Conservation and Environment


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SSSI  - Site of Special Scientific Interest 



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.





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British Red Data Book


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