Numbers and Trends 1 Migratory Waterbirds in the Wadden Sea 1980 – 2000 Overview of Numbers and Trends of Migratory Waterbirds in the Wadden Sea 1980-2000 Recent Population Dynamics and Habitat Use of Barnacle Geese and Dark-Bellied Brent Geese in the Wadden Sea Curlews in the Wadden Sea - Effects of Shooting Protection in Denmark Shellfi sh-Eating Birds in the Wadden Sea - What can We Learn from Current Monitoring Programs? Wadden Sea Ecosystem No. 20 - 2005 2 Numbers and Trends Colophon Publisher Common Wadden Sea Secretariat (CWSS), Wilhelmshaven, Germany; Trilateral Monitoring and Assessment Group (TMAG); Joint Monitoring Group of Migratory Birds in the Wadden Sea (JMMB). Editors Jan Blew, Theenrade 2, D - 24326 Dersau; Peter Südbeck, Niedersächsischer Landesbetrieb für Wasserwirtschaft, Küsten- und Naturschutz (NLWKN), Direktion Naturschutz, Göttingerstr. 76, D - 30453 Hannover Language Support Ivan Hill Cover photos Martin Stock, Lieuwe Dijksen Drawings Niels Knudsen Lay-out Common Wadden Sea Secreatariat Print Druckerei Plakativ, Kirchhatten, +49(0)4482-97440 Paper Cyclus – 100% Recycling Paper Number of copies 1800 Published 2005 ISSN 0946-896X This publication should be cited as: Blew, J. and Südbeck, P. (Eds.) 2005. Migratory Waterbirds in the Wadden Sea 1980 – 2000. Wadden Sea Ecosystem No. 20. Common Wadden Sea Secretariat, Trilateral Monitoring and Assessment Group, Joint Monitoring Group of Migratory Birds in the Wadden Sea, Wilhelmshaven, Germany. Wadden Sea Ecosystem No. 20 - 2005 Numbers and Trends 3 Editorial Foreword We are very pleased to present the results of The present report entails four contributions. the twenty-year period 1980 - 2000 of the Joint In the fi rst and main one, the JMMB gives an Monitoring on Migratory Birds in the Wadden Sea overview of numbers and trends 1980 - 2000 for (JMMB), which is carried out in the framework of all 34 species of the JMMB-program. Regarding the Trilateral Monitoring and Assessment Program selected species respectively species groups - such (TMAG), in the 20th issue of the Wadden Sea as Barnacle Geese and Dark-bellied Brent Geese, Ecosystem series Curlews as well as shellfi sh-eating birds - specifi c This report succeeds the two reports on joint aspects related to habitat use, hunting and mussel activities in the fi eld of migratory bird monitor- and cockle fi shery are discussed in more detail by ing in 1992/93 (Rösner et al., 1994) as well as in different authors in the following three additional 1993/94 (Poot et al., 1996). In 1994, the evaluation contributions of the issue. of international Wadden Sea birds counts in the We would like to thank all those who con- period 1980 - 1991 was published by Meltofte et tributed with great effort to the surveys and the al., 1994. Besides these issues on results of migra- preparation of the report, mainly the numerous tory birds monitoring, a review on important and fi eld workers and their organizations, the national potential roosting sites in the Wadden Sea were coordinators of the JMMB-program as well as the published by the JMMB in 2003. The results of all authors of the report. Our particular thanks go to these reports and further recent data have been Jan Blew, the lead author, who took care of han- taken into account in the compilation of trends dling and analyzing the data as well as compiling in this report. and writing the report. Bettina Reineking Common Wadden Sea Secretariat September 2005 Wadden Sea Ecosystem No. 20 - 2005 4 Numbers and Trends Wadden Sea Ecosystem No. 20 - 2005 Numbers and Trends 5 Overview of Numbers and Trends of Migratory Waterbirds in the Wadden Sea 1980-2000 Blew, J., Günther, K., Laursen, K., van Roomen, M., Südbeck, P., Eskildsen, K., Potel, P. and Rösner, H.-U. _____________ page 7 Recent Population Dynamics and Habitat Use of Barnacle Geese and Dark-Bellied Brent Geese in the Wadden Sea Koffi jberg, K. and Günther, K. ___________________ page 149 Curlews in the Wadden Sea - Effects of Shooting Protection in Denmark Laursen, K. _____________________ page 171 Shellfi sh-Eating Birds in the Wadden Sea - What can We Learn from Current Monitoring Programs? Scheiffarth, G. and Frank, D. ____________________ page 185 Wadden Sea Ecosystem No. 20 - 2005 6 Numbers and Trends Wadden Sea Ecosystem No. 20 - 2005 Numbers and Trends 7 WADDEN SEA ECOSYSTEM No. 20 Overview of Numbers and Trends of Migratory Waterbirds in the Wadden Sea 1980 – 2000 Jan Blew Klaus Günther Karsten Laursen Marc van Roomen Peter Südbeck Kai Eskildsen Petra Potel Hans-Ulrich Rösner 2005 Common Wadden Sea Secretariat Trilateral Monitoring and Assessment Group Joint Monitoring Group of Migratory Birds in the Wadden Sea Wadden Sea Ecosystem No. 20 - 2005 8 Numbers and Trends Wadden Sea Ecosystem No. 20 - 2005 Numbers and Trends 9 Contents Acknowledgements _______________________________________ 11 Summaries ______________________________________________ 13 Summary ___________________________________________________________________13 Sammenfatning ______________________________________________________________14 Zusammenfassung ____________________________________________________________15 Samenvatting _______________________________________________________________17 1. Introduction __________________________________________19 2. Data and Methods _____________________________________20 2.1 Implementation of the JMMB Program ________________________________________ 20 2.2 Area and site selection ____________________________________________________ 21 2.3 Species selection _________________________________________________________24 2.4 Fieldwork _______________________________________________________________24 2.5 Classifi cation of winters ___________________________________________________ 25 2.6 Data exchange, data processing and trend analyses ______________________________ 26 2.6.1 Data exchange _____________________________________________________26 2.6.2 TRIM – its potential and limitations _____________________________________ 26 2.6.3 Phenologies ________________________________________________________27 2.6.4 Trend analysis ______________________________________________________27 2.6.5 Trend categories ____________________________________________________29 2.7 Presentation of data ______________________________________________________30 2.7.1 Presentation of data in fi gures and tables _________________________________ 30 2.7.2 Presentation of data: Rules and conventions _______________________________30 3. Quality of Data _______________________________________ 32 3.1 Coverage of main staging areas through site selection ____________________________ 32 3.2 Counting coverage ________________________________________________________ 32 3.2.1 Synchronous counts in January _________________________________________ 32 3.2.2 Synchronous counts in months other than January __________________________32 3.2.3 Spring tide counts ___________________________________________________ 33 3.2.4 Special counts of target species ________________________________________ 34 4. Species Accounts ______________________________________35 4.1 Great Cormorant _________________________________________________________ 37 4.2 Eurasian Spoonbill ________________________________________________________39 4.3 Barnacle Goose __________________________________________________________40 4.4 Dark-bellied Brent Goose ___________________________________________________ 42 4.5 Common Shelduck ________________________________________________________44 4.6 Eurasian Wigeon _________________________________________________________46 4.7 Common Teal ____________________________________________________________48 4.8 Mallard ________________________________________________________________50 4.9 Northern Pintail __________________________________________________________ 52 4.10 Northern Shoveler ________________________________________________________54 4.11 Common Eider ___________________________________________________________56 4.12 Eurasian Oystercatcher ____________________________________________________58 4.13 Pied Avocet _____________________________________________________________60 4.14 Great Ringed Plover _______________________________________________________ 62 4.15 Kentish Plover ___________________________________________________________ 64 4.16 Eurasian Golden Plover ____________________________________________________ 66 4.17 Grey Plover _____________________________________________________________ 68 4.18 Northern Lapwing ________________________________________________________ 70 4.19 Red Knot _______________________________________________________________ 72 4.20 Sanderling ______________________________________________________________ 74 4.21 Curlew Sandpiper ________________________________________________________ 76 Wadden Sea Ecosystem No. 20 - 2005 Numbers and Trends 10 4.22 Dunlin _________________________________________________________________ 78 4.23 Ruff ___________________________________________________________________ 80 4.24 Bar-taild Godwit _________________________________________________________ 82 4.25 Whimbrel _______________________________________________________________84 4.26 Eurasian Curlew __________________________________________________________86 4.27 Spotted Redshank ________________________________________________________ 88 4.28 Common Redshank _______________________________________________________ 90 4.29 Common Greenshank ______________________________________________________92 4.30 Ruddy Turnstone _________________________________________________________