1. G. S. Robertson () and D. Baines, Game and Wildlife Conservation Trust, Uplands Research, Barnard Castle, Co Durham, UK. Present address for GSR: Epidemiology Research Group, Room 138, Ashworth Laboratories, King's Buildings, Univ. of Edinburgh, EH9 3JT.
2. N. J. Aebischer, Game and Wildlife Conservation Trust, Burgate Manor, Fordingbridge, Hampshire, UK.