Background The marsh fritillary butterfly, (Euphydryas aurinia), has suffered a 20-50% decline in its distribution in Europe over the past 25 years. The rate of decline in the UK has been particularly severe, mainly as a consequence of the loss of traditional livestock grazing, which leads to unmanaged pastures. The Breney Common and Goss and Tregoss Moors cSAC in Cornwall, however, remains one of the marsh fritillary butterfly’s strongholds. The cSAC, consisting of two component sites 10 km apart, is at the centre of the Mid-Cornwall Moors’ Euphydryas aurinia metapopulation. This represents 5% of the UK population and circa 1% of the estimated European population. The lifestyle of the butterfly requires conservation actions at the metapopulation level. Even with the designation of a cSAC, there is a need to ensure that a cluster of suitable breeding sites is present over a wider area. For the metapopulation to be sustained, a minimum of 70 ha of suitable breeding habitat should be available to allow for the vagaries of local extinctions and (re)colonisations. Objectives The LIFE Nature project aimed to increase the area, connectivity and quality of suitable breeding habitat across the cSAC and at seven satellite sites for the marsh fritillary butterfly population. To do this, English Nature brought together a partnership of three statutory agencies, two NGOs (the Cornwall Wildlife Trust and Butterfly Conservation) and landowners. Results Implementation of the project has led to an increase in favourable condition habitat for the marsh fritillary butterflies on about 130 ha across the project sites. Connectivity between sites has improved markedly through the removal of stands of exotic trees and clearance of willow and gorse scrub. Importantly, the A30, the major trunk road through Cornwall, which previously passed through the middle of the SAC has been re-routed, allowing connection between the important heathland communities that had been isolated before the LIFE project. This involved a partnership with the Highways Agency, and was the first time that they had been involved in a conservation project of this type. LIFE project work included installing management and grazing infrastructure and reinstating livestock grazing on the sites. Two herds of cattle were established and local hardy ponies were also utilised, to complement scrub clearance and burning. Results led to the restoration of the traditional wet heathland. Land users were leased cattle on long-term leases, and also encouraged to enter agri-environment schemes (along with other landowners), which offer opportunities to help support the overall economic sustainability of the LIFE actions. The project actively engaged with local communities to encourage their use of the project sites and also increase their appreciation of these important heathland areas. Dissemination was a key strength of this project, with excellent coverage in the local and national press. The improved understanding of species ecology and metapopulation dynamics generated by the project also provided strong demonstration value, applicable Europe-wide, for Euphydryas aurinia and for other species which require a similar landscape-scale approach. The project provides strong contributions to the objectives of the UK Biodiversity Action Plan for the species and it also supported the Highways Agency Biodiversity Action Plan. Further information on the project can be found in the project's layman report (see "Read more" section).