Shetland is home to a high proportion of coastal-dwelling otters that have been studied for years.
Scotland’s Eurasian otter population has a high proportion of coastal-dwelling individuals, which spend their time flitting between land, sea and freshwater pools.
Hunched down with my back leaning up against the cool peat bank, I scan my binoculars across the algae-covered rocks, kelp and wind-whipped sea. Local naturalist, photographer and guide Brydon Thomason had already spotted them: “See that triangular-shaped rock? Go up from that and then slightly left.” Nothing.
Then, suddenly, the rocks grow wet, brown fur, sleek heads and long Labradorlike tales – otters. First the mother, then her three cubs, slip with one fluid movement into the water. They are a single writhing mass, twisting and gliding over each other as they swim out into the bay off the east coast of Yell, one of the North Isles of Shetland.
“This is magic,” Brydon whispers. He grew up on the archipelago and has studied these mammals for more than 30 years, yet his excitement still matches my own. This is my first-ever sighting of the species. I’ve been told that wild otters live along the riverbank near my home in Somerset, but they remain elusive.
The female we are watching is nine years old: “She’s a really special lady – most otters only live until they are four or five,” says Brydon. “She’s such a good mother and has raised so many cubs in adverse conditions.”
Eurasian otters can breed at any time of year (river-dwelling otters will usually produce cubs throughout the year) but along the coast where fish stocks are far more seasonal, the breeding season is too. In the northern and western isles of Scotland, the majority of cubs are born mid-summer, emerging from their natal holt in autumn. By the winter, families like this one are busy feeding together along the coastline.
They still, it seems, have plenty of time to play, tumbling on the rocks, rolling around and nipping at each another in the water. At one point, the head of a grey seal appears, its soulful eyes taking in the performance. Quick as a flash, a brave cub doggy-paddles through the water and chases it away, only to quickly return to the safety of its family.
Watching this group, it is strange to think that otters are largely solitary creatures. Apart from raising young and breeding, they live alone along the islands’ cold, wind-blasted shores. “These cubs are about six months old. At about 10–12 months, they will leave their mother,” Brydon tells me.
Once the cubs have broken away, some females may even miss a season to give themselves time to recover, however, this female is generally consistent each year, Brydon explains. Occasionally, if the mother is in good condition and prey availability is at its peak, she will come into season before the cubs have dispersed, at which point she will force them to leave: “It’s an emotive time when the family separates,” Brydon admits. “But that’s nature.”
For the time being, this energetic trio of youngsters still has a lot to learn: namely, how to hunt. As the mustelid family moves forward, Brydon and I approach gingerly along the top of the beach, keeping low and downwind, to avoid detection. The cubs continue to dive and emerge with small fish, which are eaten in the water, or unwieldy crabs, with which they grapple on the rocks. Crustaceans are easy prey and a tempting choice for juveniles – particularly in late winter when fish stocks are low – but they have a low nutrient value, so adults concentrate their efforts on catching fish.
Night and day
One of the marked differences between coastal otters and river otters is when they are most active. If they live in a freshwater
These days, the otters here are regularly seen predating octopuses, which are thriving in the warmer waters.
habitat, they are largely nocturnal, whereas coastal otters are diurnal, feeding at each low tide, to coincide with the behaviour of their prey, making this Scottish archipelago one of the best places to see them in the UK.
Zoologists Hans Kruuk and Jim Conroy have spent years studying otters in Shetland and were able to observe many catches. They found that otters preferred solitary, bottom-dwelling species to shoaling or mid-level fish: primarily eelpout but also rockling, sea scorpion and butterfish. These species are all nocturnal feeders, making them lethargic during the day and easier to catch, perhaps explaining coastal otters’ daytime appearances.
However, Hans acknowledges that, over the past decade, the otters’ diets seem to have shifted: “This is because there has been a change in fish populations around Shetland,” he says. “Eelpout now are nowhere near as important as they used to be, probably largely because of increasing sea temperatures. Otter breeding in Shetland was once synchronised with the eelpout cycle. Now that seasonality seems to have mostly gone.”
These days, the otters here are regularly seen predating octopuses, which are thriving in the warmer waters. In fact, the
carnivorous mammals will target on-shore species, too: fulmar, shag, red-breasted merganser, auks and dabbling ducks all make for a tasty meal. And if the weather is stormy at sea, the otters will even hunt the odd rabbit.
In his poem, An Otter, Ted Hughes describes otters as “…Neither fish nor beast… Four-legged yet water-gifted...” His words capture the adaptability of a species that occupies different environments in the UK. Freshwater otters can use up to 80km of river or waterway, but the abundance of feeding opportunities in coastal habitats means otters, such as those in Shetland, can range in areas as small as 4–5km.
How did they reach the archipelago? Shetland has no native land mammals, so it’s possible the otters hitched a ride, perhaps with the first settlers – it was certainly inhabited by Neolithic farmers by 3000BC and possibly earlier. Or they may have been introduced by the Vikings, so that they could be hunted for their pelts.
Their fur is the same as that of their river-dwelling cousins, but they have found a way to cope with seawater with the help of freshwater pools, many of which can be found close to the shore on the Northern Isles. “Otters in water are entirely dependent on their thick, long fur for insulation,” says Hans. “But after swimming in saltwater, it gets sticky, just like your hair would, and isn’t as effective; hence the need to wash in freshwater once or twice a day, to maintain its condition.” In comparison to Shetland, Orkney has a very porous geology and little onshore fresh water, so it’s suspected fewer otters live there as a result.
Reading the signs
We clamber over the shore’s bank, slightly away from the otters, in search of pools and holts, which tend to lie close to one another. As I stand, I’m struck full-force by a salty smack of sea air. The landscape here is stripped back to its essentials, as if hastily painted in broad brushstrokes: land, sea, sky. The panoramic nature of the view along the coast makes it easier to study otters here and to discover field signs.
A strong whiff of fish on the wind signals the presence of spraint – a chalky scattering of otter faeces made up of fish bones, scales and sometimes crab shells. Otters use spraint to define their territories and communicate with each other – sharing information on identity and breeding status. It’s a telltale sign that their living quarters might be close.
Sure enough, within a few strides we come across an elongated crevice in the soft, peat soil, filled with still, inky black water
– a bathing pool, just a few metres from the rocky shore. And then Brydon points out what appears to be part of the upturned keel of a plastic boat. Underneath, our otter mother has scraped the earth away to form a ‘couch’, a sheltered place to rest and regain energy during the day. Holts, I’m told, are more likely to be found underground.
Otters will generally have a few holts over a territory of several kilometres. This information was central to Hans and Jim’s oft-quoted Shetland population surveys, which were undertaken between 1988 and 1993. The zoologists counted otter holts over a large sample of sea coasts, with different coastal habitats, and used this to estimate total otter numbers for the islands and their 1,287km of coastline: 1,000 was the figure they struck upon. The result made Shetland home to one of the densest population of otters in Europe. I had read this repeatedly in natural-history books and tourist leaflets during my stay, but how accurate was it today?
“We don’t actually have a current population estimate for otters across Shetland,” says Daniel Brazier, operations manager for the Northern Isles at Scottish Natural Heritage (SNH). “We only have regular data for a few areas surveyed more or less annually, such as Yell Sound Coast
Special Area of Conservation, plus a couple of other nearby islands.” Using Hans’ method, the SNH surveys revealed periods of a year or two when the number of active holts dropped, coinciding with a higher proportion of crab remains in spraints – indicating a shortage of fish: “This may just be cyclical,” Daniel warns. “I can’t give a definite reason for such events.”
Generally, the population appears to be relatively stable in Shetland. Still, I’m getting the impression that these are slippery beasts to pin down. Daniel Forman, an ecologist from Swansea University, has set up the Coastal Otter Project, which encourages members of the public to record their sightings: “Otters are so secretive that they are very tricky animals to survey,” he enthuses.
“You just can’t count them easily. Also, their strict legal protection in the UK means that – with good reason – researchers are unable to do the studies they might be able to with other species.” He explains that only about 40 per cent of otters belong to a settled breeding population, utilising holts, and the other 60 per cent move over incredibly large areas. Therefore, the counting of holts, while very helpful, can only ever give estimated figures.
More to discover
Not so far away, in Orkney, new surveying methodologies are in the early stages of development in a joint project between the North Isles Landscape Partnership and Heriot-Watt University. It’s clear that there is more to learn about coastal otters – not just on Scotland’s Northern Isles, but across the entire UK. “Marine environments are crucial to the otter population,” says Daniel. “And they are utilising a broader range of habitats – sandy beaches, dunes, docks, salt marshes, estuaries, as well as rocky shorelines.”
Most of the time, otters remain unseen, save for a fresh patch of spraint or a paw print in the wet mud, so I soak up every precious second watching this particular family. Brydon and I follow them until the end of the day, when they disappear around the edge of the coastline, melting back into the browns and umbers of the kelp and rocks.
CATHERINE SMALLEY is a nature writer and former BBC Wildlife sub editor. She visited Shetland in June 2019, courtesy of Belmont House on Unst.
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