The Brant (called Brent Goose in Europe) is a small dark goose that occurs throughout much of the northern hemisphere. In contrast to other goose species, Brant are characterized by their extensive use of native coastal habitats outside the breeding season. Three to four subspecies are recognized (see Systematics), mainly on the basis of plumage characteristics. The two/three North American subspecies are further separated into four subpopulations based on genetics, location of breeding and wintering areas, and migration routes.
This goose breeds from the low to the high Arctic, and migrates long distances to wintering areas. Different subpopulations nesting in arctic Canada and Alaska winter in areas as distant and widely separated as Baja California, the Puget Sound, the coastline of the mid-Atlantic states, and Ireland. In summer, salt marshes, especially those containing the graminoids Carex and Puccinellia, are key habitats for nesting and raising young. These same habitats, along with large freshwater lakes with abundant moss and sedge shorelines, are also used during the flightless molt. Wintering locations are usually characterized by an abundance of native intertidal plants used as forage, particularly the seagrass, Zostera; no other species of goose relies so heavily on a single plant species during the nonbreeding season. In contrast to European populations, Brant wintering in North American have, for the most part, not switched to agricultural habitats.
Like other geese, this species provides biparental care, accompanies its young through their first migration, and usually mates for life. Brant show fidelity to both wintering and breeding areas. In the low Arctic, Brant often breed in relatively dense colonies, but in the high Arctic nesting is more dispersed. During brood-rearing, the availability and abundance of salt marsh foraging habitat directly affects growth and recruitment of goslings, thereby influencing local population dynamics. During winter, their strong dependence on certain food plants makes them vulnerable to occasional heavy losses from starvation, more so than most other geese. Further, oceanographic conditions experienced at wintering locations directly affect their subsequent breeding condition and reproductive performance. These vulnerabilities necessitate careful population-monitoring and regulation of hunting.
Brant have been extensively studied in Europe, Asia, and North America but much remains to be learned. Key studies in e. North America include those on breeding and molting by Barry ( Barry 1956 , Barry 1962 ) and Ankney ( Ankney 1984 ), and those on wintering and population dynamics by Kirby (Kirby and Obrecht Kirby and Obrecht 1980 , Kirby and Obrecht 1982 ; Kirby et al. Kirby et al. 1985a , Kirby et al. 1986 ) and Ladin et al. (2011). Main studies in w. North America include those on breeding by Mickelson ( Mickelson 1975 ), by Sedinger and Flint ( Sedinger and Flint 1991 , Sedinger et al. 1995a , Flint and Sedinger 1992 , Flint et al. 1995 , Sedinger et al. 2006, 2008), on molting by Derksen et al. ( Derksen et al. 1982 ) and Singer et al. (2012), on migration and wintering by Dau ( Dau 1992 ), Lindberg et al. (2007), Ward et al. (2009), and Sedinger et al. (2011), on staging by Reed et al. ( Reed et al. 1989b ), Moore et al. (2004), Lee et al. (2007), and Smith et al. (2012), on survival rates by Ward (Ward et al. Ward et al. 1997 , Ward et al. 2004) , Sedinger (Sedinger et al. 2002, 2007), and Nicolai et al. (2012), on food habits by Lee et al. (2004), Moore and Black (2006), and Mason et al. (2007), and on current status and conservation by Sedinger et al. ( Sedinger et al. 1993 , Sedinger et al. 1994 ), Ward et al. (2005), and Shaughnessy et al. (2012). Canadian high Arctic populations have been studied by Boyd (Boyd and Maltby Boyd and Maltby 1979 , Boyd and Maltby 1980 ; Boyd et al. 1988 ) and Cotter and Hines (2001).