-
This
stunningly beautiful butterfly was just managing to hang
on at one or two colonies in the Lakeland area but by 2005
none were reported, suggesting it had become extinct.
-
After
the Second World War there were over 200 colonies in north
Cumbria from Ennerdale to Penrith. Colonies from the Solway
Mosses, Ennerdale and Eskdale have long since gone. The
butterfly was once abundant just 3 km west of Carlisle in
the meadows around Orton Woods and a few km further west
at Finglandrigg Wood.
- The
remaining colonies were so isolated that efforts to improve
the habitat had no beneficial effect because there was no
mixing between colonies and in-breeding led to low productivity
and weak specimens.
- Fortunately
in 2004 it was realised that the last remaining colony was
under threat and 168 larvae were removed under licence for
captive breeding. A further 800 larvae were added to these
under licence from a strong colony in Argyll, Scotland, that
was genetically similar.
- After
successive years of breeding, by early 2007 around 40,000
larvae were held in captivity. In March of that year some
37,000 were released back to four prepared sites, again under
licence. The largest number were released at a central Lakes
site, with others on the Solway, in West Cumbria and near
Penrith. Hopefully this will lead to a resurgence of the species
in the county.
- Three
of the four sites are on private land and their locations
will not be divulged. The fourth site is Finglandrigg NNR
between Kirkbampton and Kirkbride on the Solway Plain. This
wardened site is being used to provide an opportunity for
members of the public to see this terrific species. At the
car park (map ref NY 283572) follow the butterfly trail about
a mile through the wood until you come to an open area through
a gate with a sign on it saying 'you've finally made it, this
is the site'!
- In
2007 there were very encouraging signs that the release programme
was working well, except at the Penrith site where conditions
are still not ideal. Good numbers of adults were seen during
the flight season and larval webs found from mid-August onwards.
-
Massive declines in populations throughout Europe make this
the only butterfly in the U.K. to gain protection
under the E.U. Habitats and Species Directive.
-
Colonies
do undergo huge fluctuations in size
over the years, but it is the disappearance of colonies
that is worrying.
-
The
Orton Wood colony
was studied for 55 years. Between 1881 and 1894 it increased
from common to very abundant, before declining over the
next ten years, then becoming scarce between 1906 and 1912
and very rare between 1913 and 1919. Numbers increased steadily
between 1920 and 1925 and by 1935 it was described as excessively
common. Sadly this colony is now extinct.
-
The
Marsh Fritillary is predominantly a species of damp unimproved
grassland on the western side of Britain; its food plant
is Devil's-bit Scabious (although
it will use Honeysuckle when pressed). The peak flight time
in Cumbria is usually the first two
or three weeks of June.
-
The
'improvement' of old pasture
for intensive agriculture leads to the eradication of the
foodplant. Colonies become fragmented and the species cannot
survive population crashes by recolonisation from neighbouring
colonies nor can genetic reinforcement occur by mixing of
populations.
-
The
larvae need direct sunlight
- they like to bask in the warmth as an aid to digestion
(don't we all!).
-
Bad,
particularly wet,
weather
at critical times (and for several years in succession)
affects the success of the species. Numbers are further
reduced by a parasitic wasp,
which injects its eggs into the larvae so that they are
eaten from within!
-
Recolonisation
depends on the presence of adjacent colonies; females will
wander several kilometres, especially towards the end of
their flight period (when the weight of eggs carried is
reduced).
-
The
Ministry of Defence look after
possibly the largest colony in Europe - in 1999 it was estimated
that 10,000 larval webs were present on the Salisbury Plain
Training Area. Nice to know our taxes are being put to good
use!!
|
