Nature · Birds

Dartford warbler

Resident · 12–13 cm

Curruca undata — Sylviidae (typical warblers)

A small, dark, long-tailed warbler of gorse and heather, and one of very few British warblers that does not migrate. That makes it desperately vulnerable to hard winters: the freeze of 1962–63 cut the British population to about ten pairs. It has since recovered on the lowland heaths of Dorset, Hampshire and Surrey, and it was named from a specimen shot on Bexley Heath near Dartford in 1773.

How to spot them

▸Long tail held cocked up, often at an angle, as it flits between gorse sprigs
▸Slate-grey above, wine-red or maroon below, with a red eye-ring and white flecks on the throat
▸Sings a short scratchy rattle from the very top of a gorse spray, then drops out of sight
▸Resident, not migratory, so it crashes after severe winters
▸Lowland heath with gorse in southern England; a scolding 'tchirr' call

How to know it

Long tail cocked up as it flits low between gorse sprays, slate-grey above and wine-red beneath

Dartford warbler — the cocked tail and maroon underparts are diagnostic.

One of very few British warblers that does not migrate, reduced to about ten pairs by the winter of 1962–63

Dartford warbler — the famous 'Big Freeze' crash.

Named from a bird shot on Bexley Heath in Kent in 1773, in a town it no longer occupies

Dartford warbler — described by Thomas Pennant and John Latham.

Sings a short scratchy rattle from the very tip of a gorse spray before dropping out of sight

Dartford warbler — the song is brief and buzzy, not the whitethroat's fuller scratch.

Recovered to a few thousand pairs on the lowland heaths of Dorset, Hampshire and Surrey, and needs mature gorse to survive winter

Dartford warbler — heathland fires are now a main threat.

A red eye-ring and white throat flecks on a bird otherwise dark as a shadow among heather

Dartford warbler — Curruca undata, formerly Sylvia undata.

Quick-fire facts

•Scientific name Curruca undata (long placed in Sylvia); undata means 'wavy', for the pattern of the throat
•It was named from a specimen shot on Bexley Heath near Dartford, Kent, in 1773 — it no longer occurs there
•The severe winter of 1962–63 cut the British population to about ten or eleven pairs
•BTO BirdFacts gives about 2,200 pairs (2017); the standing national estimate, from the 2006 survey, was 3,214 territories, and the BTO's 2025 Heathland Birds Survey will update it
•Amber-listed in Birds of Conservation Concern 5 (2021) and on Schedule 1 of the Wildlife and Countryside Act 1981
•It is one of very few resident British warblers: most, such as the whitethroat and the willow warbler, migrate to Africa
•Its strongholds are the lowland heaths of Dorset, Hampshire and Surrey, with outposts in Devon, Suffolk and Wales
•It often feeds in the company of stonechats, following them through the gorse
•Heathland wildfire is now one of the greatest threats, along with the loss of the mature gorse it shelters in

Drill it — 8 cards

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Sources

British Trust for Ornithology — BirdFacts: Dartford Warbler
RSPB — Dartford Warbler