small pearl-bordered fritillary


A large-scale planting of marsh violets is set to take place across the Shropshire Hills in England to halt the decline of the small pearl-bordered fritillary, Boloria selene, a rare UK butterfly.

The small pearl-bordered fritillary’s UK distribution has plummeted by 71% since the mid-1970s, and the species is now classified as vulnerable, according to the 2022 State of UK Butterflies report.

The National Trust hopes this planting will enhance habitats for the butterfly and other rare species such as snipe, curlew, and devil’s bit scabious flowers.

Once abundant until the 1950s, the small pearl-bordered fritillary populations have suffered due to factors including global warming, which forced colonies to move north and west, wetland drainage reducing their habitats, and changes in land management that allowed rushes to overtake marsh violets, according to Charlie Bell, a National Trust project manager.

Small pearl-bordered fritillary caterpillars thrive on marsh violet leaves, and the adults lay their eggs on these plants.

“The caterpillars hatch out into a ready-made buffet, they don’t really need the flowers.” The butterflies ignore the flowers too, feeding instead on nectar from other plants such as brambles, marsh thistles and ragged robin flowers, she said.

“There might be a few populations … then one gets wiped out and the distance between the remaining populations is too great for them to mix.” That situation left individual colonies isolated and vulnerable to extinction. “Ideally, there’d be lots of small populations and movement between them to keep them healthy.”

The butterflies themselves feed on nectar from plants like brambles, marsh thistles, and ragged robin flowers, ignoring the violet flowers.

By planting marsh violets near existing fritillary colonies, the project aims to boost the caterpillars’ food supply and reconnect fragmented groups. While there is hope that the butterflies might start laying eggs this June or July, it is more likely that they will begin using the new marsh violets next summer, Bell said.

This National Trust-led initiative plans to plant 20,000 marsh violets this year, with about 3,000 being planted today and the rest after the summer.

“We are trying to see what works and learn lessons from this spring planting. We will be monitoring the plants so we can tweak our technique if we need to, for the autumn planting,” Bell said.

The project also involves the Shropshire Wildlife Trust, Natural England, the Shropshire Hills National Landscape Partnership, landowners, and volunteers.

Dave Wainwright, head of conservation for England at the charity Butterfly Conservation, welcomed the project, saying it was “on a scale that it needs to be, to really make a difference for the small pearl-bordered fritillary”. The trick, he said, was to find the conditions that suited the marsh violets and allowed them to survive. “This idea of connecting patches in the landscape is really crucial so if one patch becomes unsuitable then the butterflies have an alternative habitat,” he added,

ohn Tilt, of the West Midlands Butterfly Conservation group, also welcomed the project. “It’s a butterfly that’s quite common in Scotland but is now lost from the Malvern Hills and some of the rest of the West Midlands more generally. They are a very beautiful species,” he said.

Previously, the small pearl-bordered fritillary benefited from the common practice of coppicing, where some woodland trees were felled to let in light and create bare ground for marsh violets to thrive. This practice declined in the 1940s and 1950s, contributing to the butterfly’s decline.



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