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1 December 2011 Sex Ratio and Survival of Mandarin Ducks in the Tachia River of Central Taiwan
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Sound management of the Mandarin Duck (Aix galericulata) requires an understanding of its survival and cause-specific mortality, yet these parameters have not been studied in Taiwan. From January 1999 to December 2002, a study was conducted along the Tachia River, in central Taiwan, where the largest population of Mandarin ducks resides. The sex ratio was male-biased for adults (average 2.10:1) but not for juveniles (average 0.92:1). Ducks (34 males and 42 females) were radio-tagged and monitored two to three times per month for 1–47 months. Annual survivorship was 0.80 and 0.44 for male and female ducks, respectively; lower female survival may lead to a male-biased sex ratio. Forty-three ducks died, the greatest proportion from unknown causes, followed by avian predators, mammalian predators and anthropogenic activity. Mortality occurred year-round, but female mortality was greatest from spring to fall, 9–10 carcasses, while male mortality (seven) was greatest in the winter.

Yuan-Hsun Sun, Cara Lin Bridgman, Hsing-Lu Wu, Ching-Feng Lee, Mark Liu, Po-Jen Chiang, and Chao-Chieh Chen "Sex Ratio and Survival of Mandarin Ducks in the Tachia River of Central Taiwan," Waterbirds 34(4), 509-513, (1 December 2011).
Received: 20 May 2011; Accepted: 1 September 2011; Published: 1 December 2011

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