The little fens
Herts’ rare wetland habitats that need our help
The morning sun begins to clear the mist from the meadow, a willow warbler is singing as it hops from stem to stem in the reed bed, and a marsh harrier lazily drifts overhead – Hertfordshire’s fens are waking up and the sight is beautiful. These wetlands, a real rarity in the county, provide a home for endangered birds and mammals as well as precious habitat, shelter and food for rare plants, insects and reptiles.
A fen is a marshy wetland that receives water and nutrients from surface and groundwater as well as rainfall. The name is from the Old English ‘fenn’ meaning marsh, dirt or mud. Fen meadows are special habitats providing the conditions for a rich variety of wildlife, yet they are one of the least well recognised. It is not surprising perhaps, considering they can be difficult to access and much of the wonderful wildlife in them is hidden from view.
Fens in England have been declining for many years as a result of water abstraction, pollution and pressures from development. From the 17th century, fens were drained for farming and later for development, leading to 99 per cent being lost in the UK.
Fens should have waterlogged or damp conditions throughout the year, but throughout the UK many are poorly managed or drained of water for peat extraction, farmland and developments, resulting in this wildlife-rich habitat being destroyed. Fen habitat is complex and needs careful and continuous management through conservation grazing, reed cutting and ditch and scrub clearance.
Fens provide a home for wintering wetland birds such as snipe, shelter and food for mammals like the endangered water vole and habitat for moths like the vulnerable wainscot as well as many insects, frogs, newts, grass snakes and plants.
The water vole is the fastest-declining mammal in the UK with a 95 per cent decline in its population in the last century. It relies on ditches to dig burrows and on wetland plants such as sedges and rushes for food and cover from predators, so Herts’ fens provide a valuable habitat.
Wading birds, such as snipe, require specific habitats to thrive – too wet and they cannot breed, too dry and they can no longer forage for food. Snipe last bred in the county at Rye Meads near Hoddesdon in 1998. Although not currently breeding, snipe still winter here, but numbers have fallen dramatically from over 500 in the 1980s to only 85 in 2012.
Caring for Herts’ fens
About 114 hectares of fen or marsh habitats remain in Hertfordshire. Herts and Middlesex Wildlife Trust manages a number of these sites including Rye Meads, Thorley Wash near Bishop’s Stortford and Purwell Ninesprings in Hitchin. These habitats are in a good condition thanks to the hard work of the trust’s nature reserve teams, volunteers and supporters. Rye Meads is classified as a Site of Special Scientific Interest and Internationally Important Wetland site for wintering birds.
The trust continually works to conserve and improve Herts’ fens. This year’s summer drought means the vital conservation work is more important than ever – especially for delicate wetland habitats. Winter is the ideal time for conservation work without disturbing wildlife. Ditches are cleared to control water levels, cattle are brought on to graze the reserves – stopping woody plants from dominating, and scrub is cleared to reduce overshadowing.
The trust has launched an appeal for supporters of its work on Herts’ precious fens. Find out more at hertswildlifetrust.org. uk/fenappeal
Water vole numbers have declined 99 per cent in the UK. Fens are a key refuge Photo: David Francis
Rye Meads, near Hoddesdon
Wading birds, like this snipe, require specific wetland habitat