The Severn Estuary is internationally important for birds and
for wildlife habitats. It may seem just like mud and saltmarsh to
many, but over the whole of Europe, these estuarine environments
are quite rare and very important.
The Severn Estuary is one of the most important estuaries in the
UK for wintering wildfowl and waders, especially when there is severe
weather affecting other sites further north and on the east coast
of the UK. The Estuary regularly supports over 20,000 birds, with
over 100, 000 recorded in the winter season of 1994-95. Species
include European white-fronted goose, dunlin, shelduck, wigeon,
teal and ringed plover.
It is part of a European network of sites known as Natura 2000
- 'your nature' which is special in a European context. These sites
try to put people at the heart of nature conservation and are about
'people and nature', not 'nature without people'.
Species and Habitats of the Severn Estuary
The following habitats and species are all features for which the
Severn Estuary is designated as a Site of Special Scientific Interest
(SSSI). Some are also features for which the site has been designated
as a Ramsar Site and SPA and also proposed for inclusion in the
possible SAC. Definitive information on the features included in
each designation can be found in formal designation
documents, which are held by all the local authorities with
jurisdiction over any part of the designated site.
| Bewick’s Swan –
feed on the saltmarshes and the coastal grazing marshes in
the upper part of the estuary, but will also roost on the
intertidal mud and sandbanks. |
Sabellaria Reefs – formed
by the activity of Sabellaria alveolata (or the honeycomb worm)
that builds protective tubes of sand grains and which can form
colonies as large reefs on hard substrates in the lower intertidal
and subtidal zones. |
| European white fronted geese – overwinter
on the Severn, roosting at night on the estuary sandbanks and
feeding during the day on saltmarshes, permanent pastures and
other farmland. |
Saltmarsh – occurs in
a zone all around the outer edges of the estuary often in
a stepped formation between the low and high tide. It provides
important feeding areas for waterfowl and a safe haven from
the tides that flood the mudflats twice a day. Upper saltmarsh
in particular makes ideal high water roost sites. European
white-fronted geese, redshank and shelduck also feed on the
saltmarsh itself.

|
| Shelduck – exploit the rich resources
of invertebrates found in the intertidal mudflats. They feed
in groups and are found all around the estuary. Bridgwater Bay
is the second largest late summer and autumn moulting area for
shelduck in Europe. |
Redshank & Dunlin – feed throughout
the estuary, mainly on invertebrates found in the muddier
finer sediments. Dunlin are found mostly on mid shore areas,
whereas redshanks are often found in creeks and sub-estuaries.
|
Shingle and rocky shore – provide feeding
areas for many wildfowl and waders and are important roost sites
at high tide. Many of the rocks are offshore and are therefore
generally free from human disturbance
. |
| Fish - migratory fish species including salmon,
sea trout, river and sea lamprey and twaite and allis shad,
migrate through the estuary from the sea to spawn in the estuaries
rivers. |
Coastal grazing marsh –
low lying wet
grasslands found at the edge of the estuary, often behind the
flood defences. These habitats are important as feeding and
roosting grounds for a number of important bird species, particularly
grazing birds such as Bewick’s Swan and European white
fronted goose. In some areas they also provide essential summer
breeding grounds for wading birds such as redshank. Grazing
marshes support a network of freshwater and brackish rhines
and ditches. |
| Intertidal mudflats and sandflats –
provide a refuge and a rich, plentiful source of food (invertebrates)
for a wide range of migratory birds. The flatness of the landscape
also allows unrestricted views to detect predators |
Sandbanks – composed of a mix of mud,
sand and gravel sediments that are continuously covered by water.
The subtidal sandbanks in the Severn are highly impoverished
as a result of estuary conditions. This makes them distinct
from others in the UK due to the low number of species and individual
animals found. |
Rhines & ditches – These provide
habitats for a wide range of aquatic and brackish plant species
and a diverse population of notable invertebrates. |
continue with what's special...
|