UK Butterfly Monitoring Reveals 33 Declines and 25 Increases Among 59 Species Over 50 Years

# UK Butterfly Populations Show Long-Term Declines More than half of the UK’s butterfly species have seen their numbers fall over the past five decades, according to data from the UK Butterfly Monitoring Scheme. The scheme has collected more than 44 million records over 50 years, tracking 59 species since 1976. Of these, 33 species have declined, while 25 have shown population growth.

Some UK butterfly populations have collapsed by nearly 90 percent over the past five decades. The small tortoiseshell butterfly numbers have fallen by 87 percent since 1976. Pearl-bordered fritillary numbers have dropped by 70 percent since 1976, and white-letter hairstreak numbers have fallen by 80 percent since 1976.

One mountain species has too little data to assess since 1976. The scheme has gathered more than 44 million records from 782,000 volunteer surveys since 1976. Volunteers have walked more than 932,000 miles at more than 7,600 sites for the UK Butterfly Monitoring Scheme.

Species Recoveries Amid Overall Declines The red admiral numbers have risen by 330 percent since 1976.

Orange tip numbers are up more than 40 percent since 1976. The comma butterfly numbers have recovered since 1976. The large blue butterfly has increased by 1,866 percent since 1983. The large blue butterfly was declared extinct in Britain in 1979 and has undergone successful reintroduction after 1979 extinction.

Targeted conservation efforts have helped the silver-studded blue recover, and targeted conservation efforts have helped the black hairstreak recover.

2023 Data Reflects Average Numbers Despite Weather The UK recorded its sunniest year on record in 2023.

In 2023, butterfly numbers were only average overall despite the sunniest year. Over one third of UK butterfly species had below average numbers in 2023. Professor Richard Fox described the findings as 'damning'.

" Professor Fox added that habitat restoration remains critical for species such as the high brown fritillary, northern brown argus and Duke of Burgundy.

Experts Highlight Value of Long-Term Monitoring Dr Marc Botham said: "Butterfly numbers naturally fluctuate from year to year depending on the weather, which is why the UK Butterfly Monitoring Scheme is so important.

" Prof Jane Hill describes the data collected by the scheme over the last five decades as 'extraordinary' and says it represents a gold standard for wildlife surveys worldwide.