The upland goose or Magellan goose (Chloephaga picta) is a sheldgoose of the shelduck-sheldgoose subfamily of the Anatidae, the biological family that includes the ducks and most duck-like waterfowl such as the geese and swans. Sheldgeese resemble true geese and display similar habits, yet they are more closely related to shelducks and ducks. This species nests and breeds close to water (rivers, ponds, oceans) either on the ground or near it among vegetation, usually in grasslands or coastal meadows in the Falkland Islands or in southern Patagonia and Tierra del Fuego at the beginning of the austral summer. Population estimates suggest the insular subpopulations are stable, but continental populations show a recent decline in abundance. Upland geese are herbivorous, specializing in plant leaves, stems and seeds.
Taxonomy
The upland goose was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with the other ducks, geese and swans in the genus Anas and coined the binomial name Anas picta. Gmelin based his description on the "painted goose" that had been included by the English ornithologist John Latham in his A General Synopsis of Birds. The species had been observed in 1775 on Isla de los Estados during Captain James Cook's second voyage to the Pacific Ocean. The naturalist Joseph Banks had provided Latham with a water-colour drawing of the goose by Georg Forster, who had accompanied Cook. It is the holotype for the species and is held by the Natural History Museum in London. The upland goose is now placed with four other species in the genus Chloephaga that was introduced in 1838 by the English naturalist Thomas Campbell Eyton. The genus name comes from the Ancient Greek khloē, meaning "grass" and -phagos, meaning "-eating". The specific epithet picta is from the Latin pictus, meaning "painted. There are strong morphological and genetic similarities between the bird fauna of the Falkland Islands and the Southern Cone of South America, and most native bird species are usually present in both insular and continental populations. The biogeography of the region suggests that these similarities exist because in the geological past, birds from the continent might have reached the Falkland Islands either across a former land connection, during periods of lowered sea levels, or through long-distance dispersal. Genetic analyses place the Magellan goose as a sister taxa to the kelp goose.
Subspecies Two subspecies of upland goose are recognised. The smaller mainland form, C. p. picta, also known as the lesser Magellan goose, is found from central Chile and south-central Argentina south to Tierra del Fuego. The larger insular form, C. p. leucoptera or greater Magellan goose, is indigenous to the Falkland Islands, located to the east of the southern part of South America.
Description Upland geese males are similar to other sheldgeese, notably the kelp goose (Chloephaga hybrida) due to their predominantly white plumage, while females resemble the ruddy-headed goose (C. rubidiceps) due to their similarly barred breast plumage. This species is 60–72.5 centimetres (23.6–28.5 in) long. Greater Magellan geese (leucoptera subspecies) are the largest birds of the genus Chloephaga. Males typically weigh 3.5–4.5 kg (7.7–9.9 lbs) and females range from 2.9 to 3.5 kg (6.4–7.7 lbs). Lesser Magellan geese (picta subspecies) males weigh 2.7–3.6 kg (6.0–7.9 lbs) on average and females 2.9–3.5 kg (6.4–6.8 lbs). Upland geese display strong sexual dimorphism in their plumage. Males have white heads and breast plumage with black legs, whereas females have reddish-brown heads and breast plumage with yellow-orange legs. However, two interbreeding morphs exist for males. One morph causes black-barred breast plumage while the other causes white breast plumage. A greenish-bronze speculum is also located on the inner secondary flight feathers of the adult male. Males make a whistling "wheep" sound, while females make a low, rattling "a-rrr" sound. Upland geese molt both their primary and secondary feathers in ponds or sheltered sea inlets, usually between late November and early January. Molting frequency depends on breeding success to some degree, since most adults that molt have either not yet mated or failed to breed. Some greater Magellan geese skip this molt, retaining their ability to fly during the austral summer. While unusual, skipping this important process might have energetic advantages, since molting season can be very nutritionally taxing. In Chapter VI of On the Origin of Species, author Charles Darwin noted that the upland goose has webbing between its toes that appeared to be "rudimentary in function, though not in structure", and concluded that this was a vestigial anatomical feature in this bird.
Habitat and distribution
Habitat Upland geese usually live in small, scattered groups on most pasture types (temperate grasslands, arid lowland scrubs), favouring areas with short green grasses. However, recent land use changes towards crop fields and managed pastures have forced them to adapt to and colonize such modern landscapes.
Distribution
Upland geese occupy the southern South American Continent (southern and central Chile and Argentina) and the Falkland Islands, with a continental distribution ranging from central Chile/southern Argentina to Tierra del Fuego, near Antarctica. Lesser Magellan geese usually reside in Patagonia or southern Chile and migrate north during the winter towards central Argentina, to their wintering grounds. Southernmost populations are more likely to migrate, with migrants reaching flight speeds of over 40 km/h (25 mph). In 2013, researchers identified a lesser Magellan goose in southern Brazil, redefining the northern edge of their wintering grounds. Greater Magellan geese, however, do not migrate and rarely leave the Falkland Islands. In general, population densities are highest around ponds and in green grasslands. Computer modelling of population ranges suggests that their distribution is favoured by the ample presence of green grasses to feed and breed in, and hindered by human presence, notably urbanization and oil extraction. There is also a sizeable introduced population on the sub-Antarctic South Georgia Island.
Behaviour and ecology
Breeding
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