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Biber, O., M. Moritzi & R. Spaar (2003)

Der Weissstorch Ciconia ciconia in der Schweiz - Bestandsentwicklung, Altersaufbau und Bruterfolg im 20. Jahrhundert.

Further information

Ornithol. Beob. 100: 17–32

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reto.spaar@vogelwarte.ch

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Abstract

The White Stork Ciconia ciconia in Switzerland - population trend, demography and breeding success in the 20th centruy. - Throughout central Europe, populations of the White Stork have decreased heavily during the 20th century, in Switzerland earlier than in other countries. Following its extinction in 1950, the White Stork was reintroduced to Switzerland. By 1989, the breeding population exceeded the size it had in 1900 and has now levelled off at around 180 pairs. Despite an intensive care, i.e. supplementary feeding during the breeding season, average breeding success is relatively low ( 1.7 young per pair, 1969 -1998) compared to the original wild population and to populations in other countries. The overall mean breeding success did not differ between pairs with and without access to supplementary food in immediate vicinity of nest site, respectively. The proportion of unsuccessful broods in Switzerland (41 %) is considerably higher compared to reported values of other regions (15-25 %). The average age of first breeding (3.1 years) is low compared to other countries; it is possibly the result of shorter migration distances. At the end of the 1990s, the wild population of White Storks in Switzerland shows clear signs of ageing of the population, mainly caused by a generally low breeding success and a low recruitment rate of young into the breeding population. This will probably lead to a negative population trend in the following years. Conservation measures should focus on the improvement of habitat quality to increase breeding success and on the reduction of the mortality during migration and in the winter quarters to increase recruitment rates.