SOUTHERN ENGLAND — A 2025 survey recorded 264 pairs of Dartford warblers on Royal Society for the Protection of Birds (RSPB) reserves across southern England, marking a 44% increase over the past five years. The rise is attributed to large-scale heathland restoration efforts by RSPB staff and volunteers.
Dartford warblers, small birds with grey-brown plumage, a red eye ring, russet breast, and long tail, depend on dense gorse within mature lowland heathland for food and shelter. These birds specialize in hunting spiders and caterpillars hidden among spiky gorse, which also provides secure nesting sites. However, they are particularly vulnerable to harsh winter conditions, which have historically threatened their survival.
The species faced near extinction in England during the 1960s, when only a few pairs remained in Dorset. Since then, conservation initiatives have gradually rebuilt their numbers. The current UK population stands at approximately 4,100 pairs, according to a heathland birds survey. In 2025, Dartford warblers were observed at 14 RSPB nature reserves.
RSPB Arne in Dorset hosted 97 pairs—the largest concentration among surveyed sites—followed by 41 pairs at RSPB Minsmere in Suffolk and 25 at RSPB Aylesbeare in Devon. Additional sightings included 23 pairs at RSPB Farnham Heath in Surrey, 17 at RSPB North Warren in Suffolk, and 15 at RSPB Broadwater Warren in Kent.
Both RSPB Farnham Heath and RSPB Broadwater Warren were conifer plantations two decades ago. Restoration work has involved removing non-native tree plantations, converting former arable land back to heath, and linking isolated patches of habitat to create larger, more resilient ecosystems. Lowland heathland—one of the UK’s most endangered habitats—has declined by 80% since the 1800s due to forestry expansion and shifts in land use.
“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,” said Peter Robertson, senior site manager.