Cape Barren geese are large birds found in Australia. They are one of the rarest of the world's geese. They are bulky birds and their almost uniformly grey plumage, bearing rounded black spots, is unique. The tail and flight feathers are blackish and the legs are pink with black feet. The short, decurved black bill and green cere gives it a very peculiar expression. Males of this species are somewhat larger than females.
Cape Barren geese do not migrate. The major area of their distribution is offshore islands near South Australia and Tasmania. During the breeding season, these geese are usually found in grassy areas, tussock grass, or bushes. During the rest of the year, they can be seen on beaches, coastal pastures, in brackish lagoons, and along the shores of freshwater lakes.
Cape Barren geese are diurnal birds, spending most of the day grazing. These birds can drink salty and brackish water, due to which they are able to live on separated offshore islands throughout the year. Cape Barren geese don’t tend to swim and will enter the water only in order to protect their chicks. At the breeding season, these birds congregate into loosely organized colonies, where nests are at a distance from each other. Pair are very territorial and fiercely defend their nesting site against any intruders. When threatened, the goose starts lifting its folded wings again and again while stretching out and pumping its neck and speeds up the movements as the level of aggression increases. Cape Barren geese attack, either rushing forward and keeping their head low and stretched out or running upright with spread wings. Usually, during the mating season, mated pair of Cape Barren geese imitates these movements, performing them as a "triumph ceremony".
Cape Barren geese are herbivorous, eating only plant matter. The usual diet of these birds includes tussock grass Poa poifornis, which is a common plant on the islands of their habitat. In addition, these birds consume a wide variety of grass species, leaves, seeds, and stems.
Cape Barren geese are monogamous; they mate for life and each mated pair establishes and strongly defends its territory. Cape Barren geese breed during the winter months, from May to June. Usually, the male builds the nest with vegetation on the ground after which the female lays 3-6 eggs, that are creamy-white in color. Then the female incubates the eggs for 34-37 days. Goslings hatch precocial (well-developed) and both parents care for their young and protect them. Around 70-76 days after hatching, the goslings fledge. They then congregate into small groups, reaching nearby islands or even the continent.
Although nowadays the species is not endangered, in the 20th century it has been heavily hunted, which nearly led to its complete extinction. Currently, the population of the Cape Barren goose has highly increased and it's protected by a number of wildlife agencies. However, threats are still present: a part of their breeding grounds can turn into agricultural lands, thus reducing the habitat of this species. It is necessary for these islands to have the status of nature reserves with limited grazing allowed, in order to avoid dense scrubland.
The global population of these birds is considered to be stable and not endangered. The total number of Cape Barren goose population is about 16.000-18.000 birds, approximately 11.000-12.000 of which are mature individuals. In the IUCN Red List, the species is classified as Least Concern (LC).
Cape Barren geese play an important role in the ecosystem of their habitat. They feed upon various plant species and thus act as seed dispersers.