Butterflies bounce back
Butterflies have bounced back to a 20-year high. The latest results from the annual UK Butterfly Monitoring Scheme (UKBMS) reveal that the winged insects had their best year since 1997.
It is believed a combination of an unusually warm and wet summer was behind the boom. This helped not only adults to emerge but also aided the development of butterflies in their early life cycle.
The UKBMs also showed just over half of UK butterfly species showed higher population levels in 2019 compared with 2018.
The annual survey, which dates back to 1976, is a joint effort between Butterfly Conservation, the UK Centre for Ecology & Hydrology, the British Trust for Ornithology and the Joint Nature Conservation Committee.
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.”
He said the reasons behind it included environmentally-friendly agricultural schemes, increased woodland cover, climate warming, increases in grazing levels by wild animals and a decline in the rate of intensive farming.
There were several winners this year. The marbled white butterfly had its best year in the survey’s 44-year history. Its annual abundance was up by 66%. While the ringlet had its second best year in the series (up 23%), and the dark green fritillary had its third best year (up 51%).
It was also a strong year for two of our three regular migrant butterflies which undergo periodic influxes. Painted lady numbers were up by a massive 1,993%, its third best year in the series. While the red admiral’s annual abundance was up by 195%, its fifth best year in UKBMS’ history.
Prof Brereton added: “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 silverspotted skipper that have been the focus of intensive conservation efforts in recent decades by Butterfly Conservation and partners are no longer in long-term population decline.” But he sounded a note of caution as not all butterflies are thriving.
He said: “The longterm situation for butterflies in general does remain a cause of concern though, with more species declining than increasing since the 1970s.”
Losers in the 2019 survey included some of our most common and most colourful species. The common blue dropped in annual abundance by 54%.
The large white and the green-veined white also fell by 40% and 43%, respectively. Of particular concern is the rare heath fritillary, which is restricted to a tiny number of sites in southern England. This butterfly saw its annual abundance drop by 34%. The butterfly’s ongoing decline raises fears for its long-term future.
But it was better news for the The rare Lulworth skipper, which was up by 138%, and the Duke of Burgundy, which bounced back to have its eighth best year in the series.
The survey was conducted by thousands of volunteers collecting data throughout the summer. Last year a record 3,014 sites were monitored across the UK.