Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird

Under climate warming, migratory birds should align reproduction dates with advancing plant and arthropod phenology. To arrive on the breeding grounds earlier, migrants may speed up spring migration by curtailing the time spent en route, possibly at the cost of decreased survival rates. Based on a decades-long series of observations along an entire flyway, we show that when refuelling time is limited, variation in food abundance in the spring staging area affects fitness. Bar-tailed godwits migrating from West Africa to the Siberian Arctic reduce refuelling time at their European staging site and thus maintain a close match between breeding and tundra phenology. Annual survival probability decreases with shorter refuelling times, but correlates positively with refuelling rate, which in turn is correlated with food abundance in the staging area. This chain of effects implies that conditions in the temperate zone determine the ability of godwits to cope with climate-related changes in the Arctic

Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird

Advancing phenological timing is a risk for migratory birds, particularly in the Arctic where change is most rapid. Here, the authors show that bar-tailed godwits can adjust for phenological shifts by fuelling faster at staging areas to arrive at breeding sites in time

Dataset and Code for: Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird

Our study combines data on godwits and their food resources at the main wintering, spring refuelling, and breeding sites along the flyway. To track in detail how individual birds connect these sites, we instrumented eight godwits with satellite transmitters in 2016. To estimate population trends, we counted birds each winter from 2002 to 2016 at the main wintering area, the Banc d’Arguin, Mauritania, West Africa. For godwits staging in the Wadden Sea during northward migration, we assessed the relationship between the annual refuelling rates and the density of their main prey, adult lugworms (Arenicola marina), using a 21-year dataset and a hierarchical Bayesian model that accounted for year-specific arrival dates and arrival mass of godwits