Threatened Heath Fritillary Butterflies See Major Population Increase in England

There is new hope for one of the rarest butterflies in the UK as a surge of heath fritillary butterflies (Melitaea athalia) has been observed in parts of England this spring and summer.

As The Guardian reported, the number of heath fritillary butterflies seen in England, particularly in Exmoor, is on the rise following a sunnier spring and improved habitat conditions.

This year, there have been around 1,000 of the butterflies spotted at the National Trust Holnicote Estate, up from 600 butterflies in 2024.

At another small site, there are now at least 186 heath fritillary butterflies, up from four butterflies in 2024, The Guardian reported.

“It’s wonderful to see such strong numbers of Heath Fritillary on Exmoor this year. They’ve clearly benefited from the warm, sunny spring, emerging as adults weeks ahead of schedule,” Jenny Plackett, South West England conservation manager at the nonprofit Butterfly Conservation, said in a statement. “We’ve recorded butterflies at several new sites, including areas where they haven’t been seen since the 1990s.”

According to The Wildlife Trusts, the heath fritillary butterfly was on the brink of extinction in the UK in the 1970s. The number of butterflies declined 90% from 1981 to 2019 and their distribution declined 58% from 1995 to 2019, Butterfly Conservation reported. Major efforts from conservationists have helped prevent the rare butterfly from going extinct in the UK altogether.

The species remains endangered under the GB Red List and is found within sites at Somerset, Devon, Cornwall in southwestern England and Kent in southeastern England. Conservationists have also reintroduced some butterflies at sites in Essex.

Together, National Trust and Butterfly Conservation have made strides to improve habitats to attract the butterflies and increase their population. As The Guardian reported, conservationists have established grazing cattle and other vegetation management tactics, which have helped establish the sunnier site conditions along woodlands that the butterflies prefer.

However, the surge in butterflies this year also came earlier than their usual cycle of emergence, which brought up some concerns for conservationists.

Basil Stow, a National Trust ranger at the Holnicote Estate, said that “the early emergence is a mixed blessing. If unsettled weather follows, it could cut short the butterfly’s flight season and disrupt its life cycle.”

“It’s a reminder of how delicately balanced nature is and how climate extremes can threaten even our most carefully-managed landscapes,” Stow added.

Rounding off #InsectWeek with more good news! 📰 More than 1,000 Heath Fritillaries have been recorded so far this year on National Trust’s Holnicote estate in Somerset. This is a significant rise from around 600 at the same time last year. Full story 👉 buff.ly/8f1ervl 📷: Jen Spittle Photography

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— Butterfly Conservation (@savebutterflies.bsky.social) June 29, 2025 at 7:27 AM