Roost selection by Pink-footed Anser brachyrhynchus and Greylag A. anser Geese in East Central Scotland

Abstract

The choice of winter roosts made by Pink-footed and Greylag Geese in Strathallan and Strathearn was examined over seven and three winters respectively. In Strathallan both species roosted on a central complex of three lochs. Pink-footed Geese also used another four permanent waters and four floodwater pools, while Greylag used another three permanent pools, three floodwater pools and three stretches of river. Three of the Pink-footed sites were not used by Greylag and four of the Greylag sites were not used by Pink-footed Geese. Use of the main roost by Pink-footed Geese showed little variation with season, occupancy being 89% in autumn, 90% in winter and 93% in spring (post-shooting season). Greylag showed a much lower occupancy which fell through the winter with 74%, 55% and 8% at the main roost complex in autumn, winter and spring respectively. In Strathearn almost all Pink-footed Geese occupied the main roost in autumn and winter but 20% of birds used two floodwater sites in spring. Occupancy of the main Greylag roost was again much lower falling from 83% in autumn to 24% in spring with geese using another eight permanent or floodwater pools not used by Pink-footed Geese. The main determinant of choice of roost was freedom from disturbance by people, and especially from shooting. All other factors such as exposure, shoreline vegetation, including trees and availability of shoreline grazing, seemed unimportant. The findings are discussed in relation to censusing these populations in a national context.