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 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. 2013, Gardner et al. 2014, Gutièrez-Pinto et al. 2014 )

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

Climate change

Climate change ? Size change

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

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

Bergmann’s rule: warmer = smaller

Bergmann’s rule through time: warmer = smaller?

Climate change ? Size change

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

? Climatic fluctuations Heat loss efficiency Food availability Size change

How? Through its effects on juvenile growth

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

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

Research questions

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)?

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)?

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

Material & Methods

Data French Constant ringing Effort Site (CES) Multi-species >100 000 biometric data

Monitored at least 1 year Data French Constant ringing Effort Site (CES) Multi-species Multi-sites 41 species >100 000 biometric data 250 sites Monitored at least 1 year

Monitored at least 1 year Data French Constant ringing Effort Site (CES) Multi-species Multi-sites Long term 15 years 2000-2014 41 species >100 000 biometric data 250 sites Monitored at least 1 year

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

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

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)

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

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

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

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

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

Results

Results Drivers of body size

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

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

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

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

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

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

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

Discussion

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

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

Discussion: No negative effect of hot years Not in France Israel, Australia Temperature is not a major stress In tempetare climate Tewksbury et al., 2008. Science, 320:1296-1297

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

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

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

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

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

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 ?

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

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

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: nicolas.dubos@mnhn.fr THANKS

Did the climate change since 2000 in France? SD

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

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