Eurasian Otter - Lutra lutra

Status: Near Threatened … Otter cubs only open their eyes about five weeks after they are born

Type: Mammal

Location: One of the widest distributions of a UK mammal species, the Eurasian Otter is found throughout Europe, eastern Russia and China, south and south east Asia and north Africa.

Size: Males (also known as dog otters) can reach a length of 130cm from nose to tail, while females (bitch otters) are smaller.

Habitat: Otters are voracious fish eaters, with fish making up over 80% of their diet, so they have evolved to live in a variety of habitats where fish are plentiful. Otters are not considered a marine mammal, because they cannot survive without access to fresh water, but they often use coastal habitats, as well as lakes, swamps, rivers and streams. Otter populations in the Himalayas are found well above 3000 metres altitude.

Main Threats:
Survival in the wild, particularly for a carnivore, is not easy and so the life expectancy of this species is only up to 4 years. There have however been a incidences of otters living for 8-12 years, although very few survive that long.

The conservation status of this ancient species has been a concern in the UK since they became close to extinction here after dramatic population declines from the mid 1950’s to the 1980’s. These declines were linked to the use of organochlorine pesticides, including dieldrin, in agricultural practices. When leached in to waterways, these chemicals had a serious impact on top predators, including the otter, due to the way the chemicals become more concentrated in animals higher up the food chains. Although the chemicals were eventually withdrawn, the otter population was slow to recover.

Pollution from pesticides, mercury, oil spillages and PCB’s are still a hazard to otter populations in some countries, as well as habitat destruction on land and in the water. Traffic injuries are also a problem, as more roads are built through their habitats. In parts of their range, otters are also threatened by hunting, and bycatch in some fishing gears (e.g. nets and traps). In some areas of western Europe, including the UK, many otter populations have now recovered well in response to the increasing health of waterways and coastal habitats, but population decreases across the entire range of this iconic mammal mean that it is globally listed as ‘near-threatened’.

The Eurasian otter is very well adapted to the aquatic environment. It has short limbs, webbed feet and claws, and highly sensitive whiskers, enabling it to detect prey in murky waters. Its sense of sight, smell and hearing is acute. The position of the eyes high on the head allow it to see out of the water whilst the rest of the body is below. The thick fur is made up if 2 layers, a thick outer waterproof one protecting a warm inner one. The fur traps a layer of air to enable insulation. When underwater the otter can close its ears and nose. Although it is an excellent swimmer and hunter of fish, it can only hold its breath for a short time, most dives average at about 30 seconds. As the cubs are not natural swimmers, hindered by their fluffy coats, they are often dragged to the water by the mother at about 16 weeks of age, after which their swimming and hunting skills develop rapidly.

When underwater, the otter can close its ears and nose.

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