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. 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. One theory on the etymology of the name (American Heritage Dictionary) is that "-lag" derives from this "lagging behind", although the Oxford English Dictionary analyses "-lag" as a dialectical word for "goose", of unknown origin. In Great Britain their numbers have declined as a breeding bird, retreating north to breed wild only in the Outer Hebrides and the northern mainland of Scotland. However during the 20th century, feral populations have been established elsewhere, and they have now re-colonised much of England. The breeding habitat is a variety of wetlands including marshes, lakes, and damp heather moors. In Norway, the number of greylag geese is estimated to have increased three- to fivefold during the last 15-20 years. As a consequence, farmers' problems caused by goose grazing on farmland has increased considerably. This problem is also evident for the pink-footed goose. 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.