Fen Management Handbook - Scottish Natural Heritage

& Coutts 2004). They allow high water levels to be maintained near to the site’s surface whilst
avoiding extensive flooding. The areas of wet mud and water/mud interface of the resultant habitat
are important foraging areas for feeding adults and chicks of both waders and Yellow Wagtail.
In summer, late June onwards, the sward and tussocks should continue to be maintained as in spring
where as water levels can be allowed to draw down to allow agricultural operations to take place,
e.g. hay cutting. The timing and approach used in taking cuts of hay need to minimise on the risk of
destroying flightless wader broods.
In autumn and winter, grazing where possible, should take place to ensure maintenance of optimal
sward heights. Field wetness needs to be managed at field surface level so that extensive shallow
pools are created. This management regime is also beneficial to wintering wildfowl and waders, the
former which graze the vegetation, and this in turn can produce a good sward height for breeding
waders. Prolonged winter flooding can be detrimental to soil invertebrate populations that the
breeding species are dependent upon (Ausden et al. 2001). Any prolonged winter flooding of
areas of wet grassland managed for breeding waders should ideally be controlled so that one area
is flooded for 4-5 years and then rotated to a second area. This allows recovery of the invertebrate
populations between periods of flooding.
Sensitive periods
Species breed within this habitat from March to August, so disturbance should be minimised within
this period which includes avoidance of damaging mechanical operations, eg. silage cutting. Curlew
are particularly sensitive to disturbance during the breeding season.
Birds of high marsh and carr
Habitat features
The features included here are the areas in a fen of tall vegetation growing in soils that are not
overlain by water throughout the year and may not be waterlogged in the height of summer. The
vegetation can consist of Common Reed, sedges and rushes mixed with taller grasses, Common
Nettle and willow herb spp. Areas will also contain encroaching and/or managed scrub, most
frequently Alder and willow spp. with Hawthorn and Blackthorn on the driest margins. The scrub is
a key component of this habitat feature although it may be considered a threat to the integrity of the
fen.
Recommended management
The management of scrub of all types is described in Bacon (2003) and this includes guidance on
the management of scrub for birds within wetland habitats, including fens.
A mosaic of high marsh and carr vegetation provides the feeding and nesting conditions for a
diversity of bird species, particularly passerines including species that have the majority of their
population in other habitats. The objective for this suite of birds, where compatible with other
significant conservation features, is to maintain a proportion of scrub on site of differing ages through
regular, cyclical management. The retention of scattered bushes within swampy and/or high marsh
is important for species such as Reed Warbler, where the benefit is in diversifying the feeding
opportunities available. Where carr woodland does begin, the interface with swamp or high marsh
is of particular importance being a highly productive feeding area for a variety of migrant passerines,
especially in autumn. Where the scrub or carr borders wet swamp and whilst providing cover over
exposed bare mud, this provides favoured foraging grounds for the resident Cetti’s warbler.
Coppicing of marginal scrub or carr woodland on a 5-15 year cycle is beneficial to several
bird species such as grasshopper and sedge warblers and reed buntings (Merritt 1994). Such
management avoids closure of the canopy which would exclude most passerines typical of open
fens whilst attracting a wider range of scrub and woodland generalists to become established (Fuller
1982). The diversity of scrub or carr can be reflected in the species supported. In autumn, the berry
laden alder, buckthorn and hawthorn found on East Anglian fens, attracts large numbers of thrushes
and starlings. Of the more typical and widespread Salix spp and alder carrs, it’s the seed of the alder
that attracts in winter the large finch flocks characteristic of fen carr e.g. redpoll and siskin.
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