Abstract
Currently there are two most discussed hypotheses explaining impact of climate on bird populations. First, conditions in wintering sites in sub-Saharan Africa, particularly droughts, negatively affect survival of long-distance migrants.
Second, increasing spring temperatures negatively affect breeding productivity of long-distance migrants due to mismatch of the peak of seasonal food supply with the arrival of long-distance migrants to the breeding grounds (mismatch hypothesis). Both of these hypotheses have been proven by many studies, however, a complex, multiple-species study comparing the strength of both of these effects is still lacking.
Here we correlate survival and productivity from Constant Effort Sites data in Czech Republic with spring temperature on breeding grounds and precipitation and moisture on wintering grounds. This way we are able to compare the strength of both hypotheses across wide species spectrum.
Our study will hopefully increase our understanding of the mechanisms how climate change affects bird populations. The project is supported by Czech Science Foundation (project no. 13-06451S) and the Grant Agency of Charles University in Prague (project no. 633212).