It shares the Solway Firth with another National Nature Reserve in England....
The Reserve covers an area of 5,500 ha and consists of saltmarsh, vast mudflats and grazing land. It is an internationally important wintering site for waterfowl and wading birds. Virtually the entire population of Svalbard Barnacle goose overwinters here, ca. 40,000. More than 130,000 wading birds have been recorded in winter. In addition, many thousands of birds stop for "bed and breakfast" while passing through.