The Otter (Lutra lutra)
Because it’s found throughout Europe and Asia, the otter we see in Ireland is called the Eurasian Otter. Though habitat loss and pollution have taken their toll, thankfully, otters still thrive in the rugged wet areas of the west of Ireland and Scotland. Otters are related to pine martens, mink, stoats and badgers.
Adult males can weigh 14kg, so the otter is our largest native freshwater aquatic mammal. Females rarely exceed half that. From nose to tail-tip, a fully-grown male can reach 120cm, though larger specimens have been reported. Short, powerful legs end in strong claws and the toes are webbed. The muscular tail acts as a rudder when swimming. Fur-colour varies but, like almost all aquatic creatures, is lighter underneath. A broad, flattish head bears small, rounded ears and forward-facing eyes. The senses of smell and hearing are particularly acute, eyesight less so. The body is sleek and streamlined for graceful, acrobatic swimming. On land, otters move in a series of awkward humping movements. Otter eat all fish but eels are a favourite. Prey is eaten on shore and this is when otters are usually seen. Some otters become quite bold and will raid ornamental ponds. One local treats a neighbour’s koi pond as a kind of ultra-fresh sushi bar.
Otters always live beside water, usually in a burrow called a ‘holt’, though naturally-occurring features are also used – among large rocks, or deep within the tangles of large tree-roots. In very remote places, like rocky islands with no grazing animals or men, where the ground is not suitable for tunnelling, they sometimes live aboveground on a ‘couch’ made of flattened vegetation.
Curiously, despite their webbed feet and watery habitat, otter cubs have to be taught to swim! In fact, it is thought that young otters actively dislike getting wet and have to be persuaded to take the plunge by their parents.
Though otters that live near river-mouths will hunt in the sea, the Eurasian otter is not a sea otter – true sea otters live along the west coast of North America.
Tarka
Proving the otter’s popularity with us humans, two well-known otter-books have been turned into films, Gavin Maxwell’s Ring of Bright Water and Tarka The Otter, by Henry Williamson. I’d always thought it farfetched that, in the former, the slain otter’s cubs should turn up at their domesticated father’s old home, even though their mother was a wild otter and their father had been killed before they were born. It smacked of inherited rather than learned behaviour patterns. I always thought that, apart from very rare cases, like being reared from the very start by humans, an otter’s instinct would be to shun the proximity of man, but, over the past several years, I’ve had to reassess that belief. I know of a case where a hand-reared female otter, long returned to the wild, began to visit a house – not the one she’d been reared in – and, every evening she comes though the cat-flap, bringing her cubs with her when she has a litter. Such behaviour is incredibly rare. Her adopted feeders’ many cats retire to a prudent safe distance when she arrives and watchfully let her have her fill and depart again.
In recent years, escaped or released mink have appeared in numbers in the otter’s watery domain. They are quite easily distinguished, though: otters are larger and mink are generally darker in colour. Mink, aggressive and voracious feeders, may yet displace the native otter in much the same way as the introduced grey squirrel has all but eliminated its native red cousin, by competition and greater adaptability.
