Caithness Field Club

The Eurasian Otter
Gordon Wilson

The otter is a sad casualty of the 20th century, killed off by pollution - loss of traditional territories - death by road traffic, fishing nets and lobster pots - even illegal shootings.

Otters are the semi-aquatic members of the family which includes stoats, weasels, badgers, ferrets, polecats and pine martins, all of which reside in Caithness in some numbers.

Today, in Caithness we have a tremendous resurgence of the otter population. Having surveyed otters in the coastal habitat for the past ten years, I can now state that from Melvich to Duncansby Head on the North coast and Duncansby to Latheron on the East coast, wherever an all year round supply of fresh water is available,there are either holts or other signs of visits from otters. In this area, I have never found fresh water outlets that do not have spraint marking and otter presence. The otter is a protected predator. However, it is at the top of the aquatic food chain - highly sensitive to habitat change, pollution and disturbance.

By identifying the threats to the otter, we are also identifying the threats to our own environment. Fortunately, the Caithness coast and inland waters are pollution free and the rivers have pure, clear water - despite publicity against Dounreay. Sandside Bay also has pairs of resident otters and is relatively pollution free.

Otters that inhabit the sea shore need the availability of fresh water sources. Essentially, they need to keep their fur clear of salt, which if not removed would lower their body temperature and they could die of hypothermia. However, the clear water in Caithness has solved this problem and allowed the substantial increase of the otter population.

Now that all the coastal sites have been populated, after the breeding season is over the need of the young to find their own territory creates an overspill. Most young are born in May and June; young otters stay with their parents, usually only the female one, for 13-15 months before going on their own. Junior otters, being unable to find more sea room are moving up river, re-populating the unoccupied areas and the many lochs, some of which have not known otters for centuries. Even in Thurso last year, otters were regularly spotted at the mouth of the Thurso river. At the salmon pool below the cemetery, a breeding pair produced three young and many people observed them feeding as a family between the pool and the river walk, even as far down as the Thurso bridge.

Otters may rarely take a salmon but their basic foods are - Seabased, crabs, sea anemones and a variety of small fish. - river based, the basic diet is eels, minnows, small trout, frogs - though they will not eat the skins. They are also carnivorous, liking domestic poultry - ducks, rabbits etc. A pair of otters above Halkirk on the Thurso river have devastated the local rabbit population. They have even been spotted stalking geese - however they were soon seen off!

Sprainting is the marking of otter's territories. At the sea shore, it occurs above and below the high tide marks. River sprainting spots are often quite conspicuous - the grass being very green due to constant fertilisation.

The otter's coat has two layers of fur. The outer layer consists of long hairs, 17-18 mm. long, and underneath is another layer 8-9 mm. long. The otter whose habitat is the sea must remove the salt daily from its coat and all otters must groom to remove unwanted parasites. Due to the double layers of hair, an otter often appears to look larger when out of the water.

For those who wish to spot otters especially in the sea where they often feed amongst the seal colonies - a seal just rises and falls back into the sea when it surfaces and submerges; the otter always turns turtle - head over heels - and when diving, it always leaves an upright rat-like tail, the last bit of it to enter the water.

See that and you saw an otter.

See that and you saw the clear, unpolluted waters of Caithness.