Justification While the overall population of this species has increased from a low of perhaps just 30 birds in the mid-1900s to over 1,700 individuals in 2006, this growth is partly maintained by the regular release of captive-bred individuals. 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.

Family/Sub-family Anatidae

Species name author (Vigors, 1834)

Taxonomic source(s) AOU checklist (1998 + supplements), Sibley and Monroe (1990, 1993)

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.

Population estimate

Population trend

Range estimate (breeding/resident)

Country endemic?

250-999

increasing

1,900 km²

Yes

Range & population Branta sandvicensis is endemic to the Hawaiian Islands (USA). Fossil analysis suggests that it once occurred throughout the main Hawaiian islands²⁰. However, along with other species, it declined due to habitat loss and alteration, and predation by humans and introduced predators^19,20. The species is now the focus of conservation efforts. In 2006, the total population was estimated to be 1,744 individuals, based on figures of 829 on Kaua`i, 360 on Maui, 74 on Moloka`i, and 481 on Hawai`i<sup>19</sup>. Between 1960 and 2006, over 2,400 captive-bred individuals have been released on Hawai`i, Moloka`i, Maui and Kaua`i¹⁹. During the drought years of 1976-1983, the majority of released birds (c.1,200) perished⁸. Of 63 birds released between the 2000-2001 and 2005-2006, 55 (87%) survived their first year¹⁹. On Hawai`i, the population is partly dependent on continued releases<sup>9</sup>, although large numbers are no longer needed to maintain a stable population<sup>14</sup>. This is the most genetically diverse population<sup>17</sup>. On Kaua`i, numbers are increasing^14,19 and recruitment appears to be increasing¹⁹. The population on Maui is considered to be more or less stable¹⁹.

Ecology: In 1949, the remaining populations on Hawai`i inhabited rocky, sparsely vegetated, high volcanic slopes. Following habitat loss and alteration for agriculture<sup>20</sup>, the optimal habitat is now apparently grassland, where there is an abundance of high protein food, adjacent to natural scrubland nesting areas<sup>5,7,8</sup>. Breeding success and productivity are currently low except on Kaua`i. In recent studies less than 10% of all breeding-age females successfully bred^4,17, although this may not be the case on Kaua`i¹⁹.

Threats The development of agricultural systems by the Polynesians, and later by European settlers, resulted in the extensive loss and alteration of habitat²⁰. 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<sup>2,5,7,13,19</sup>. Other threats include disease and parasites, inbreeding depression, loss of adaptive skills in captive-bred birds and dietary deficiencies. Feral cats carry a protozoan organism Toxoplasma gondii which causes toxoplasmosis, a disease that can be fatal in the species<sup>18</sup>. Road-kills are an important threat on Hawai`i¹⁰ and probably on Maui¹⁹. Indeed road-kills were found to be the most common cause of known adult mortality on Hawai`i from 1989 to 1999<sup>16</sup>. 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 species¹⁶.

Conservation measures 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 (Hawai`i) National Wildlife Refuges, and several state sanctuaries<sup>4,14</sup>. Extensive research has been conducted on factors limiting population growth<sup>e.g.1,11,12</sup>. Predators are controlled, and supplementary food and water are sometimes provided at particular sites<sup>14,19</sup>. Despite the low average fledging success rate recorded in the Hawai`i Volcanoes National Park from 1989 to 1999, this was more than double the rate in the previous 15 years, owing to predator control and supplementary feeding during breeding seasons¹⁶. Other efforts have involved habitat restoration and reducing human disturbance^16,19, especially to breeding birds¹⁹. Releases of captive birds continue, albeit at a reduced rate¹⁹.

Conservation measures 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^5,6,16. Ensure Kaua`i remains mongoose-free<sup>3</sup>. Continue captive breeding and husbandry<sup>6,8,11</sup>. Optimise genetic diversity in flocks with few founders<sup>11</sup>. Develop community education programme, particularly with regard to road-kills<sup>5,14,16</sup>. Establish large predator-free reserves in lowland areas with better quality forage in which the above targets can be addressed<sup>2,3</sup>. Expand habitat restoration efforts<sup>16</sup>. In the Hawai`i Volcanoes and Haleakalâ National Parks, prevent visitors from feeding the birds and speeding¹⁶.

References 1. Bailey and Black (1995). 2. H. C. Baker and P. E. Baker in litt. (1999). 3. H. C. Baker and P. E. Baker in litt. (2000). 4. Banko et al. (1997). 5. Black (1995). 6. Black (1998). 7. Black et al. (1994). 8. Black et al. (1997). 9. Callaghan et al. (in prep.). 10. M. Morin in litt. (1999). 11. Rave (1995). 12. Rojek and Conant (1996). 13. T. C. Telfer in litt. (1999). 14. C. Terry in litt. (1999). 15. USFWS (2004a). 16. Rave et al. (2005). 17. F. Woog in litt. (2006). 18. Hess and Banko (2006). 19. A. Marshall, D. Hu and K. Misajon in litt. (2007). 20. Olson and James (1991).

Further web sources of information

Audubon WatchList

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

Text account compilers Phil Benstead (BirdLife International), Jeremy Bird (BirdLife International), Stuart Butchart (BirdLife International), Alison Stattersfield (BirdLife International), Tom Stuart (BirdLife International), Joe Taylor (BirdLife International), Helen Temple (BirdLife International)

Contributors Helen C. Baker (US Fish & Wildlife Service), Paul E Baker (US Fish & Wildlife Service), Jeff Black (Department of Wildlife, Humboldt State University), Rick Camp (US Geological Survey), Arleone Dibden-Young (Nene O Molokai), Scott Fretz (Hawaii Division of Forestry and Wildlife), Marcos Gorresen (US Geological Survey), Darcy Hu (US National Parks Service), Annie Marshall (US Fish & Wildlife Service), Kathleen Misajon (US National Parks Service), Marie Morin (US Fish & Wildlife Service), Tom Telfer (Hawaii Division of Forestry and Wildlife), Carol Terry (Hawaiian Department of Land and Natural Resources), Eric VanderWerf (US Fish & Wildlife Service), Bethany Woodworth (US Geological Survey), Friederike Woog (Staatliches Museum für Naturkunde Stuttgart)

IUCN Red List evaluators Stuart Butchart (BirdLife International), Joe Taylor (BirdLife International)

Recommended citation BirdLife International (2009) Species factsheet: Branta sandvicensis. Downloaded from http://www.birdlife.org on 9/2/2010

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