Cattle have helped boost numbers of the globally endangered large blue butterfly.
The species was last recorded at Minchinhampton and Rodborough Common, Gloucestershire, 150 years ago and was declared extinct in Britain in 1979.
But a National Trust and Natural England initiative which involved targeted grazing of Luing, Hereford and Longhorn cattle on some of the slopes that had been traditionally less attractive to the free roaming cattle throughout the year, has provided the perfect conditions for the Myrmica sabuleti ant which is vital for the butterfly’s success.
The scrub control has also encouraged growth of wild thyme and marjoram where the butterfly likes to lay its eggs. These are also the main source of food for the butterflies.
David Simcox, research ecologist and co-author of the commons management plan said: “The butterfly needs high densities of the heat-loving red ant, Myrmica sabuleti which has a crucial role to play in the lifecycle of the butterfly.
"The grazing cows create the ideal conditions for them by keeping the grass down so sunlight can reach the soil which gently warms it creating perfect conditions for the ants, which are cold-blooded and therefore need warmth in order to actively scout for food throughout the spring, summer and autumn."
Richard Evans, area ranger for the commons, added: "None of this would’ve been possible without the combined efforts of conservationists and the local graziers.
“One of the greatest legacies of the re-introduction is the power of working together to reverse the decline of threatened species and the benefit the habitat improvements will have for other plants, insects, birds and bats on the commons.”