Wysocki D. (2004) Alternative mating strategies in the urban population of the European Blackbird Turdus merula in Szczecin (NW Poland). ARDEA 92 (1): 103-107

This paper is aimed at describing the frequencies of European Blackbird mating strategies observed in an urban population in Central Europe. The study was carried out in 1997-2003 in two Szczecin city parks: Park Z (21.9 ha) and Park K (16 ha). The birds' behaviour was observed by 1-3 persons every other day from dawn to mid-day (6-8 h day-1). In the 813 breeding events of 310 pairs observed over 7 years in Park Z, 4 cases of polygyny (the second female laid an egg), 5 attempts at polygyny (the second female built the nest only), 1 attempt at polyterritorial polygyny (the male defended two different territories and guarded two different females at the beginning of the breeding season), 3 cases of sequential polyandry, 1 case of sequential polygyny, and 2 cases of simultaneous polyandry were recorded. Moreover in 2003 the case of the sharing of one nest by two pairs of Blackbirds was found. Observations in Park K focused on a total of 418 breeding events of 127 pairs. A single case of polygyny and sequential polyandry was recorded. No increased breeding success was found among bigynists, while sequential polygyny did lead to a clearly higher breeding success. Causes underlying the diversity of mating strategies observed are discussed