The butterfly effect

Butterflies bounce back to their best year in over 20 years

THE unusually warm and wet summer last year gave Britain’s butterfly population a muchneeded boost, with just over half of species increasing in number between 2018 and 2019.

The latest results of the annual UK Butterfly Monitoring Scheme (UKBMS) show that 2019 was the best year for butterflies for over 20 years.

Of the 58 species that regularly occur in the UK, 28 saw their numbers increase last year - making it the best year overall since 1997.

Four species had their best year on record - Chequered Skipper (up 175% compared to 2018), Marbled White (66%), Orange-tip (63%), and Brimstone (32%).

Other summer flying species to particularly benefit included Large Blue (which was up by 1,000% compared to when monitoring started in 1983), Silver-spotted Skipper (up by 633% since 1979), and Clouded Yellow (up by 586% since 1979) .

As well as this, Painted Lady numbers went up by a massive 1,993% in a single year to their third highest number since 1976.

Meanwhile, the rare Lulworth Skipper, which is restricted to the Dorset coast and has been in freefall in recent years, rallied with its annual abundance up by a whopping 138%.

It wasn’t all good news for summer flying butterflies, however.

The Common Blue dropped in annual abundance by 54%, Adonis Blue by 40%, Green-veined White by 43% and Large White by 40% - with all four species having below average years.

Of particular concern is the rare Heath Fritillary, which is restricted to a tiny number of sites in southern England, saw its numbers drop by 34%.

This ongoing decline raises fears for the long-term future of the butterfly, whose numbers have fallen by a shocking 91% due to the cessation of traditional management practices.

Professor Tom Brereton, Associate Director of Monitoring and Research at Butterfly Conservation said: “The results from the 2019 season are really encouraging and provide evidence that the overall rate of decline of butterflies is slowing and for some species being reversed.

“Reasons for this include positive conservation through agrienvironment schemes, increased woodland cover, climate warming, increases in grazing levels by wild animals and a slowing in the rate of agricultural intensification.

“We’re really heartened to see a shift in the fortunes of many of our most loved species. Encouragingly a number of Priority Species such as Adonis Blue, Brown Hairstreak,

Dingy Skipper, Large Heath, Marsh Fritillary, Silver-studded Blue, Small Blue and the Silver-spotted Skipper that have been the focus of intensive conservation efforts in recent decades by Butterfly Conservation and partners are no longer in longterm population decline.

“The long-term situation for butterflies in general does remain a cause of concern though, with more species declining than increasing since the 1970s.”

The UKBMS has run since 1976 and involves thousands of volunteers collecting data through the summer.

Last year 3,014 sites were monitored across the UK, with this record level exceeding 3,000 sites for the first time.