A heath in late July, an hour after sunset, and the whole place sounds like a slowed-down clock. Somewhere in the dark a nightjar churrs — a dry, reeling purr that rises, falls, and stops as suddenly as it began. Fourteen hours earlier, on the same patch of gorse, a Dartford warbler scolded you from a bush you had already walked past twice. These two birds are the signatures of lowland heath, and both are easier to find than most people expect — provided you know when to go and how to behave when you get there.

Two Birds, One Fragile Habitat

Lowland heath is not wilderness. It stayed open for centuries because people grazed it, cut it and burned it. When that stopped, birch and pine moved in and the open ground went with it. What survives is a patchwork: heather, gorse, bare gravel, a few scattered trees. That structure is what these birds need, and it explains why they are so fussy.

Nightjars want bare ground to nest on, low vegetation to hide in, and trees to sing from. Dartford warblers want dense, tangled gorse with heather beneath — cover thick enough that you can stand a metre away and never see the bird. Neither does well on tidy, uniform land.

The Nightjar: Heard Far More Often Than Seen

Nightjars arrive from Africa from late April, and by mid-May the males are churring. For most visitors that sound is the encounter: a mechanical, reeling purr, roughly the pitch of a distant engine, delivered from a dead branch or fence post. On a still night it carries for hundreds of metres.

What to listen for

Learn three sounds. The churring song, which changes pitch and speed as the bird turns its head. A soft, repeated "kwoo-eech" flight call, often the first clue that a bird is airborne. And wing clapping — a sharp double crack in flight. Hear all three and you have found a territory, not just a bird.

Where to look

Open heathland, forest rides, and recently felled plantations: anywhere with short vegetation, bare patches and a few song posts. By day, nightjars roost on the ground or lengthwise along a branch, mottled grey-brown and almost invisible, with white bars on the wings and tail of males. Walking a heath in daylight without noticing one is entirely normal.

The Dartford Warbler: Small, Loud, Rarely Cooperative

Dartford warblers live here year-round, so you don't need to wait for spring migrants. They are tiny, long-tailed, and usually seen as a dark shape flicking to the top of a gorse bush before dropping out of sight. The male has a slate-grey head and deep reddish-brown underparts; the female is paler and browner.

Your ears will find them first. Listen for a scolding "churr" or a sharp "tchick" from deep inside the scrub — the sound of a bird telling you it has seen you. On calm, sunny mornings from February to May, males sing from the tops of gorse bushes, a scratchy, hurried warble. Hard winters hit this species badly and numbers take years to recover, which is one reason early spring viewing is a privilege rather than a guarantee.

When to Go Through the Year

• April to early May: Dartford warblers singing and relatively visible; nightjars just arriving, though cool evenings are still poor for churring.
• Mid-May to July: the peak window for nightjars. Warm, still, dry evenings are essential — a breezy night shuts activity down.
• July and August: nightjars still churring, but young birds are on the ground or newly flying, which is exactly when disturbance costs most.
• September: nightjars head south; try calm evenings early in the month.
• October to February: Dartford warbler season. Fewer people, and mild mornings often bring birds up onto gorse tops.

Watching Without Causing Harm

Heathland birds are already squeezed by habitat loss, and well-meant attention can add to it. These rules aren't etiquette for its own sake; they are the difference between watching a bird and changing its behaviour.

• Skip the playback. Taped calls pull birds off feeding and nesting, and they are unnecessary once you know the real thing.
• Use a red torch and keep the beam low. Never sweep it across open ground. If a churring nightjar stops or shifts perch, you are too close.
• Stay on paths. Nightjar eggs and chicks sit on bare ground and are nearly impossible to spot. A short cut across a clearing can end a breeding attempt without you ever knowing.
• Keep dogs on a lead. Ground-nesting birds and curious dogs do not mix.
• Think before posting locations. General area names are fine; precise pins on scarce breeding sites are not.
• Check local rules. Both species have extra legal protection at the nest in the UK, and some reserves restrict dusk access or ask visitors to apply for permits.

What to Take on a Heath Evening

Binoculars, a midge net or repellent in summer, and a warm layer — heaths lose heat fast once the sun drops. Wear long trousers and check for ticks afterwards; heathland in summer is tick country. If you'll be out after dark, tell someone where you're going and stick to marked routes on the way back. A notebook matters more than you'd think: noting time, temperature and wind alongside what you heard is what turns one lucky evening into a repeatable skill.

Your First Trip: A Simple Plan

Choose a reserve with open heath and public access, arrive about forty-five minutes before sunset, and walk slowly to a spot with clear ground and a few trees. Stand still, listen, wait. Churring usually begins half an hour or so after sunset and often pauses again — stay put rather than chasing the sound.

For Dartford warblers, come back on a different morning. Be on site soon after sunrise on a calm, bright day, work along the gorse edges slowly, and stop every hundred metres to listen. If you hear the churr, keep your eyes on the bush rather than the bird. Give it two or three minutes and it will usually show.

Part of the pleasure here is the difficulty: a churring nightjar in near-darkness, a warbler that appears for four seconds. Keep the encounter short, leave the heath as you found it, and come back next year for the same sound.

Photo: StudioFriluma / Pixabay