The Marsh fritillary butterfly has experienced a 55% decline in the number of colonies in the UK since 1970 and a decline of up to 50% across Europe since 1980. It is one of the most highly protected butterflies in Europe.
To survive it requires a number of linked, lightly grazed wet grassland sites that are untreated by chemical fertilisers and herbicides, this habitat has declined by 97% since 1940.
The butterfly was historically relatively common across north and West Cumbria but the numbers dwindled as a consequence of changes in agricultural practice. The last surviving handful of Cumbrian Marsh fritillary caterpillars, then only present at one site, were taken into captivity under licence by Natural England in 2004. They were cross bred with stock from closely related Scottish colonies and were released back into 4 sites in spring 2007.
Latest News 2015
After a warm dry year in 2014 we are hoping for further expansion of the Gillerthwaite and Mill populations. The Mill population was found to be the most densely populated Marsh fritillary site in England following last years surveys which is great news.During 2015 we hoep to increase our monitoring with some of our Wild Ennerdale volunteers and Forestry Commission staff lending a hand.
The Marsh fritillary in Ennerdale.
The Marsh fritillary was present on Ennerdale Longmoor common until it became extinct in 1979.Following a vegetation and habitat survey by Dr Keith Porter of Natural England the site was deemed suitable in the short term for reintroduction of captive bred Marsh Fritillary subject to longer term reintroduction of grazing by cattle to reduce the amount of long vegetation and scrub present on the site.The site is the hub for a number of smaller satellite sites to be established in the area around Longmoor and three potential sites in the Ennerdale valley, Mireside, Broadmoor and Hunter Howe have been identified.
Following the initial release of larvae at Longmoor in 2007, a further 8000 larvae were released at Mireside farm and 2500 released at Hunter Howe farm on Monday 12th April 2010.Marsh fritillary habitat at Mireside farm has been greatly improved by the National Trust and tenant farmers Judith and Andy Weston who have carried out localised strimming of some areas and introduced grazing by ponies. Additionally a large area of birch scrub has been felled by the trust and this area has been planted up with 5000 Devils Bit Scabious plants, the food plant of Marsh Fritillary larvae by Butterfly Conservation.
As is the case at Longmoor, annual population monitoring will be carried out by Butterfly Conservation at each site. This will entail counts of flying adult butterflies in mid to late May and counts of larval webs in late August.
In April 2011, 3800 Larvae were released in the middle of the Ennerdale valley, just east of Ennerdale YHA. See our Filckr Marsh Fritillary Slideshow.