Résumé
This chapter discusses the potential consequences of mistiming and identifies a number of ways in which either individual birds or bird populations potentially can adapt to reproductive mistiming. When different components of the food chain shift at different rates, this will lead to mistiming, and it is believed that such mistiming resulting from climate change will be a general phenomenon. The environment at the time avian produce their eggs is, in general much, earlier than the environment when selection will occur on, for instance, synchrony between offspring needs and prey availability. The evolved response mechanisms are appropriate for the range of prevailing conditions, and climate change is a trend that will at first fall within the normal range of temperatures. In the short term, an increase in temperatures may, therefore, allow birds to cope with their existing reaction norms. If these temperatures fall outside the normal range, or if periods in spring differ in their temperature change, the prevailing reaction norms become maladaptive. It is assumed that birds respond to climate change by changes in their laying date solely. However, investigation on pied flycatcher shows that rather than just using laying date as a way to advance hatching date, they use the whole complex of laying date, clutch size and start of incubation. Birds may also adjust other correlated life-history traits as some species show no change in laying date but do respond in whether or not they make a second brood.