Why slow walks work best along northern rivers

Otters have quietly returned to most of our northern catchments, from the Eden and the Ure down through the Coquet and the Wear. Yet a live otter is still a rare, heart-stopping glimpse. What you will find far more often, if you walk slowly and look down rather than ahead, is the evidence they leave behind: prints in the mud, smoothed chutes down the bank and small dark deposits on boulders that tell you exactly where an animal passed in the night.

The trick is to treat a riverside walk as a slow read rather than a route march. Aim for two miles in three hours, not the other way round, and give yourself permission to stand still for ten minutes at every bend, bridge and side stream. Otters use the same runs again and again, so a stretch that seems empty in October will often be busy by February.

Reading five-toed prints in soft mud

The best ground is mud that is soft enough to hold a print but firm enough not to slump — a thin layer of silt over clay, or the drying margins of a backwater after a night of rain and a bright, drying morning. Look below the waterline where the level has recently dropped, and on the aprons of silt at the mouth of every tributary.

An otter's fore print is roughly 5–7 cm across, with a broad, rounded pad and five distinct toes. Because the toes are webbed at the base, you often see a thin bridge of mud connecting them rather than five separate dots. Claws are non-retractable and usually blunt, so small claw marks may show at the tips. Hind prints are longer, sometimes 8–9 cm, and can look almost like a small hand.

• Mink: smaller, around 3–4 cm, with a more rounded pad and toes that crowd together.
• Dog: four toes, obvious claw marks, and no webbing line between the pads.
• Otter: five toes, broad pad, webbing, and often a skid or drag mark nearby.

Measure before you decide. Slip a small ruler or a marked stick into your pocket — a phone photo with a coin beside the print is only useful if you note what the coin was.

Slides, runs and the bank itself

Where a bank is steep and muddy, look for polished chutes, usually 30–50 cm wide, that look as though someone has been down them on a tea tray. These are otter slides, used for entering and leaving the water, and they often carry a faint groove where the tail has dragged. Fresh slides are slick and free of frost-shattered edges; older ones weather into a duller, cracked surface.

Follow the line of a slide upward and you may find a run through the grass, or a patch of flattened vegetation on a ledge above the flood line — a couch where an otter has rested and rolled. Holm oaks, alder roots, rock crevices and the shadowed sides of old stone bridges are all classic holt sites. Never poke about inside one; a disturbed holt may be abandoned for good.

Spraints: the clearest sign of all

Spraints are the otter's calling card. They are oily droppings, dark and loose to firm, often glistening, and frequently left on a prominent stone, a tussock, a bridge ledge or the top of a gravel bar. Look at junctions, bends and the mouths of side streams — anywhere an otter might want to announce itself to a neighbour. You will often find several within a hundred metres, as though the animal has dotted an i every few steps.

They are usually dark brown to black, sometimes with visible fish scales and small bones, and may contain a purple tinge if crayfish have been on the menu. The smell divides people: some describe it as faintly fishy, sweet and hay-like, others as oddly jasmine. It is certainly not the sharp stink of fox or mink scat.

Do not touch spraints. They can carry bacteria and parasites, and otters and their resting places are protected by law. Record what you see, note the position, and leave it exactly where it lies.

Keeping a nature journal that actually helps

A journal is only as good as its detail. For each find, note the date, time, weather, recent rainfall and river level, plus a rough location. Sketch the print with a scale bar drawn to the side — a quick five-minute drawing will teach you more about pad shape than a photograph will.

• Photograph with something of known size in frame, and write down what it was.
• Note the substrate: silt, clay, sand, gravel, or mud over rock.
• Record direction of travel and the distance between prints.
• Log what else was about — dippers, grey wagtails, heron tracks, deer slots.
• Revisit the same stretch monthly and note what has changed.

Walking well near otters

Go at first light or in the last hour of daylight, when otters are most active. Walk upstream where you can, so your scent does not carry ahead of you, and keep your voice low. Keep dogs out of the water and on a short lead near likely holts, and if you are lucky enough to see an animal, stay at least 30 metres away and let it decide the distance.

Stay on public footpaths, follow the Countryside Code, close gates behind you and wash your hands before eating. Do all that, walk slowly, and a quiet northern river will start showing you far more than you ever expected.