Conservationists in North Wales are celebrating after moves to reverse the dramatic decline of the Small Pearl-bordered Fritillary in Clocaenog Forest boosted its chances of survival.
Clocaenog's population of the butterfly, which is already near extinct in large parts of England, plummeted from 2,400 in 2003 to just 1,200 in 2011.
But a joint effort to improve the butterfly's habitat by Forestry Commission Wales and Butterfly Conservation Wales is paying dividends and has resulted in an increase in numbers.
The steady decline of the butterfly in Clocaenog was recorded over the past 11 years as foresters examined population dynamics of a number of species, including red squirrel and black grouse.
The discovery prompted Butterfly Conservation Wales and Forestry Commission Wales to put in place an urgent management programme for the species.
Contractors were brought in to clear scrub and conifer alongside five kilometres of rivers and streams in the forest, creating sheltered, open habitats with marsh violet (the caterpillar's foodplant) which the butterfly could once again use for breeding and feeding.
Mike Whitley, Forestry Commission Wales manager for the Clocaenog area, explained: "Clocaenog Forest is a huge area with a wide variety of habitats supporting many different wildlife species.
"It's great to see this rolling programme of conservation work benefiting many different species, in particular the Small Pearl-bordered Fritillary."
The butterfly is a UK Biodiversity Priority Species and a Species of Principal Importance in Wales as defined by the Natural Environment and Rural Communities Act, which classifies it as needing conservation action to prevent further decline.
Wales and Scotland represent its remaining strongholds in the UK but, although it is still relatively abundant on the upland fringe in Wales, the butterfly has declined dramatically in the lowlands and in woodlands.
Some six hectares of scrub - about the size of eight rugby pitches - has already been cleared over the past two years and the work will continue so that the future of the butterfly in Clocaenog can be assured.
Clare Williams from Butterfly Conservation Wales, said: "We are very pleased to be working with Forestry Commission Wales on this long running research project.
"It has helped to improve our understanding of how the butterfly responds to forest management at a landscape scale. It's great now to be able to use this research to guide successful management to help ensure the continued survival of this beautiful butterfly."