Fig. 3
From: Fuelling conditions at staging sites can mitigate Arctic warming effects in a migratory bird
Estimation of refuelling time and refuelling rate of godwits in the Wadden Sea for a sample year. a Annual refuelling time for year k (k = 1998 in the figure) \({\mathrm{RT}}_k\) in the Wadden Sea was estimated as a difference between average arrival and departure dates. Mean arrival date to the Wadden Sea \({\mathrm{T}}0_k\), and its standard deviation \(\sigma {\mathrm{T}}0_k\) were estimated from citizen science data on arrival date accounting for observation duration and for variation in observation efficiency between observation sites. Dates of departure from the Wadden Sea were obtained by subtracting the estimated time taken by the migration between Wadden Sea and Taimyr (5.5 days) from dates of first arrival at Taimyr. b Annual arrival mass for females \({\mathrm{W}}0_{k\,{\mathrm{female}}}\) was estimated from godwits captured immediately upon arrival from West Africa birds in Castricum. c Population-level female annual refuelling rate \(\alpha _{k\,{\mathrm{female}}}\) estimation combined arrival date \({\mathrm{T}}0_k\) and arrival mass \({\mathrm{W}}0_{k\,{\mathrm{female}}}\) estimates with body mass values obtained from godwits refuelling in the Wadden Sea. d For males, arrival mass \({\mathrm{W}}0_{k\,{\mathrm{male}}}\) and e refuelling rate \(\alpha _{k\,{\mathrm{male}}}\) were estimated separately as males fuel up slower but are lighter and need to accumulate less fuel for migration
