The sites and breeding biology of Shelduck Tadorna tadorna in theLoire estuary

摘要

The breeding success and chronology of the Shelduck Tadorna tadorna have been monitored in the Loire estuary. Between 1987 and 2001, we made several visits a year between May and July, using a boat to observe the young all over the estuary (from Saint-Nazaire to Cordemais). During the study period, we observed a total of 510 broods or nursery, corresponding to 600 broods. The results obtained in this study indicated that the average peak of hatching per year was the third of June. The average number of young per brood was also calculated. We were able to assess the total number of breeding pairs which was estimated to about 120 at the end of the period. Compared to the data collected in the seventies, the number breeding pairs showed a strong increase. However, a stable trend in number of broods and also in number of breeding pairs occurred at the beginning of the 1990's. The increase of human activities may have had a negative impact. The study allowed to localize the best sites for raising young Shelduck and the best feeding places. An adaptated management of these places is probably necessary to preserve Shelduck reproduction.