Ringing and recovery data prove poor at detecting migratory short-stopping of diving ducks associated with climate change throughout Europe

Climate change has been shown to affect the distribution of many bird species. International Waterbird Census (IWC) data revealed that Tufted Duck Aythya fuligula and Goldeneye Bucephala clangula have shifted their European wintering distributions northeastwards as a direct response to increased winter temperatures. We tested whether it was possible to detect this shift in the wintering distribution of these species as well as Pochard Aythya ferina, using ringing and recovery data. Goldeneye conformed to our hypothesis, with its recovery distances decreasing significantly by about 400 km from the southwest to northeast from 1950 onwards, but this change could not be linked to winter temperatures. Conversely, Tufted Duck directly violated our hypothesis with its recovery distances increasing significantly by about 400 km but again this change could not be explicitly linked to winter temperatures. Pochard in contrast exhibited no change in its recovery distances. Thus, of the three species examined, ringing recoveries showed no trend in one species and of the two species where migratory short-stopping has been well described, one exhibited contraction whilst the other an apparent expansion in recovery distances. We conclude that ringing and recovery data provide little utility in detecting changes in migratory behaviour of these waterbirds.