Winter Birdwatching on an Estuary Nature Reserve

Why the Quiet Months Are the Best Months

Summer on an estuary is a crowded, green, distracting sort of place. By December the leaves are down, the reedbeds have collapsed into straw, and the last of the summer visitors have long gone. What arrives instead is the reason so many of us wrap up and head out in the coldest weeks of the year: tens of thousands of waders and wildfowl, down from Iceland, Scandinavia and Arctic Russia, settling onto the mudflats to feed and roost.

The estuary in winter is a larder. Mud is astonishingly productive — full of worms, cockles, ragworm and small crustaceans — and the birds that depend on it have nowhere else to go when the northern lakes and tundra freeze. Cold weather also works in the watcher's favour. Birds burn energy fast, so they feed hard and gather in tight, spectacular flocks rather than scattering thinly across the flats. The lack of foliage does the rest.

There is also the sheer peace of it. On a frosty weekday morning you may have an entire hide to yourself, a flask in one hand and a flock of several thousand knot wheeling over the water like a shaken sheet.

Read the Tide Before You Read the Birds

The single most useful skill on an estuary is tide reading. At low water the birds are spread over square miles of mud, often too distant to identify properly. As the tide pushes in, they are squeezed progressively closer to shore — and the last hour or two before high water can be extraordinary.

• Aim for a rising tide, roughly two hours before high water. This is when the roosts fill up in front of the hide.
• Choose spring tides over neap tides. On a big spring tide the mud is completely covered and everything has to come to the nearest high ground. On a neap, the water may barely reach the roost and the birds stay scattered.
• Allow for a lag. High water at the estuary mouth can be half an hour or more ahead of the same tide several miles upstream. Local tide tables are usually marked by location for a reason.
• Cold snaps are gold. A hard frost pushes birds off frozen inland fields and onto the estuary, often bringing scarcer species within range.

Arriving at low water is not wasted time — it is your chance to watch feeding behaviour, learn the mud, and work out which channels the birds will follow as the water rises.

What You Might See: Waders, Wildfowl and Raptors

The waders are the heart of it. Expect dunlin in their thousands, knot packed into dense, restless balls, grey plover standing hunched and silver on the mud, bar-tailed godwit probing deep with those extraordinary bills, plus oystercatcher, curlew, redshank and turnstone along the tide line. Learn the calls — curlew's rising whistle, redshank's alarm, the piping of oystercatchers — and you will know what is about before you lift your binoculars.

Wildfowl gather on the open water and graze the saltmarsh. Look for wigeon whistling softly, tight rafts of teal, smart shelduck, elegant pintail and family parties of brent geese cropping the grass. On the reedbed edges, watch for a bittern creeping out of the stems on the coldest mornings.

And then the raptors. A peregrine putting up ten thousand waders at once is one of the great sights of the British winter, and you will often hear the panic before you see the cause. Merlin hunt low and fast along the tide line, marsh harriers quarter the reeds, and at dusk a short-eared owl may drift across the saltmarsh on stiff, moth-like wings.

Kit That Keeps You Out There Longer

Estuary birdwatching is a standing-still-and-getting-cold business. The watchers who see the most are simply the ones who stay comfortable longest.

• Layers, not one thick coat. Thermal base, fleece mid-layer, windproof and waterproof shell. You will be colder in a hide than walking to it.
• Boots you trust. Wellies or waterproof walking boots — estuary paths are muddy, and wet feet end a session early.
• Binoculars first, scope second. A good 8x42 pair will handle most of what you see. A scope on a sturdy tripod transforms distant roosts, but only take one if you are happy carrying it.
• Warm hands matter. Gloves with fold-back fingertips, plus a couple of hand warmers, make the difference between an hour and a morning.
• The practical extras. Flask, something to eat, a lens cloth, a notebook and a printed tide table.

Hide Etiquette and Staying Safe on the Mud

Winter birds are living on a tight energy budget. Every unnecessary flush costs them calories they may not be able to spare, so treat a roost as you would a sleeping patient.

• Approach hides slowly and quietly, close doors gently behind you, and keep your voice down.
• Never walk out onto the mudflats. Estuary mud is soft, deep and riddled with channels that fill fast. People get cut off every winter, and some do not get back.
• Stay on marked paths and respect roped-off roost areas. They exist because the birds need them, not to inconvenience you.
• Keep dogs under close control, or leave them at home. Many reserves restrict dogs entirely during the winter months.
• Photographers: no flash, no baiting, no creeping closer. A long lens and patience always beat a flushed flock.

Making the Most of a Short Winter Day

Days are short, so plan around the light. Get there before dawn if you can — the sound of hundreds of curlew and redshank calling out of the darkness over the incoming tide is worth the early alarm, and the first light on a flock of wigeon is something you will remember.

Midday, when the tide is slack, is the quiet spell. Use it to walk the reserve, check the saltmarsh and reedbed edges, or simply warm up. Then settle back into a hide for the afternoon, when birds return to feed as the water drops again and the raptors make their last patrols before dusk.

Finally, return to the same spot through the winter. Note what you see, roughly where and when, and which tides produced the best viewing. Estuaries are surprisingly predictable places. Learn one properly across a season and you will stop hoping for a good day and start knowing exactly when to go.