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Titre :
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Local and Seasonal Variation in Sex-Ratios of Diving Ducks in South Sweden during the Non-Breeding Season
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Auteurs :
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Leif Nilsson
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Publisher :
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Ornis Scandinavica (Scandinavian Journal of Ornithology), 1(2)
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Type de document :
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Article
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Année de publication :
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1970
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Format :
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115-128
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Langues:
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Anglais
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Résumé :
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[The sex-ratio of diving ducks during the non-breeding season was studied in southernmost Sweden in 1959-69. Differences in sex-ratio between flocks of different sizes and between different parts of a locality were found in Aythya fuligula and Bucephala clangula. Seasonal variations in sex-ratio were found in all species. Autumn migration was initiated by males in A. fuligula and A. ferina, and by females and immature birds in B. clangula, Mergus merganser and M. albellus. In all these species males initiated spring migration and dominated over the females in most Swedish winter localities. In A. marila the percentage of males increased from autumn to spring, whereas the opposite was found in Clangula hyemalis.]
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En ligne :
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https://www.jstor.org/stable/3676029
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