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Appendix 2 . In n. Europe, male significantly (1.04–1.09 times) larger than female for all measurements (Ingolfsson 1969a). Within populations, sex of individuals determined by body measure-ments; sex of 96% of individuals determined solely by bill measurements (Harris 1964b). No discrimin-ant function for determining sex of Great Black-backed Gulls in North America (P. Cavanagh pers. comm.).