Monitoring wintering waterbirds

Since 1967 waterbirds are counted throughout Europe and in adjacent regions. This international waterbird census is coordinated by Wetlands International. The waterbird census is an important tool to estimate population size and trends of birds and to identify important wintering sites.


  1. Monitoring population trends and distribution of wintering populations of waterbirds.
  2. Identification of sites of international and national importance for waterbirds.
  3. Monitoring waterbird populations in waterbird reserves of international and national importance listed in the federal inventory.
  4. Compiling basic information for the conservation of wintering waterbirds in Switzerland, in particular in the framework of the federal hunting legislation.


Volunteer collaborators of the Swiss Ornithological Institute count all waterbirds every year in mid-November and mid-January. All the major waterbodies and a number of smaller lakes and rivers in Switzerland are covered. In the waterbird reserves of international importance monthly counts are carried out in collaboration with regional organisations. Data are stored in a national database and forwarded to Wetlands International for incorporation in the database of the International Waterbird Census. Results are published in annual reports.


Based on the waterbird counts, the Swiss Ornithological Institute has compiled inventories of waterbird sites of international and national importance. These inventories served as the basis for the waterbird reserves established by the federal authorities.


The most recent annual report (in German and French) can be found here. Previous reports are listed under publications.

Volume 6 of the series «Avifauna Report Sempach» gives an overview on the history of the census, population trends and the importance of Switzerland and the main lakes and rivers for waterbirds outside the breeding season. The report is available in German and French.

In addition, detailed results can be downloaded via the following Excel files:

Project management

Nicolas Auchli


The Federal Office for the Environment FOEN supports the monitoring programme.
Wetlands International


Pavón-Jordán, D., P. Clausen, M. Dagys, K. Devos, V. Encarnaçao, A. D. Fox, R. Frost, C. Gaudard, M. Hornman, V. Keller, T. Langendoen, L. Lawicki, L. J. Lewis, S.-H. Lorentsen, L. Luigujoe, W. Meissner, B. Molina, P. Musil, Z. Musilova, L. Nilson, J.-Y. Paquet, J. Ridzon, A. Stipniece, N. Teufelbauer, J. Wahl, M. Zenatello & A. Lehikoinen (2019):
Habitat- and species-mediated short- and long-term distributional changes in waterbird abundance linked to variation in European winter weather.
Fox, A. D., A. Caizergues, M. V. Banik, K. Devos, M. Dvorak, M. Ellermaa, B. Folliot, A. J. Green, C. Grüneberg, M Guillemain, A. Haland, M. Hornman, V. Keller, A. I. Koshelev, V. A. Kostiushyn, A. Kozulin, L. Lawicki, L. Luigujõe, C. Müller, P. Musil, Z. Musilova, L. Nilsson, A. Mischenko, H. Pöysä, M. Sciban, J. Sjenicic, A. Stipniece, S. Svazas & J. Wahl (2016):
Recent changes in the abundance of Common Pochard Aythya ferina breeding in Europe.
Fox, A.D., L. Dalby, T.K. Christensen, S. Nagy, T.J.S. Balsby, O. Crowe, P. Clausen, B. Deceuninck, K. Devos, C.A. Holt, M. Hornman, V. Keller, T. Langendoen, A. Lehikoinen, S-H. Lorentsen, B. Molina, L. Nilsson, A. Stipniece, J-C. Svenning & J. Wahl (2016):
Seeking explanations for recent changes in abundance of wintering Eurasian Wigeon (Anas penelope) in northwest Europe