A butterfly that went extinct in England more than 40 years ago has been successfully reintroduced to the woodlands where it last lived.Butterfly Conservation has brought the Chequered Skipper back to Rockingham Forest in Northamptonshire using a donor population in Belgium.The project started in 2018 and Butterfly Conservation has now declared the first five years a success.The news comes after the charity declared a Butterfly Emergency in the UK in September following the worst-ever results of its annual Big Butterfly Count. Butterfly Conservation says this successful reintroduction shows one of the ways humans can start to undo years of damage to the natural environment.Butterfly Conservation Chequered Skipper Project Manager Susannah O’Riordan said: "The results from this project are very exciting: we've never carried out a project exactly like this before and it was a real experiment, but it's been a success. We have brought this wonderful butterfly back to England.“Our work can now help inspire and inform future reintroductions and all kinds of conservation projects - for butterflies and beyond.”Up until the 1950s, the Chequered Skipper was still locally common in damp woods and fens in the East Midlands, including Rockingham Forest.However it had started declining due to landowners changing the way they managed woodlands – planting conifer trees which created denser, darker areas, and stopping traditional coppice management which meant open spaces were no longer maintained.Following a final rapid decline, the Chequered Skipper was extinct in England by 1976, with small numbers surviving in Scotland. The species is still common in parts of Europe and Asia but there are worrying declines in several countries.Butterfly Conservation started looking at the possibility of a reintroduction in 2010 and spent eight years assessing the feasibility.One of the main factors that convinced the charity to attempt the project at Rockingham Forest was that landowners, including Forestry England and Bedfordshire, Cambridgeshire & Northamptonshire Wildlife Trust, worked with Butterfly Conservation to change how they managed the woodlands from 2015: the partners started managing 23 hectares of vegetation specifically to create habitats into which the Chequered Skipper could expand and thrive.Forestry England also improved the woodland habitat by widening the ‘rides’ through the forest – open corridors between the trees - and creating other open, sunny habitats which benefit the butterflies.The scientists even ran computer simulations to model what effect climate change could have on Rockingham Forest by 2070, and concluded that rising temperatures and increased rainfall could actually favour the species.Finally, the team found a healthy population of Chequered Skipper in an area of Belgium that was similar to Rockingham Forest and, in 2018, embarked on their first collection.During the capture and transport of the Belgian butterflies, the team scoured their equipment and shoes with disinfectant and used surgical-grade hand sanitiser. They were even accompanied by a vet from the Zoological Society of London who carried out health checks on every single butterfly before and after their journey.The charity has now carried out four translocations and released a total of 128 butterflies (101 females and 27 males) into Rockingham Forest - 71 at Fineshade Wood between Corby and Stamford, and 57 at a secret second location.The next stage of the project was to monitor the new population and answer the most important question - whether the butterflies were breeding, and if so how much.For this, Butterfly Conservation successfully trialed a deceptively simple-sounding new technique – taking photographs.The standard way to monitor individual wild animals is ‘mark and recapture’, for example catching a butterfly in a net, placing a small mark on its wing, then releasing it.However, the unique patterns on Chequered Skipper wings  mean individual butterflies can be identified when looked at up close, so a new technique was trialed by then-PhD student Jamie Wildman, in which volunteers took photographs of as many Chequered Skippers as they could, then simply compare the unique wing markings in the pictures to work out the number of individuals actually seen.The technique worked perfectly and, crucially, is less invasive and disruptive for the butterflies.Dr Wildman published a paper about the success of this technique in the journal Biodiversity and Conservation in April, adding to the project's list of achievements.In 2019 alone, the team recorded an impressive 105 sightings of Chequered Skipper butterflies at Fineshade Wood that were the offspring of the original translocated insects, confirming that the butterflies were breeding successfully in England for the first time since the 1970s. In total more than 350 individual Chequered Skippers have now been counted.In addition, the area that the butterflies were living in increased each year up to 2022, with a slight retreat in 2023. Numbers remained stable this year, but with some tantalising sightings in new areas, showing the population is still expanding its range.With the right funding and resources, Butterfly Conservation says it should be possible to create at least one functioning ‘metapopulation’: a self-sustaining population that has the potential to expand to permanent new breeding grounds, increasing its chances of survival. The team are now looking for more sites to focus work.Butterfly Conservation has deemed the first five years of the project a success, but also stressed that this success was only possible because of years of dedicated research and planning and, crucially, changes in habitat management by Forestry England and other woodland managers.Butterfly Conservation Chief Scientist Dr Nigel Bourn, Susannah and others involved in the project also published a paper in the Journal of Insect Conservation this summer celebrating the success of the scheme and highlighting the implications for conservation work across the UK and beyond.Dr Bourn said: "We have so much to celebrate and we're delighted to be able to call the first five years a success, however there's a caveat: this project shows us that restoring wildlife is possible, but only if we put in dedicated and sustained effort to tackle the reasons the species went extinct in the first place. “Climate change will bring more challenges and opportunities, but whatever they are we need to ensure we are creating and sustaining precious wild habitat for our wonderful and beloved native species to survive."Find out more about the Chequered Skipper and the reintroduction project at butterfly-conservation.org/butterflies/chequered-skipper