Polluted environment does not speed up age-related change in reproductive performance of the Pied Flycatcher

Environmental pollution can exacerbate deterioration in fecundity with advancing age, directly via the toxic effects of pollutants or indirectly via pollution-related resource (e.g. dietary antioxidants) constraints. Since there are very few studies on age-related changes in reproduction with regard to pollution, we analyzed a long-term (25 years) set of reproduction data from a small insectivorous and migratory passerine bird, the Pied Flycatcher Ficedula hypoleuca, to determine whether female birds showed a faster age-related decrease in average breeding parameters in a metal-polluted area around a copper-nickel smelter than in the control area. In our population-level analysis, all the breeding parameters (clutch size, hatching success, fledging probability, and fledgling number) were lower in the polluted area. Nevertheless, none of them indicated a faster decrease with age in the polluted area. Clutch size and fledgling number increased after the first breeding, but showed no significant change later on. Hatching probability decreased slightly after the second breeding, while fledging probability showed no significant age-dependent variation. Our results suggest that moderate long-term pollution does not reduce the viability of our study population via a faster age-related decrease in fecundity.