More than half a century after the Dartford warbler almost vanished from the English countryside, the charismatic heathland bird appears to be staging a comeback.

A survey has revealed the highest number of Dartford warblers ever recorded on reserves run by the bird conservation charity RSPB, with 264 pairs counted in 2025, a 44% increase in five years.

Dartford warblers are small birds that may be glimpsed perched on top of gorse singing a scratchy song, and are found on lowland heathland in southern England.

They are grey-brown, with a distinctive red eye ring, russet breast and long tail. They are particularly sensitive to harsh winter weather and, as a ground-nesting species, rely on dense gorse in areas of mature heathland for food and shelter.

In the 1960s their population crashed, leaving only a few pairs in Dorset and the species on the brink of extinction in England.

The RSPB says their comeback is thanks in part to conservation efforts by nature reserve staff and volunteers to restore the birds’ heathland habitat. A heathland birds survey puts the UK population at approximately 4,100.

Lowland heathland is one of the most threatened habitats in the UK, with 80% lost since the 1800s owing to forestry and change of land use, the RSPB said.

To help counter this, RSPB staff and volunteers have been restoring the habitat on nature reserves by removing conifer plantations, reverting arable land to heath, and joining up areas of fragmented heathland, providing Dartford warblers with the dense gorse they need.

Spiky gorse provides a safe nesting place and hunting ground for the warblers, which specialise in picking spiders and caterpillars from their hiding places.

Dartford warblers were recorded at 14 RSPB nature reserves, including 97 pairs at RSPB Arne, in Dorset.

Peter Robertson, the reserve’s senior site manager, said: “Restoration of heathland across RSPB Arne has been on a landscape scale. Staff and volunteers have helped connect and enlarge fragmented patches of heathland to give wildlife, such as the Dartford warbler, the space to thrive. The sound of Dartford warblers singing is everywhere now.”

Other pairs counted were at RSPB Aylesbeare, in Devon (25), RSPB Minsmere (41) and RSPB North Warren (17), both in Suffolk, RSPB Farnham Heath, in Surrey (23) and RSPB Broadwater Warren, in Kent (15). The last two reserves were conifer plantations 20 years ago.