Habitat choice in pink-footed geese: quantifying the constraints determining winter site use.
Abstract
Over 85% of the world population of pink-footed geese (Anser brachyrhynchus) winter in Britain and throughout their winter range they use crops vulnerable to damage from grazing. The number of geese that a wintering area can support depends on the amount of food in that area and the restrictions limiting their use of this food source. Such restrictions may include travel distance from the roost site, selection of sites within the feeding range and the extent to which these sites are exploited. The geese roosting at Scolt Head Island, north Norfolk were studied from 1990 to 1993. Study fields predominantly contained three crop types: the stubble remains of harvested cereal fields, sugarbeet and winter-sown cereals. For most of the winter the geese fed predominantly upon the harvested remains of sugar beet, a crop which only occurred on between 8 and 13% of fields. Beet fields closest to the roost site were used first and the geese fed further from the roost as the beet remains in these fields was depleted. Small fields were avoided by the geese. Fields closer to roads were used significantly less. The harvested remains of sugarbeet are of virtually no commercial value in this area. However, the geese also use winter cereals on which they are regarded as pests. By minimizing disturbance of geese on sugarbeet, farmers could potentially increase the amount of time geese spend on beet by up to 80%. The total area of beet remains could be increased by reducing winter sowing of cereals; this would be especially effective on fields close to the roost site. These measures together are likely to reduce significantly the exploitation of vulnerable cereal fields by geese.