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An indicator of the impact of climatic change on European bird populations.
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Transcript of An indicator of the impact of climatic change on European bird populations.
An indicator of the impact of climatic
change on European bird populations
Richard D. Gregory Stephen G. WillisFrédéric Jiguet
Petr VoříšekAlena Klvaňová Arco van StrienBrian Huntley
Yvonne C. Collingham
Denis Couvet &
Rhys E. Green
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
Background
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
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
Purpose of a climatic change indicator:
1. Predictions from bioclimate envelope models (mid-end century 2070-2099)
2. Observed trends in European birds (1980-2005 derived from the PECBMS)
The indicator combines two independent strands of work:
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-transpirationThe 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).
Serin Serinus serinus
Present simulated range
~1961-1990
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
40
60
80
100
120
1980 1985 1990 1995 2000 2005Year
Po
pu
latio
n in
de
x (1
98
0=
10
0)
-43% Common Farmland (33 species)
-15% All common (124 species)
-14% CommonForest (28 species)
European trends for 124 common bird species were available from the PECBMS
1
10
100
1000
1980 1985 1990 1995 2000 2005Year
Popu
latio
n in
dex
(198
0=10
0)
Jynx torquilla
Picus canus
Picus viridis
Dryocopus martius
Dendrocopos major
Dendrocopos minor
1
10
100
1000
1980 1985 1990 1995 2000 2005Year
Popu
latio
n in
dex
(198
0=10
0)
Troglodytes troglodytes
Prunella modularis
Erithacus rubecula
Luscinia megarhynchos
Phoenicurus phoenicurus
Turdus merula
Turdus philomelos
Turdus viscivorus
1
10
100
1000
1980 1985 1990 1995 2000 2005Year
Popu
latio
n in
dex
(198
0=10
0)
Hippolais icterina
Sylvia borin
Sylvia atricapilla
Phylloscopus sibilatrix
Phylloscopus collybita
Phylloscopus trochilus
Regulus regulus
Muscicapa striata
Ficedula albicollis
Ficedula hypoleuca
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
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’
Step One
Observed increase
Observed decrease
Retrodicted range decrease Retrodicted range increase
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
-0.2
-0.1
0
0.1
-0.03 -0.02 -0.01 0 0.01 0.02 0.03
CLIM value
Obs
erve
d tr
end
We found a highly significant +ve correlations between interspecific variation in recent population trends & the CLIM projections
-0.1
0
0.1
0.2
0.3
0.4
0.5
CLIM
HaA
2
CLIM
HaB
2
CLIM
EcA
2
CLIM
EcB
2
CLIM
GfA
2
CLIM
GfB
2
CLIM
Ens
CLIM
Ens -
CLIM
Ens+
CS
T
Climatic Response Predictor
Sta
ndard
ised r
egre
ssio
n c
oeff
icie
nt
?
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
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 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 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
Step Two
60
65
70
75
80
85
90
95
100
105
110
1980 1985 1990 1995 2000 2005
Year
Wei
ghte
d po
pula
tion
inde
x
(A) Weighted population trend of species predicted to gain range in response to climatic change (30 species)
60
65
70
75
80
85
90
95
100
105
110
1980 1985 1990 1995 2000 2005
Year
Wei
ghte
d po
pula
tion
inde
x(B) Weighted population trend of species predicted to lose
range in response to climatic change (92 species)
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
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
Step Two
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
1980 1985 1990 1995 2000 2005
Ind
ex o
f cl
imat
ic c
han
ge
imp
acts
on
bir
d p
op
ula
tio
ns
50
60
70
80
90
100
Index valuePiecewise regression
160B
120
140
We can present the CII in a more accessible fashion for a wider general audience
60
70
80
90
100
110
120
130
140
1980 1985 1990 1995 2000 2005Year
Inde
x of
clim
atic
impa
cts
on b
ird p
opul
atio
ns
Increasing climatic impact on bird populations
Decreasing climatic impact on bird populations
Note that the pattern in the CII closely resembles that of observed climatic change in Europe
1980 1985 1990 1995 2000 2005
Ind
ex o
f cl
imat
ic c
han
ge
imp
acts
on
bir
d p
op
ula
tio
ns
50
60
70
80
90
100
Index valuePiecewise regression
160B
120
140
Year
1980 1985 1990 1995 2000 2005
Sta
nd
ard
ised
cli
mat
ic i
nd
ice
s
-3
-2
-1
0
1
2
GDD5MTCOMTEMPPiecewise regression
C
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
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
Year
1980 1985 1990 1995 2000 2005Ind
ex o
f cl
imat
e ch
ang
e im
pac
ts o
n b
ird
po
pu
lati
on
s
50
60
70
80
90
100
Adjusted index valueUnadjusted index value
120
140
160
Key messages1. 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:
1. Sardinian Warbler2. Subalpine Warbler3. Bee-eater4. Cirl Bunting5. Cetti’s Warbler6. Hoopoe7. Golden Oriole8. Goldfinch9. Great Reed Warbler10.Collared Dove
A few winners (?) ‘Top 10’ - Increasing birds projected
to increase
And many losers (?) ‘Bottom 10’ - Declining birds
projected to decline
1. Snipe2. Meadow Pipit3. Brambling4. Willow Tit5. Lapwing6. Thrush Nightingale7. Wood Warbler8. Nutcracker9. Northern Wheatear10.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/jour
nal.pone.0004678
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