Strategic placement of Rock Ptarmigan Lagopus muta nests adjacent to boulders

Capsule Rock Ptarmigan place their nests adjacent to boulders, in their lee and on their sunnier aspects. Aims To investigate the proximity and orientation of Rock Ptarmigan nests in relation to boulders and vegetation height. Methods The distances from boulders of 61 Rock Ptarmigan nests and 60 random points were compared. Orientation variables of nests from boulders were analysed with circular statistical formulae. Results Rock Ptarmigan nests were closer to boulders than random points. The mean orientation of nests relative to adjacent boulders was south-east and the prevailing wind was westerly. Vegetation height at nest sites was taller than at randomly selected sites. Conclusion Rock Ptarmigan which nest next to, in the lee of, and on the south-eastern aspects of boulders, probably gain advantages of protection from the prevailing wind and passive thermoregulation from solar heat.