Whinchat survival estimates across Europe: can excessive adult mortality explain population declines?

Abstract

AbstractEuropean farmland birds show massive large‐scale population declines due to agricultural intensification. Long‐distance migrants are particularly affected as their populations appear to undergo larger declines than those of residents and short‐distance migrants, raising the question about the impact of non‐breeding environmental conditions and their potential impact on annual survival. The whinchatSaxicola rubetra,an Afro‐Palaearctic migrant inhabiting open habitats, has strongly declined over the last decades. Most of the conservation effort for this species has focused on improving the breeding success in Europe, but it remains unclear whether habitat changes in non‐breeding areas may also have contributed to the population declines through a decrease in adult survival. We studied survival of whinchats from eight breeding populations across Europe by analysing capture–recapture data. We found that apparent survival was consistently higher in males than in females and higher in successful than in failed breeders independently of the sex. True adult survival may, however, hardly differ between sexes being about 0.5 and 0.6 and a simple population model suggests true juvenile survival to be between 0.2 and 0.35. Adult survival was unrelated to population trends suggesting that the main demographic problem of the whinchats is likely insufficient reproduction, a feature that is shared with other declining grassland specialists. Finally, in line with results on other migratory farmland species, our study suggests that conservation activities for whinchats should in first place focus on Europe.