Demography of Ficedula hypoleuca (Passeriformes, Muscicapidae) in southern part of its range

摘要

Demography of the pied flycatcher (Ficedula hypoleuca) was studied in southern Karelia in 1979-1996. The age structure of this population did not differ from that in other parts of the range. Mortality was 47% in adults and 80% in young birds. The average expected duration of life is 1.6 years. There is no selection of partners by age. 9% of the birds kept the former partner during two seasons. Bigamy is registered in 5.8% of males (from 2 to 17% in a year). The hypothesis of the best genetic qualities of bigamous males is denied, Two-year-old females lay their eggs earlier and have greater clutches than one-year-old ones. Pairs with two-year-old males start reproduction earlier than one,,; with one-year-old males. Despite the birds of different age have no gain in the numbers of fledglings. In Karelia age differences in reproduction are displayed only in seasons with early warm springs, The equation of regression describing with sufficient accuracy (p = 0.01) the dynamics of bird numbers in the controlled area (y): y = 1.18x_1 , O.09x_2, where x_i - number of coming back males (%), x_2 - maximum numbers in autumn of the previous sea.son. Significant annual fluctuations in the population numbers are mainly related to the level of bird mortality beyond the reproduction period.