Pokarm nurogęsi Mergus merganser L. żerujących zimą na Sanie pomiędzy Zwierzyniem a Leskiem (południowo-wschodnia Polska)

The food composition of goosander was determined based on the stomach contents of dead birds found along the San River between the localities of Zwierzyn and Lesko on February 12-14, 2012. The food composition of six birds was determined. The number of birds feeding in the study area was estimated to be between 0.7 to 11 individuals per 100 m of the river. The dominant prey of the goosander were brook trout (90.2% of the sample at a weight share of 80.7%), and European bullhead (70.2% of the sample at a weight share of 16.8%). The size of the trout identified ranged from 8 to 28 cm, while that of the bullhead was from 12 to 14 cm. The food biomass consumed by the birds during the period studied was determined to be 310 kg 24 h-1.