BTO Research Report No. 486 Photo: © Rob Martin The Effects of Climate Change on Migratory Waterbirds within the African-Eurasian Flyway Authors Ilya M.D. Maclean1, Mark M. Rehfisch1, Simon Delany2 & Robert A. Robinson1 October 2007 1 British Trust for Ornithology, The Nunnery, Thetford, Norfolk IP24 2PU 2 Wetlands International, PO Box 471, 6700 AL Wageningen, The Netherlands Report of work carried out by The British Trust for Ornithology under contract to the AEWA Secretariat British Trust for Ornithology Registered Charity No. 216652 1 CONTENTS CONTENTS........................................................................................................................................2 List of Tables.......................................................................................................................................4 List of Figures .....................................................................................................................................4 List of Appendices ..............................................................................................................................5 EXECUTIVE SUMMARY.................................................................................................................7 1. INTRODUCTION....................................................................................................................11 2. CLIMATE CHANGE WITHIN THE AEWA AGREEMENT AREA ....................................13 2.1. Temperature change.........................................................................................................13 2.1.1. Global......................................................................................................................13 2.1.2. Africa.......................................................................................................................14 2.1.3. Europe and the eastern Nearctic..............................................................................15 2.1.4. Middle East and Asia Minor ...................................................................................15 2.2. Rainfall change and drought ............................................................................................16 2.2.1 Global......................................................................................................................16 2.2.2. Africa.......................................................................................................................16 2.2.3. Europe and the north-eastern Nearctic ....................................................................17 2.2.4. Middle East and Asia Minor ...................................................................................17 2.3. Global changes in wind patterns ......................................................................................17 2.4. Global large-scale climate circulation patterns................................................................18 2.5. Sea-level rise....................................................................................................................18 3. CURRENT EFFECT OF CLIMATE CHANGE ON WATERBIRDS ....................................21 3.1. Changes in range and distribution....................................................................................21 3.1.1. Changes in breeding range ......................................................................................21 3.1.2. Changes in wintering range.....................................................................................22 3.1.3. Changes in migratory routes ...................................................................................24 3.2. Timing of biological events .............................................................................................26 3.2.1. Timing of migration ................................................................................................26 3.2.2. Timing of breeding..................................................................................................26 3.2.3. Mechanisms, evolutionary traps and constraints.....................................................27 3.3. Changes in demography...................................................................................................28 3.3.1. Survival ...................................................................................................................28 3.3.2. Productivity.............................................................................................................30 3.3.3. Population impacts ..................................................................................................31 3.4. Effects of changing rainfall patterns ................................................................................32 3.4.1. The Sahel region and crucial stop-over sites...........................................................33 3.5. Effects of sea-level rise....................................................................................................33 3.6. Wind, Storms and Hurricanes ..........................................................................................35 3.7. Indirect impacts of climate change ..................................................................................35 3.7.1. Climate change and land-use change ......................................................................35 3.7.2. Climate change and water-use change ....................................................................35 3.7.3. Climate change and flood-defences ........................................................................36 3.7.4. Climate change and tourism and recreation ............................................................36 4. FUTURE EFFECTS OF CLIMATE CHANGE ON WATERBIRDS.....................................37 4.1. A framework for modelling future changes: approaches and limitations ........................37 4.1.1. Extrapolation...........................................................................................................37 4.1.2. Experiments.............................................................................................................37 4.1.3. Phenomenological models.......................................................................................37 4.1.4. Behaviour-based models .........................................................................................38 4.1.5. Expert opinion.........................................................................................................38 4.1.6. Outcome-driven models ..........................................................................................38 4.1.7. Scenarios .................................................................................................................39 4.2. Future distribution and range changes .............................................................................39 4.3. Future changes in timing of biological events .................................................................41 4.4. Future changes in predation and parasitism.....................................................................42 2 4.5. Future changes in demography ........................................................................................42 4.6. Future effects of changing rainfall patterns .....................................................................43 4.7. Future effects of sea-level rise .........................................................................................43 4.8. Future indirect impacts of climate change .......................................................................45 4.7.1. Future climate change and land-use change............................................................45 4.7.2. Future climate change and water-use change..........................................................45 4.7.3. Future climate change and flood-defences..............................................................46 4.7.4. Future climate change and recreational disturbance ...............................................46 5. POSSIBLE MEANS OF ADAPTING TO CLIMATE CHANGE...........................................49 5.1. Site management..............................................................................................................49 5.2. Protected area networks ...................................................................................................49 5.3. Management of the wider countryside.............................................................................50 5.4. Minimising other impacts ................................................................................................50 6. SPECIES ESPECIALLY VULNERABLE TO CLIMATE CHANGE....................................53 6.1. Criteria used to assess vulnerability.................................................................................53 6.1.1. Population size ........................................................................................................53 6.1.2. Range score .............................................................................................................54 6.1.3. Fragmentation score ................................................................................................54 6.1.4. Habitat score............................................................................................................55 6.1.5. Food score ...............................................................................................................55