Long-distance migratory birds threatened by multiple independent risks from global change

Abstract

Many species migrate long distances annually between their breeding and wintering areas1. Although global change affects both ranges, impact assessments have generally focused on breeding ranges and ignored how environmental changes influence migrants across geographical regions and the annual cycle2,3. Using range maps and species distribution models, we quantified the risk of summer and winter range loss and migration distance increase from future climate and land cover changes on long-distance migratory birds of the Holarctic (n = 715). Risk estimates are largely independent of each other and magnitudes vary geographically. If seasonal range losses and increased migration distances are not considered, we strongly underestimate the number of threatened species by 18–49% and the overall magnitude of risk for 17–50% species. Many of the analysed species that face multiple global change risks are not listed by International Union for Conservation of Nature as threatened or near threatened. To neglect seasonal migration in impact assessments could thus seriously misguide species’ conservation.Climate and land-cover change can affect the summer and winter ranges and migration distances of migratory birds. Accounting for all of these factors, rather than just summer range as is typical, significantly increases the number of species under threat.