Biometrical analysis of an urban population of the Blackbird (Turdus merula) in Szczecin in Poland

In years 1996-2001, a biometrical investigation of an urban population of the Blackbird was conducted in two parks of Szczecin. Altogether, 388 birds were measured, including 191 females and 197 males. Adult females were bigger than young females (in all analysed parameters). Among males there were differences in wing, tail and total head lengths. In both sexes the strongest correlation occurred between wing and tail measurements and between bill and total head lengths. The body mass of females did not depend on their age and was not changing significantly in the course of year. However, in the case of males the young birds were lighter than the adults. Moreover, the males caught in winter were heavier than those caught in spring.