Encountering extreme weather during migration: individual strategies and their consequences

Migratory birds can encounter extreme weather when they arrive on their breeding grounds in spring. These recently‐arrived Icelandic black‐tailed godwits encounter snow quite frequently in spring, but how does the same species cope with extreme weather in breeding grounds further south, where cold weather is much less common? Photo credit: Tómas G. Gunnarsson.In Focus: Senner , N.R. , Verhoeven , M.A. , Abad‐Gómez , J.M. , Gutiérrez , J.S. , Hooijmeijer , J.C.E.W. , Kentie , R. , Masero , J.A. , Tibbitts , T.L. & Piersma , T. ( 2015 ) When Siberia came to the Netherlands: the response of continental black‐tailed godwits to a rare spring weather event . Journal of Animal Ecology , 84 , 1164 – 1176 . The way that animal populations respond to changing weather conditions is a major focus of current research, fuelled by the need to predict the future consequences of climatic changes. Severe weather events can provide valuable opportunities to uncover the mechanisms through which the weather influences population demography but opportunities to track individual responses to such events are rare. Senner et al . ([Senner, N.R., 2015]) report on an exceptional opportunity to address this issue, when their detailed studies of a migratory shorebird population were interrupted by an extreme weather event that coincided with spring migration, a key period in the annual cycle of migratory species. Through tracking of individuals across the migratory range, Senner et al . ([Senner, N.R., 2015]) show that, while individual schedules were severely disrupted by the harsh weather, with many individuals undertaking reverse migrations and experiencing delayed breeding, breeding success was unaffected. This study highlights the complexities involved in predicting the ecological consequences of extreme weather events and the key role of behavioural flexibility in mitigating the costs to individuals.