An ambitious conservation project has reintroduced chequered skippers to their former English stronghold
England’s last chequered skippers mysteriously vanished in the mid-1970s. Now they are returning to their former stronghold.
Rockingham Forest has a wood that must remain a secret. In May, the oaks are brilliant green, the air is filled with the scent of bluebells and the only sound is the gentle descending riff of a willow warbler. Broad forest rides are smothered with the purple of bugle and early purple orchids, yet there is still a sense of emptiness. An occasional speckled wood sails past, but these sunny glades are not bustling with butterflies.
Fifty years ago, the ancient royal hunting forest of Rockingham in Northamptonshire buzzed with a small, feisty and fast-moving butterfly: the chequered skipper. Then, abruptly, this insect vanished.
This summer, however, the real chequered skipper is returning, in a highprofile but highly secretive project. It’s the biggest reintroduction backed by Butterfly Conservation, which celebrates its 50th birthday this year. But how easy is it to bring back a lost species?
In any reintroduction the first step is to understand what caused the extinction. The trouble is, the chequered skipper’s rapid demise is shrouded in mystery. This has always been a baffling butterfly. In the 1940s, a hitherto overlooked population was discovered in the Scottish Highlands, over 600km from the species’ only English stronghold in the East Midlands. Somehow, this creature had survived in Scotland while vanishing from everywhere else in Britain.
During the 1970s, conservationists belatedly realised that the decline of coppicing and planting of conifers in once-sunny broadleaved woodlands was making the chequered skipper disappear. In 1973, a young ecologist, Lynne Farrell, was hurriedly dispatched to Northamptonshire. “I concluded that a lot of the sites had been afforested, shading out the rides, and there were very few flowering plants,” she remembers. The next summer, she couldn’t find a single butterfly. “I thought, ‘My God, we’re too late. I can’t do anything about this – it’s gone.’”
Fleeting glimpse
A specimen was eventually found by one of Farrell’s students on 6 June 1975 – on a golf course, of all places. Farrell raced to photograph it. That individual was the last she saw of the English chequered skipper, although odd sightings were logged the following year. After the hot summer of 1976, however, the species was extinct in England.
It’s been a long road back: reviving something as small as a butterfly is an intricate operation. It was Prof Jeremy Thomas who pioneered the art of insect reintroduction in Britain, with his life-long project to bring back the large blue. This beautiful butterfly became extinct in 1979, three years after the chequered skipper.
Today, the Polden Hills in Somerset and the Cotswolds in Gloucestershire boast a bigger population of large blues than anywhere else in the world. But it took Thomas and his colleague David Simcox more than a decade of labour to get the caterpillars they brought over from Sweden in a campervan to grow into a viable population.
Lepidopterists tried introducing the chequered skipper into Lincolnshire in the 1990s, but the butterfly soon died out again. Nigel Bourn, Butterfly Conservation’s director of conservation science, helped the Lincolnshire team and is now on the Rockingham reintroduction. What’s different
The forest rides have healthy tufts of the caterpillar’s favourite food plant: false brome.
this time? Bourn believes the sites in Lincolnshire were too small, and landowners didn’t know how to manage them correctly after the reintroduction. The individual butterflies may not have been in tip-top condition either, because it took several days to bring them over from the Continent.
Bourn is now more optimistic. The chequered skipper’s return is part of the Back from the Brink project to save 20 species from extinction in England. As Rockingham Forest project officer, Susannah O’Riordan’s job is to revive 15 key species across the 520km2 of Rockingham.
A key task is to work with landowners to widen forest rides to bring back more sunshine and flowers. In the wood where the skipper is being returned, the rides have been well cut back for several years; they are sunny and filled with scrub, wildflowers, grasses and ditches. Most importantly, there are healthy tufts of the caterpillar’s principal food plant: false brome. Other potential food plant grasses are here too. “There’s quite a lot of variety in this wood so the butterfly can choose where it goes,” says O’Riordan.
It sounds simple but it’s not. The caterpillars eat leaf tips, and, rather than going deep into the turf in winter like many butterfly larvae, make themselves shelters called hibernacula, constructed high on the grass. This makes them vulnerable to cutting.
Forest rides must be mown, but O’Riordan is working to ensure that rides where the butterflies are established are cut on a slow rotation, over three or four years. Each cut will cause some caterpillars to disappear, yet enough should survive. “It’s about long-term management and tweaking that management once the skipper is established,” says Bourn.
Even so, a question mark still hangs over the butterfly’s extinction in England. Lynne Farrell’s studies led her to conclude that as well as sunny rides, the chequered skipper requires access to wet areas or rivulets. Moisture, says Bourn, is important because this butterfly spends nearly 10 months of the year as a caterpillar. During that time, its grassy food mustn’t shrivel and die.
The Butterfly Conservation team has matched Northamptonshire’s climate with southern Belgium, so that’s where they decided to catch the butterflies. There’s “ever so slightly less rainfall” in Northamptonshire, and a Belgian lepidopterist has warned that some of Rockingham’s rides are too hot and dry. But the woods are mostly on heavy clay, and full of ditches and wet patches. As long as 2018 isn’t another 1976, the first chequered skipper caterpillars hatched in England for 42 years – beginning to munch their favourite grasses as you read this – should survive.
For all the meticulous preparations, isn’t a reintroduction ultimately a bit of guesswork? “I’d prefer to add ‘educated’ before that word,” laughs Bourn. “We’ve done habitat assessments and with improvements to a couple of key sites since the 1970s there’s now enough suitable habitat, but we can only prove it by putting them in and seeing that.”
While Thomas painstakingly relocated large blue caterpillars, the chequered skipper team is catching freshly emerged, mated female butterflies. It might seem logical to catch the skippers in Scotland, where extra surveying has revealed a far more extensive population than was previously believed. But as well as enduring a different climate, the Scottish skipper caterpillars feed on purple moor-grass, which does not grow in Rockingham.
Catching the skippers
Modern technology – the Channel Tunnel – helps. In late May, a team of four crack Butterfly Conservation catchers, including Bourn and O’Riordan, travelled to southern Belgium. Assisted by Belgian volunteers, they caught 42 butterflies – 31 females and 11 males. (They needed the males in the unlikely event that one or two of the females they caught weren’t already mated.)
Again, it sounds easy but it’s not: I’ve watched chequered skippers in Scotland and the females are much less visible than the males, which perch on scrub and aggressively defend their territory. When it dashes, this butterfly moves like a miniature Time Lord, vanishing from one space and almost instantaneously reappearing in another.
Expect the unexpected when chasing butterflies: the Butterfly Conservation scientists were also soaked by Belgian thunderstorms and chased by wild boar. Wearing special suits, the catchers placed each butterfly into an individual container. These were collected in a coolbox, which mimicked a cold afternoon, when the butterflies naturally sit tight and save energy.
The butterflies can be kept alive like this for several days but the team whisked them to Britain as quickly as possible, driving in a van overnight to the wood. Late at night the butterflies were released into two tents made of very fine mesh and placed in two optimum spots on the forest rides. The tents were open at the base, so the butterflies could spend the night perched on their foodplant.
Next morning, the tents were lifted away, and once each butterfly had warmed up, volunteers tracked them as they sped away. It was a moment of great excitement – and trepidation. “We’re hoping they don’t just disappear into oblivion,” says O’Riordan. “We want to monitor how many there are every day, which habitat they are using and where they are egg-laying.” That information will be crucial in learning how best to manage the skippers’ new home.
For one volunteer, Andy Wyldes, watching this golden insect buzzing rapidly down the rides is a welcome reacquaintance with a very old friend: he last saw the species more than 40 years ago, aged 11, on an outing with the
Kettering Natural History Society. “We were doing some conservation management, chopping down some non-native turkey oaks, and our group leader said, ‘Get over here boys, now’. We got down and had a look at the chequered skipper. The leader said, ‘Make the most of this opportunity because they are disappearing fast.’ The next thing we knew, the species had gone.”
Keeping a secret
There’s one last challenge – keeping this great rarity’s new forest home a secret. Because the caterpillar lives quite high up on grasses, it is vulnerable to being trampled. The reintroduction team are desperate to protect the habitat from butterfly lovers – like me.
Back in the early 1990s, I was one of a few obsessives to discover the location of Site X, where the large blue was first reintroduced. My dad and I travelled 450km to visit, and were promptly ejected by a watchful warden, who refused to confirm or deny the butterfly’s presence. “They managed to keep Site X secret for about 20 years,” marvels Bourn. “We just can’t do that these days.”
There’s so much more interest in butterflies today, in this age of social media gossip and vibrant local butterfly groups.
This butterfly moves like a miniature Time Lord, vanishing and then suddenly reappearing.
“We hope if we can keep a lid on it for a year, then we can put caterpillars into a second site as soon as possible, one that isn’t known and visited,” says Bourn.
What are the chances of success? Bourn is bullish. “We’re quite confident that the caterpillars will establish,” he says. Lynne Farrell is more cautious. “A bit less than 50/50,” she says. “But by recreating rotational management and opening up rides, even if they don’t get chequered skippers, they might end up with half of our 14 other target species.” The Back from the Brink money covers four years. “That’s a very, very short time in ecological terms,” cautions Farrell. “So yes, they need more funding!”
For all the challenges, “this is dream stuff really,” as Wyldes puts it. Reviving the chequered skipper is what drives amateur and professional conservationists alike: not just saving what little is left, but restoring habitat and populating the gaps in our countryside with the buzzing, flitting, marauding diversity of life that should be enjoying it.
PATRICK BARKHAM
is a nature writer and author of Butterfly Isles and Coastlines (both Granta).
FIND OUT MORE
Discover more about Butterfly Conservation, which turns 50 this year: www.butterflyconservation.org.