Geese

Geese are large birds in the subfamily Anserinae of the waterfowl family Anatidae, consisting of ducks, geese, and swans.

Geese occur in many types of aquatic habitats, on all continents but Antarctica. Most geese breed in freshwater marshes, salt marshes, or marsh-fringed, open-water wetlands. Geese typically winter in those sorts of natural habitats and in estuaries, although in some regions they also use grainfields in winter, mostly for feeding. Geese are more terrestrial than either ducks or swans, and they typically feed on roots, rhizomes, and shoots of graminoid (grass-like) plants, and on seeds and grains, when available.

Geese are not sexually dimorphic, meaning that there are no obvious, external morphological traits that serve to distinguish between the female, properly named a goose, and the male, or gander. Ganders do tend to be somewhat larger, but size is not a reliable indicator of gender. Like other waterfowl, geese undertake a simultaneous moult of their major wing feathers, and are flightless at that time. This moult occurs during the breeding season, while the geese are taking care of their young.

Most species of goose undertake substantial migrations between their breeding and wintering grounds, in some cases traveling thousand of miles, twice yearly. Flocks of migrating geese commonly adopt a V-shaped formation, which is aerodynamically favorable, because it reduces resistance to passage, so less energy is expended in flying. Geese can be rather noisy when flying in groups, which may sometimes be heard before they are seen.