Abstract
The mating system of Cinclidae is basically monogamous, although polygyny occasionally occurs. However, there is no record of polygyny in the Brown Dipper (Cinclus pallasii). In this study, polygynous behavior of male Brown Dippers was observed during the mating season. The breeding home range of Brown Dippers was studied from December 2005 to March 2006 in Takano River, Kyoto Prefecture, central Honshu, Japan. Four dippers were caught and marked with colored plastic bands for field identification. The home ranges were determined by following these individuals, and the areas of the home ranges used were determined by the time-mapping method. During the mating season, one male mated with two females and established a polygynous home range. The male finally bred monogamously as a result of another male invading a part of his home range; however, this observation indicates the possibility of polygyny in the Brown Dipper.
