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Fritillary butterflies remain a focus of much conservation
effort in Wales. For some, like the Marsh Fritillary, it is because
Wales has a significant proportion of NW European populations. For
others, it is because they are endangered in these islands, on the
north western edge of their European range. One such is the High
Brown Fritillary Argynnis adippe.
The High Brown Fritillary has suffered a massive decline in
Wales. Back in 2003 (Natur Cymru 7, p22) we talked about
the last two Welsh sites: seven years on, efforts on the last Powys
site, at Allt Dolanog, were too late to save the butterfly there.
However, work focussing in the Vale of Glamorgan has been hugely
successful. So, for once, let us celebrate a success and see what
lessons we can learn.
The last site in Wales is centred on the Alun Valley in the
western Vale. The butterfly occupies just five 1km squares, with
the next nearest population across the Bristol Channel on Exmoor.
The total landscape is about 254 hectares of unimproved habitat.
However, only 15ha were thought to be suitable breeding habitat for
the High Brown Fritillary. We realised had to do more, and quickly,
to save the butterfly. Baseline data and transect results helped
all the partners agree to a shared vision of what needed to be
The work focussed on knocking back the scrub, bramble and dense
bracken on the valley slopes. By 2007, an additional 48ha had been
restored and up to a further 2ha are now cut each year on a rolling
cycle. However, it was clear that manual cutting would not sustain
the site on its own. Three further grants from the Countryside
Council for Wales and PONT have seen 17ha of the private land
fenced and in 2010 a livestock corral was erected. This will allow
rough grazing by ponies, and possibly cattle, to be reintroduced,
enabling volunteer effort to focus on the unfenced areas and
clearing the scrub regrowth that the livestock leave.
Over 90 people have attended walks and workshops to see the
butterflies and work that had been done. The project put out press
releases and a newsletter, but having the Heritage Coast as a
partner has helped disseminate the message to schools and visitors,
as part of their programme of talks and events, reaching a far
bigger audience than the project on its own could achieve.
The partners felt we needed to look at restoring former sites,
where the butterfly had been present in the late 1990s. We visited
11 sites and recommended work on eight of these. However, to put it
in to context, only 8.82ha of suitable or potentially suitable
habitat was found compared with the 69ha in the Alun Valley
landscape, so a key recommendation was to expand the Alun Valley
work as already described.
Butterfly Conservation used Species Challenge funding to start
work on the eight other sites. Even though it was a relatively
small pot of money, it went a long way to helping build relations
on two other local commons.
At Y Graig above Llantrisant, three years’ work cutting back
dense bracken and opening paths has allowed the commoners to
re-introduce grazing. This prominent site was regularly subject to
large scale arson but, thanks to the work, the scale of burns has
been reduced and suitable habitat is being created. At Mynydd
Ruthin, where grazing restoration is much more difficult, the work
mainly involved clearing scattered thorn bushes and arson has
remained a potential problem.
How do we know it is working?
Adult numbers declined up to the trial coppicing in 1999, but
since the scale of this work was extended from 2003, numbers have
dramatically increased. Annual numbers are fluctuating, possibly
due to the weather, but even the low points have still been above
the best pre-1999 high in 1995.
In 2006 the abundance of violets, the larval foodplant, had
increased by 112% and the sward height more than halved compared to
the 2002 baseline figures. These are both positive signs that the
management is working. This work was repeated in 2010. Violet
abundance has fallen back but is still well above 2002 figures;
sward height has remained static; and grass/moss and bramble have
Searching for larvae
The larvae are very well camouflaged and it takes a great deal
of patience to spot them. The figures suggest that the larvae tend
to feed on the open bracken slopes rather than the hazel scrub
edge. As 80% of larvae found since 2006 were found on the recently
managed sub sites, it suggests the females are preferentially
selecting managed bracken stands for egg laying. However, we have
not yet corrected this for survey effort.
The future conservation focus for this butterfly has to be on
its existing locality where most of the habitat is. However, we
will continue to look for opportunities to work with commoners on
other sites. The High Brown Fritillary is a target species for the
targeted element of Glastir but it is difficult to see at the
moment how this will help, as the scheme’s focus is on soil carbon
and water quality.
There is potentially more habitat to be created in the Alun
Valley by getting the secondary hazel scrub in to a coppice cycle.
But perhaps most important is introducing grazing by cattle or
ponies on to both the private and common land to create the niches
needed by violets and the High Brown Fritillary.
Russel Hobson is Head of Conservation and
Richard Smith is High Brown Fritillary Project
Officer, Butterfly Conservation Wales.
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