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

Butterfly Numbers Are Dropping, But Five Species May Thrive

The UK’s shifting climate, amplified by global warming, has allowed certain butterfly species to thrive in recent decades, according to a major insect tracking initiative. Yet the broader trend reveals a concerning decline among the country’s most iconic species. Data spanning over half a century indicates that many of these butterflies are facing sharp population drops, raising alarms about biodiversity loss.

The UK Butterfly Monitoring Scheme (UKBMS), a pioneering citizen science project since 1976, has amassed more than 44 million records from 782,000 volunteer surveys. This extensive dataset highlights a stark divide in butterfly survival rates, with 33 of the 59 native species showing decline and 25 experiencing growth. One mountain-dwelling species remains inconclusive due to limited data.

Among the species rebounding are the Red admiral, which now overwinters in the UK, and the Comma, whose numbers have surged since the survey began. The Orange tip has seen a 40% increase, while the Black hairstreak, once scarce, is recovering due to targeted conservation work. The Large Blue, previously extinct in 1979, also benefits from habitat restoration efforts.

Adaptability vs. Specialization

Experts note that species thriving in diverse environments—like farmland, parks, and gardens—have fared better than those reliant on specific habitats. Warmer temperatures, linked to climate change, are extending breeding seasons and geographic ranges for adaptable types. However, specialists such as the pearl-bordered fritillary and white-letter hairstreak are struggling, with the latter losing 80% of its population and the former declining by 70%.

“Most British butterflies reach their northern range limit in the UK, so they have opportunities to expand further north into northern England and Scotland,” says Prof Jane Hill, a butterfly researcher at the University of York.

Prof Richard Fox, head of science at Butterfly Conservation, emphasizes the loss of diversity in butterfly communities. “Just as we have lost family-run shops and traditional skills from the nation’s high streets, we’ve lost variety and diversity in the butterfly communities that can exist in our damaged and simplified landscapes,” he adds.

The scale of the dataset underscores the dedication of volunteers, who have collectively traversed over 932,000 miles across 7,600 sites. Steve Wilkinson, director of the Joint Nature Conservation Committee, highlights the importance of this work. “Without this evidence timeline, we would be flying blind,” he says. “Understanding where conservation efforts are making a real difference and where we need to strengthen efforts depends entirely on the quality and continuity of data that our volunteers make possible.”

Conservation strategies focus on safeguarding and expanding habitats crucial for survival, especially as land use changes threaten ecosystems. Challenges persist because some species and their caterpillars depend on narrow food sources, like primroses for the Duke of Burgundy or violets for the pearl-bordered fritillary. Projects such as Butterfly Conservation’s Magdalen Hill Downs reserve aim to maintain varied habitats to support this delicate balance.