The Severn estuary lies at the mouth of three major rivers: the Severn, Wye and Avon, and many smaller rivers. The immense tidal range, the second highest in the world, and classic funnel shape combine to create one of the most spectacular tidal bores. These characteristics make the Severn estuary unique in Britain and very rare worldwide.
On 16 December, 1945, Peter Scott came to the Severn Estuary at Slimbridge to observe the wintering flocks of white-fronted geese. Amongst the flock he spotted a lesser white-fronted goose, just the third time one had been recorded in Britain at the time. He decided that this would be an ideal place to set up what is now the Wildfowl & Wetlands Trust. Today WWT manages 325 hectares of grazing marsh and grasslands on the shores of the estuary.
The habitats of the Severn estuary
The intertidal zone of mudflats, sandbanks, rocky platforms and saltmarsh is one of the largest in Britain. The estuary supports internationally important numbers of waterfowl, important invertebrate populations and large numbers of migratory fish.
The estuary also has a very diverse geological setting. It is important in geomorphology, the study of landforms and the processes that shape them, because it gives scientists clues to the way coastline and landforms and past changes in sea level, sediment supply, climate and river flow all interact.
The large size and the complex relationship between the intertidal and marine habitats and the wildlife they support make this a unique ecosystem.
The wildlife of the Severn estuary
The intertidal sand and mudflats with their high densities of invertebrates provide food for many migratory wildfowl and waders. In winter the estuary regularly supports internationally important 
numbers of dunlin, Bewick's swan, European white-fronted goose, shelduck, gadwall and redshank. In the spring and autumn even more birds, including ringed plover and whimbrel pass through the estuary. In total the estuary provides habitat for over 70,000 waterbirds.
The estuary supports 36 species of our 41 recognised estuarine fish, including species such as twaite shad, allis shad, river lamprey, salmon and sea trout which migrate through the estuary from the sea to spawn in the rivers feeding the estuary. Extensive runs of elvers return from the sea in late winter and spring.
The Severn estuary and people
The ecosystems of the Severn estuary have provided a source of food and income for people over centuries with many Severn-side cities, towns and villages celebrating its bounty with festivals. However fish stocks, particularly eel and salmon, have declined over a number of years and fishing is now restricted to a few areas along the Severn and festivals such as the eel festival in Frampton-on-Severn are distant memories.
The Severn has provided an important shipping channel through the ages linking SW England with the Americas and Africa. As a result of this trade link ports such as Bristol, Avonmouth, Cardiff, Port Talbot, Swansea and inland ports such as Gloucester, through the construction of the Gloucester-Sharpness canal, flourished.