Movement patterns of diving ducks Aythya sp. in western Europe

Abstract

Millions of birds have been ringed worldwide over the past 100 years to provide a better understanding of their movements and demography. Yet despite this impressive effort, knowledge of migration patterns and strategies, including the location of stopover sites and migratory connectivity, remains incomplete because recapture and ring recovery rates are often extremely low. Using re-encounter records for ringed birds found dead or recaptured, and visual sightings reported for individuals ringed and fitted with nasal saddles, we investigated the patterns of post-nuptial movements of Common Pochard Aythya ferina and Tufted Duck A. fuligula caught in France during the breeding season. So far, most ringing effort for these diving duck species has focussed on populations in northeast Europe, whilst migration patterns for the declining populations which breed in southwest European countries, including France, remain almost entirely unknown. Surprisingly, a large proportion of the individuals re-encountered at least once after capture were eitherresident birds or had initiated post-breeding movements to the north or east, to wintering sites spread over a large area encompassing northern France, Belgium, the Netherlands and Great Britain, as well as to the Alpine lakes (Lake Geneva and Lake Constance). The relatively large proportion of residents and short-distance migrants among the ringed individuals highlights the importance of harvest management schemes being assessed at the local scale, in the same manner as for more sedentary species.