Extract from “Countries Of The World France”, Written by Roseline Ngcheong-Lum. Times Edition Pte Ltd. Singapore, 1999.

Amazon eBay: Mont Saint Michel Bay is an exceptional coastal wetland both in terms of its physicala nd ornithologicafle atures. The Bay is in the Normano-bretong ulf (Figure 1) which opensi ntot he EnglishC hannel. The Laboratoryo f the Natural and Modificate Systems Evolution from Rennes I Universityw orksh ere on a Europeanc ontractd ealingw ith organic matter exchange between terrestrial and marine environments. In this context, wader populations, as consumers of benthic macrofauna have been studied. In this paper, we describe and discuss the importance of the Mont Saint Michel Bay for waders during the different phases of the annual cycle (winter, migration, summer) as well as duringh ardw inters( by examiningt he betweenyear variations of January numbers). In a second paper (Le Dr•an-Qu•nec'hdu et aL 1995b), we report on the spatial distributiono f the main wader speciesp resent. STUDY SITE The studya rea comprisesc oastlinew hichs tretchesf rom Granville in the north-east to Cancale in the south-west and includes the S•e and S•lune estuary (Figure 1). More than2 00 km2 o f mudflati s uncoveredat everyt ide. The intertidal area can achieve a width of more than 10 km. The saltmarshes are very seldom flooded and the lowest lines of the mussel farms are very seldom exposed. In between, there is an area which is exposed daily. The tidal range can achieve 15 m during the September spring tide: there are important tidal currents and intense sediment movements in relation to the small mean depths (Hamon 1984). Currents and sediment movements are more important in the central part of the bay which has led to silting around Mont Saint Michel. Macoma balthica dominates the macrobenthos (Hamon 1984). METHODS Two counts each month were carried out during two annualc ycles as part of an ornithologicasl tudyo f the Mont Saint Michel Bay (Boret et al. 1981). We collected data with the help of surveys for the IWRB International Waterfowl Census (Mah•o 1981-1992), counts by Borer and Mah•o and by the Manche section of the Normandy OrnithologicaGl roup (NOG). These countst ake place m mid-January each year. To limit the potential errors outlined by Smit & Piersma (1989), a countp rotocowl as developeda fter a preliminary studyo f bird distributionin the bay, at differents tates of tide and tidal levels. The tidal range is so large that the birds can be only counted accurately at high water midway between neap and spring tides. On neap tides, the birds are too far from the observer. On spring tides, the submersion of the whole saltmarsh means that waders have to stay in flight throughout the high water period. During the winter 1992/93, co-ordinated counts were made by the ornithologicasl ectiono f the SSPNB-Ille et Vilaine (Society for the Study and the Protection of Nature in Brittany) and the Manche section of the NOG. Yates & Goss Custard (1991) made comparisonsb etween highw ater and low water countso f shorebirdso n the Wash (east England) which is of similar size Twenty-five of their under-estimates at low water were due to the great difficultyo f countinga ll areas used by waders. This problem, which is also experienced in the Mont Saint Michel Bay, has led PB and RM to investigatet hose conditionsw hich give completec ounts. Some unusually low totals, for example in 1993 for Knot Calidris canutus, can simply be explained by an incomplete count. [Granville] •[•-I saltmarsh • mussel farms •1-3'-•1o yslebr eds • • fisheries TLLW theoric limit of lower water TLI qkm S•e v • •. • v Couesnort ChapelieS ainteA nne! [Vivier st,r Meq M i c h el Figure 1. Mont Saint Michel Bay: the study area. MONT SAINT MICHEL BAY: AN INTERNATIONALLY IMPORTANT WINTERING AREA The number of Dunlin CalidrJsa lpin& Oystercatcher Haematopus ostralegus, Grey Plover Pluvialis squatarola, Curlew Numenius arquata, Black-tailed Godwit Limosa limos& Bar-tailed Godwit Limosa lapponica and Knot show a winter peak, particularly in January (Table 1). On average, from 1981 to 1993 (Figure 2a), a little more than 53,000 waders are present in January in the whole of the bay. This is equivalent to 0.7% of the total western Palearcticw ader population,2 .3% of the north-western Europe population and 12.5% of the French littoral total (after Smit & Piersma 1989).