A comma butterfly on a field scabious flower. © HeitiPaves/iStock
Although the summer brought conditions that usually help butterflies to thrive, being warmer than average and quite dry, results from the count found that the majority of butterfly species in the UK had fallen, with some producing their worst numbers since the scheme began in 2010.
Some widespread species experienced their worst summers since 2010, with numbers of comma butterfly down by 46 per cent, gatekeeper numbers down by 40 per cent, and small copper by 30 per cent.
Small tortoiseshell and peacock butterfly species also saw a sharp drop and were down by 47 per cent and 42 per cent respectively on the previous year.
As yet, it is unclear just why butterfly species suffered more this summer when the weather should have enabled them to flourish.
Even more puzzling is that their numbers were even lower this year than in summer 2012, which was a particularly cold, wet summer; conditions that butterflies generally struggle in.
Butterfly Conservation’s Head of Recording, Richard Fox, theorised that the very mild winter or cold spring may have had a particularly negative effect on the insects, or that intensive farming practices could have hit species hard.
But although some butterfly populations suffered a decline, others fared better, including the red admiral, which was up by 70 per cent compared to 2015, and experienced its highest abundance yet since the count began.
This year, the Big Butterfly Count clocked 38,237 counts logged by 36,000 people, spotting around 390,000 butterflies during a three-week period in midsummer.
As the count continues, it aims to shed more light on the mystery of why certain species are hit harder than others.
“The importance of Big Butterfly Count is that it takes place every year over a long period,” said Fox.
“The longer it goes on the more we can learn about the causes that are driving the declines and in some cases, increases of our beautiful butterfly species.”
See the full results of the study at Big Butterfly Count.
Read more wildlife news stories in BBC Wildlife Magazine