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Hawaiian Goose Branta sandvicensis

Justification
The overall population of this species has increased from a low of perhaps just 30 birds in the mid-1900s to over 2,000 individuals in 2011. The majority of the population outside Kaua'i does not breed successfully in the wild, so the effective population size is very small and consequently the species is listed as Vulnerable.

Taxonomic source(s)
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.

Identification
64 cm. Small, attractive, grey-brown goose. Body with scaly pattern of grey, brown and white. Black face and crown to nape. Golden-buff neck with feathers forming dark furrows. Cheeks tinged ochre. Juvenile similar but browner. Similar spp. Small subspecies of Canada Goose B. canadensis has all-black neck with white throat patch. Brent Goose B. bernicla has entirely dark head, neck and breast. Voice Two-part nasal call with accent on either first or second syllable ah-AHRK or NAY-nay in flight. Cackles in flocks. Sometimes a series of similar notes kip-kip-kip-kip- etc. Also soft, drawn-out nay calls when approached. Hints Often heard before seen.

Distribution and population
Branta sandvicensis is endemic to the Hawaiian Islands (U.S.A.). Fossil analysis suggests that it once occurred throughout the main islands (Olson and James 1991). However, along with other species, it declined due to habitat loss and alteration, and predation by humans and introduced predators (Olson and James 1991, A. Marshall, D. Hu and K. Misajon in litt. 2007). The species is now the focus of conservation efforts. Between 1960 and 2006, over 2,400 captive-bred individuals have been released on Big Island, Moloka'i, Maui and Kaua'i (A. Marshall, D. Hu and K. Misajon in litt. 2007). During the drought years of 1976-1983, the majority of released birds (c.1,200) perished (Black et al. 1997). Of 63 birds released between 2000-2001 and 2005-2006, 55 (87%) survived their first year (A. Marshall, D. Hu and K. Misajon in litt. 2007). On Big Island, the population has been partly dependent on continued releases, although large numbers are no longer needed to maintain a stable population (C. Terry in litt. 1999, A. Marshall in litt. 2012). This is the most genetically diverse population (F. Woog in litt. 2006). The population on Maui is considered to be more or less stable (A. Marshall, D. Hu and K. Misajon in litt. 2007). On Kaua'i, numbers had increased to c.1,400-1,600 by 2011. There is now a large population at Kaua'i Lagoons adjacent to the airport, and the state plans to move around 400 from there to sites on Maui, Big Island and Moloka'i.  In 2011, the population was estimated at around 2,500 birds state-wide (A. Marshall in litt. 2012).

Population justification
The total population was estimated to be 1,241 individuals in 2004 (based on counts in 2003), 1,744 individuals in 2006 (A. Marshall, D. Hu and K. Misajon in litt. 2007) and c.2,500 individuals in 2011 (A. Marshall in litt. 2012). However, it is expected that fewer than 1,000 have bred successfully in the wild, and maintenance of the current population relies partly on the regular release of captive bred individuals. Hence the effective number of mature individuals falls within the band 250-999.

Trend justification
The total population was estimated to be 960-1,000 birds in 1999, 1,241 individuals in 2004 (USFWS 2004a), 1,744 in 2006 (A. Marshall, D. Hu and K. Misajon in litt. 2007) and 2,500 in 2011 (A. Marshall in litt. 2012). On Kaua'i, population growth from 2004-2006 can be attributed solely to natural recruitment as no releases of captive-bred birds occurred during that time period. On Maui, the population remains steady, owing in part to captive releases, as well as to predator control. On Big Island, the population has slightly increased, partly owing to natural recruitment at Hakalau National Wildlife Refuge, better recruitment at Hawai'i Volcanoes National Park post-drought, and some captive releases (A. Marshall, D. Hu and K. Misajon in litt. 2007).

Ecology
In 1949, the remaining populations on Big Island inhabited rocky, sparsely vegetated, high volcanic slopes. Following habitat loss and alteration for agriculture (Olson and James 1991), the optimal habitat is now apparently grassland, where there is an abundance of high protein food, adjacent to natural scrubland nesting areas (Black et al. 1994, Black 1995, Black et al. 1997). Breeding success and productivity are currently low except on Kaua'i. In recent studies, less than 10% of all breeding-age females successfully bred (Banko et al. 1997, F. Woog in litt. 2006), although this may not be the case on Kaua'i (A. Marshall, D. Hu and K. Misajon in litt. 2007).

Threats
The development of agricultural systems by the Polynesians, and later by European settlers, resulted in the extensive loss and alteration of habitat (Olson and James 1991). A lack of suitable habitat, especially for rearing young, is the most important limiting factor, combined with predation by the introduced small Indian mongoose Herpestes auropunctatus (except on Kaua'i), dogs, cats, pigs and rats (Black et al. 1994, Black 1995, H. C. Baker and P. E. Baker in litt. 1999,  T. C. Telfer in litt. 1999, A. Marshall, D. Hu and K. Misajon in litt. 2007). Other threats include disease and parasites, inbreeding depression, loss of adaptive skills in captive-bred birds and dietary deficiencies. Feral cats carry the protozoan organism Toxoplasma gondii which causes toxoplasmosis, a disease that can be fatal in the species (Hess and Banko 2006). Road-kills are an important threat on Big Island (M. Morin in litt. 1999) and probably on Maui (A. Marshall, D. Hu and K. Misajon in litt. 2007). Indeed road-kills were found to be the most common cause of known adult mortality on Big Island from 1989-1999 (Rave et al. 2005). Recruitment is low in this species, as found in the Hawai'i Volcanoes National Park over the same period. Yearly average hatching success was only 55% (range 44-77%), probably because of introduced predators rather than inbreeding. A yearly average of only 30% (range 0-50%) of nestlings fledged, with most lost to starvation, dehydration and predation. Recruitment into the breeding population is low, with only 42% of tracked fledglings eventually attempting to breed. An average of 35% of the population breed each year, probably limited by food availability, which affects female condition. Drought is another limiting factor for this species (Rave et al. 2005).

Conservation Actions Underway
CITES Appendix I. The species benefits from a suit of protected areas, including Hawai'i Volcanoes and Haleakallâ (Maui) national parks, Kîlauea Point (Kaua'i) and Hakalau Forest (Big Island) national wildlife refuges, and several state sanctuaries (Banko et al. 1997, C. Terry in litt. 1999). Extensive research has been conducted on factors limiting population growth (e.g. Bailey and Black 1995, Rave 1995, Rojek and Conant 1996). Predators are controlled, and supplementary food and water are sometimes provided at particular sites (C. Terry in litt. 1999, A. Marshall, D. Hu and K. Misajon in litt. 2007). Despite the low average fledging success rate recorded in the Hawai'i Volcanoes National Park from 1989-1999, this was more than double the rate in the previous 15 years, owing to predator control and supplementary feeding during breeding seasons (Rave et al. 2005). Other efforts have involved habitat restoration and reducing human disturbance, especially to breeding birds (Rave et al. 2005, A. Marshall, D. Hu and K. Misajon in litt. 2007). Releases of captive birds continued until the late 2000s (A. Marshall, D. Hu and K. Misajon in litt. 2007), but have now ceased. Translocation of birds from Kaua'i to other islands is on-going, as there is a large population at Kaua'i Lagoons, near the airport (A. Marshall in litt. 2012). Conservation Actions Proposed
Continue to monitor population trends. Carry out further research into the factors limiting breeding and causing low recruitment. Manage and restore habitat, and control predators (Black 1995, Black 1998, Rave et al. 2005). Ensure Kaua'i remains mongoose-free (H. C. Baker and P. E. Baker in litt. 2000). Optimise genetic diversity in flocks with few founders (Rave 1995). Develop community education programme, particularly with regard to road-kills (Black 1995, C. Terry in litt. 1999, Rave et al. 2005). Establish large predator-free reserves in lowland areas with better quality forage in which the above targets can be addressed (H. C. Baker and P. E. Baker in litt. 1999, H. C. Baker and P. E. Baker in litt. 2000). Expand habitat restoration efforts. In the Hawai'i Volcanoes and Haleakalâ national parks, prevent visitors from feeding the birds and speeding (Rave et al. 2005). Conduct a telemetry study to determine habitat use outside of the breeding season, as non-breeding areas have been largely unstudied (A. Marshall in litt. 2012).


References
Bailey, T.; Black, J. 1995. Parasites of wild and captive Nene Branta sandvicensis in Hawaii. Wildlife 46: 59-65.

Banco, P. C.; Black, J. M.; Banko, W. C. 1999. The Hawaiian Goose (Branta sandvichensis). In: Poole, A.; Gill, F. (ed.), The birds of North America, pp. 1-32. The Academy of Natural Sciences and The American Ornithologists' Union, Philadelphia and Washington, D.C.

Black, J. M. 1995. The Nene Branta sandvicensis recovery initiative: research against extinction. Ibis 137: S153-S160.

Black, J. M. 1998. Threatened waterfowl: recovery priorities and reintroduction potential with species reference to the Hawaiian Goose. In: Marzluff, J.M.; Sallabanks, R. (ed.), Avian conservation, pp. 125-140. Island Press, Washington, DC.

Black, J. M.; Marshall, A. P.; Gilburn, A.; Santos, N.; Hoshide, H.; Medeiros, J.; Mello, J.; Natividad Hodges, C.; Katahira, L. 1997. Survival, movements, and breeding of released Hawaiian Geese: an assessment of the reintroduction program. Journal of Wildlife Management 61: 1161-1173.

Black, J. M.; Prop, J.; Hunter, J. M.; Woog, F.; Marshall, A.; Bowler, J. 1994. Foraging behaviour and energetics of the Hawaiian Goose Branta sandvicensis. Wildfowl 45: 65-109.

Hess, S. C.; Banko, P. C. 2006. Feral cats: too long a threat to Hawaiian wildlife.

Olson, S. L.; James, H. F. 1991. Descriptions of thirty-two new species of birds from the Hawaiian Islands: Part 1. Non-passeriformes. Ornithological Monographs 45: 1-88.

Rave, E. H. 1995. Genetic analysis of wild populations of Hawaiian Geese using DNA fingerprinting. Condor 97: 82-90.

Rave, E.H.; Cooper, A.; Hu, D.; Swift, R.; Misajon, K. 2005. Population and reproductive trends of Nene Branta sandvicensis in Hawaii Volcanoes National Park, 1989-1999. Wildfowl 55: 7-16.

Rojek, N. A.; Conant, S. 1996. Food preferences and response to novel native berries by captive reared Nene Branta sandvicensis goslings. Wildfowl 47: 67-80.

U.S. Fish and Wildlife Service. 2004. Draft revised recovery plan for the Nene or Hawaiian goose (Branta sandvicensis). USFWS, Portland, Oregon, U.S.A.

Further web sources of information
Audubon WatchList

Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

U.S. Fish and Wildlife Service - Draft Recovery Plan

Text account compilers
Benstead, P., Bird, J., Butchart, S., Sharpe, C J, Stattersfield, A., Stuart, T., Taylor, J., Temple, H., Khwaja, N.

Contributors
Baker, H., Baker, P., Black, J., Camp, R., Dibden-Young, A., Fretz, S., Gorresen, M., Hu, D., Marshall, A., Misajon, K., Morin, M., Telfer, T., Terry, C., VanderWerf, E., Woodworth, B., Woog, F.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Branta sandvicensis. Downloaded from http://www.birdlife.org on 21/09/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/09/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Nene (Branta sandvicensis)

Key facts
Current IUCN Red List category Vulnerable
Family Anatidae (Ducks, Geese, Swans)
Species name author (Vigors, 1834)
Population size 250-999 mature individuals
Population trend Increasing
Distribution size (breeding/resident) 1,900 km2
Country endemic? Yes
Links to further information
- Additional Information on this species