1. Body size and climate change: assessing the explanatory power of climatic anomaly in temperate songbirds
Nicolas Dubos
Conservation lab, Muséum National d’Histoire Naturelle
Isabelle Le Viol, Alexandre Robert, Céline Teplitsky, Manon Ghislain, Olivier Dehorter & Pierre Yves Henry

2. 2 or 3 common reponses to climate warming?
Global changes
Climate warming
Species response:
Phenological shifts (Menzel et al. 2006)
Distribution changes (Root et al. 2003)
Body size decline (Yom-Tov et al. 2006, Edeline et al , Gardner et al. 2014, Gutièrez-Pinto et al )

3. Climate warming drives body size
Third universal response to climate change?

4. Climate change

5. Climate change ?
Size change

6. Climate drives body size
Driver = Temperature ?
Bergmann’s rule (1847)

7. Bergmann’s rule: warmer = smaller
+ Heat conservation efficiency
+ Heat loss efficiency

8. Bergmann’s rule: warmer = smaller

9. Bergmann’s rule through time: warmer = smaller?

10. Climate change ?
Size change

11. Climate drives body size
Body size driven by indirect effects of climate
Food availability

12. ? Climatic fluctuations Heat loss efficiency Food availability
Size change

13. How?
Through its effects on juvenile growth

14. How? Through its effects on juvenile growth
Through its effects on size-dependent mortality

15. How? Through its effects on juvenile growth
Through its effects on size-dependent mortality

16. Research questions

17. Direct effect of climate (Temperature / heat loss efficiency)?
Research questions
1. Which driver ?
Direct effect of climate (Temperature / heat loss efficiency)? ? ? OR
Size
Climatic variable
Indirect effect of climate
(Food availability / Protein intake during growth)?

18. Direct effect of climate (Temperature / heat loss efficiency)?
Research questions
1. Which driver ?
2. Which mechanism ?
Through effects on juvenile growth ?
Through effects on size-dependent mortality ?
Direct effect of climate (Temperature / heat loss efficiency)? ? OR
Indirect effect of climate
(Food availability / Protein intake during growth)?

19. Many advances but… Previous conclusions derived from
1 species / population
1-2 sites
Museum specimen

20. Material & Methods

21. Data French Constant ringing Effort Site (CES) Multi-species
> biometric data

22. Monitored at least 1 year
Data
French Constant ringing Effort Site (CES)
Multi-species
Multi-sites
41 species
> biometric data
250 sites
Monitored at least 1 year

23. Monitored at least 1 year
Data
French Constant ringing Effort Site (CES)
Multi-species
Multi-sites
Long term
15 years
41 species
> biometric data
250 sites
Monitored at least 1 year

24. Measurement for body size?
Data
Measurement for body size?
Wing length
Body condition
Based on mass and wing length
Performed by trained ringers®

25. Which climate variables are relevant?
Data
Which climate variables are relevant?
Daily mean temperature & Daily sum precipitation (E-OBS)
2000–2014
0.25°

26. Data Which climate variables are relevant?
Daily mean temperature & Daily sum precipitation (E-OBS)
2000–2014
0.25°
Monthly NDVI (Copernicus) => Net Primary Production => Food availability
5 x 5 km
Local anomalies (centered on site mean value)

27. Methods: Statistical analysis
=> 1. Which climatic driver ?
Methods: Statistical analysis ?
Size
Climatic variable
Generalised linear mixed models (GLMM)
Multi-model inference (AIC)

28. Methods: Statistical analysis
2. Size-dependent mortality ?
Population body size
Juveniles (1st year) t

29. Methods: Statistical analysis
2. Size-dependent mortality ?
Population body size
Juveniles (1st year)
2nd year t
t+1

30. Methods: Statistical analysis
2. Size-dependent mortality ? t
Juveniles (1st year)
2nd year
t+1

31. Methods: Statistical analysis
2. Size-dependent mortality ? t
Juveniles (1st year)
2nd year
t+1

32. Results

33. Results
Drivers of body size

34. Results
1. Drivers: Juveniles
Best models ^2 ^2 * ^2

35. Pseudo R² = 1% Results 1. Drivers: Juveniles
Relationships Body size ~ climate / NPP
Pseudo R² = 1%
ΣAICw = 0.13
ΣAICw = 1
ΣAICw = 0.34 ^2
mean

36. Based on extensive data
Results
1. Drivers: Juveniles
Relationships Body size ~ climate / NPP
Pseudo R² = 1%
Based on extensive data
(40 species)
ΣAICw = 0.13
ΣAICw = 1
ΣAICw = 0.34 ^2
mean

37. Based on intensive data (6 species)
Results
1. Drivers: Juveniles
Relationships Body size ~ climate / NPP
Pseudo R² = 13%
Based on intensive data (6 species)
ΣAICw = 0.13
ΣAICw = 1
ΣAICw = 0.34 ^2
mean

38. Results 1. Drivers: Adults No effect on adult body size
(current year / previous year / previous moult)

39. Results 2. Effect of NDVI: Juvenile growth or
Size-dependent mortality? t
Not explained by NDVI
(nor any climatic variable)
t+1

40. Results 2. Effect of NDVI: Juvenile growth or
Size-dependent mortality? t
Not explained by NDVI
(nor any climatic variable)
t+1
NDVI = effect on growth

41. Discussion

42. 1. Main driver = Food or Temperature ?
Discussion:
1. Main driver = Food or Temperature ?
Statistical support for food availability
as a main driver of juvenile growth
Main driver = Food
But poor explanatory power

43. Discussion: No negative effect of hot years
Not in France
Nor in Germany (Salewski et al., 2014)
Nor in Netherlands (Husby et al., 2011)

44. Discussion: No negative effect of hot years
Not in France
Israel, Australia
Temperature is not a major stress
In tempetare climate
Tewksbury et al., Science, 320:

45. Discussion: No negative effect of hot years
in Tempetare climate
So why a positive effect of hot years ?

46. Discussion: No negative effect of hot years
in Tempetare climate
So why a positive effect of hot years ?
Metabolic gain for heat maintainance ?
= more metabolic allocation for body growth

47. Discussion: No negative effect of hot years
in Tempetare climate
So why a positive effect of hot years ?
Metabolic gain for heat maintainance ?
= more metabolic allocation for body growth
Indirect effect on primary production ?
= more food available for body growth

48. Discussion:
Universal response to warming? => Depends on the latitude?

49. Discussion: 2. Environmental effects on juvenile growth or Size-dependent mortality ?
Body size = juvenile growth + size-dependent mortality ?
Adult analysis => no effect

50. In France (temperate climate)
Discussion: Environmental effects on juvenile growth or Size-dependent mortality ?
In France (temperate climate)
At the breeding period
Body size = juvenile growth + size-dependent mortality ?

51. Summary Food or Temperature? FOOD (effect on growth)
In temperate climates
Food or Temperature?
FOOD (effect on growth)
Only on most common species
Next step: local determinants; density dependence?
Warmer = larger ?
Not in cool climates
Difference between hot and cool climates?
Next step: Global scale analysis

52. Conclusions
Body size change = a localised component of biodiversity response to global changes ?
Toward a mechanistic understanding of ecological processes ~ climate change
Implications for biodiversity conservation and evolutionary ecology

53. Acknowledgements Data gatherers: All the 442 volonteer ringers
My supervisors: I. Le Viol P.-Y. Henry
Helpers: Léo Bacon, Boris Leroy, Vincent Devictor, Eric Edeline, Morgane Barbet-Massin, Karine Princé, Reto Schmucki, Pierre Fiquet, Frederic Jiguet, Romain Julliard
Funder: LabEx BCDiv
Listeners: you
Contact:
THANKS

54. Did the climate change since 2000 in France?SD

55. Which climate variables are relevant?
Local climatic anomaly in mean values of the breeding season (May – July)
Each site
Mean

56. Which climate variables are relevant?
Local climatic anomaly in mean values of the breeding season (May – July)
Each site
Mean