Logo

Start With the Signs, Not the Animal

Otters have returned to most of our river catchments over the past thirty years, but a healthy stretch of water rarely means a guaranteed sighting. A hunting otter can cover ten to twenty kilometres of river in a single night, so the odds of standing in the right place at the right moment are slim. What you can rely on is sign. Otters mark their territories constantly, and those marks stay put long after the animal has moved on.

Before you go looking, find a promising stretch. You want slow, quiet water with plenty of fish, soft muddy or sandy banks, overhanging trees, and undercut edges where roots trail into the water. Add a bridge, a weir pool or the mouth of a tributary and you have classic otter country. Walk it once in daylight, looking down as much as forward, and you will usually find out within an hour whether otters are using it.

Spraints: The Otter's Calling Card

The single most useful thing to learn is the spraint — otter droppings, left deliberately in conspicuous places as a message to other otters. Fresh spraint is almost black and tarry, and it smells strangely pleasant: somewhere between jasmine tea, mown hay and a fishmonger's slab. It is usually four to eight centimetres long and glittering with fish bones, scales and the occasional crayfish shell.

Because otters want their spraints found, they deposit them in predictable spots. Check flat stones at the water's edge, the ledges under bridges, the bases of tree roots, the apex of a river bend, and any boulder standing clear of the current. Older spraints fade to pale grey and crumble when touched. A stone bearing two or three spraints of different ages is a regularly used marking point — an excellent place to sit quietly at dusk.

Footprints, Slides and Flattened Grass

After rain, the muddy margins become a notebook. An otter's front print is roughly six to eight centimetres wide, with five toes, a broad star-shaped pad and often a hint of webbing between the toes. Claw marks are usually absent, which helps separate it from a dog or fox. Look for a trailing line where the tail has brushed through soft silt, and for five-toed prints in pairs along a run.

Other signs to watch for:

• Slides — smooth, polished chutes down steep banks where otters enter the water, sometimes with mud smeared across the top.
• Couches — flattened hollows in grass, reeds or rushes where an otter has rested, often with a few fish scales nearby.
• Runs — narrow tunnels worn through bankside vegetation, leading to the water's edge.
• Holts — the dens themselves, usually among tree roots or in an undercut bank. Look but do not approach; otters and their resting places are fully protected by law, and disturbance near a holt is an offence.

Timing: Dawn, Dusk and the Edges of the Day

The first hour after sunrise and the last hour before dark give you by far the best chance. Otters are crepuscular by habit, though on quiet, undisturbed rivers they will sometimes fish openly in the middle of the day. If your stretch has a tidal section, work the two hours either side of low water, when fish are concentrated and the banks are exposed.

Conditions matter as much as the clock. Overcast, still, damp weather is ideal; bright sun and a hard blue sky push activity later. Light rain is no deterrent at all — it deadens sound and scent. Winter and early spring are the best seasons for reading sign, because the bankside vegetation is down and spraints stand out clearly. Summer brings dense cover but also cubs, which often fish clumsily in daylight, so early mornings can be rewarding.

How to Watch Without Disturbing Them

Good fieldcraft is everything. Approach the water slowly, and move upstream with the wind in your face so your scent carries away from the bank you are watching. Sound travels far over water, so keep conversation to a minimum and avoid crunching along gravel margins.

• Use binoculars and stay behind a hedge, a bank or a fallen trunk rather than standing on the skyline.
• Keep a working distance of 30 to 50 metres. If an otter stops, lifts its head and stares, you are too close — settle back and let it resume.
• Keep dogs on a short lead, and never let them swim in the stretch you are surveying.
• After dark, use a red-filtered torch in brief sweeps rather than a white beam, and avoid flash photography.
• Never follow an otter that slips into cover, and give any holt or couch a wide berth.

Telling an Otter From a Mink

Many a hopeful sighting turns out to be an American mink. Mink are smaller and darker, a uniform chocolate brown with no pale throat, and they often run along the bank rather than diving. An otter is bulkier and more bullet-shaped, with a broad head, a cream or pale grey throat bib, and a thick, tapering tail. In the water, an otter swims low with only its head and shoulders showing, then rolls forward and dives with a smooth arch and a splash of the tail. Prints tell the story too: mink leave a dainty two-and-a-half to three-centimetre track, less than half the size of an otter's.

If you find good sign, note the grid reference and photograph it with something for scale, then report it to your local records centre. Records help the people managing the river protect the stretches that matter — and a quiet, well-recorded bend is far more likely to still hold otters in ten years' time.