Butterfly numbers are dropping but here are five species you may see more of

Butterfly numbers are dropping but here are five species you may see more of

Over the past five decades, rising temperatures and ample sunlight have supported the survival of certain British butterfly species, as revealed by the UK Butterfly Monitoring Scheme (UKBMS). This long-term project, which has compiled over 44 million observations from 782,000 volunteer surveys since 1976, highlights a critical shift in butterfly populations. While some species are thriving, the overall trend shows significant declines for many of the UK’s iconic butterflies.

The UKBMS data reveals that among the 59 native species tracked, 33 are in steep decline, 25 have seen population growth, and one mountain species lacks sufficient data for assessment. Notable increases include the Red admiral, now overwintering in the UK due to milder conditions, and the Comma butterfly, which has rebounded since the survey began. The Orange tip’s numbers have risen by more than 40%, while the Black hairstreak, once rare, is recovering from targeted conservation efforts.

Conversely, the Large Blue butterfly has made a remarkable comeback after being declared extinct in 1979. This revival underscores how conservation initiatives can reverse population drops. However, the findings also point to a growing split between adaptable species and habitat specialists. Butterflies that thrive in diverse environments—such as farmland or urban gardens—are better equipped to handle climate shifts, while those dependent on specific ecosystems, like woodland clearings or chalk grasslands, are struggling.

“The data collected by the scheme over five decades is extraordinary,” says Prof Jane Hill, a butterfly specialist at the University of York. “It sets a gold standard for wildlife surveys globally.”

Prof Hill explains that butterflies, being cold-blooded, are particularly responsive to warming conditions. This allows species near their northern range limits to expand into areas like northern England and Scotland. Yet, specialists face challenges as their preferred habitats shrink due to land-use changes and environmental pressures. Without suitable new spaces, these species cannot adapt quickly enough, leading to sharp declines.

Among the most affected are the white-letter hairstreak, whose caterpillars emit a glow under UV light, and the pearl-bordered fritillary, which relies on violets for its larvae. Both have seen population drops of 80% and 70%, respectively. Even adaptable species, like the small tortoiseshell, are experiencing declines of 87%, illustrating the complexity of the situation.

“Just as traditional high street shops and skills have disappeared, so too have the diverse butterfly communities once found in our landscapes,” notes Prof Richard Fox, head of science at Butterfly Conservation.

Steve Wilkinson, director of the Joint Nature Conservation Committee, emphasizes the importance of the UKBMS’s long-term dataset. “Without this evidence timeline, we would be flying blind,” he says. The project’s success relies on the dedication of volunteers, who have collectively logged over 932,000 miles across more than 7,600 sites.

Conservation efforts now focus on preserving and expanding habitats, especially in response to agricultural intensification and habitat loss. Some species, like the Duke of Burgundy, depend on narrow food sources—primroses and cowslips—making their survival increasingly fragile. Initiatives such as Butterfly Conservation’s Magdalen Hill Downs reserve aim to create varied environments that support a broader range of species.