Włodzimierz Meissner
Ornis Polonica 2010, 51: 21-29
https://doi.org/10.12657/ornis.2010.1.2
Abstract: The paper provides an analysis of the biometric traits of the Coots caught in 1990–2009 in northern Poland. No significant differences have been found between the first-year individuals and adults with respect to the mean length of the head with the bill, of the bill, wind or tarsus with a toe. Juveniles were lighter than the adult birds examined. They also had a smaller frontal shield. Both in the young and adult individuals, the body mass was gradually declining from autumn to spring. Before the spring migration, no increase in the weight was noted, which may have been caused by a high (93%) proportion in the sample of birds caught at the same place (Sopot). This suggests that at this particular site there were birds which did not undertake long routes. The length of the frontal shield underwent seasonal changes. In adult individuals, its length and breadth were observed to be decreasing from autumn to winter, whereas in spring the frontal shield was found enlarging both in adult and juvenile birds. The mean nail length in the Coots from Sopot and Nowogard was significantly higher than in the individuals caught on the river near the village of Swornegacie. This difference stemmed from the fact that the birds in Sopot and Nowogard were intensely fed by people, and, staying on sandy (Sopot) or concrete-asphalt (Nowogard) substratum, they wore their nails down. This indicates low usefulness of this particular measurement for biometric analyses.
