Any of various large, heavy-bodied waterfowl (family Anatidae), especially those of the genera Anser (so-called gray geese) and Branta (so-called black geese), which are found only in the Northern Hemisphere. Intermediate in size and build between ducks and swans, geese are less fully aquatic than either, and their legs are farther forward, allowing them to walk readily. Geese have a specially modified bill for grasping sedges and grasses, their main diet. The sexes are alike in coloration; males (called ganders) are usually larger than females. Both sexes utter loud honking or gabbling cries while in flight or when danger appears. Geese pair for life. Flocks traveling in V-formations migrate between their northern breeding grounds and southern wintering grounds. See alsobarnacle goose; Canada goose; greylag; nene.