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

A half-century of citizen science data has revealed a stark divide in the fortunes of British butterflies, with adaptable species flourishing in a warming climate while habitat specialists suffer alarming declines. The findings, released by the UK Butterfly Monitoring Scheme (UKBMS), draw on more than 44 million records gathered from 782,000 volunteer surveys since 1976, making it one of the largest and longest-running wildlife monitoring projects in the world. Of the 59 native species monitored, 33 have declined, 25 have improved, and one mountain species has too little data to assess. The results highlight what Butterfly Conservation describes as a growing gulf between generalist species that can thrive across varied environments and specialists tied to specific habitats. Several species have benefited significantly from increasingly warm and sunny weather driven in part by climate change. Red admirals, some of which now spend winter in the UK rather than migrating, are among the winners. Comma butterflies, distinguished by their ragged wing edges, have recovered substantially since the survey began. Orange tip numbers have risen more than 40% since 1976. Conservation efforts have also yielded notable successes. The Black hairstreak, one of the UK's rarest butterflies, is recovering thanks to targeted habitat work. The Large Blue has bounced back after being declared extinct in 1979, also through dedicated conservation programmes. Prof Jane Hill, a butterfly expert at the University of York, describes the data collected over the last five decades as "extraordinary" and says it represents a gold standard for wildlife surveys worldwide. She explains that because butterflies are cold-blooded insects, they generally thrive in warmer conditions. "Most British butterflies reach their northern range limit in the UK, so they have opportunities to expand further north into northern England and Scotland," she adds. However, butterflies whose lifecycles are tied to specific habitats such as woodland clearings or chalk grasslands are struggling. Many are declining at alarming rates as those environments come under pressure from land-use changes, including farming intensification. They are failing to expand their ranges because of a lack of suitable new habitats to colonise. The losses have been dramatic. The white-letter hairstreak, whose caterpillars glow under ultraviolet light, has fallen by 80% since monitoring began. The pearl-bordered fritillary, a striking orange-and-black butterfly whose caterpillars feed only on violets, has declined by 70%. Even among more adaptable butterflies, the picture is mixed: the once-common small tortoiseshell has plummeted by 87%. "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," said Prof Richard Fox, head of science at Butterfly Conservation. The scale of the dataset reflects an enormous public effort, with volunteers walking more than 932,000 miles across more than 7,600 sites. "Without this evidence timeline, we would be flying blind," said Steve Wilkinson, director of the Joint Nature Conservation Committee, which advises the four UK governments and helps run the UKBMS. "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," he said. Conservation challenges are compounded by how particular some butterfly species are about their food sources. Many have evolved to rely exclusively on one or two specific plants: the Duke of Burgundy on primroses and cowslips, the purple emperor on goat or grey willow. This is why Butterfly Conservation's Magdalen Hill Downs reserve aims to sustain a diverse range of habitats, explains the charity's reserves officer, Fiona Scully. Pointing across chalky fields covered with blooming cowslips, she lists just some of the native plants thriving there: "Lady's bedstraw, toadflax, betony, scabious, knapweed – we've just got so many." It is this variety that makes the site a stronghold for butterflies, she says. Despite these efforts, recent monitoring results underscore the scale of the challenge. Even though the UK experienced its sunniest year on record in 2025, conditions typically favourable for butterflies, it ranked only as an average year for the insects, coming 20th out of the past 50, with no species recording its best year. This pattern echoes findings from Butterfly Conservation's Big Butterfly Count, which saw record participation from more than 125,000 people yet reported only average butterfly numbers per count.