Do wintering conditions constrain adaptation to climate change in migrants?

Migrants evolved time schedules and routes to make use of seasonal habitats, but are confronted with rapid human-induced environmental change in both winter and breeding habitats. Previous research on effects of climate change on annual cycle adaptation has shown that responses are often insufficient, and that species least able to advance spring arrival at the breeding grounds have declined most. Forecasting annual cycle responses of migrants should not just consider changes at one end of their annual cycle, but need to integrate breeding and non-breeding processes, preferably over several years. We aim to better understand the year-round ecological factors experienced by Afro-Palearctic migrants that affect migration decisions, in order to predict their ability to adapt to ongoing changes in climate and habitat. We do this in the migratory pied flycatcher which has become a model system in organismal responses to climate change at the breeding grounds, but for which phenological relations at their African wintering sites are poorly understood. We aim to understand i) how variation in ecological conditions at African wintering sites affect preparation for migration and subsequent annual cycle performance, ii) whether harsh circumstances during their African winter stay or spring migration prevent rapid adaptation towards earlier arrival schedules. We combine (1) multi-year and repeated tracking from wintering and breeding grounds, (2) in-depth ecological research at wintering grounds (including DNA-based diet analyses), (3) long-term pedigree data of our Dutch breeding population (2007-onwards; 300 pairs) to look at environmental effects on inheritance of arrival dates and fitness consequences.