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. Upland geese are herbivorous, specializing in plant leaves, stems and seeds. 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, Genetic analyses place the Magellan goose as a sister taxa to the kelp goose. 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. 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

thumb|in [[Santa Cruz Province, Argentina]]

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. with migrants reaching flight speeds of over . There is also a sizeable introduced population on the sub-Antarctic South Georgia Island.

Behaviour and ecology

Breeding

thumb| upright=0.7|Egg in the collection of the [[Muséum de Toulouse]]

Upland goose breed in southern Patagonia or their native islands during the austral summer. They are monogamous, although divorce can occur, and generally return to breed in the same territory every year. They breed non-colonially in densely vegetated areas, generally in September and October on the mainland, and in November on the Falkland Islands. which was created in collaboration with Falkland Conservation.

Males attract females through a courtship display in which they whistle loudly, to which the female responds with softer cackles. As they are monogamous and territorial, a violent fight may break out if a male encroaches on another's territory. Males have been found injured or dead after these fights.

The simple nest is either on the ground or within of it, usually concealed by dense vegetation, and often located near water. However, a recent study claims that while sheldgeese do reduce wheat cover, they do not reduce overall wheat yield and they might even provide an ecosystem service through weed grazing.

Threats and conservation

In the early 20th century, the Argentinian government declared the three Patagonian sheldgeese species (Ruddy-headed goose, Ashy-headed goose, and Upland goose) as pests due to claims of excessive grazing and negative effects on crop yields.

References

  • Male vocalizations on Birds of the World
  • Female vocalizations on Birds of the World
  • New Island Nature Reserve