BOTH C R G BIJLSMA & H SCHEKKERMAN (2008) Breeding in a warming world: movement or misery?. LIMOSA 81 (4): 154-162.

Climate change has a profound effect on the phenology of many organisms, but the response of laying dates in birds is often not sufficient to match the response of their main food sources. During the last 20 years the migratory Pied Flycatcher Ficedula hypoleuca advanced its breeding phenology by about 8 days, whereas the peak date of their caterpillar food has advanced by 16 days. In the Netherlands, populations breeding in areas with early caterpillar peaks have declined strongly, most probably because their breeding date does notmatch the food peak any longer. In this contribution we lay out our research on how these birds could adapt to this enormous change in their environment. We focus on whether dispersal could be a way to restore the synchrony between the timing of the annual cycle of the individual bird and its main food supply. When birds arrive too late on their former breeding grounds, they could try to find a place where the phenology of the food matches better. This could be at a small scale, by selecting areas with a late phenology, or at a large scale by long-distance dispersal to more northern areas. For the small spatial scale we show that in our study area in SW Drenthe there is consistent among year variation between woodlots in both the phenology of Oak Quercus robur bud burst and the laying date of Pied Flycatchers (Fig. 2), hence birds could gain from selecting late areas. We also show that birds that were born relatively late in the season indeed dispersed further (Fig. 4, right), which may be to seek areas with a later phenology. During the coming years we will investigate whether birds indeed disperse in order to adapt to climate change, both at small and large spatial scales, and whether this will adaptation will be sufficient to meet these new challenges of their environment.

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