programs at Hawai`i Volcanoes National Park and Haleakala National Park. The Wildfowl Trust in England has also played a major role in the survival of the Hawaiian Goose; they propagate and distribute the Nene to many zoos, aviaries, and the wild. Today Nene are being raised in captivity at the Maui Bird Conservation Center at Olinda and the Keauhou Bird Conservation Center on the Big Island, both operated by the Peregrine Fund. Young birds are then released into protected habitats by the State.

The Hawaiian Goose was listed as an endangered species in 1967 under the Federal Endangered Species Act. The Hawaiian Goose Recovery Plan was published in 1983. It outlines the essential elements to accomplish a goal of establishing 2,000 geese on Hawai`i and 250 on Maui. These elements are to minimize the mortality rate in the wild, continue release of captive-bred birds, and to protect and improve habitat where the Nene can maintain their populations naturally.

State Bird of Hawaii Unmasked as Canadian by Ben Harder for National Geographic News. February 6, 2002 With winter cold settled over much of North America, it would be hard to blame any native of Canada for contemplating a move to Hawaii. So perhaps it should be no surprise that Canada geese did it some time ago. Unexpectedly, scientists have learned that the distinctive-looking and endangered Hawaiian goose, known as the Nene (nay-nay), is a not-so-distant relative of commonly known Canada geese. "Rather than being a sister species of the Canada goose, the nene is an evolutionary descendent of the Canada goose," said Helen F. James, a biologist at the Smithsonian Institution in Washington, D.C. Hawaiian Geese In the foreground is the Nene, or Hawaiian goose (Branta sandvicensis). The nene-nui, or greater nene (Branta hylobadistes), is at center and the giant Hawaii goose (an undescribed species) is at the back. The nene is an endangered species; the other two species are extinct and known only from fossils. All three evolved in the Hawaiian Islands from an ancestor much like the modern Canada goose. Illustration by Julian Hume; special thanks to the Smithsonian Institution, National Musuem of Natural History. The discovery shows how quickly a population that becomes isolated can develop specialized adaptations, especially when its new habitat happens to be a young island with few animals already in residence. Sadly, the story of the nene's closest relatives, two extinct species of Hawaiian geese, also indicates how rapidly isolated populations can be exterminated by human activities. The finding suggests the need for a re-classification of living Canada geese by subdividing them into two separate groups: those closely related to the nene and those more evolutionarily distant. Based on genetic similarities, the second group would also include the barnacle goose, a population of distinctive-looking geese that is currently recognized as a species by itself. Considered Hawaii's state bird, the nene lives in a considerably different environment than that of its Canadian kin. "We are used to seeing Canada geese in wetlands and near water," said James. But in their adopted tropical habitat of Hawaii, the birds "evolved to become more independent of wetland habitats," she said. The Hawaiian goose also sports distinctive plumage. "Canada geese have all black necks, whereas nene have the sides and front of the neck buff-colored with distinctive dark furrows," said James. These outward differences belie a strong genetic resemblance and a close evolutionary link between the birds. In fact, the nene is more closely related to some subspecies of Canada geese than some of the Canadian subspecies are to each other, according to research conducted by James, Ellen E. Paxinos, and their colleagues. The surprising discovery will help scientists understand how,and how quickly, Hawaii's birds evolved to become different from their ancestors that first settled the Pacific islands. Goose Chase: The researchers' finding suggests that the nene and several other species of Hawaiian geese now extinct branched off from a population of Canada geese and colonized the tropical paradise about half a million years ago. "A single population of Canada goose became resident in the Hawaiian islands and gave rise to the diverse geese of the islands," the researchers wrote last month in Proceedings of the National Academy of Sciences. "The endangered nene is the only surviving member of [that evolutionary] radiation." To study the geese's ancestry, James and her colleagues used clues coded in genetic material obtained from fossils and from living populations of geese. Tracking the path of the feathered Hawaiian immigrants, the researchers traced them back to a branch within the family of Canada geese. The researchers' sleuthing began with a comparison of genetic sequences from the nene, several types of living Canada geese, and fossils of several extinct geese from Hawaii. Thirteen fossil geese that died between 500 and about 5,000 years ago provided ancient DNA samples for Hawaiian birds. "I've been astonished at the degree of the Hawaiian fossils' preservation," said James. "The birds died in lava-tube caves, where they were less exposed to ultraviolet radiation." UV light breaks down DNA. To salvage as much DNA as possible, the scientists looked at an abundant type of DNA that exists inside the tiny energy-producing organelles of cells, called mitochondria. The more genetic differences, or mutations, that are in the mitochondrial DNA of two related animals, the greater the length of time that has passed since they descended from a common ancestor. And because mutations accumulate at a predictable rate, scientists can estimate how much time has passed since two populations diverged from a common ancestral band. Paxinos is now doing a similar analysis of the geese using DNA from the nuclei of cells from fossils and living geese in the hope of supporting the current finding. All in the Family: The research team found that the nene and two extinct species of Hawaiian geese were all closely related to one other genetically. Surprisingly, all the Hawaiian geese were almost as closely related to two subspecies of Canada geese as they were to each other. Still more surprising, those two Canadian varieties, known as the dusky Canada goose and the giant Canada goose, respectively, share more genetic similarities with the nene and its extinct relatives than they do with other Canada geese. This makes Hawaii's geese a genetic subset of the Canadian species. Based on the genetic analysis, the researchers said the common ancestor of all Hawaiian geese must have settled the islands within about the past 500,000 years. That happens to have been about the time volcanoes first created the big island of Hawaii, which suggests that the birds showed up when that island was still young. From the traits of these two related Canadian populations, the common ancestor of the Hawaiian birds must have been larger than the modern nene, James and her colleagues inferred. The largest of the Hawaiian geese, called the giant Hawaii goose, was flightless and is now extinct. From fossil evidence and modern data, the researchers also compared characteristics of the different species of geese, such as bone structure and body shape. The results showed that different subspecies of Canada geese have a predictable relationship between body size, wing length, and skull shape. Larger birds in this group have consistently longer wings and narrower heads. The Hawaiian geese, the nene and its extinct cousins, don't follow this pattern. The giant Hawaii goose had relatively short wings, while the nene has the longest wings of the three species, despite having the smallest body size. Even so, the nene's wings are much shorter than the wings of similar-size populations of Canada geese. The different patterns of body shape also suggest that the larger birds in Hawaii evolved to fill ecological niches that geese in Canada don't occupy, such as grasslands, rain forests, and open lava fields. And it indicates that the larger Hawaiian geese were poor fliers or flightless. Part of the reason for the diverse forms and unique biology of the Hawaiian geese, the researchers said, is that Hawaii had no mammalian herbivores when the geese arrived. Their relatively rapid evolution would have enabled the birds to occupy many ecological niches that, in their native Canada, were already full and therefore off limits to them. In addition, the new avian settlers had no land-based predators in their adopted homeland. Therefore, an ability to fly would be less essential to survival for the largest of the birds, the researchers speculated. Because the island geese don't migrate south during winter months like their Canadian cousins, they also didn't need the same long wings that Canada geese use to save energy during extended flights. In the long run, the inability to fly might have been the giant Hawaii goose's undoing: The species became extinct after humans arrived on the island hundreds of years ago, probably as a result of habitat destruction and hunting. The National Geographic Society supported the team's research through a grant to Robert C. Fleischer, who was the senior author of the published paper. PAXINOS, E. E.; H. F. JAMES; S. L. OLSEN; M. D. SORESONS; and R. C. FLEISCHER. 2002. mtDNA from fossils reveals a radiation of Hawaiian Geese recently derived from the Canada Goose (Branta canadensis). PNAS 99:1399-1404. By Ben Harder for National Geographic News February 6, 2002

References:

BALDWIN, P. H. 1945. The Hawaiian Goose, its distribution and reduction in numbers. Condor 47:27-37.

BANKO, P. C. 1988. Breeding biology and conservation of the Nene, Hawaiian Goose (Nesochen sandvicensis). Ph.D. Thesis, University of Washington, Seattle.

BANKO, W. E. and W. H. ELDER. 1989. Population histories: Species accounts, sub-grassland birds: Hawaiian Goose, Nene. University of Hawaii.

BLACK, J. M. 1990. The Nene Branta sandvicensis Recovery Initiative: research against extinction.. Nene Recovery Action Group Plan, Wildfowl and Wetlands Trust, Slimbridge, U.K. Ibis 137: 153-160.

BLACK, J. M., F. DUVALL, H. HOSHIDE, J. MADEIROS, C. N. HODGES, N. SANTOS and T. TELFER. 1991. The Current status of the Hawaiian Goose Branta sandvicensis and its recovery programme. Wildfowl 42: 149-154.

BLACK, J. M. and P. C. BANKO. 1994. Is the Hawaiian Goose (Branta sandvicensis) saved from extinction? Pp. 394-410 in P.J.S. Olney, G.M. Mace and A.T.C. Feistner, eds. Creative Conservation: interactive management of wild and captive animals. London, Chapman and Hall.

COLLAR, N. J., M. J. CROSBY, and A. J. STATTERSFIELD. 1994. Birds to Watch 2. The World List of Threatened Birds. Birdlife International. Cambridge, U.K.

DEVICK, W.S. 1981a. Status of the Nene population on the Island of Hawaii between 1975 and 1980. Unpublished doc. DOFAW, DLNR, Hawaii.

DEVICK, W. S. 1981b. Status of the Nene population on the Island of Maui between 1975 and 1980. Unpublished doc. DOFAW, DLNR, Hawaii.

ELDER, W. H. and D. H. WOODSIDE. 1958. Biology and management of the Hawaiian Goose. Trans. North American Wildlife Conference 23: 198-215.

ELLIS, S., C. KUEHLER, R. LACY, K. HUGHES, and U.S.SEAL. 1992. Hawai'ian Forest Birds Conservation Assessment and Management Plan. Final Report produced by the participants of the Hawai'ian Forest Birds Conservation and Management Plan Workshop held 7 - 12 December 1992, Hilo, Hawaii. Captive Breeding Specialist Group, IUCN - The World Conservation Union/Species Survival Commission.

HARDER, B. 2002. State Bird of Hawaii Unmasked as Canadian. National Geographic News.

HAWAIIAN AUDUBON SOCIETY. 1997. Hawaii's Birds. Hawaiian Audubon Society, Honolulu, Hawai'i.

KEAR, J. and A. J. BERGER. 1980. The Hawaiian Goose. Poyser, Staffordshire, U.K.

MADGE, S. and H. BURN. 1988. Wildfowl. Helm, London.

PAXINOS, E. E.; H. F. JAMES; S. L. OLSEN; M. D. SORESONS; and R. C. FLEISCHER. 2002. mtDNA from fossils reveals a radiation of Hawaiian Geese recently derived from the Canada Goose (Branta canadensis). Proceedings of the National Academy of Sciences 99:1399-1404.

SMITH, J. D. 1952. The Hawaiian Goose (Nene) Restoration Program. The Journal of Wildlife Management. Vol.16. No. 1.

UNITED STATES FISH AND WILDLIFE SERVICE. 2001. Hawaiian Goose abstract from USFWS website. Honolulu, Hawaii.

Christian Melgar. Worthing, West Sussex, UK. 2002.

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