Grzegorz Kaczorowski
Ornis Polonica 2016, 57: 264–273
https://doi.org/10.12657/ornis.2016.4.3
Abstract: In 2012–2014, spring migration dynamics, phenology and sex ratio of Pochard and Tufted Duck were studied at the fish ponds (127 ha of, 1 m average water depth) in the western part of Lesser Polish Upland (SE Poland). In total, 8 016 Pochards and 8 378 Tufted Ducks were recorded in during 150 surveys. Arrivals from wintering grounds for both species occurred at the same time: 25.02–11.03 in the Pochard and 1–10.03 in the Tufted Duck. Pochard migration peaked at the beginning of April (1–5.04) and in the second decade of April (11–15.04) in the Tufted Duck. The sex ratio was male-biased, both in the Pochard (75%) and Tufted Duck (62%). Males/drakes formed bachelor groups which accounted for 3.6% in Pochards and 2.6% in Tufted Ducks. Couples were observed more frequently in the Tufted Duck (15% of all individuals vs. 4% in the Pochard). The results clearly show the male-biased sex ratio spring and early summer, which is characteristic for populations returning from wintering quarters in Western and Southern Europe.
Keywords: bachelor groups, migration dynamics, Pochard, sex ratio, southeast Poland, Tufted Duck
