Otter, Lutra lutra, Holt, Couch, Dog, Bitch, Welp, Pup, Bevy, Lodge, Romp
These are one of the coolest mamals we have in the UK. After fighting off extinction, they are slowly returning to cleaner waterways throughout the UK.
Otters are semi-aquatic mammals of the Mustelidae family and are related to stoats, weasels, skunks and badgers.
They are sleek, streamlined swimmers with powerful jaws and sharp teeth. They have tapering bodies and tail, ideal for fast swimming. They are brown with paler under parts, short, strong legs and webbed feet, small ears and a broad flat head. Their ears, eyes and nostrils are set on top of head to help surface swimming.
The otter is very appealing, and extremly playful but few people ever see a wild otter in Britain.
Until the 1950s, they could be found throughout most of the country but today they are very rare.
Otters were once hunted for their fur by dogs and were thought of as a pest, competing with fishermen for fish. In spite of these hunting pressures, otters were widespread throughout Britain and the population remained steady until the 1950s. It was at this point that they declined rapidly.
The reason for the decline has been attributed to pollution and the clean up of waterways. Pollution caused by run off has been one of the main factors. Now, as we clear up our rivers, the otter is slowly coming back. Otters are very shy, solitary animals and need large territories. Males have a territory of around 40 km of riverbank. They mark their territory with droppings called spraints. Otters live in Holts that are often built away from the bank itself
The male otter (dog) has a head and body of up to 90cm (36 in) and a tail of 40 cm (16in); the female (bitch) is smaller. They range from 75cm (Asian Short-clawed) to 2.75m (Giant Brazilian).
Their life span in the wild is around 9-10 years in the wild; many have lived to be 20 in captivity.
Their diet is mainly fish. Eels are a favourite but its menu includes salmon, trout, hapless water birds, courting frogs and the occasional rabbit. They have a keen sense of smell and sharp hearing on land. In clear water, they can spot prey with their eyes and in murky waters their whiskers detect the twitching of fish.
The European otter lives near water, whether it is the rivers or the sea. They live in dens known as holts and mark their territories, which may cover many kilometers of river, with distinctive piles of spraint - otter poo.
The Eurasian otter exists in scattered populations in the British Isles. They are found mainly on the coast of Scotland and Ireland, along the Welsh borders, the South-West and East Anglia.
Otters are mainly nocturnal and hunt in open, marshy places, rivers, lakes, seashores and estuaries. They will often travel a long way over land, from one river system to another, in search of food. They are strong, agile swimmers and catch fish by chasing them underwater. They grip the prey with sharp teeth and powerful jaws, carrying the catch ashore to eat it. An adult otter needs to eat 20% of its body weight in food every day - about 2.5kg. In undisturbed areas an otter often spends part of the day playing away from water, near to a 'lying up' den, which is usually under riverside tree roots.
An otter grooms itself frequently and this keeps its coat sleek and waterproof. The coat's long, stiff guard hairs are covered with oil to repel water. The thick under fur traps an insulating layer of air and the skin never gets wet.
Otters breed throughout the year. The dog and bitch live separate lives, meeting only for mating. Usually there are two or more females living in a male's territory and when they are receptive, he will mate with all of them. They find each other by scent and by whistling. The two often playfully chase each other and pretend to fight.
The gestation period is about 62 days and during this time the bitch builds a holt, an underground burrow, often under the roots of a waterside tree. In Scotland, where otters frequent seashores and lochs, the holt may be in a more open space such as a rocky cairn. The holt is lined with grass or moss and this is where a litter of two or three cubs is born. At birth they are about 12cm in length and are covered in very fine grey fur; their eyes open when they are four - five weeks old. The cubs are helpless for the first 6 weeks of their lives, relying entirely on their mother's milk. The mother drives the father away as soon as the cubs are born and he plays no part in their upbringing. Coastal otters need access to freshwater pools to wash. The cubs develop an adult waterproof coat at two or three months and this is when their mother teaches them to swim. To begin with, they are often reluctant to go into the water and may have to be pushed in! An otter family is very playful and enjoys sliding games, using a steep snowy or muddy river bank to toboggan down on their chests, forepaws tucked in! The young soon become proficient underwater hunters and the family splits up when the cubs are about a year old. They may stay on in the mother's territory for a few more months and then leave to look for territories of their own.
The use of pesticides were greatly increased during the 1950s, mainly aldrin and dieldrin. These were then washed off the land into rivers etc. and contaminated fish with tiny amounts of poison. Even though the fish may not be affected, the poison gradually accumulates in an otter eating a lot of fish, resulting in its death. Although most of these pesticides have been restricted since 1962, otter numbers have not increased a great deal since.
Otters have been protected by law since 1981. In September 2004, a dead dog otter was found on a railway line in Frimley in Surrey, which we guessed had been electrocuted as it crossed the line. It may have been dead but it was the first positive sighting of an otter for over 45 years in this area.
Otters disappeared from the South-East in the early 70s and in recent years, work has been carried out to try and get them to recolonise their former sites.
In the past few years they have returned to both the Rivers Thames and Loddon, and as the Blackwater is a tributary of the Loddon, it was only a question of time before otters would find their way into the Blackwater and start moving upstream.
When the dead otter was found Steve Bailey, Manager of the Blackwater Valley Countryside Partnership, had this to say, “This is great news. The river was once in a terrible condition and many organisations have put in a lot of hard work over a long period to return it to a state where it now supports an abundance of wildlife. Otters can only survive in a healthy river system, so the fact that an otter has been found in the Valley indicates the river is ‘complete’ once again.”.
East Anglia is one of the remaining strongholds of otters; conservationists there are breeding them in captivity and releasing them into the wild. Special otter havens have been established by landowners in co-operation with conservationists. Some artificial holts have been built where natural cover is inadequate and unpolluted water. There are signs that these measures will help to re-establish otter populations in at least some of their former haunts.