Integrated population monitoring of Wadden Sea birds: the example of the avocetRecurvirostra avosetta

Abstract

Besides the well estabished countings of breeding birds, the monitoring of breeding success in a selection of sites seems to be the most promissing method for improving the knowledge on the population processes of Avocets. Measuring the breeding success does not take much time and does usually not involve any disturbance to the birds. Measuring mortality rates can only be done by ringing, which involves catching and hence disturbing the birds. Colour-ringing of a relatively small number of adults and chicks per annum will be sufficient to notice whether drastic changes in mortality and recruitment rates occur, provided enough working-time can be devoted to checking colour rings in and before the breeding season. Studies of turnover rates at resting sites seem to be impractical at present. The main emphasis in winter should be to fill the gaps in knowledge at the southern end of the flyway.