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An indicator of the impact of climatic change on European bird populations Richard D. Gregory Stephen G. Willis Frédéric Jiguet Petr Voříšek Alena Klvaňová Arco van Strien Brian Huntley Yvonne C. Collingham Denis Couvet & Rhys E. Green Background Evidence is accumulating that climatic change has altered many biological phenomena across the globe, including the geographical ranges and abundance of plants and animals, and the timing of events in their lives such as growth, reproduction and migration Birds laying earlier - BTO Nest Record Scheme Leaf burst earlier in Europe Scientists and policy makers have called for the development of indicators of the impacts of climatic change on biodiversity based upon these phenomena Purpose of a climatic change indicator: To capture biological impacts, to describe how they are changing in an accessible way, & to raise awareness of the consequences of climatic warming for wildlife & for people In addition, to assist in setting targets for the reduction of impacts & help guide the implementation of mitigation & adaptation measures The indicator combines two independent strands of work: 1. Predictions from bioclimate envelope models (mid-end century 2070-2099) 2. Observed trends in European birds (1980-2005 derived from the PECBMS) The starting point is the EBCC’s Atlas and the climate envelope models fit to distribution data for European breeding birds Bird distributions mapped in late 1980s -- 50-km UTM squares -presence & absence of species Based on the bioclimatic envelope models for each bird species, Brian Huntley et al., have published the first ‘Climatic Atlas’ of its kind for any taxa The ‘Climatic Atlas’ uses 3 simple bioclimate variables to model European bird distributions: 1. ‘MTCO’ Mean temperature of the coldest month 2. ‘GDD5’ Annual temperature sum above 5 degrees C 3. ‘AET/PET’ Ratio of actual to potential evapo-transpiration The models provided a good fit to our data (area under the curve – AUC – of a receiver operating characteristic – ROC – plot; mean AUC of the 122 species = 0.967; lowest value = 0.907). Present simulated range ~1961-1990 Serin Serinus serinus Future ‘potential’ range under a modelled climatic change scenario: HadCM3 B2 for ~2070-2099 We have the PECBMS population trends e.g. European Wild Bird Indicator 2008 Population index (1980=100) 120 -14% CommonForest (28 species) 100 80 -15% All common (124 species) 60 -43% Common Farmland (33 species) 40 1980 1985 1990 1995 Year 2000 2005 European trends for 124 common bird species were available from the PECBMS 1000 10 1 1980 Jynx torquilla Troglodytes troglodytes Picus canus Prunella modularis Picus viridis DryocopusErithacus martius rubecula 100 Luscinia Dendrocopos majormegarhynchos Hippolais icterina Phoenicurus Dendrocopos minor phoenicurus Turdus merula Sylvia borin 1000 10 1985 Population index (1980=100) 100 Population index (1980=100) Population index (1980=100) 1000 Turdus philomelosSylvia atricapilla 100 Phylloscopus collybita 1990 1 1980 Turdus viscivorusPhylloscopus sibilatrix 1995 Year 10 1985 2000 1990 2005 1995 2000 Phylloscopus trochilus Regulus regulus 2005 Year Muscicapa striata Ficedula albicollis Ficedula hypoleuca 1 1980 1985 1990 1995 Year 2000 2005 We developed the indicator in two steps: First, we tested the performance of projections of change in the extent of species’ geographical range (termed ‘CLIM’, based upon climatic envelope models) as predictors of observed interspecific variation in population trends of European birds Testing the performance of envelope models is necessary to address concerns about their accuracy in predicting species’ responses to climatic change We expect a positive correlation between observed change in abundance and ‘CLIM’ Having found a robust relationship of this kind, our second step was to construct an indicator based upon the divergence in population trends between species expected to be positively and negatively affected by climatic change Step One The ‘CLIM’ value for a species is the loge of the ratio of the extent of the future potential range to that of the recent simulated range (CLIM >0 predicts range expansion, CLIM <0 predicts range contraction) We also looked at the influence of habitat choice, migratory behaviour & body mass (as a proxy for life history characteristics) in predicting bird trends Step One To test for sensitivity of the scenario projections we considered results from: • 3 General Circulation Models (GCM): HadCM3, Echam4 & GFDL • 2 Scenarios from the Special Report on Emissions Scenario (SRES): A2 & B2 • = 6 variants termed ‘CLIMHaA2’, ‘CLIMHaB2’, ‘CLIMEcA2’, ‘CLIMEcB2’, ‘CLIMGfA2’ and ‘CLIMGfB2’ • We also calculated the average of these 6 to create an ‘ensemble forecast’, termed ‘CLIMEns’ Population trends of 108 bird species in 20 European countries 1980 – 2005 correlated significantly with projected trend in climate suitability from the climate envelope models 0.1 Observed decrease Observed trend Observed increase 0 -0.1 -0.2 -0.03 -0.02 -0.01 0 0.01 0.02 CLIM value Retrodicted range decrease Retrodicted range increase 0.03 We found a highly significant +ve correlations between interspecific variation in recent population trends & the CLIM projections Standardised regression coefficient 0.5 0.4 0.3 0.2 0.1 0 -0.1 CST CLIMEns+ CLIMEns - CLIMEns CLIMGfB2 CLIMGfA2 CLIMEcB2 CLIMEcA2 CLIMHaB2 CLIMHaA2 Climatic Response Predictor ? Lots of assumptions. One is that the bioclimate variables have changed since 1980 in the direction of the GCMs for the longer-term predictions • We tested this by examining the relationship of CLIM & the recent trend in climate suitability based upon observed climate change 1980-2005 • We used the climate envelope models and the annual values of the bioclimate variables to calculate probability of occurrence in each year for each species • We then regressed these against year for each species and the slope of this line is what we call the ‘Climate Suitability Trend’ (CST) Encouragingly, we found: 1. A highly significant relationship between interspecific variation in CLIM and CST - So climate suitability for species is changing just as we’d predict 2. A marginally significant relationship between observed population trend and CST when controlling for confounding variables - So bird numbers are changing just as we’d predict over this period, but the link is quite weak Step Two Our second step was therefore to construct an indicator from the observed population trajectories of 122 bird species with data available for any part of the period 1980 – 2005 We divided these species into those for which the climatic envelope model projection indicated an increase in potential geographical range (CLIMEns+) and those with projected decreases in geographical range (CLIMEns-). Step Two For each of the two groups of species, we calculated a multispecies population index from population indices for individual species, with the weight of the contribution of each species to the index being being its absolute value of CLIMEns Extreme CLIM values for species (+ve or –ve) have greater influence on the line So birds predicted to be strongly affected by climate in our models strongly influence the direction of the index 110 105 (A) Weighted population trend of species predicted to gain range in response to climatic change (30 species) 95 90 85 80 75 70 65 60 1980 1985 1990 1995 2000 2005 Year 110 105 (B) Weighted population trend of species predicted to lose range in response to climatic change (92 species) 100 Weighted population index Multi-species population indices for both species groups declined in the early 1980s, but from the latter part of that decade onwards, CLIMEns+ (30 species) increased, whilst CLIMEns- index (92 species) continued to decline Weighted population index 100 95 90 85 80 75 70 65 60 1980 1985 1990 1995 Year 2000 2005 Step Two The impact of climatic changes (both +ve and -ve) on bird populations can then be summarised in a single indicator, the ‘Climatic Impact Indicator’ (CII) This is calculated in a given year as the ratio of the index for CLIMEns+ species to that for CLIMEns- species, and has 95% confidence limits obtained using a bootstrap method Index of climatic change impacts on bird populations The Climatic Impact Indicator (CII), reflecting the divergence of the indices for the two groups, declined slightly in the early 1980s, but has shown a roughly linear increase from then onwards 160 B 140 120 100 90 80 70 Index value Piecewise regression 60 50 1980 1985 1990 1995 2000 2005 We can present the CII in a more accessible fashion for a wider general audience Index of climatic impacts on bird populations 140 130 Increasing climatic impact on bird populations 120 110 100 90 80 70 60 1980 Decreasing climatic impact on bird populations 1985 1990 1995 Year 2000 2005 B 140 Note that the pattern in the CII closely resembles that of observed climatic change in Europe 120 100 90 80 70 Index value Piecewise regression 60 50 1980 1985 1990 1995 2000 2005 2 C Standardised climatic indices Index of climatic change impacts on bird populations 160 1 0 -1 GDD5 MTCO MTEMP Piecewise regression -2 -3 1980 1985 1990 1995 Year 2000 2005 But what does the CII show? • It shows conformity between observed population trends & projections of how each species’ population should respond to climatic warming • The CII increases when population trends go in the direction predicted by the models • The CII decreases when population trends go in the opposite direction predicted by the models Index of climate change impacts on bird populations We can also create the CII adjusting for the confounding effects of habitat, migratory behaviour & body mass on the trends – but it is basically unchanged 160 140 120 100 90 80 70 Adjusted index value Unadjusted index value 60 50 1980 1985 1990 1995 Year 2000 2005 Key messages 1. Climate change is having a detectable effect on common bird populations at a European scale, including evidence of negative as well as positive effects 2. The number of bird species whose populations are observed to be negatively impacted by climatic change is 3 times that of those positively affected in our sample 3. The Climatic Impact Indicator (CII) has increased strongly in the past 20 years, coinciding with a period of rapid warming 4. Potential links between changes in bird populations and ecosystem functioning are not well understood. It is suggested that increasing climatic effects might alter ecosystem functioning & resilience The novelty of the findings: • Shows a strong link between observed population change and forecast change in range extent in a large species assemblage (widespread/common European birds) • New observation that this link is apparently equally strong for species predicted to be negatively & positively impacted by climatic change • Application of these results into an index of biotic impact of climatic change, provides first time a robust, accessible indicator of a phenomenon of global concern So what does this mean for the birds? Potentially, at least, wide-scale changes in bird communities across Europe with: A few winners (?) ‘Top 10’ - Increasing birds projected to increase 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Sardinian Warbler Subalpine Warbler Bee-eater Cirl Bunting Cetti’s Warbler Hoopoe Golden Oriole Goldfinch Great Reed Warbler Collared Dove And many losers (?) ‘Bottom 10’ - Declining birds projected to decline 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Snipe Meadow Pipit Brambling Willow Tit Lapwing Thrush Nightingale Wood Warbler Nutcracker Northern Wheatear Lesser Spotted Woodpecker Special thanks to the PECBMS network Special thanks to the data providers and organisations responsible for national data collection and analysis: Adriaan Gmelig Meyling (Statistics Netherlands). Norbert Teufelbauer, Michael Dvorak, Christian Vansteenwegen, Anne Weiserbs, Jean-Paul Jacob, Anny Anselin, Karel Šťastný, Vladimír Bejček, Jiří Reif, Henning Heldbjerg, Michael Grell, Andres Kuresoo, Frederic Jiguet, Risto Väisänen, Martin Flade, Johannes Schwarz, Tibor Szép, Olivia Crowe, Lorenzo Fornasari, Ainars Aunins, Ruud P. B. Foppen, Magne Husby, Przemek Chylarecki, Geoff Hilton, Juan Carlos del Moral, Virginia Escandell, Ramón Martí, Åke Lindström, Hans Schmid, David G. Noble, Juha Tiainen, Romain Julliard, Ward Hagemeijer, David G. Noble, Norbert Schäffer, Nicola Crockford, Zoltan Waliczky, David Gibbons, Simon Wotton, Adrian Oates, Gregoire Loïs, Dominique Richard, Anne Teller, Jeremy Greenwood, Lucie Hošková, Václav Zámečník, Lukáš Viktora, Tomáš Telenský, & Zdeněk Vermouzek. Gregory R.D., Willis, S.G., Jiguet, F., Voříšek, P., Klvaňová, A., van Strien, A., Huntley, B Collingham, Y.C., Couvet, D. & Green, R.E. (2009). An indicator of the impact of climatic change on European bird populations. PLoS ONE 4(3): e4678. doi:10.1371/journal.pone.0004678 FREELY AVAILABLE AT: http://www.plosone.org/article/info:doi/10.1371/journal.pone.00046 78 Next steps • • • • • • Update CII with new trend data Repeat at national and regional scales Build non-breeding ranges for migrants Explore CII trend pattern and trends Explore new modelling approaches and climate/data Correlate projected range change with observed range change • We are looking for funding