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Butterfly species have disappeared from almost half of the places they once flew in the UK since 1976, according to a study.
The distribution of 58 native species has declined by 42% as butterflies disappear from cities, parks and forests. Those found only in certain habitats, such as wetlands or calcareous grasslands, fared even worse, with a 68% reduction in distribution.
Butterfly Conservation scientists, who produced their UK State of Butterflies 2022 report from almost 23m butterfly records, said a “major step change” was needed to reverse a catastrophic decline in insect populations.
The report shows that many of the most threatened species have recovered through targeted conservation action or been successfully reintroduced to specific areas, but butterflies and other flying insects continue to disappear from much of Britain.
“We focused on the most threatened butterfly species, which is stopping them from becoming extinct,” said Richard Fox of Butterfly Conservation, lead author of the report. “But the millions of pieces of data in the report have revealed a huge challenge, and we need a huge change in our approach to tackle this and meet the government’s now legally binding target of halting the decline of to reach wildlife. This report shows that we are not stopping the decline of wildlife.”
The overall figure for the decline in butterfly abundance is a modest 6%, but this average figure is derived from data collected from nature reserves and nature-rich landscapes, which include the wider population decline.
Species such as whitewood, grayling, wallaby, white admiral and pearl warbler have suffered sharp declines in distribution and abundance. The gray distribution decreased by 92% and abundant by 72% between 1976 and 2019.
There have been some successes, related to climate change or concerted conservation action. Among the beneficiaries of global warming, which has facilitated their expansion further north through Britain, are strong-flying species such as the purple emperor, which has seen its distribution up by 58% and abundance by 110%, and the comma, whose distribution has increased by 94%. and abundance by 203%.
Conservation successes include the big blue, which was reintroduced using caterpillars from Sweden after it went extinct in 1979. Its abundance has increased by 1,883%.
But in many cases, although targeted conservation work in certain nature reserves has increased the abundance of rare butterflies, they have always disappeared from other areas, their range is shrinking and their populations have lost resilience as a result.
The swallow has increased in abundance by 51%, doing well in nature reserves that are precisely managed to meet its needs, but its distribution or presence in the wider landscape has decreased by 27%. Chalk grassland specialists such as silver-spotted skipper and blue adonis have increased in abundance by 596% and 130% respectively, but their distribution has fallen by 70% and 44%. This shows that they are no longer able to survive in many of their consequences, and are unable to colonize new areas.
The biggest butterfly declines are in England. The picture looks more positive in Scotland, where species have, on average, increased in abundance by 37% and distribution by 3%.
But Fox said these figures were the reason for the huge success of a few species, such as the wagtail and the white lettered striper, which have managed to move further north with climate change. “It’s not a cause for celebration,” he said. “Butterflies that you might think of as iconic examples of Scotland’s natural heritage, such as the mountain ring, the Scotch argus and the northern brown argus, are doing badly.
“UK butterflies are the best and most comprehensively monitored group of insects anywhere in the world. Butterflies fulfill that very important role as an indicator for thousands of other species and for the general state of our environment. This report makes very grim reading in that regard.
“It will take bold steps from the government and everyone to take responsibility. Everyone with a garden can help, but the biodiversity crisis is such that just planting a few pollinator-friendly plants is not enough. We need to create a habitat where butterflies and other wildlife can live and not just visit for a snack.”
Julie Williams, chief executive of Butterfly Conservation, said: “This report is further evidence of the decline of nature in the UK. We are completely dependent on the natural world for food, water and clean air. We need quick and effective action on this. The decline in butterflies that we have seen in our lifetime is appalling and we cannot stand by and watch the UK’s biodiversity be destroyed.”