Description
Chippenham Fen is a site of national importance for its wide range of wetland habitats and associated birds and insects. It has formed in a chalk rich, spring fed basin. This has formed a fen with peat soils that has been too difficult for past drainage and so has been spared from agricultural intensification. The site is now an island of biodiversity in an otherwise arable area.
The site has peat varying from a few centimetres to two metres depth and is is affected by surrounding drainage and recent work has been carried out to block ditches in order to keep water on the site.
The wealth of wildlife found on this, now isolated, site gives a glimpse into the past and an idea of what a rich area the fens would once have been before they were drained.
Habitats
Peat fen
With peat varying from centimetres to two metres there is a mosaic of wet habitats including wet grassland, saw sedge and open fen with pools of open water in places.
Wet woodland
Around the periphery of the site are stands of alder and willow woodland, which turns to more mixed woodland on drier parts of the site.
Grassland
There are areas of chalk grassland which grade into the fen grassland. The damp neutral grassland meadows are also developing a fen meadow flora. All of the site is grazed periodically with cattle (previously water buffalo).
Ditches
The water levels are controlled within a series of ditches which support a rich aquatic flora.
Key species
Cambridge milk parsley
An incredible 308 species of higher plant have been recorded at Chippenham Fen. Notable species include: Cambridge milk-parsley, saw-sedge, southern marsh orchid, marsh fragrant orchid, early marsh orchid, marsh helleborine, fen pondweed, water violet, bogbean, bog pimpernel and 114 species of mosses and liverworts.
Cambridge milk parsley is a specialist of lowland damp meadows, fen peats overlying chalk, and rough-grazed marshy pastures. Due to most of the Cambridge fens having been historically drained, this is now a very rare plant limited to three sites in the UK.
Breeding birds
Breeding birds include marsh harrier, woodcock, snipe, and 9 species of warbler in the fen and woodland. The woodland also supports spotted flycatcher and occasionally lesser spotted woodpecker.
Reed leopards and snail-killing flies
This site has an exceptional invertebrate list with 26 rare species and is recognised as the best fenland site for flies including snail-killing flies and soldier flies
Over 600 species of moth including the reed leopard and silver-barred moth that are only found in a few other sites in the UK.
17 species of dragonfly and damselfly can also been found on the site.
Rosser’s sac spider
163 species of spider have been recorded including Rosser’s sac spider. This is a rare and globally endangered wetland spider that lives only in specific fenland habitats in Great Britain. So named because during the day, it hides inside a tiny silk tube made inside a folded leaf, it is only found on two sites in the UK.
The wasp spider is a large, visually spectacular orb-weaver spider famous for its striking yellow, black, and white striped abdomen. Historically a rare sight in the UK, this species has rapidly expanded its territory from the southern coast of England up into the Midlands and Wales, largely driven by a warming climate. Despite its formidable, wasp-like appearance, it is completely harmless to humans.
Common frog
Grass snakes, common lizard, frogs and toads all use the wetland habitats on the fen.
Mammals
Water vole, water shrew and harvest mouse have been recorded.
Further information
This is a leased site with no access away from the public right of way. Permits are issued for research purposes.
Cambridgeshire NNRs:
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