Distribution, phenology and long-term trends of Dunlin Calidris alpina in France

The coasts of France are known as wintering and staging areas for Dunlin, but the function and importance of the sites at which they are found remains unclear, especially during migration. This study updates information on the numbers and the distribution of Dunlin in France using International Waterbird Census data (counts in January 1977–2013, organized by Wetlands International) and monthly counts carried out at the main sites during 2000–2012.

Over the past ten years, France has supported around 312,000 Dunlins in winter, which is about 23% of the wintering population of Europe. About a third were recorded at sites on the north coast (North Sea and Channel), while two-thirds were on the Atlantic coast. Numbers peaked in midwinter. The Mediterranean shore, where intertidal areas are limited, did not support many Dunlin in winter. At the national level the total number in midwinter has been more or less constant for the past 37 years, but with different trends on the Channel and Atlantic coasts. Importantly, around 50% of the midwinter population was concentrated at only eight sites. Most of the Dunlin that winter in France belong to the subspecies alpina which breeds in N Scandinavia and Russia, but significant numbers of migrant Greenlandic and Icelandic Dunlin (subspecies arctica and schinzii) occur on the central Atlantic coast in April or May. Patterns of autumn migration remained unclear. Information on the occurrence of subspecies or the different breeding populations is lacking; however, phenology at the main wintering and staging sites has varied substantially, suggesting that they are used by birds of different origin and/or age.