Nesting of the House MartinDelichon urbicain the City of Poznań (1976–1978 and 1982–1989)

Abstract

Observations of nesting populations of the House Martin were carried out on three study plots in the city of Poznań: a city centre area (599.0 ha) and two housing estates (567.1 ha and 125.6 ha), a total area of 1291.7 ha. Throughout the 1980s House Martin numbers increased continuously over the whole area, the greatest population density being 4.6 occupied nests per 10 ha. The number of breeding pairs in the city centre was stable, and the density there varied from 2.1 to 3.0 occupied nests per 10 ha. The highest density of occurrence was recorded in the new housing estates, where increases in the House Martin population were recorded. These was related to the construction of new buildings, which provided fresh nesting sites. The nests were built at heights from the first to the fifteenth storey. Over 96% of the nests in the housing estates were built in the corners of the window openings. In the entire study area the preferred nesting sites were on the southern (35.2%), northern (26.1%) and eastern (13.3%) sides of buildings. In the city centre the greatest number of nests had south-facing entrances, while in one of the other study plots, the entrances to most nests faced north. No more than 7% of the total number of martins' nests available in a given year were occupied by Passer domesticus.