Of the 57 species studied in 2016, 40 experienced a decline since the previous year, revealed the annual UK Butterfly Monitoring Scheme (UKBMS) in its latest report.
Many species, including the grizzled skipper, wall, grayling, white-letter hairstreak, white admiral and the highly threatened heath fritillary, all recorded their worst ever years.
The heath fritillary saw numbers fall by 27% since 2015, and 82% in the last decade, while seven of the eight specie of skipper fell in numbers compared to 2015.
“Worryingly, not even the pleasant summer weather of 2016 was enough to help butterflies bounce back from a run of poor years,” said Professor Tom Brereton, head of monitoring at Butterfly Conservation.
In spite of the warm, dry summer, the study suggests that a mild winter followed by a cold spring created the conditions that contributed to the drop in both rare and common species.
“The results show that butterflies are failing to cope with our changing climate and how we manage the environment. As butterflies are regarded as good indicators of environmental health this is hugely concerning for both wildlife and people,” Brereton added, before going on to say that the declines have “knock-on effects to their ecosytems.”
In spite of the overall decline, some species have experienced an incline in numbers. The large blue, previously extinct from the UK, rose by 38% since 2015, its second best year on record, while the widespread red admiral recorded a rise of 86%.
The UKBMS, established in 1976, relies upon thousands of volunteers for its data collection. Last year a record 2,507 sites were monitored across the UK.
“We are really grateful to the thousands of volunteers who get involved in monitoring the UK’s butterflies,” said Anna Robinson, monitoring ecologist at the Joint Nature Conservation Committee.
The evidence provided by the UKBMS is of great importance in showing the need for conservation action to improve the situation.”
For more information, visit the Butterfly Monitoring Scheme website.
Image: Heath Fritillary/Credit:Getty