New data on breeding ecology and mating system in the black-browed reed warbler Acrocephalus bistrigiceps in Primorsky krai

A local population of the black-browed reed warbler Acrocephalus bistrigiceps was studied in 2004-2005 in Gajvoron settlement (44º44΄N, 132º46΄E). Breeding schedule, habitat distribution of nests and breeding success are briefly described in this paper. Apart of monogamy and regular occurrence of polygyny in the Black-browed Reed Warbler, cases of polyandry and polygamy are reviled in this species which are yet undescribed forms of mating systems in this species. Despite of this fact, monogamy remains the predominant breeding systems in this population of black-browed reed warbler. Principal causes of the low level of polygyny in the study area are (1) occurrence of reproductive losses mostly during first nesting attempts and, as consequence, compensatory nesting of the same pairs, and (2) a tendency of equal input of mates into parental care. It seems that monogamous breeding is responsible for rather high (about 46%) and stable breeding success in this local population.