How have these long-lost butterflies and moths been resurrected from regional extinction?
PUBLISHED: 06:00 28 September 2019 | UPDATED: 08:45 28 September 2019
Some of East Anglia's long-lost butterflies and moths are making a comeback after decades of regional extinction. But what has caused this sudden resurrection? CHRIS HILL reports.
A raft of rare butterflies and moths have re-emerged after decades of apparent extinction in East Anglia - encouraged back by habitat restoration work and a warming climate.
This summer's resurgent wildlife includes the first sighting of the purple emperor butterfly in Norfolk's largest ancient woodland at Foxley Wood since the 1970s - 50 years after it was declared extinct in the county.
Meanwhile, the silver-washed fritillary and the white admiral have both recently been spotted at Wheatfen Nature Reserve, near Surlingham on the Norfolk Broads, where they have been absent for 70 years and a decade, respectively.
And the spectacular Clifden nonpareil moth, regarded as a "holy grail" among moth enthusiasts, has also been spotted again across East Anglia, half a century after it was believed to have been lost as a breeding resident in the UK.
The moth has a wingspan that can reach almost 12cm and a vivid blue stripe, which gave rise to its alternative name of the Blue Underwing - but which also made it a valuable target for Victorian butterfly collectors.
Like many lost species, conservationists say it also suffered from habitat loss and the growth of intensive agriculture. But with more sympathetic land management in recent years, coupled with a more favourable climate, the moth has joined the list of species making a comeback.
There have been numerous sightings recorded across the south of England this year, where it has recolonised and is breeding again.
Although it has not yet been confirmed if the moths are breeding again as Norfolk residents, there have been four confirmed sightings in the county this year, plus another possible one, meaning there is a good chance of beating the record of seven migrant moths spotted in the hot summer of 1976.
Kiri Stuart-Clarke, a volunteer at the Norfolk branch of the charity Butterfly Conservation, said: "The Clifden nonpareil used to live and breed in the Broads until the 1930s, but it was collected out of existence. It was a Victorian butterfly collector's dream because of its blue stripe.
"The ones that we see in Norfolk and Suffolk now are migrants from the continent, but there is no reason to suggest they would not breed here again, because they did up until the 1930s."
She said the wider trend of butterflies and moths returning from regional extinction was due to a combination of factors - including a rare positive outcome from climate change.
"The collecting has died away and there has been a lot of amazing habitat restoration work on nature reserves at places like Foxley and Wheatfen," she said.
"The climate is helping too. Butterflies like warmer conditions than we might have had historically. If more numbers are starting to appear on the continent we get the benefit of that, as population density can trigger migration.
"People have learned a lot about land management as well. When we had a phase of very intensive farming and pesticide use, it did wipe out some of the low-density species like the purple emperor. But there have been great improvements in land management since then, so things are coming together to help these species."
The return of the purple emperor to Foxley Wood was attributed to the Norfolk Wildlife Trust's restoration of the woodland, recreating the habitats which were lost when large parts of the wood were converted to a conifer plantation in the 1960s. The felling of large oaks triggered the decline and disappearance of the butterfly from what was once a breeding stronghold.
At Wheatfen, warden Will Fitch has tailored the woodland management to re-introduce lost species, resulting in the long-awaited return of the rare silver washed fritillary and white admiral which have re-joined more than 20 butterfly species at the reserve.
"I am thrilled to see the return of these stunning butterflies to Wheatfen and owe a great deal of thanks to the many hours of hard work undertaken by the volunteers to ensure these species thrive," he said.
Mr Fitch said 2019 has also been a bumper year for moths too and two particular species - the tree lichen beauty and white pont - have both immigrated from the continent in their thousands during a successful breeding year.