Lutra lutra

FACTS AND FIGURES

Recognition: Brown fur, often pale on underside; long slender body; small ears; long thick tail; webbed feet; swims very low in the water, head and back barely showing.

The much smaller mink is dark brown, almost black when wet, has a short furry tail, and swims buoyantly with much of its body visible.

Head/body length: about 60-120cm; tail about 40-45cm

Weight: average 10.1 kg for males; 7.0 kg for females.

Lifespan: Otters can live to be ten years old, though few survive more than five years.

Diet: Fish, especially eels and salmonids are eaten, and crayfish at certain times of the year. Coastal otters in Shetland eat bottom-living species such as eelpout, rockling and butterfish. Otters occasionally take water birds such as coots, moorhens and ducks. In the spring, frogs are an important food item.

GENERAL ECOLOGY

A secretive semi-aquatic species which was once widespread in Britain.

By the 1970s, otters were restricted mainly to Scotland, especially the islands and the north-west coast, western Wales, parts of East Anglia and the West Country (though they remained common and widespread also in Ireland). This decline was caused by organo-chlorine pesticides. Since these were withdrawn from use, otters have been spreading back into many areas, especially in northern and western England.

They are still (2009) scarce in much of central and south-east England, but have turned up in every county. Otters live along rivers, lakes and sea coasts, and, at times, in marshy areas some distance from open water. Coast-living otters need fresh water to clean salt from their fur, which otherwise loses its ability to keep the otter warm. With the exception of parts of the West coast of Scotland, otters are generally nocturnal.

Otters can travel over large areas. Some are known to use 20 kilometres or more of river habitat. Otters deposit faeces (known as spraints, with a characteristic sweet musky odour) in prominent places around their ranges. These serve to mark an otter's range, defending its territory but also helping neighbours keep in social contact with one another. Females with cubs reduce sprainting to avoid detection.

In England and Wales otter cubs, usually in litters of two or three, can be born at any time of the year. In Shetland and North-west Scotland most births occur in summer. Cubs are normally born in dens, called holts, which can be in a tree root system, a hole in a bank or under a pile of rocks. About 10 weeks elapse before cubs venture out of the holt with their mother, who raises the cubs without help from the male. Initially females catch food for their cubs, who remain with her for about a year.

CONSERVATION

Otters are strictly protected by the Wildlife and Countryside Act (1981) and cannot be killed, kept or sold (even stuffed specimens) except under licence.

In the late 1950s and early 1960s otters underwent a sudden and catastrophic decline throughout much of Britain and Europe. The cause was probably the combined effects of pollution and habitat destruction, particularly the drainage of wet areas. Persistent organ-ochlorine pesticides, which otters accumulate in their bodies because they are at the top of the food chain, were in widespread use at the time.

Otters require clean rivers with an abundant, varied supply of food and plenty of bankside vegetation offering secluded sites for their holts. Riversides often lack the appropriate cover for otters to lie up during the day. Such areas can be made more attractive to otters by establishing "otter havens", where river banks are planted-up and kept free from human disturbance. Marshes may also be very important habitat, for raising young and as a source of frogs.

While otters completely disappeared from the rivers of most of central and southern England in just 50 years, their future now looks much brighter. There is evidence that in certain parts of the UK the otter is extending its range and may be increasing locally. However there is no room for complacency. Otter populations in England are very fragmented and the animals breed only slowly.

Attempts have been made to reintroduce otters to their former haunts, by reintroducing captive bred and rehabilitated animals. These reintroductions are not easy, but have been very successful is some places.

FREQUENT QUESTIONS

What can I do to help otter conservation?

Contact your local Wildlife Trust, they may be involved in conservation work on otters.

Where can I see otters?

There are very few places where you can regularly watch otters in the wild, apart from Shetland and the West coast of Scotland. However, several wildlife parks keep otters. The Otter Trust has sites at Earsham, near Bungay, Suffolk and at North Petherwin near Launceston, Cornwall. The Chestnut Centre, near Chapel-en-le-Frith, Derbyshire, also has otters.

FURTHER INFORMATION

Woodroffe, G.L. (1994) The Otter. The Mammal Society, London.

Harris, S. & Yalden, D.W. (2008) Mammals of the British Isles: Handbook, 4th edn. The Mammal Society, Southampton.

Available from The Mammal Society.