An indicator of the impact of climatic change on European bird populations

1. An indicator of the impact of climatic change on European bird populations

2. Richard D. Gregory Stephen G. WillisFrédéric Jiguet Petr VoříšekAlena KlvaňováArco van StrienBrian Huntley Yvonne C. Collingham Denis Couvet &Rhys E. Green

3. 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 Scientists and policy makers have called for the development of indicators of the impacts of climatic change on biodiversity based upon these phenomena Leaf burst earlier in Europe

4. 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 peopleIn addition, to assist in setting targets for the reduction of impacts & help guide the implementation of mitigation & adaptation measures Purpose of a climatic change indicator:

5. The indicator combines two independent strands of work: • Predictions from bioclimate envelope models (mid-end century 2070-2099) • Observed trends in European birds (1980-2005 derived from the PECBMS)

6. 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

7. 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

8. 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 • ‘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).

9. Present simulated range ~1961-1990 Serin Serinus serinus Future ‘potential’ range under a modelled climatic change scenario:HadCM3 B2 for ~2070-2099

10. We have the PECBMS population trends e.g. European Wild Bird Indicator 2008 -14% CommonForest (28 species) -15% All common (124 species) -43% Common Farmland (33 species)

11. European trends for 124 common bird species were available from the PECBMS

12. 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 birdsTesting the performance of envelope models is necessary to address concerns about their accuracy in predicting species’ responses to climatic change

13. 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 negativelyaffected by climatic change

14. 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

15. 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’

16. 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 Observed increase 0.1 0 Observed decrease Observed trend -0.1 -0.2 -0.03 -0.02 -0.01 0 0.01 0.02 0.03 CLIM value Retrodicted range increase Retrodicted range decrease

17. We found a highly significant +ve correlations between interspecific variation in recent population trends & the CLIM projections ?

18. 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)

19. Encouragingly, we found: • A highly significant relationship between interspecific variation in CLIM and CST - So climate suitability for species is changing just as we’d predict • 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

20. 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 – 2005We 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-).

21. Step Two For each of the two groups of species, we calculated a multi-species 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 CLIMEnsExtreme CLIM values for species (+ve or –ve) have greater influence on the lineSo birds predicted to be strongly affected by climate in our models strongly influence the direction of the index

22. 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

23. 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

24. 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

25. We can present the CII in a more accessible fashion for a wider general audience

26. Note that the pattern in the CII closely resembles that of observed climatic change in Europe

27. But what does the CII show? • It shows conformitybetween observed population trends & projections of how each species’ population shouldrespond 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

28. 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

29. Key messages • Climate change is having a detectable effect on common bird populations at a European scale, including evidence ofnegative as well as positive effects • 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 • The Climatic Impact Indicator (CII) hasincreased strongly in the past 20 years, coinciding with a period of rapid warming • Potential links between changes in bird populations and ecosystem functioning are not wellunderstood. It is suggested that increasing climatic effects might alter ecosystem functioning & resilience

30. 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

31. So what does this mean for the birds?Potentially, at least, wide-scale changes in bird communities across Europe with:

32. A few winners (?) ‘Top 10’ - Increasing birds projected to increase • Sardinian Warbler • Subalpine Warbler • Bee-eater • Cirl Bunting • Cetti’s Warbler • Hoopoe • Golden Oriole • Goldfinch • Great Reed Warbler • Collared Dove

33. And many losers (?) ‘Bottom 10’ - Declining birds projected to decline • Snipe • Meadow Pipit • Brambling • Willow Tit • Lapwing • Thrush Nightingale • Wood Warbler • Nutcracker • Northern Wheatear • Lesser Spotted Woodpecker

34. 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.

35. 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.0004678FREELY AVAILABLE AT:http://www.plosone.org/article/info:doi/10.1371/journal.pone.0004678

36. 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