A novel model applied on the constant effort mist-netting reveals important patterns in population dynamics of long-distance migratory birds

Abstract

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. Alternatively, it might be a result of changes in the non-breeding grounds that affect survival.

Detailed study of the population dynamics, demographic parameters, and possible climatic drivers can help to reveal these causes in different species. We used capture-mark-recapture data from a constant effort sites (CES) mist-netting volunteer citizen science programme.

These CES data provide good coverage for 16 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 (namely temperature, GDD5, and plant phenology) and non-breeding grounds (water availability) and compared their importance in different species.