May 16
Some of Britain’s most threatened butterflies are showing promising signs of recovery after decades of decline, according to a new study.

Good news for some butterflies

The new data comes from the UK Butterfly Monitoring Scheme, which has been monitoring changes in butterfly populations across the United Kingdom since 1976. The biggest winner of 2010 was the wood white, which has suffered a 96% decline since the 1970s, but whose population increased six-fold last year.

Photo of wood white butterfly on common spotted orchid

The wood white butterfly population increased six-fold in 2010.

The marsh fritillary, in serious decline since the 1950s, more than doubled its numbers between 2009 and 2010, and recent reports suggest that marsh fritillaries are also thriving so far in 2011.

Although Britain’s butterflies remain in long-term decline, the populations of three-quarters of threatened species increased in 2010. This change in fortunes has been put down to targeted conservation action, combined with better weather last year after a series of disastrously wet summers. Butterfly experts hope that if Britain experiences a similar summer this year, some of the country’s most threatened species could continue to make a significant recovery.

Photo of female marsh fritillary butterfly

The marsh fritillary, another butterfly species which did well in 2010.

According to Dr Tom Brereton, Head of Monitoring at Butterfly Conservation, “Over the last decade, Butterfly Conservation has developed a large number of landscape scale projects… to improve and restore habitats for threatened butterflies. This has particularly helped the marsh fritillary and more recently the wood white and some other species too are beginning to recover. It shows these projects are working, given time. This is extremely welcome news and shows that we can reverse butterfly losses if the effort can be maintained.

Many butterflies still under threat

Unfortunately, it was not good news for all species. One of the UK’s rarest butterflies, the Lulworth skipper, had its worst year on record in 2010, as did one of the most common species, the meadow brown. It was also a bad year for migrants, whose numbers were down by 90% from 2009.

Photo of Lulworth skipper feeding

The Lulworth skipper has declined by 93% over the last decade. Habitat management for other butterflies may actually be detrimental to this species.

Although climate change may be benefitting some species due to warmer summers, it could also be bad news for others which need cooler conditions or are unable to adapt to rapid change.

Monitoring long-term trends

More than three-quarters of British butterfly species have declined in recent decades, and nearly half are now seriously threatened. Although many species are still under threat, the results from 2010 come as welcome news for butterfly conservation, and show the importance of long-term monitoring and conservation work.

Photo of painted lady butterfly

The painted lady arrived in the UK in large numbers in 2009, but there was no repeat of this massive immigration last year.

Dr Marc Botham, a butterfly ecologist at the Centre for Ecology & Hydrology, said, “The continued dedication of thousands of volunteers enables us to analyse both short and long-term trends in the abundance of butterflies. Butterflies are highly sensitive to how our countryside is changing and the UKBMS data has revealed how butterflies are already being impacted by climate change as well as whether our conservation measures are working.

Find out more at the Butterfly Conservation website.

View photos and videos of butterflies and moths on ARKive.

Liz Shaw, ARKive Species Text Author