SUMMER 2019 provided a welcome boost to butterfly populations, according to the latest survey.

In their best year since 1997, just over half of UK species showed higher numbers in 2019 compared with 2018, making it the eighth best year in the 44-year series.

Butterflies most likely benefited from an usually warm and wet summer.

Summer flying species benefitting included the marbled white, which had its best year in the series with annual abundance up by 66%, ringlet (second best year, up by 23%), dark green fritillary (third best year, up 51%), and meadow brown (fifth best, up 38%). The rare Lulworth skipper, restricted to the Dorset coast which has been in free fall in recent years rallied with its annual abundance up by a whopping 138%.

It wasn’t all good news for summer flying butterflies though as the common blue dropped 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. It fell by 34%, raising fears for the long-term future of the butterfly whose numbers have fallen by 91% due to the ending of traditional management.

However, 2019 was an excellent year for two of our three regular migrant butterflies which undergo periodic influxes, with red admiral annual abundance up by 195% (making it the fifth best year in the series) and painted lady numbers up by a massive 1993% (third best year in the series).

Other well-performing species included several spring flying species such as the chequered skipper which was up by 175%, orange-tip, up 63%, and brimstone, up 32%, all of which had their best year on record. The threatened Duke of Burgundy also bounced back to log its 8th best year. These species were all likely to have benefited from warmer than average spring weather, whilst the Duke of Burgundy is benefitting from targeted efforts.

The survey comes from the annual UK Butterfly Monitoring Scheme led by Butterfly Conservation, the UK Centre for Ecology & Hydrology, British Trust for Ornitholog and Joint Nature Conservation Committee.

Prof Tom Brereton, associate director of monitoring and research at Butterfly Conservation said: “The results from 2019 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 agri-environment schemes, increased woodland cover, climate warming, increases in grazing levels by wild animals and a slowing in the rate of agricultural intensification.

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

Dr Marc Botham, of the UK Centre for Ecology & Hydrology, said: “The analysis shows a wide range of species benefited from a couple of warm summers. In addition to record numbers of spring species such as orange-tip and brimstone, it was also encouraging to see annual increases in garden favourites such as peacock and small tortoiseshell, after some poor years recently.”

“Despite this, some wider countryside species such as Wall and Small Skipper remain at low levels compared to what they used to be.”