The population of one of the UK’s rarest butterflies has been strengthened following the introduction of the Heath Fritillary to a new site in the Exmoor National Park.
Butterfly Conservation (BC) and the National Trust have worked closely with the Park Authority to introduce the Heath Fritillary into newly created coppiced clearings at Hawkcombe near Porlock, Somerset.
The butterfly is already found in a nearby heathland combe on the National Trust’s Holincote Estate at Halse Combe, around 3km from the introduction site.
Following extensive work by the Park Authority to create suitable coppice clearings within their woodland at Hawkcombe Wood, the right habitats have now been created and it is hoped the diminutive fritillary will thrive on the site following the introduction.
The Heath Fritillary is one of the UK’s rarest and most threatened butterflies and is restricted to just four locations in the UK - Exmoor on the Devon and Somerset border, the Tamar Valley on the Devon and Cornwall border, the Blean Woods in Kent and the South Essex Woodlands.
Historically, the butterfly has been referred to as the ‘Woodman’s Follower’ as it is linked to the traditional coppice management of woodlands, following the cycle of cutting around a wood.
Jenny Plackett, Butterfly Conservation’s Two Moors Threatened Butterflies Project Officer, said: “I am really delighted that the butterflies have bred at the new site and made it through their first year. More colonies in Exmoor will undoubtedly make the population here stronger and we are hopeful that the butterfly will spread into new sites from Hawkcombe.”
Some 37 Heath Fritillary adult butterflies were introduced into the coppice clearings in Hawkcombe last June and have bred successfully.
Searches for Heath Fritillary caterpillars at Hawkcombe in April revealed at least eight had survived through the winter. Volunteers have recently recorded more than 20 adults flying in the area.
On Exmoor, the Heath Fritillary uses sunny, warm and sheltered heathland combes, where it breeds on Common Cow-wheat found growing in association with young Bilberry plants. Both of these plants are found in abundance in the newly cleared areas at Hawkcombe.
Although the butterfly is stable on Exmoor, there are just 10 colonies remaining so there is urgent need to maintain existing habitat and where possible create additional suitable habitat patches for colonisation.
Exmoor National Park have been carrying out management in Hawkcombe Wood in recent years to try to create suitable habitat for the butterfly by coppicing oak woodland where the ground flora is suitable, and widening the rides to improve connectivity between the clearings. Further work is planned over the coming years to ensure a continued supply of suitable habitat.
It is hoped that the butterfly will eventually find its way into nearby historically occupied habitat at Shillet Combe and Bagley Combe.