Butterfly Conservation in the Heddon Valley

A pair of male High Brown Fritillary butterflies in June at Heddon Valley, Devon — A pair of male High Brown Fritillary butterflies in June at Heddon Valley | © National Trust Images/Matthew Oates

The Heddon Valley is home to an array of butterfly species, including the High Brown Fritillary.

As one of the rarest butterflies in the UK, the high brown population numbers were on a steep decline, losing 85% of its population since the 1970s. Thanks to the work done by the West Exmoor Ranger and volunteer team, these numbers are now back on the rise.

The High Brown requires a specific habitat of bracken and violets, laying its eggs under the cover of the bracken and feeding on the violets. But bracken can easily become overrun if not managed well, making it impossible for the butterflies to get under to reproduce.

Over the last decade, the Rangers and volunteers have been trialling different bracken management methods to create runnels (channels within the bracken) for the butterflies to get under the plant. With the help of volunteers, the Rangers initially spent time creating these runnels manually by bashing and crushing the bracken down with planks of wood. Although this worked well it was extremely time-consuming, limiting the amount of space that could be improved, so a new solution had to be found.

Ranger controlling a robotic flail on a steep slope — A ranger controlling the robo-flail in the Heddon Valley | © Joshua Day

In more recent years a remote controll flail cutter has been used to achieve similar results in a shorter space of time. This, however, does not compare with the natural process of runnel creation by using large grazing animals.

Our four-legged rangers, the longhorn cattle and three mangalitsa pigs (our newest additions to the west Exmoor team) have also been introduced to areas where we are working to create ideal butterfly habitats. The animals do a far better job than a man-made process ever could, simulating the behaviour that wild boar and cattle would have displayed many years ago, and allowing our rangers to work on other important conservation projects.

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Video

Conservation grazing on West Exmoor

A short video about the amazing work our pigs, cattle and ponies do across West Exmoor

With the help of Butterfly Conservation and volunteers, yearly surveys have been carried out to watch how the species numbers change with different management techniques and we are beginning to see a positive rise, particularly with the use of livestock.