Abstrakt
Climate change affects various aspects of bird ecology including population dynamics and numerous studies provided various examples of these effects. Still, we do not fully understand how the climate poses limits on bird populations.
Specifically, we need to elucidate the links between climatic effects on particular phases of species’ annual life cycle and their abundance, as well as how the relative importance of particular mechanisms varies in relation to altitude and geography. Here we relate climatic conditions in the breeding (snow cover, icy days, temperature, GDD5 and evapotranspiration) and wintering (precipitation and NDVI for long-distance migrants) grounds to yearly variations in population size, productivity and survival of common birds.
We use data from two biogeographic regions, Continental (represented by the Czech Republic) and Mediterranean (represented by Catalonia), comparing the strength of the respective climatic factors in both regions. The main hypothesis is that the temperature-related variables will play more important role in Czech Republic, while precipitation in Catalonia.
To ensure maximum strength of inference and to address the spatial variability, population models are carried out to the level of monitoring plots. We test whether breeding productivity is negatively affected by spring/summer droughts and if harsh winters handicap resident birds; whether advanced spring favors residents and short distance migrants and handicaps long-distance migrants due to mismatch of timing the arrival and food peak - we test if this effect is more important than climatic conditions in Africa for long-distance migrants.
Our study will hopefully increase our understanding of the mechanisms how climate change affects bird populations.