Wiltshire and Swindon Biological Records Centre

Otter – Lutra lutra

Otters are very secretive creatures, and despite their large size they are very difficult to spot, they are solitary, nocturnal and elusive animals. The best time to see Otters is at dawn or dusk alongside rivers and water bodies, they may be hard to see as they are very agile and quick in the water, but they have a distinctive bounding gait when on land.

Otter, WWT/Darin Smith


Habitat

Otters require clean rivers with an abundant, varied supply of food and plenty of bankside vegetation offering secluded sites for their dens (holts). Most clean rivers throughout Wiltshire support Otters, they can also be found in lakes.

Description

As Otters are hard to spot it is normally best to look for signs such as their droppings (spraint) or paw prints, these will be mostly around their dens or amongst tree roots on a riverbank. Droppings are normally found in prominent places such as a rock next to the river, and they smell like jasmine tea!

Otters have a broad, fleshy tapering tail, a long sleek body and webbed feet, all of which make it an excellent swimmer. They have sleek fur that is brown on the upperparts and is white underneath including their neck and chin; the fur is short and very dense allowing a layer of air to be trapped when the Otter is in the water which helps to insulate it. The ears and nose are closed whilst the Otter is underwater. They have short legs and their heads are fairly small with a blunt muzzle.

Biology

Long sensitive whiskers help the Otter to detect prey underwater, which consists mainly of fish, but also sometimes small birds and frogs. Otters can consumer up to 15% of their body weight in a day.

Otters are very territorial and mostly live alone, they marked their territories by spraints in prominent places. The sizes of a territory depends upon the availability of food and have been known to range from 2-20km. Territories are marked against those of the same sex so male and female territories may overlap. In their territory will be their den known as a holt which will often be in a tree root system or under a pile of rocks.

Otters can breed at any time of year and there are normally up to 3 cubs born and they are dependent on their mother for a year. After 10 weeks the young Otters emerge from the den with their mother where she starts to teach them to fish. She does this by releasing live fish for them to re-catch.

Threats

Historically Otters were hunted for their fur which was highly prized, this alongside being hunted for ‘sport’ and to protect fish stocks meant the number of Otters across Britain and in Wiltshire declined dramatically in the late 1950's into the 1960's. Pollution of watercourses and fish through pesticides also had a big impact on Otter numbers.

Today habitat destruction through the building of roads and the loss of previously undisturbed riverbanks along with pollution are the main causes for their decline; many rivers lack the tall vegetation that Otters need to conceal their holts. Many are also killed on roads which are when they are most likely to be seen as they are so elusive that the only time we get to see them is when they are hit by vehicles. These records are still important so let us know if you come across any road casualties.

They were once widespread but their populations, although slowly recovering (they occur on most rivers in Wiltshire), are still quite fragmented.

Conservation

The Otter is protected under the Wildlife and Countryside Act (1981), listed under schedule 5 and 6. This makes it an offence to kill, injure or trap an otter, be in possession of a live or dead otter or any part of one, or intentionally destroy, obstruct access or disturb any otter shelter or animal while it occupies the shelter. It is also a UK and Wiltshire BAP (Biodiversity Action Plan) species; the UK BAP aims to maintain and expand existing populations and ensure that by the year 2010, breeding populations have been restored to all catchments and coastal areas where post-1960 records exist.



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