Variation in Autumn Migration Strategy in the First-Year Wood SandpipersTringa glareola

Abstract

Abstract. Wood Sandpipers are generally known to follow a time-minimization migration strategy on their autumn passage. We investigated whether the migration strategy adopted by first-year Wood Sandpipers is susceptible to temporal variations. Wood Sandpipers were trapped during the July–September period from 1997 to 2007 at the Jeziorsko reservoir, central Poland. Intra- and inter-seasonal variation in stopover length, refuelling rates, departure fat loads and flight range were investigated. There was a constant decline in the refuelling rates over the course of the migratory season, reaching 0.55 g/day at the end of August. Such low refuelling rates are considered typical of energy-minimizers. Despite showing high refuelling rates at the beginning of the season, first-year Wood Sandpipers left the stopover site with relatively low fuel reserves, resulting in a low potential flight range of about 1200 km, which suggested travelling in small hops — a trait characteristic of energy-minimizers. There was al...