Population trends and migration strategy of the Wood SandpiperTringa glareolaat Ottenby, SE Sweden

Abstract

Long-term ringing data are useful for understanding population trends and migration strategies adopted by migratory bird species during migration. To investigate the patterns in demography, phenology of migration and stopover behaviour in Wood Sandpipers Tringa glareola trapped on autumn migration at Ottenby, southeast Sweden, in 1947 − 2011, we analysed 65 years of autumn ringing data to describe agespecific trends in annual trappings, morphometrics and phenology, as well as fuel deposition rates and stopover duration from recapture data. We also analysed the migratory direction of the species from recovery data. Over the years, trapping of both adults and juveniles has declined significantly. Median trapping dates were 10 July for adults and 6 August for juveniles. Average migration speed of juvenile birds was 58.1 km d −1. Adults stayed on average 3.5 days and juveniles 5.2 days, with average fuel deposition rates of 2.5 and 0.7 g day −1 respectively. Juvenile birds probably vary their strategy according to time of season and prevailing conditions. Both adults and juveniles followed the Mediterranean Flyway, but juveniles displayed significantly more southerly and significantly more scattered migratory directions.