Tracking Otters Along Undisturbed British Riverbanks

Why undisturbed banks matter

Otters have made a remarkable recovery in Britain, but they remain shy, largely nocturnal and fiercely territorial. The best banks are those left to their own devices: crumbling earth ledges, alder roots, reedbeds, fallen willows and quiet backwaters where the current slows. These places offer holts — hidden dens in root systems or rock piles — and clean water with plenty of fish, crayfish, frogs and the occasional waterbird. If a stretch is tidy, mown, heavily fished or busy with dogs, otters may pass through but rarely linger. Your first job is simply to find a river or canal that feels forgotten. Walk a kilometre or two without expecting to see anything. Look for the sort of bank where you would happily hide.

Reading the signs: spraints, footprints and slides

Otter surveying is mostly about droppings, tracks and flattened vegetation. Learn these three and you can read a river like a familiar page.

• Spraints. These are the otter's calling cards: dark, tarry, sometimes containing fish scales or bone fragments. They are usually left on prominent features — a flat stone, a bridge ledge, a tussock, the top of a fallen trunk — often at the meeting point of two watercourses or at the edge of a pool. Fresh spraints smell faintly sweet, like hay or jasmine tea, with a fishy undertone. Old ones are dry and crumbly. If you find several in a line along a bank, you are on a regular route.
• Footprints. In soft mud or silt, an otter print is broad and rounded, with five toes and often a hint of webbing. The pad mark is wider than a dog's, and you may see claw marks, though not always. Look along the water's edge after rain, or on low sandbanks and gravel bars. A trail of prints leading into vegetation is a strong clue.
• Slide marks. Otters love to slide. On steep muddy or grassy banks you may find smooth, repeated chutes, often ending in a splash pool. These are especially obvious in winter or after heavy rain. A slide can be used for generations, so treat it as a sensitive spot and do not stand on it.

When to look: dawn, dusk and the seasons

Otters can be active at any hour, but the reliable windows are the first hour after dawn and the last hour before dark. In quiet places, and especially in winter when nights are long, they sometimes fish in daylight. Summer can be harder because vegetation is high and people are about, but early mornings are still productive. Spring brings cubs, so avoid lingering near holts; autumn and winter often give the clearest signs, as banks are bare and spraints stand out. Check tide tables if you are on an estuary or coastal river — otters often move with the tide, hunting the shallows as the water rises or falls.

Fieldcraft for a quiet watch

Arrive early, settle in and then stop moving. Choose a position with a clear view of a bend, a pool or a confluence, and put the wind behind you or across your face. Otters have excellent hearing and a good sense of smell, so avoid rustling waterproofs, perfumed insect repellent and loud conversation. Use binoculars rather than approaching. If you see an otter, let it dictate the distance; a quietly watching human on a bank is far less threatening than one who stands up or follows. Keep dogs on a short lead and away from the water's edge. At night, a red filter on a torch is less disturbing than white light, but use it sparingly. Better still, rely on moonlight and let your eyes adjust.

What to take and how to stay comfortable

Riverbank vigils are usually cold, damp and longer than you expect. Wear dull, quiet clothing and take a waterproof mat or folding stool so you can sit still without fidgeting. Binoculars of 8x42 or 10x42 are ideal in low light. A small notebook is useful for sketching spraints and recording dates, but do not post precise locations online. Take a flask, a torch with a red filter and a midge net in summer. Wellington boots are fine for muddy banks, but avoid wading unless you must; the bank is the otter's living room. Leave no litter, and take away any fishing line you find, as it is lethal to otters and other wildlife.

Responsible otter watching

Otters are protected in the UK under the Wildlife and Countryside Act 1981, and disturbing them at a holt or resting place is an offence. That protection is not a barrier to watching; it is a reminder to keep your distance and put the animal first. Do not bait fish to bring otters closer, do not use recorded calls, and never block a slide or holt entrance. If you find a dead otter, report it to the relevant environmental body — records help conservation. The reward for patience is not a photograph, but the memory of a dark shape slipping through the water, leaving barely a ripple. On an undisturbed British riverbank, that is more than enough.