Adam Zbyryt
Ornis Polonica 2016, 57: 107–116
https://doi.org/10.12657/ornis.2016.2.1
Abstract: The distribution and numbers of the Grey Heron Ardea cinerea colonies were studied within Podlasie Province (20,187 km2). In 1980–2014 at least 31 heronries were recorded in the studied area, but in 2015 the presence of only 12 active heronries (39%) was confirmed. The average breeding density was 0.6 colony per 1000 km2. In total 455 pairs nested there, with the average density of 23 pairs per 1000 km2. The average colony contained 38 nests. Small (≤50 nests) and big (> 100 nests) heronries made up 75% and 17%, respectively. Grey Herons bred most frequently in small (mean area 2.2 ha) single-species (92%) forest patches with dominating pine (58%) and alder forests (17%) of 46 years on average. Colonies were located in the vicinity of rivers and oxbows (50%), lakes (33%) and ponds (17%), at an average distance of 1441 m from a nearest water body. The majority of colonies (83%) were situated close (< 200 m) to the buildings (mean distance 434 m). Grey Herons used 12 species of nesting trees and bushes, mainly Scots’ pines Pinus sylvestris (40%), willows Salix sp. (21%), and European elders Sambucus nigra (17%). The number of colonies and breeding pairs of the Grey Heron declined in the central and southern part of the area during the study period. This may have resulted from deliberate disturbance and excessive shooting.
Keywords: Ardea cinerea, breeding colony, colony size, Grey Heron, mixed colony, Podlasie
