Butterfly Numbers Are Dropping But Here Are Five Species You May See More Of
Climate Change and Butterfly Adaptation
Over the past 50 years, milder and sun-drenched conditions have enabled certain British butterfly species to thrive, partly due to climate change. However, the broader trend reveals a concerning decline among many of the UK’s most iconic butterflies. The UK Butterfly Monitoring Scheme (UKBMS), a key initiative tracking insect populations, has shown that 33 out of 59 native species are experiencing population drops, while 25 have seen improvements. One species, found in mountainous regions, lacks enough data for a clear assessment.
Monitoring the Butterfly Population
The UKBMS, established in 1976, has gathered over 44 million records from 782,000 volunteer surveys. This makes it one of the most extensive and long-standing citizen science projects in the world. Volunteers have traversed more than 932,000 miles across over 7,600 sites, contributing to a comprehensive snapshot of butterfly dynamics. The data underscores a stark split between species that adapt well and those that depend on specific environments.
Species Showing Improvement
Some butterflies have benefited from the warming climate. The Red admiral, for example, has become a winter resident in the UK, a shift linked to milder temperatures. Comma butterflies, known for their frayed wing edges, have rebounded since the survey began. Orange tip numbers have risen by over 40% since 1976, and the Black hairstreak, once critically rare, is recovering due to targeted conservation. The Large Blue, declared extinct in 1979, has also seen a resurgence thanks to habitat restoration efforts.
Experts Highlight Environmental Shifts
“The data collected over five decades is extraordinary and sets a global benchmark for wildlife tracking,” says Prof Jane Hill, a butterfly specialist at the University of York. She notes that butterflies, being cold-blooded, perform better in warmer climates. “Most British butterflies reach their northern range limit within the UK, so they have potential to spread further into northern England and Scotland,” she adds.
Conversely, butterflies reliant on specialized habitats—like woodland clearings or chalk grasslands—are struggling. As these environments face threats from land-use changes and habitat loss, species dependent on them are declining rapidly. The white-letter hairstreak, whose caterpillars emit a glow under UV light, has dropped by 80% since the scheme started. The pearl-bordered fritillary, which feeds exclusively on violets, has also declined by 70%.
Challenges for Conservation
Even adaptable butterflies face mixed outcomes. The small tortoiseshell, once widespread, has declined by 87%. “We’ve lost variety and diversity in butterfly communities much like traditional skills on high streets,” observes Prof Richard Fox, head of science at Butterfly Conservation. The success of conservation efforts hinges on maintaining diverse habitats, particularly in response to intensified farming and environmental degradation. Some species, such as the Duke of Burgundy, rely on specific plants like primroses and cowslips, making them vulnerable to habitat simplification.
The Role of Volunteers
Steve Wilkinson, director of the Joint Nature Conservation Committee, emphasizes the importance of the volunteer-driven data. “Without this evidence timeline, we would be flying blind,” he says. The continuity and quality of the UKBMS’s records depend entirely on public participation, enabling precise tracking of conservation progress and gaps. Projects like Butterfly Conservation’s Magdalen Hill Downs reserve aim to preserve a variety of habitats, addressing the needs of species with particular dietary requirements.
