Affiliation: | Culterty Field Station, Department of Zoology, University of Aberdeen, Newburgh, Grampian, AB41 OAA, UK;Sea Mammal Research Unit, c/o B.A.S., High Cross, Madingley Road, Cambridge, CB3 OET, UK;Department of Biology, University of Waterloo, Waterloo, Ontario, Canada, N2L 3GI |