In 1949, the remaining populations on Hawai‘i were restricted to rocky, sparsely vegetated, high volcanic slopes. Historically, the species is likely to have used grasslands, grassy shrublands, and dryland forest (USFWS 2004). It currently occurs in a variety of habitats including golf courses, pastures, lava flows, upland grasslands and shrublands (USFWS). The optimal habitat during the breeding and moulting seasons appears to be lowland grassland, including exotic 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, Leopold and Hess 2013). During the non-breeding season it prefers subalpine shrubland (Leopold and Hess 2013, 2014). The species is likely to have originally been an altitudinal migrant, nesting primarily in leeward lowlands below 700m, and moving to montane habitats above 900 meters in the non-breeding season (Black 1995, USFWS 2004). Seasonal movements are now being seen in some recovered populations (USFWS 2004, 2011, Hess et al. 2012). Although a weak flier, the species is capable of flying between islands, and there have been several records of individuals flying between Maui and Hawai‘i (Banko and Elder 1990). It feeds on a wide range of plants (Banko et al. 1999). It breeds from August to April, with most eggs hatching in December and January (Banko et al. 1999).

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, it declined due to habitat loss and alteration, hunting, and and predation by introduced predators (Olson and James 1991), and by 1951 only around 30 wild individuals remained, restricted to Hawai‘i Island (Smith 1952). Following an extensive reintroduction programme beginning in the 1960s, reintroduced populations are now also found on Maui, Kaua‘i and Moloka’i Islands. For some time, all populations were dependent on continued releases of captive birds to persist (USFWS 2004), but releases ceased by the late 2000s (USFWS 2011). The populations on Kaua‘i, Hawai‘i Island and Maui are now considered to be self-sustaining, although they continue to be reliant on predator control and habitat management (USFWS 2018). The population on Moloka’i is not yet successfully breeding (USFWS 2019), and so it is excluded from this assessment.  In 2014, a pair nested on O‘ahu, having colonised the island naturally (USFWS 2014).

Conservation Actions Underway
CITES Appendix I. The species was listed as Endangered in the USA under the Endangered Species Act from its inception until 2020, when it was downlisted to Threatened status (USFWS 2019). The species benefits from a suite 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 (C. Terry in litt. 1999).

The population size is monitored regularly, with separate populations generally monitored separately (USFWS 2004). 

Captive breeding began in 1949 and the release of captive-bred individuals began in the 1960s, ending in the late 2000s (USFWS 2011). Over 2,800 captive-bred individuals were released on Hawai‘i, Moloka’i, Maui and Kaua‘i (VanderWerf 2012). The populations on Kaua‘i, Hawai‘i Island and Maui are now considered to be self-sustaining, although they continue to be reliant on predator control and habitat management (USFWS 2018). Predators have been controlled at most areas where the species nests (USFWS 2004, VanderWerf 2012), and fences are used to exclude predators from breeding areas at some sites (VanderWerf 2012). Habitat has been restored at key sites through mowing, controlled grazing, control of alien plants and reintroduction of native plants (USFWS 2004). Supplementary food has been provided at some sites (VanderWerf 2012). A range of educational activities have taken place to raise awareness of the species's conservation (USFWS 2004). Press releases, posters, signs and postcards are used to raise awareness of the need for careful driving near nesting sites (USFWS 2018). Agreements have been put in place with private landowners to maintain or improve habitat, control predators and reintroduce the species to their land (USFWS 2004). 

Conservation and Research Actions Proposed
Standardise monitoring protocols and continue to monitor population trends. Continue studies on movement patterns and habitat use. Monitor threats, including collisions with wind turbines. 

Protect, manage and restore habitat, particularly lowland grasslands on Hawai‘i Island, and ensure habitat connectivity to enable altitudinal migration (USFWS 2004). Control alien predators, including mongooses, rats and cats (Black 1995, Black 1998, Rave et al. 2005, Work et al. 2015). Establish and maintain strict biosecurity protocols to ensure Kaua‘i remains mongoose-free (H. C. Baker and P. E. Baker in litt. 2000, USFWS 2019). Continue education activities to raise awareness of the species's conservation and threats, particularly with regard to road-kills (Black 1995, C. Terry in litt. 1999, Rave et al. 2005). Address conflicts between the species and human activities, such as crop damage and the risk to aviation (USFWS 2004). Optimise genetic diversity in flocks with few founders (Rave 1995).