The use of the Solway Firth,Britain, by barnacle geese Branta leucopsis Bechst. in relation to refuge establishment and increases in numbers

This paper analyses data on movements and distribution of barnacle geese Branta leucopsis over a period of 15 years to examine the influence of the enlargement of a disturbance-free refuge at Caerlaverock on the Solway Firth on the numbers, distribution and feeding habits of the geese. The Solway barnacle geese form the whole of the discrete population breeding in the Svalbard (Spitsbergen) archipelago.The use of the refuge by geese increased markedly following its establishment, and a high proportion of the birds were accomodated there, especially in early winter. As the population increased, however, (from 3200 in 1970 to 10 500 in 1984), the geese dispersed in greater numbers to other habitats within the Caerlaverock area and elsewhere on the Solway. The creation of the new refuge has been, as was the declaration of the National Nature Reserve in 1957, responsible for the increase in numbers through reducing annual mortality rate, much of which was due to illegal shooting.The most significant change in distribution was the increase in the use of arable grassland in spring and this was attributed to the semi-natural saltmarsh at Rockcliffe, the traditional spring haunt, reaching capacity. The use of stubble grain also increased, but its availability is sporadic due to variation in late summer weather.The creation and management of the refuge achieved the objectives of redistributing the geese and allowing numbers to increase. It was also, at least partly, responsible for bringing about changes in feeding habits. This analysis has demonstrated that if the impacts of refuge establishment are to be fully understood, studies must be detailed and must include areas outside the refuge itself and its immediate environs.Detailed concurrent investigations on the dynamics of this population indicate that the slowing down of growth in numbers is due to some limitation on the breeding grounds. Continued monitoring and sensitive management over the whole of the winter range are essential not only to ensure the well-being of the population but also to minimise the conflict between the geese and farmers. Detailed investigations of possible changes in the saltmarsh habitat are also urgently needed.