A goose (pl.: geese) is a bird of any of several waterfowl species in the family Anatidae. This group comprises the genera Anser (grey geese and white geese) and Branta (black geese). Some members of the Tadorninae subfamily (e.g., Egyptian goose, Orinoco goose) are commonly called geese, but are not considered "true geese" taxonomically. 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" may refer to such bird of either sex, but when paired with "gander", "goose" refers specifically to a female one ("gander" referring to a male). 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.