Fen Management Handbook - Scottish Natural Heritage

Management requirements for protected invertebrate species
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Species Management
Lesser Whirlpool Ramshorn
Anisus vorticulus
Narrow-mouthed Whorl Snail
Vertigo angustior
Des Moulin’s Whorl Snail
Vertigo moulinsiana
Medicinal Leech
Hirudo medicinalis
Southern Damselfly
Coenagrion mercuriale
Norfolk Hawker
Aeshna isosceles
Lesser Silver Water Beetle
Hydrochara caraboides
Marsh Fritillary
Eurodryas aurinia
Swallowtail Butterfly
Papilio machaon britannicus
Fen Raft-spider
Dolomedes plantarius
References and sources of further information
Found in unshaded ditches and drains with a rich flora. Occupied drains should be
cleared frequently enough to prevent domination by tall emergents, but no more
frequently than essential; rotational clearance over short stretches is preferable.
Requires unshaded short vegetation on marshy ground subject neither to
desiccation nor to prolonged flooding. Maintaining the very precise hydrological
conditions required is critical; management by grazing is the easiest way of
maintaining short vegetation, but it is important to avoid excessive grazing and
trampling; cutting is preferable to arrest successional change to tall dense
vegetation or scrub.
Requires tall wetland vegetation over wet but unflooded ground. Maintain a high
water table; avoid water pooling and retention; grazing should be light, rotational,
or entirely avoided; management by rotational cutting is acceptable, but vegetation
should be not less than 70 cm in height in late summer
Maintain well-structured warm marginal shallows; good amphibian populations are
useful in providing tadpoles as food for young leeches; grazing livestock provide
food for adults.
Requires shallow, slow-flowing, unshaded, base-rich runnels and streams.
Maintaining open, unshaded conditions and good water quality is critical. Grazing
is the preferred management of surrounding land to maintain open conditions.
Breeds in well-vegetated unshaded drainage ditches. Rotational management
to maintain open conditions and avoid domination by tall emergents, with
management only as frequent as essential. Allow for presence of water soldier, an
invasive plant. Vulnerable to brackish incursion.
Requires well-vegetated unshaded ditches and ponds. Infrequently managed water
bodies in grazed land, with mats of surface vegetation, seem particularly useful;
management of any water body should be small-scale and cautious, but open
conditions must be maintained.
Requires grassland with varied structure including large stands of devil’s-bit
scabious. Grazing is the only way of maintaining suitable conditions in the longterm,
but must be carefully adjusted to avoid loss of structural variation.
Requires tall herbaceous fen vegetation with abundant Cambridge milk-parsley.
Suitable conditions are maintained by rotational cutting, but the timing of cutting is
critically important, avoiding winter.
Requires small pools with marginal saw sedge in its single known fen site; suitable
conditions can be maintained by clearance as necessary of any water bodies, but
if other fen colonies are discovered, it may be that they will occupy a somewhat
different habitat.
Alexander, K.N.A. 2004. Revision of the Index of Ecological Continuity as used for saproxylic
beetles. English Nature Research Reports, no. 574.
Benstead, P., Drake, M., Jose, P.V., Mountford, O., Newbold, C. & Treweek, J. 1997. The Wet
Grassland Guide: Managing floodplain and Coastal Wet Grasslands for Wildlife. RSPB,
Sandy, UK.
Benstead, P., Jose, P., Joyce, B and Wade, M. 1999. European Wet Grassland. Guidelines for
management and restoration. RSPB, Sandy.