Schmid, H., M. Burkhardt, V. Keller, P. Knaus, B. Volet & N. Zbinden (2001)

    Die Entwicklung der Vogelwelt in der Schweiz/L'évolution de l'avifaune en Suisse.

    Further information

    Avifauna Report Sempach 1, Annex. 444 S.





    Bird communities are not static. The numbers of individuals in a population can vary greatly from year to year, due to factors such as meteorological conditions during the breeding season or in the wintering quarters. Long-term changes become apparent only if populations are monitored closely and continuously. Only then can a monitoring programme fulfil its role as an early-warning system providing the basic information necessary for conservation. Monitoring bird populations is one of the core activities of the Swiss Ornithological Institute in Sempach. Over the years a large volume of data has accumulated allowing trends in bird populations to be analysed. The present documentation puts the emphasis on population trends in time and adds to the Breeding bird atlas (Schmid et al.1998) and the Avifauna (Winkler 1999a). It allows to show trends for a wide number of species, but also to identify the gaps in our knowledge.
    Several monitoring programmes have been running for different groups of species. They are described in the first part of the book. Observations of rare and scarce breeding birds and visitors are collected in the database of the "information service". Since 1984 these observations have been recorded following a set of rules rather than being purely accidental. The "five-day-period programme" (Pentadenprogramm) and the "breeding bird programme" (Brutvogelprogramm) have been developed to take variations in observer effort into account. While the first is particularly suited to present the phenology of occurrence through-out the year, the second allows to identify trends in number of sites occupied by breeding birds. The "monitoring programme for common breeding birds" (Monitoring Häufige Brutvögel) has only been running since 1999. No results have therefore been included in this volume. However, results are presented from several smaller programmes such as "breeding birds in wetlands" (Monitoring Feuchtgebiete), "annual breeding bird reports" (Jahresübersichten), "continuous survey plots" (Dauerbeobachtungsflächen) or special projects for particular species. Results are also presented for the waterbird census (Wasservogelzählungen) in winter.
    The main part of the book consists of about 270 species accounts. The amount of data available differs greatly between species. Overall, waterbirds are the best documented group. In winter, they occur on the Swiss lakes and rivers in large concentrations. Since the start of the census in 1967, numbers of most species have increased significantly. Over the last decade, however, a stabilisation or decline have been observed for several species. Trends of breeding birds are, in general, not well documented. Good data sets exist for some raptor species. They indicate mostly stable or increasing populations. On the other hand, a marked decline has been observed for many farmland species and for species sensitive to disturbance or to changes in particular habitat requirements.
    Key words: Monitoring, population trends, Switzerland.