Acta Zoologica Cracoviensia, 30() 1987
Correlation between height and site distribution of the nest holes occupied by Jackdaws Corvus monedula Linnaeus,1758, in Poland
Abstract:
The distribution of nests occupied by Jackdaws was analyzed in three colonies: a castle in Cracov, the old ruins of Kamieniec and the iron frame-work of a railway bridge in Wrocław, each of which provided man-made nest-holes of the same type at different altitudes. The nesting pairs preferred the holes above the minimum height of ca. 3.5 meters, selecting the upper holes (modal value 10-12 m) most frequently in two colonies. In Kamieniec, where the walls have large vertical extent up to 38 meters, the nest-sites in habited revealed more even distribution. The aggregations of nests in the two colonies are discussed on the basis of e. g. the total “compactness of colony” (measured by a special index Cj), of colonial interactions between birds and of connections to adjacent grassland areas.
