Long-Term Survey Reveals Decline in UK Butterfly Species
A volunteer-led survey spanning fifty years has revealed that more than half of the butterfly species in the UK are experiencing declines.
Data from the UK Butterfly Monitoring Scheme indicate that 33 of the 59 butterfly species recorded in the country have decreased in number since 1976.
The scheme, coordinated by Butterfly Conservation based in Wareham along with partner organizations, has compiled over 44 million records through volunteer surveys conducted over the past five decades.
Factors Driving Declines
Experts attribute the long-term declines primarily to habitat loss, pollution, and climate change, with rarer species being particularly affected.
The monitoring programme is the largest of its kind globally and has tracked butterflies at more than 7,600 sites. Volunteers have collectively walked distances equivalent to 40 times around the Earth to gather data.
While some adaptable butterfly species have shown population increases, those dependent on specific habitats such as woodland or chalk grassland are facing significant challenges.
Species-Specific Trends
The Pearl-bordered Fritillary has declined by 70% since monitoring began, and the White-letter Hairstreak has experienced an 80% decrease.
Conversely, species such as the Red Admiral have thrived, with numbers increasing by over 300%, benefiting from warmer temperatures that allow them to survive year-round in the UK.
Despite 2025 being the sunniest year on record, butterfly populations overall had an average year, ranking 20th out of the past 50 years.
Conservation Perspectives
"These figures show what type of wildlife is able to survive in the UK's modern landscapes," said Professor Richard Fox from Butterfly Conservation.
He emphasized that restoring habitats is essential to reversing declines and noted that conservation efforts are becoming "increasingly urgent."
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