Old Hall Marshes NR RSPB

Old Hall Marshes are part of the Blackwater Estuary RSPB reserve. The site is part of the Blackwater Flats and Marshes, a key site in this Nature Conservation area. It is proposed as part of a special Protection Area under the EEC Directive on the Conservation of wild Birds (Directive 79/409/EEC). It is also proposed as a Wetland of International Importance under the Ramsar convention. 

Old Hall Marshes are comprised of a large area of grazing marsh almost completely surrounded by intertidal mudflats and salt marsh, together with more restricted habitats such as sea wall and brackish dykes. The central core of agriculturally unimproved neutral grassland represents the largest remnant of traditionally managed reclaimed grazing marsh in eastern England, whilst an associated area of reedbed is the largest in Essex. This large block of marsh, along with areas of improved grassland at the western end of the site, supports eleven species of birds in nationally important numbers, with two of these species also reaching levels of international significance. The diverse range of habitats also supports 284 species of vascular plants including 20 nationally scarce species. The invertebrate fauna is similarly rich, including at least 4 Red Data Book species and 37 notable species.

The site supports internationally important numbers of wintering Dark-bellied Brent Geese (typically around 2% of the total world population), and of migrating Ringed Plover. A further seven species of wildfowl and wader reach nationally important numbers in winter: Curlew, Dunlin, Goldeneye, Grey Plover, Shelduck, Teal and Wigeon. Great Cob Island is one of a number of well-established roosting areas within the site.