Organisms’ responses to past climatic extremes provide a useful perspective for understanding the impacts of ongoing and increasingly rapid climate change. Volant organisms can disperse long distances, allowing them to find and colonize new habitats during periods of change. However, the ability to move long distances does not necessarily imply increased responsiveness or resiliency to change. For example, long-distance migratory songbirds rely on innate genetic programs that may lack evolutionary flexibility, making it more challenging to track rapid environmental change (1). The responses of migratory birds to historical climatic extremes, such as those of the Last Glacial Period, provide important context for the current challenges facing the natural world. In PNAS, Thorup et al. (2) show that a bird species could have maintained migratory behavior through the last 120,000 y, and that a migratory lifestyle might have been key to adapting to climatic shifts without suffering population declines.
