Causes of the redistribution of Pink-footed Geese Anser brachyrhynchus in Britain

The numbers of Pink-footed Geese Anser brachyrhynchus wintering in Britain have been increasing exponentially since the 1950s. The numbers of geese at virtually all roost sites have increased, but the most dramatic increase has been in Norfolk, the southernmost region occupied in Britain. This redistribution was most likely caused either by the increase in the population forcing greater numbers of geese towards more southerly sites as the result of a buffer effect, by a decrease in the quality of sites elsewhere in the range or by an increase in the attractiveness of Norfolk. Co-ordinated counts of geese around Britain and historical data of changes in agricultural practice in Norfolk were used to examine these possibilities. No evidence was found for buffer effects, degradation of sites elsewhere or an increase in food availability in Norfolk. The major difference between Norfolk and other Pink-footed Goose sites is in the food type available in Norfolk, namely harvested Sugar Beet Beta vulgaris remains. This food is of high quality and the geese are not disturbed whilst feeding on it because of its limited commercial value. The pattern of redistribution of Pink-footed Geese may therefore be the result of cultural learning of the benefits of feeding on Sugar Beet.