Butterflywatch: rare high brown fritillary thrives on Dartmoor

The high brown fritillary has also responded well in recent summers on its remaining sites in Exmoor and south Wales. Photograph: Matthew Oates/National Trust Images/PA

There always seems to be one British butterfly species in a death spiral towards extinction. The Duke of Burgundy was on the brink but targeted conservation action has brought a surge in numbers over recent seasons.

Over the last decade, the disappearance of the high brown fritillary has most worried butterfly lovers. It experienced a 96% decline since the 1950s – a once-common wood-edge butterfly turned into a rare species.