PROPOSALS to reintroduce a population of rare and endangered butterflies to Loch Lomond and the Trossachs have been shelved - after preparatory survey work found a “secret” population.

The Pearl-bordered Fritillary butterfly, which is now very rare in England and Wales, but more widely found in the north of Scotland, was thought to be locally extinct in the area.

With only one butterfly having been seen over ten years ago, Forest Enterprise Scotland (FES) was working with Butterfly Conservation Scotland, RSPB, Woodland Trust Scotland & CLEAR Services to explore the possibility of a reintroduction programme, but at least 45 have since been recorded at ten different locations.

Paul Maplebeck, of Butterfly Conservation Scotland, said: “The butterflies’ ideal habitat consists of sunny, south facing slopes with well drained soils and light woodland cover.

“Cutting edge scientific modelling was used to predict where these might be found - and it worked.

“You can imagine our surprise and delight when the surveys revealed that FES sites within the Trossachs housed a secret population.”

All of the sites where the butterflies were found were on south facing hillsides at the eastern end of Loch Katrine and featured open glades within mature woodland, with light bracken cover and clusters of favoured nectar plants such as bugle, primrose, and an abundance of common dog violet – the caterpillar’s food plant.

The survey also discovered areas of favourable habitat across FES managed ground and at sites the Glen Finglas estate owned.

The Great Trossachs Forest, which is Scotland’s second largest designated National Nature Reserve covering more than 16,000 hectares, is the long-term legacy of a forest restoration project involving Forest Enterprise Scotland, RSPB Scotland and Woodland Trust Scotland.

Katy Anderson, FES habitats manager, added: “This is a fantastic example of partnership work and how the combined experience, skills and resources – and the invaluable help of volunteers – can make a real difference.”

Nick Cooke, of CLEAR Services consultancy, said: “After 10 years of fruitless searching around Loch Katrine, this is excellent proof of the value of data modelling. We hope that this project will give the Pearl-bordered Fritillary population in the Trossachs a much brighter future.”

There will be further survey work over the next two years to help protect the species and ensure its long-term survival in the area.