Scottish butterflies join conservation Red List as species face rising extinction threat

Some of the best loved butterflies in Scotland and the UK are facing an increased risk of extinction, the latest assessments show.

More than one in every three Scottish butterflies and nearly half of all UK species are now under threat as declines continue, according to the new conservation Red List for the insects.

Two species found north of the border have been added to the list for the first time.

Compiled by scientists from the charity Butterfly Conservation, using data gathered from across the nation, the list grades all butterfly species that have bred regularly in Britain against strict criteria set out by the International Union for Conservation of Nature.

It shows four out of the 62 species assessed are already extinct and 24 are now classed as threatened, including eight flagged as endangered and 16 as vulnerable.

A further five are graded near-threatened.

Out of 37 species found north of the border, 13 – 35 per cent of the total – are on the Red List.

Of these, ten are now classed as threatened – three of them endangered and seven vulnerable – and three as near-threatened.

Another species found in Scotland, the wall butterfly, has gone from near-threatened to endangered in a decade. Picture: Iain H Leach

The Scotch argus, graded as vulnerable, and the dark green fritillary, considered near-threatened, which are both found in Scotland, have appeared on the danger list for the first time.

Meanwhile, the grayling and large heath have both moved from vulnerable to endangered in the past ten years, while the wall butterfly has gone from near-threatened to endangered over the same period.

But there has also been some positive movement.

Two butterflies found in Scotland have been added to the Red List for the first time – including the Scotch argus, which is graded as vulnerable. Picture: Tim Melling

Two Red List species found in Scotland have bucked the trend of decline – the pearl-bordered fritillary and white-letter hairstreak have seen their gradings improve from endangered in 2010 to vulnerable in the most recent list.

The four UK species which continue to be classed as extinct are the black-veined white, large tortoiseshell, large copper and mazarine blue.

Experts say the latest Red List demonstrates a worrying increase in the number of species in danger of disappearance from British shores, jumping by 26 per cent nationwide over the past decade.

Dr Richard Fox, head of science for Butterfly Conservation, said: “Shockingly, half of Britain’s remaining butterfly species are listed as threatened or near-threatened on the new Red List.

The grayling butterfly, among 37 species assessed in Scotland, has been classified has has its risk of extinction raised from vulnerable to endangered in the latest Red List, which was last updated 10 years ago. Picture: Iain H Leach

“Even prior to this new assessment, British butterflies were among the most threatened in Europe, and now the number of threatened species in Britain has increased by five, an increase of more than one-quarter.

“While some species have become less threatened, and a few have even dropped off the Red List, the overall increase clearly demonstrates that the deterioration of the status of British butterflies continues apace.”

Changes in land use remain the most important driver of decline, according to the charity, but the impact of climate change on butterflies is also evident in the new Red List.

All four British butterflies with northerly distributions, which are adapted to cooler or damper climates, are now listed as threatened – the large heath, Scotch argus, northern brown argus – or near-threatened – the mountain ringlet.

Seven species have moved from near-threatened to threatened, including the striking swallowtail and Adonis blue.