| Goose (plural geese) is the general English name for a considerable number of birds, belonging to the family Anatidae. This family also includes swans, most of which are larger than geese, and ducks, which are smaller. In non-technical use, the male goose is called a "gander" and the female is the "goose"; young birds before fledging are known as "goslings". A group of geese on the ground is called a gaggle; when flying in formation, it is called a wedge or a skein. A number of other waterbirds, mainly related to the shelducks, have "goose" as part of their name. True geese are medium to large birds, always associated to a greater or lesser extent with water. Most species in Europe, Asia and North America are strongly migratory as wild birds, breeding in the far north and wintering much further south. However, escapes and introductions have led to resident feral populations of several species.|
Geese have been domesticated for centuries. In the West, farmyard geese are descended from the Greylag, but in Asia the Swan Goose has been farmed for at least as long. All geese eat a largely vegetarian diet, and can become pests when flocks feed on arable crops or inhabit ponds or grassy areas in urban environments. They also take invertebrates if the opportunity presents itself; domestic geese will try out most novel food items for edibility. Geese usually mate for life, though a small number will "divorce" and remate. They tend to lay a smaller number of eggs than ducks, however, both parents protect the nest and young, which usually results in a higher survival rate for the young geese. Not all couples are heterosexual, as both females and males will form long-term same-sex couples with greater or lesser frequency depending on species. Of the heterosexual couples, a significant proportion are non-breeding despite having an active sexual life.
The following are the living genera of true geese:
Anser - Grey Geese, including the domesticated goose and the Swan Goose
Chen - White Geese (often included in Anser).
Branta - Black Geese.
The following two genera are only tentatively placed in the Anserinae; they may belong to the shelducks or form a subfamily on their own:
Cereopsis - Cape Barren Goose.
Cnemiornis - New Zealand Geese.
There are a number of mainly southern hemisphere birds called "geese", most of which belong to the shelduck subfamily Tadorninae. These are:
Blue-winged Goose, Cyanochen cyanopterus.
Orinoco Goose, Neochen jubata.
Egyptian Goose, Alopochen aegyptiacus.
The South American sheldgeese, genus Chloephaga.
The prehistoric Madagascar Sheldgoose, Centrornis majori.