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Dryad

Data from: Migratory birds advance spring arrival and egg-laying in the Arctic, mostly by travelling faster

Data files

Apr 10, 2025 version files 345.20 KB

Abstract

In the current, warming climate many organisms in seasonal environments advance their timing of reproduction to benefit from resource peaks earlier in spring. For migrants, the potential to advance reproduction may be constrained by their migration strategies, notably their ability to advance arrival on the breeding grounds. Recent studies show various changes in migration strategies, including wintering closer to the breeding grounds, earlier departure from the wintering grounds or faster travels by spending less time on stopover sites. However, whether such changes lead to earlier arrival or earlier breeding remain open questions. We studied changes in migration and reproduction timing in 12 populations of nine migratory birds, including seabirds, shorebirds, birds of prey and waterfowl breeding on Arctic sites bordering the Greenland and Barents Sea, a region undergoing rapid climate warming. Timing of migration and reproduction was derived from tracking and field data, and analysed to study (1) how timing has changed in response to changing moment of snowmelt at the breeding grounds, and (2) what adjustments in migration strategies this involved. We found that in years with early snowmelt egg-laying in multiple populations advanced, but only two waterfowl populations also advanced arrival in the Arctic. In contrast, arrival in the Arctic generally advanced with time, even when snowmelt or egg-laying dates did not advance. Earlier arrival with time was mostly explained by populations travelling to the Arctic faster, likely spending less time at stopover sites. Inability to forecast conditions in the Arctic may limit birds to adjust migration timing to annually varying snowmelt, but we show that several species, particularly waterfowl, are able to travel faster and advance timing of migration over the years. The question remains whether this reflects adaptations to Arctic climate change, or other factors, for example environmental changes along the migratory route.