Abstrakt
Long-distance migratory birds are experiencing long-term population declines in Europe. Due to their complex annual cycle, there are two major classes of potential factors responsible for this decline.
The cause might lie in the breeding grounds, where, for example, migrants' fecundity may be negatively affected by the trophic mismatch (i.e. when phenology of plants and insects advances faster due to climate change than the rather constricted phenology of migratory birds). Alternatively, it might be a result of changes in the non-breeding grounds that affect survival.
We used capture-mark-recapture data from a constant effort sites (CES), which is a bird ringing citizen science programme of the Czech Bird Ringing Centre based on volunteer fieldwork. These CES data provide good coverage for 8 migratory species since 2004 at more than 50 sites in the Czech Republic.
We developed a novel extension of the Pradel (1996) model which opens a new avenue to analyze CES data, allowing the decomposition of the population growth into survival and recruitment, facilitating the understanding of patterns in population dynamics. We also related the demographic parameters to the climate in the breeding grounds (temperature, GDD5, and plant phenology) and non-breeding grounds (water availability in the Sahel region and the rest of sub-Saharan Africa) and compared their importance in different species.