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 also considerable inter-seasonal variation in the adopted migration strategy. The results suggest that sandpipers caught at the beginning and at the end of the migratory season behaved as energy-minimizers, at least in some aspects of the migration strategy, unlike the intermediate migrants, which adopted a typical time-minimization schedule. These observations indicate that the migration strategies of waders may depend on the environmental conditions encountered en route and are thus likely to exhibit high intra- and inter-seasonal variation.
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1 December 2010
Variation in Autumn Migration Strategy in the First-Year Wood Sandpipers Tringa glareola
Piotr Minias,
Krzysztof Kaczmarek,
Radosław Włodarczyk,
Tomasz Janiszewski
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migration strategy
Tringa glareola
waders
Wood Sandpiper