One of Britain's most endangered butterflies, the High Brown Fritillary, is experiencing a resurgence in the Vale of Glamorgan, thanks to an innovative conservation effort involving grazing cattle. The butterfly, distinguished by its vibrant orange wings and black markings, has seen its population plummet by 62% across England and Wales since 1970, making it one of the rarest British butterfly species.
The High Brown Fritillary has highly specific habitat needs, requiring a precise combination of bracken and common dog violet. Too much bracken can stifle the growth of the dog violet, which is the primary food source for the butterfly's caterpillars. However, bracken also plays a crucial role by creating a warmer micro-ecosystem from its dead leaves ('litter') after it has been trimmed, a temperature essential for the caterpillars' development.
For over three decades, Paul Dunn and Richard Smith have spearheaded volunteer efforts in the Alun Valley at Old Castle Down. Their work initially involved extensive coppicing – the hard pruning of overgrown hedges – to craft the delicate ecosystem needed for the butterfly's survival. In a significant development over the past three years, the team has introduced cattle grazing to the common land, a practice not seen there for over half a century.
The introduction of cows has proven highly effective. Richard Smith notes that cattle are adept at trampling bracken without eradicating it entirely, which helps to maintain the necessary balance. Their movement also creates an uneven ground structure, forming small niches that can be warmer than the surrounding area, further benefiting the caterpillars. As the land is common ground without traditional fencing, the project has secured National Lottery grant funding for solar-panelled collars, enabling a 'no-fence grazing' system to keep the cattle within the designated area.
Despite annual weather fluctuations, the overall High Brown Fritillary population in this part of Wales has shown a positive increase due to these combined efforts. What began with two dedicated individuals has expanded into a team of over 40 volunteers, including Dot Williams, who joined 11 years ago. This long-term commitment has not only aided nature conservation but also fostered a strong community, with volunteers regularly meeting outside of their conservation work.