Assemblages of waterbirds

Distribution of waterbird assemblages

 
Most sites holding large numbers of waterbirds are coastal areas, with large estuaries being of particular importance. These tend to be located in the south and east of Britain. Sites selected range from the Firths of the Moray Basin – the most northerly regular wintering area for waterbirds in north-western Europe, down the Scottish and English coasts of the North Sea to sites within the Greater Thames Estuary. A further six sites lie along the coast of the English Channel.
 
There are fewer sites in western Britain, although there are many sites of high importance along the north-west coast of England (Stroud & Craddock 1996).
 
Four sites have been identified in Northern Ireland, including Lough Neagh and Lough Beg, a site of major international importance for its populations of diving ducks, a large proportion of which derive from Icelandic breeding areas. This site is also the most extensive freshwater body in the UK.
 
There are no sites holding more than 20,000 waterbirds on the west coast of Scotland, north of the Solway Firth. This tends to reflect the absence of large, productive estuarine systems, although the area is still of international importance for many wintering waterbirds (especially some geese and waders), which generally do not occur in large, multi-species aggregations.
 
Many of the sites identified are long known for their importance for waterbirds. Indeed, most were included in the first Directory of Wetlands of International Importance in the Western Palearctic (Carp 1980), as well as earlier inventories (Ratcliffe 1977; Berry 1939). In comparing the present list of sites with earlier inventories, it is notable that sites identified as SPAs are generally much more extensive than previously identified sites for the same interests. This reflects not only better knowledge of the distribution and abundance of waterbirds, but also statutory agency policy to ensure that boundaries of classified sites are so drawn that they contain and reflect the range of ecological needs of the individual species contained within them (Stroud et al. 1990a).