KROON GHJD (1972) The occurrence of the Waterrail Rallus aquaticus during the winter. LIMOSA 45 (1): 42-48.

Waterrails occur regularly during the winter-period in the fresh water tide-area. A greater number of the birds were observed during a period of freezing weather than in a period of thaw. The varying water-levels together with the temperature appear to influence the possibilities of observing the Waterrail. Partly on account of the camouflaging vegetation and the food, partly because the Waterrail, being a specific bottom and shorebird, avoids a redundance of water caused by flood and moves to floating isles of weeds and to the slope or the foot of a dyke. The birds follow the sinking water and go before the rising tide. During a frost-period the Waterrails do not spread much, consequently the concentration and the agression increase. The density of population was greatest in winter and migration took place from the investigated fresh water tide-area in springtime. About possible hibernation of our own summerbirds or other populations in the investigated area nothing can be said with certainty, because no Waterrails were caught and marked Water Rail Rallus aquaticus

[free pdf] [dutch summary]