The size of breeding territory in an urban population of the Blackbird (Turdus merula) in Szczecin (NW Poland)

Abstrakti

The size and quality of breeding territory of Blackbird populations were studied in 1997-2000 in two parks of Szczecin (NW Poland). The Blackbird density as well as timing of territory occupation influenced the territory size. A significant reduction in territory size with increasing park and plot breeding birds density was recorded; moreover the territories acquired early in the season were larger than those took later on. The breeding success was found to depend mainly on female age and shrub coverage of the territory. Older females showed higher breeding success than younger ones; the success being lower in the preferred (pre-empted) territories with denser shrub coverage. The most likely explanation for distribution patterns observed in the Blackbird territories involves elements of both the ideal free and ideal despotic distributions.