SSSI - Site of Special Scientific Interest
WRAYSBURY
AND HYTHE END GRAVEL PITS
Status:
Site of Special Scientific Interest (SSSI)
notified under Section 28 of the Wildlife and Countryside Act 1981.
Local
Planning Authorities: Berkshire County
Council, Windsor & Maidenhead Borough Council
National
Grid Reference: TQ 014737
Ordnance
Survey Sheet 1:50,000: 176 1:10,000: TQ
07 SW
Date
Notified (Under 1981 Act): 3 July 1992
Date
of Last Revision:
Area:
116.65 ha 288.24 acres
Description
and Reasons for Notification
Wraysbury
and Hythe End Gravel Pits comprise a mosaic of open water, islands,
grassland, scrub and woodland within an
area of former gravel extraction. The site supports nationally important
numbers of three species of wintering wildfowl together
with an important assemblage of breeding birds associated with open waters
and wetland habitats.
In
addition the site supports two
nationally scarce invertebrates and a number of locally uncommon plants.
The site, which incorporates four former gravel pits, lies within the
floodplains of the River Thames and the Colne Brook. The unworked areas of
the site comprise floodplain gravels and alluvium of the Quaternary
period. The site also includes part of
the Colne Brook. The flooded gravel
pits are structurally diverse with Wraysbury North pit having the most
complex shoreline and a number of
islands.
Of
note is the shingle bank in the north-east corner with a colonising
ruderal community. Small areas of swamp and
carr occur, dominated by common reed Phragmites
australis, lesser pond-sedge Carex
acutiformis and greater pondsedge
C.
riparia. Aquatic species
include the locally uncommon pondweed Potamogeton
pusillus. Wraysbury South pit
has a more regular shoreline with willow predominant along the banks and
bulrush Typha latifolia and
common reed occurring along the
shores.
The
Hythe End pits have steep banks fringed with alder and crack willow Salix
fragilis. Species
occurring around the water's edge include the locally uncommon trifid
bur-marigold Bidens tripartita and
horned pondweed Zannichellia
palustris.
The
habitat west of the Colne Brook supports an area of scrub and damp
grassland. The flora is rich, but secondary, having
developed from alluvial material deposited on the site during construction
of the Wraysbury Reservoir. Species found
here include grass vetchling Lathyrus nissolia,
spiked sedge Carex spicata and
buckthorn Rhamnus catharticus.
As a consequence of its biological richness
and structural diversity the site regularly supports more than 1% of the
national populations of wintering
tufted duck, gadwall and goosander. It is also important for the smew,
holding a significant percentage of
Britain's wintering population.
The
total number of all wintering wildfowl regularly exceeds 1,000 individuals
at any one time. As well as being used for
feeding and roosting, the site is also an important sheltered refuge,
particularly for diving duck, within
the complex of adjoining larger pits and reservoirs. Other species which
frequent the site include pochard,
goldeneye, wigeon and the introduced mandarin. The range of habitats
support an important assemblage of breeding bird species typical of
lowland open waters and their margins.
Shelduck and pochard breed along the pit margins, the banks attract
kingfisher whilst passerines, such as the grasshopper
warbler and reed warbler favour the Phragmites and scrub.

The
wet meadow area supports breeding redshank.
The pits and their margins also have a rich invertebrate community which
includes the nationally uncommon white-legged
damselfly Platycnemis pennipes and
two species listed in the British
Red Data Book*, a riffle beetle Oulimnius
major and a caddisfly Leptocerus
lusitanius.
*The
British Red Data Book is a listing of species judged to be endangered,
vulnerable or under threat in Great Britain.
|