Spotting waders on an estuary at low tide

The tide decides everything

An estuary at high water looks like an empty sheet of grey. Come back six hours later and the same view is teeming. Waders live by the tide, and low water is when the table is laid: as the sea drains away, it exposes thousands of hectares of mud and sand packed with ragworms, lugworms, cockles, shrimps and small crustaceans. For a few hours, the birds can feed virtually uninterrupted.

The best window is usually from about two hours before low water until an hour or so after the turn, when the flood begins to push the flocks back towards the shore. Spring tides, which occur around new and full moon, expose the widest mudflats and produce the most dramatic concentrations of birds. Neap tides leave much of the mud covered, and feeding flocks stay closer to the channels. Check a tide table for the nearest port and adjust for your own stretch of water — estuaries can differ by forty minutes or more from the reference port.

Reading the mud

Do not simply stare at the middle of the estuary. The action follows the receding water's edge, and waders spread across the mud according to bill length and feeding technique. Long-billed curlews push deep into soft mud; redshanks and dunlins pick and probe at the wet surface; oystercatchers hammer open mussels on the harder, stony beds. Look for subtle shifts in colour — a patch of darker, wetter mud, a shallow channel still draining, or a line of weed along the strandline. These are the larders.

Scan in bands: near water first, then middle distance, then the far shore. Heat shimmer can ruin the view on warm afternoons, so mornings and cooler days are often sharper. If a flock suddenly lifts, note the direction they fly — they are usually heading for the next exposed bank rather than leaving altogether.

What you are likely to see

Estuaries in Britain hold internationally important numbers of waders, and winter is the peak. Expect a mixed cast through the autumn and winter months:

• Curlew — our largest wader, with a long, down-curved bill and a haunting bubbling call. Often solitary or in loose groups, spread across the mud.
• Redshank — noisy, nervous, bright orange-red legs and bill base. Usually the first to alarm and send everything up.
• Dunlin — small, hunched, in tight flocks that wheel low over the water like smoke. Grey above, pale below in winter.
• Knot — dumpy and grey, gathering in dense packs right at the tide edge, sometimes in thousands.
• Black-tailed godwit — tall, elegant, with a long straight bill and a white wing bar in flight.
• Oystercatcher — bold black and white with a carrot-orange bill, piping overhead and working the mussel beds.
• Also watch for grey plover, bar-tailed godwit, turnstone, shelduck, and in winter brent geese grazing the saltmarsh.

Kit that earns its place

Binoculars of 8x42 will get you started, but an estuary is a place where a telescope transforms the experience. A 65mm to 85mm spotting scope on a sturdy tripod, with a 20-60x zoom eyepiece, lets you identify birds several hundred metres out without moving a step closer. Set it up low if you can, and use a hide where one is available — many estuary reserves have hides positioned beside a roost or a channel, which is precisely where the birds want to be.

Dress for cold wind and wet mud: wellingtons, layers, a waterproof shell, and a hat that does not flap. Take a notebook or a phone note, a flask, and a spare lens cloth. Tide tables, either printed or on your phone, are essential rather than optional.

Disturbance is the one thing to get right

Waders on an estuary are living on a tight energy budget. Every flight costs calories they cannot easily replace, and repeated disturbance can push birds off a roost and into a worse site. The rule is simple: never deliberately flush a flock. If birds lift as you approach, you are too close — stop, and let them settle before you move again.

• Stay above the strandline and use waymarked paths; do not walk out onto the mudflats.
• Keep dogs on a lead near the shore, especially in winter.
• Stay in the hide, keep noise low, and avoid silhouetting yourself against an open window.
• Give roosting flocks at high tide a wide berth — this is when they are most vulnerable.
• Keep your distance even with a telescope, and never use playback to draw birds closer.

Roosts are the birds' dormitories, and a quiet roost is a sign you are doing it right. If you can watch a flock feed and roost and bathe through a whole tide without putting them up once, you have had a very good session.

Planning your visit

Mid-autumn through late winter gives the greatest numbers, with September to November often the richest period as passage birds join arriving winter residents. Arrive well before low water, settle in, and let the tide do the work. On a still, cold morning with the mud shining and a few hundred dunlin twisting over the water, an estuary at low tide is one of the finest spectacles British birdwatching has to offer — and it costs nothing but patience.