Consultez les articles du Bulletin Aves !
Aves, 12/4 | 1975 | 177-253
The data from the International Waterfowl Censuses, January 1967-1973, have been used to compile a revised set of distribution maps for 13 selected species. The maps cover the whole of Europe, North Africa and southwest Asia, with the exception of the U.S.S.R. They are designed to show the location of the main centres, and also the importance of the dispersed populations. Each map is accompanied by table containing details of the annual counts in the various regions, and of the numbers recorded in the major concentrations. The existing numerical criteria for identifying sites of international importance to waterfowl are discussed in some details, in particular the criterion which attaches importance to any site holding 1 % or more of the estimated flyway population of a species. It is shown that this method has several advantages, and that 1 % is the appropriate level to adopt. The criterion is applied to the data for the 13 species under review and produces a list of 166 important sites, 80 in NW Europe, 56 around Mediterranean and 30 in south-west Asia. The species concerned are: Anas platyrhynchos, A. crecca, A. penelope, A. acuta, A. clypeata, Aythya marila, A. fuligula, A. ferina, Mergus albellus, Tadorna tadorna, T. ferruginea, Cygnus bewickii and Fulica atra.