Factors affecting the breeding success of the grey heron ( Ardea cinerea)in northern Poland

The aim of this study was to estimate the importance of factors a.ecting the breeding success of the grey heron (Ardea cinerea) in three colonies in the northern Poland (Mosty and Ryback), differentiated in population size, habitat type and feeding areas used by birds. The highest mean number of fledglings (39-51 days old) per nest in 2000-2002 combined was recorded at Katy Rybackie (3.2