Thousands of rare marsh fritillary caterpillars released in Lake District

BEAUTIFUL: The marsh fritillary reintroduction project is now seeing some successes

May 2011: Thousands of caterpillars have been released in a Lake District valley as part of ongoing attempts to re-establish colonies of one of Europe's most endangered butterflies.

Almost 4,000 marsh fritillary caterpillars were distributed on suitable habitat by Wild Ennerdale Volunteers, Forestry Commission staff and Butterfly Conservation under a licence from Natural England.

The caterpillars were released a mile beyond the head of Ennerdale Water. The site was considered to be ideal as it contains an abundance of Devils Bit Scabious - a plant that Marsh Fritillary caterpillars feed on.

More caterpillars were also introduced on a nearby privately-owned site at the head of the lake. There are now five sites occupied by the butterfly in the Ennerdale area, which widens the gene pool and helps survival chances.

Steve Clarke from Butterfly Conservation said: ‘The marsh fritillary is a rare and beautiful species which was present in Ennerdale until about 30 years ago when it became extinct. 

REINTRODUCTION: The caterpillars are released

Population estimated at 5,000
‘As part of an ongoing project we released caterpillars in 2007 and again last year in an attempt to reintroduce the species back into Ennerdale. This year's release is a continuation of that project and we hope that these increased numbers will further help the re-establishment of marsh fritillary in the valley.'

The area where the caterpillars were released provides great opportunities for the butterflies to spread up and down the banks of the River Liza, one of England's most natural rivers and an ideal habitat.

Walkers in Ennerdale this summer are being encouraged to keep their eyes peeled to look out for the butterflies at the end of this month and in early June.

Annually butterfly numbers are monitored by Butterfly Conservation. Last year the total population of flying adults at the western end of the valley was just over 5,000 based on timed counts. This includes an estimated 1,900 flying adults on a National Trust farm where around 8,000 larvae were released in early 2010.

Gareth Browning, area forester with the Wild Ennerdale Partnership, said: ‘It is a measure of the success of The Wild Ennerdale Partnership that the habitats in the Ennerdale Valley have been restored over the past ten years to a point where this beautiful species can be reintroduced.'