Differences in shifts of wintering and breeding ranges lead to changing migration distances in European birds

Studies on the impact of climate change on the distributions of bird species in Europe have largely focused on one season at a time, especially concerning summer breeding ranges. We investigated whether migratory bird species show consistent range shifts over the past 55 yr in both breeding and wintering areas or if these shifts are independent. We then analyzed whether patterns in changing migration distances of Finnish breeding birds could be explained by habitat use, phylogeny or body size. We used long-term datasets from the Finnish ringing centre to analyze the mean wintering latitudes of 29 species of Finnish breeding birds, then used breeding distribution data to make predictions as to whether certain species were migrating shorter or longer distances based on the comparative shifts in the wintering and breeding grounds. Our data reveal species-specific differences in changing migration distances. We show that for many species, long-term shifts in wintering ranges have not followed the same patterns as those in the breeding range, leading to differences in migration distances over time. We conclude that species are not adjusting predictably to climate change in their wintering grounds, leading to changing migration distances in some, but not all, species breeding in Finland. This research fills an important gap in the current climate change biology literature, focusing on individuals’ entire life histories and revealing new complexities in range shift patterns.