Brant goose / Brent goose

Branta bernicla

Rotgans / Ringelgans / Bernache cravant

The Brant or Brent Goose (Branta bernicla) is a species of goose of the genus Branta. The specific descriptor bernicla is from the same source as "barnacle" in Barnacle Goose, which looks similar but is not a close relation.

The species is divided three subspecies:

• Dark-bellied Brant Goose, Branta bernicla bernicla (Linnaeus, 1758) (sometimes known as Russian Brant)
• Pale-bellied Brant Goose, Branta bernicla hrota (Müller, 1776) (sometimes also known as Light-bellied Brant Goose in Europe, and Atlantic Brant in North America)
• Black Brant, Branta bernicla nigricans (Lawrence, 1846) (sometimes also known as the Pacific Brant in North America)

Branta bernicla (Sibley and Monroe 1990, 1993) was putatively split into B. bernicla, B. hrota and B. nigricans by Shields (1990) but this treatment is not followed by the BirdLife Taxonomic Working Group. Some DNA evidence suggests that these forms are genetically distinct; while a split into three separate species has been proposed, it is not widely accepted, with other evidence upholding their maintenance as a single species.

It used to be a strictly coastal bird in winter, seldom leaving tidal estuaries, where it feeds on eel-grass (Zostera marina) and the seaweed, sea lettuce(Ulva). In recent decades, it has started using agricultural land a short distance inland, feeding extensively on grass and winter-sown cereals. This may be behaviour learnt by following other species of geese. Food resource pressure may also be important in forcing this change, as the world population has risen over tenfold to 400,000-500,000 by the mid 1980s, possibly reaching the carrying capacity of the estuaries. In the breeding season, it uses low-lying wet coastal tundra for both breeding and feeding. The nest is bowl-shaped, lined with grass and down, in an elevated location, often in a small pond.

The Brant Goose is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern (IUCN, 2009).

Above: Branta bernicla bernicla

Above: Branta bernicla bernicla

Above: Branta bernicla hrota (photo by Roelof Jan Breman)

Above: Branta bernicla hrota

Above: Branta bernicla hrota

Above: Branta bernicla nigricans

Above: Branta bernicla nigricans (photo by Roelof Jan Breman)