Leuzinger, H. & S. Schuster
Zur nachbrutzeitlichen Bestandsentwicklung der Moorente Aythya nyroca im Seebachtal und in der ganzen Schweiz.
(von 1994 bis 2006 vergeben)
Bestandesentwicklung, Phänologie, Wasservogelzählungen, Kleingefiedermauser, Flügelmauser
Schweiz, Bodensee, Untersee, Thurgau, Seebachtal, Nussbaumersee, Hüttwilersee, Hasensee, Genfersee
Population trend of the Ferruginous Duck Aythya nyroca in the Seebach valley (canton of Thurgau) and in the whole of Switzerland outside the breeding season. Since 2004/05, the Ferruginous Duck Aythya nyroca has been observed regularly on the three small lakes in the Seebach valley (Nussbaumer-, Hüttwilerand Hasensee). The maximum numbers are reached between mid-September and the end of October. In autumn 2009, Ferruginous Ducks were particularly numerous; the maximum value was 54 individuals, the so far highest concentration of the Ferruginous Duck in Switzerland. Since 2002, the number of observations in the whole of Switzerland increased continuously as well. As the waterbird counts of mid-November and mid-January indicate, this development is caused by the increase mainly on Lake Geneva and the adjacent sector of the river Rhone further downstream, and to a lesser extent on Lake Constance. A population of Ferruginous Ducks has been using the lakes and ponds in the western part of Lake Constance and in the Seebach valley, only 22 km apart, since almost 20 years during body-feather moult. Since a few years, up to 20 males have been gathering in July and August in the western part of Lake Constance for the preceding flight-feather moult.
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