A goose (plural geese) is a bird of any of several waterfowl species in the familyAnatidae. This group comprises the genera Anser (the grey geese), Branta (the black geese), and Chen (which includes the white geese), the latter sometimes being placed within the genus Anser. Some other birds, mostly related to the shelducks, have "goose" as part of their names. More distantly related members of the family Anatidae are swans, most of which are larger than true geese, and ducks, which are smaller.
The term "goose" is more properly used for a female bird, while "gander" refers specifically to a male one. Young birds before fledging are called goslings. The collective noun for a group of geese on the ground is a gaggle; when in flight, they are called a skein, a team, or a wedge; when flying close together, they are called a plump.
Two genera of geese are only tentatively placed in the Anserinae; they may belong to the shelducks or form a subfamily on their own: Cereopsis, the Cape Barren goose, and Cnemiornis, the prehistoric New Zealand goose. Either these or, more probably, the goose-like coscoroba swan is the closest living relative of the true geese.
Fossils of true geese are hard to assign to genus; all that can be said is that their fossil record, particularly in North America, is dense and comprehensively documents many different species of true geese that have been around since about 10 million years ago in the Miocene. The aptly named Anser atavus (meaning "progenitor goose") from some 12 million years ago had even more plesiomorphies in common with swans. In addition, some goose-like birds are known from subfossil remains found on the Hawaiian Islands.
Geese are monogamous, living in permanent pairs throughout the year; however, unlike most other permanently monogamous animals, they are territorial only during the short nesting season. Paired geese are more dominant and feed more, two factors that result in more young.
The spur-winged goose (Plectropterus gambensis) is most closely related to the shelducks, but distinct enough to warrant its own subfamily, the Plectropterinae.
The blue-winged goose (Cyanochen cyanopterus) and the Cape Barren goose (Cereopsis novaehollandiae) have disputed affinities. They belong to separate ancient lineages that may ally either to the Tadorninae, the Anserinae, or closer to the dabbling ducks (Anatinae).
The three species of small waterfowl in the genus Nettapus named "pygmy geese"; they seem to represent another ancient lineage, with possible affinities to the Cape Barren goose or the spur-winged goose.
The maned goose, also known as the maned duck or Australian wood duck (Chenonetta jubata)
The northern gannet (Morus bassanus), a seabird, is also known as the "solan goose", although it is unrelated to the true geese, or any other Anseriformes for that matter.
In popular culture
Well-known sayings about geese include:
To "have a gander" is to examine something in detail.
"What's sauce for the goose is sauce for the gander" or "What's good for the goose is good for the gander" means that what is an appropriate treatment for one person is equally appropriate for someone else.
Saying that someone's "goose is cooked" means that they have suffered, or are about to suffer, a terrible setback or misfortune.
The common phrase "silly goose" is used when referring to someone who is acting particularly silly.