Cumbria Crack

Marsh Fritillary butterfly returns to Ennerdale valley

National Trust ranger Chris Gomersall with farmer Judith Weston and a Marsh Fritillary at Mireside, Ennerdale

[O]ne of Europe’s most protected butterflies has returned in great numbers to a Lake District valley – thanks to innovative grazing and warm weather.

Marsh Fritillary numbers have dwindled since the end of World War Two, as farming became more intensive. Once common, in the 1970s the butterflies disappeared from Ennerdale.

But now the marsh fritillary is bouncing back following a conservation programme started 10 years ago when the butterfly was reintroduced to several sites across the valley. Since then the distinctive orange and cream speckled butterflies have boomed.

Last year, volunteers at Longmoor counted 112 ‘webs’ spun by the butterfly larvae, up 560 per cent since the programme started in 2007.

At Mireside Farm, National Trust rangers, volunteers and farmer Judith Weston have worked together to boost butterfly numbers on 10 acres of wet grassland beside Ennerdale Water.

Judith Weston, who grew up on the traditional sheep farm, explained how they were one of the sites that were chosen for the first reintroduction. She said: “The land was quite marshy with frequent patches of the marsh fritillary caterpillar’s only food-plant – devil’s-bit scabious. With careful management it clearly had potential to become a home for the butterfly”.

National Trust ranger Chris Gomersall described the work that is involved in improving the butterfly’s habitat. He said:

“In the autumn we cut the rushes back with a powered scythe, it’s about a fifth of the fields, so that come the spring more light is getting to the ground flora. This encourages germination and growth of the scabious food-plant. The more food-plant there is the more caterpillars we should see. The caterpillars spin protective silk webs, like spiders, and live in colonies within the webs. We have seen the number of webs spun by the butterfly larvae almost double since 2010.”

“We’re also working with tenant farmer Richard Maxwell and grazier Richard Taylor to promote the marsh fritillary at the head of Ennerdale valley and Longmoor Common. Eight native-breed longhorn cattle, owned and managed by Richard Taylor, lightly graze the wet grassland at Longmoor, encouraging the growth of the marsh fritillaries’ favourite food plant” added Chris.

Now the butterflies are spreading across the Ennerdale valley, with conservationists putting the success down to good habitat management through light cattle grazing, and good weather at critical times of year.

Rachel Oakley, from the Wild Ennerdale partnership said: “A cattle grazing regime is helping to create a mosaic of habitats across the valley, enabling both the butterfly and its food-plant to expand.

“The middle valley fields and the river Liza corridor are seeing butterfly numbers increase and migrate eastwards up the valley. From the initial re-introduction on Longmoor, to the numbers being recorded now is a great achievement over a decade. This is down to a combined effort by farmers, volunteers and landowners. It is great news for everyone involved in helping this lovely butterfly have a bright future in Ennerdale” added Rachel.

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