A River That Breathes

The Adur is a modest river for most of its length, but it saves its finest work for the last few miles. Between Upper Beeding and the sea at Shoreham it widens into a proper estuary, and twice a day the whole character of the place changes. At high water it is a broad, grey, unremarkable ribbon. Six hours later, half of it has gone, and in its place lies a shining expanse of mud, sand and shallow channels cut through by the last of the ebb.

That twice-daily transformation is the engine behind everything else. As the water retreats it exposes a larder of extraordinary richness — marine worms, small shellfish, crustaceans and the microscopic life that lives between the grains of mud. It is why the estuary is protected as a Site of Special Scientific Interest, and why, on a cold morning in January, the place can feel busier than the high street. The birds are not here for the view. They are here to eat, and they have flown a very long way to do it.

Meet the Three You Will Almost Certainly See

You do not need to be an expert to enjoy the Adur. Start with three species and let the rest follow.

• Dunlin. A small, busy wader about the size of a starling, with a slightly downcurved black bill and a dark line through the eye. In winter it is grey-brown above and whitish below; in summer it develops a bold black belly patch. The real giveaway is the behaviour — dunlin gather in tight, murmuring flocks that swing and wheel over the mud as a single body, flashing dark and light as they turn.
• Redshank. Neat, medium-sized and unmistakable once you notice the legs: long, bright orange-red, with a bill that is orange at the base and black at the tip. The redshank is the sentinel of the estuary — the first bird to spot you, the first to lift, and the first to tell everyone else about it with a ringing, anxious teu-teu-teu.
• Curlew. The largest wading bird in Europe, standing roughly half a metre tall, with a long, elegant, downward-curving bill used to probe deep into the mud for worms and crabs. Mottled brown and beautifully camouflaged against the flats, but impossible to mistake once you hear the bubbling cur-lee call drifting across the water.

Once your eye is in, others start to appear: oystercatchers in smart black and white, grey plovers standing still and silvery, black-tailed godwits wading up to their bellies, and little egrets stalking the shallows in brilliant white. Keep a notebook. Half the pleasure is in noticing what has arrived since last time.

Reading the Tide

The single most useful thing you can learn is the tide. The best feeding action happens in the two hours either side of low water, when the mud is at its most exposed and the birds spread out across it. Spring tides — the biggest ones, around the full and new moon — pull the water back furthest and give you the widest flats to scan.

High water is not a write-off, though. As the tide pushes the birds off the mud, they gather to roost on the upper shore, the saltmarsh edge and the raised banks, often in their hundreds. It is the best moment for counting, and the best moment to appreciate just how many birds this estuary supports. Pick up a local tide table or check the times before you set out, and remember that the estuary runs a little later than the open coast.

Getting Close Without Getting Too Close

Good fieldcraft beats expensive kit every time. Use the raised bank and the footpath as a natural screen, walk slowly, and avoid sky-lining yourself against the horizon. If a flock lifts as you approach, you are already too close — stop, stand still, and let them settle. Fifty metres from feeding birds is a sensible minimum, and considerably more from a high-tide roost.

Binoculars of 8x42 are ideal for a start; a spotting scope on a tripod will transform your view of the far flats. Dress for wind, which is the real feature of estuary weather, and bring a waterproof layer whatever the forecast says. Keep dogs on a lead and well away from the water. A dog running at a roost can put hundreds of birds into the air, burning energy they need to survive a freezing night.

Staying Safe on the Estuary

The Adur looks gentle and is not always. Its mud is deep, soft and genuinely capable of holding a person fast, and the channels that lace the flats fill faster than they appear to. The incoming tide does not simply rise in front of you — it creeps up behind you along the creeks. Stay on the footpaths and the firm raised banks, and never walk out onto the mud.

• Check the tide times before you go and give yourself a generous margin.
• Tell someone where you are heading and when you expect to be back.
• Carry a charged phone in a waterproof pouch.
• If a dog goes into the mud, do not follow it — call for help instead.
• Treat the estuary as strictly no-swim water: cold, fast and full of soft ground.

Something Warm Afterwards

Estuary birding is hungry work. The reward is a proper local plate: crab sandwiches and hot chips eaten on the harbour wall, a bowl of something sturdy in a warm pub, or a flask and a bacon roll from the boot of the car if the weather is doing its worst. In late spring and summer, look for samphire and sea beet growing on the saltmarsh — both are superb with butter, and both taste unmistakably of this coast.

Time your visit with the falling tide, keep your distance, and the Adur will give you one of the finest free wildlife spectacles in the south of England. Take a flask. Stay for the turn of the tide.