The Greylag Goose, Anser anser, is a bird with a wide range in the Old World.
Within science, the greylag goose is most notable as being the bird with which the ethologist Konrad Lorenz first did his major studying into the behavioural phenomenon of imprinting.
The Greylag is the largest and bulkiest of the grey Anser geese. It has a rotund, bulky body, a thick and long neck, and a large head and bill. It has pink legs and feet, and an orange or pink bill. It is 75 to 90 centimetres long with a wing length of 41.2 to 48 centimetres. It has a tail 6.2 to 6.9 centimetres, a bill 6.4 to 6.9 centimetres long, and a tarsus 7.1 to 9.3 centimetres. It weighs 2,921 to 3,612 grams. Males are generally larger than females, more so in the eastern subspecies rubirostris.
This species is found throughout the Old World, apparently breeding where suitable localities are to be found in many European countries, although it no longer breeds in southwestern Europe. Eastwards it extends across Asia to China. In North America there are both feral domestic geese, which are similar to greylags, and occasional vagrants.
The geese are migratory, moving south or west in winter, but Scottish breeders, some other populations in northwestern Europe, and feral flocks are largely resident. This species is one of the last to migrate, and the "lag" portion of its name is said to derive from this lagging behind other geese.
Source: en.wikipedia.org/wiki/Greylag_Goose - 02.10.2008
How stressful and heady the yearly tour of the Greylag Geese in the south and back must be – especially when they want to stay together as a couple and as a family, too.