Journal of the Yamashina Institute for Ornithology
Online ISSN : 1882-0999
Print ISSN : 1348-5032
ISSN-L : 1348-5032
Original Article
Bigamous Trios in the Black-winged Stilt Himantopus himantopus himantopus: I. Pathways to form Bigamous Trios
Tamaki Kitagawa
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2009 Volume 40 Issue 2 Pages 73-82


Six cases of bigamous trios in the Black-winged Stilt Himantopus himantopus himantopus were studied during 1997-2006. One cause for the occurrence of bigamous trios is that postbreeding groups composed of a parent and a female offspring of the previous year, or that of a family and an unrelated female, have not dissolved by the next breeding season. Under conditions of a female-biased sex ratio in the non-breeding season, some females may chose bigamous trios as one of three mating options. In one trio, one female left the trio just before egg-laying, after they began to defend the nesting territory. Two bigamous trios made a joint nest, respectively. One bigamous trio made two simultaneous nests. One bigamous trio made a joint nest in one year and two simultaneous nests the following year. One bigamous trio made three nests successively.

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© 2009 Yamashina Institute for Ornitology
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