Population dynamics and whereabouts of ducks ringed in the Netherlands : an analysis of 70 years of ring data

Abstract

Between 1936 and 2006 over 140,000 ducks were ringed in the Netherlands, many of them in duck decoys. Around 41,000 ducks were reported back. The majority of those were recovered dead, but 1,400 were recaptured alive. The results were stored in a database. In this study, the database was redesigned and a demonstration website was built. The data were analyzed focussing on three species that form the majority of the duck species caught in decoys: teal (86%), wigeon (98%) and mallard (74%). The most active decoys are located along the three major Dutch rivers, east of Lake IJssel and on Texel. In winter most recoveries for these species are in western Europe. In May they are found in southern Scandinavia (teal and mallard) and Siberia (wigeon) en route to their breeding sites. For 7 species the maximum flight speed (180 - 450 km / day) and average migration speed (10 - 85 of km / day) was calculated. The average yearly survival chance of teal (0.54 ± 0.015), wigeon (0.64 ± 0.02) and mallard (0.53 ± 0.1) was determined. Several changes to the ringing process and data management are proposed, to improve our understanding of three issues through continued ring research on ducks: the impact of hunting on population dynamics, the spread of zoonoses such as H5N1 and the impact of climate change and human population growth on migratory behavior.