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Great Black-backed Gull
Larus marinus
– Family
Authors: Good, Thomas P.

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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.).


Appendix 3 . Male heavier than female. Male’s mean body mass decreases from 1,835 g in May to 1,750 g in Jun (range 1,380–2,272 g, n = 116); female’s from 1,514 g in May to 1,449 g in Jun (range 1,033–2,085 g, n = 93; Belopol’skii 1961).