Mammals

The Red Squirrel

Our once common native red squirrel (Sciurus vulgaris) has suffered a dramatic population decline in the last century, resulting in local extinctions throughout much of south England, Northern Ireland and Wales and is included as a priority species in the UK government 's conservation initiative, the UK Biodiversity Action Plan.

In the past, habitat loss and fragmentation contributed to the red squirrel population declines. However, the current threats to the red squirrels' continued survival are thought to be the sustained expansion of populations of the introduced grey squirrel (Sciurus carolinensis) and with them the potential of squirrel poxvirus transmission.

Red squirrels are very difficult to survey because they are secretive, live at low densities and their populations across the UK are very fragmented and isolated. A two year scoping study is being carried out by a consortium of organisations to try to address the problems and produce a comprehensive UK red squirrel monitoring scheme. The results of the study will be published in 2007.

Identifying 'Priority woodlands' for red squirrels is considered by the UKRSG to be one of the key methods of conservation action required by each country. An example of this is being demonstrated in Kielder Forest, the largest man-made forest in the UK . Through a partnership of Scottish and English organisations thousands of hectares of a plantation forest, which stretch from the Scottish Borders to County Durham, will be specifically managed for the red squirrel. A computer generated model has provided the basis for a planting strategy, aimed at safeguarding red squirrels in key woodland areas, while preventing grey squirrels from gaining a competitive advantage.

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The Otter

Otters(Lutra lutra) are one of the most playful animals, often appearing to take childlike enjoyment in sliding around on muddy banks or in snow.

Otters are listed as Vulnerable by the 2000 IUCN Red List. They have become extinct in much of their range, with many populations still diminishing. They are strictly protected by the Wildlife and Countryside Act (1981) and cannot be killed, kept or sold without a licence.

Although conforming to the basic mustelid body shape of a long, slim body and a skull with powerful jaws, otters show numerous adaptations to aquatic life. These include webbed toes and a powerful rudder-like tail, used for propulsion under water. Otters are capable of closing their ears and nostrils while underwater. They have two types of fur; stout waterproof guard hairs and a dense, fine underfur which provides insulation. Their fur is chestnut brown and is slightly lighter on the belly.

They have a ife span of up to 10 years.

The Eurasian otter is the only otter native to Britain. They're also found throughout Europe, as far north as the Arctic Circle, across most of Asia and northern Africa.

In the British Isles, otters are found in fresh and salt water, although coastal otters like those in Scotland and the Shetlands need access to freshwater pools to clean their insulating fur.

Apart from fish, otters also feed on crustaceans, water birds, frogs and voles. They can use their whiskers as sensing organs underwater, to monitor the movements of prey.

Otters are solitary and are active at dusk and during the night. Although they occasionally come out in the day, they usually rest in a burrow in the river bank called a holt.

Otters breed all year round, with a gestation period of about 63 days, after which two or three cubs are born. These are blind at birth and are covered in a dark or grey downy fur, finally opening their eyes after 35 days.

The cubs will remain inside the holt, in a nest of straw or weeds for a further couple of weeks, before venturing out into the open with their mother. The cubs are weaned after three to four months and reach sexual maturity after two to three years.

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The Badger

The badger is one of Britain’s best loved animals yet misunderstood mammals and as such is part of our national heritage. They are a poignant symbol of the British countryside and a protected species.

Did you know that the badger is the largest land carnivore left in the British Isles following the extinction of the bear and the wolf!

The fact that badgers are rarely seen does not mean that they are rare. They are in fact fairly common,the last estimate of the national population being around 250,000. However, throughout Europe, badger numbers are in decline. This means that the British Isles are one of the species’ strongholds.

In his poem “The Combe”, Edward Thomas describes the badger as “The most ancient Briton of English beasts”.

Badgers certainly are “ancient Britons” – the earliest fossil remains date back 250,000 years! These black and white animals have lived alongside human beings for a very long time - one badger sett is even recorded in the Domesday Book!

The European Badger (Meles meles) belongs to the family of mammals known as the mustelidae (possessing musk glands), otherwise known as the weasel family and includes the otter, stoat, polecat, ferret and pine marten.

The name badger is believed to come from the French word ‘becheur’, meaning digger. Badgers are nocturnal animals and are adapted for a life underground. Contrary to popular belief, badgers do not hibernate, although they have developed strategies for conserving their energy and body weigh during the winter months when their normal diet of earthworms and grubs are not available.

Badgers have a small head, small eyes, a thick short neck and a long wedge-shaped body with a short tail. They grow up to 30 inches (750 mm) from head to tail, with a six-inch (150 mm) tail, and can weighs between 8 and 12 kilograms. Males are slightly larger and heavier than the female. Aside from the size difference, it is very difficult to tell a male from a female badger. Male badgers are called boars, females are sows and the young are cubs.

A badger's hair is black and white - leading to a grey appearance from a distance. The badger has a black chest and forepaws with a prominent black and white striped head with white tipped ears. However, some badgers may be albino (white), melanistic (black) and erythristic (ginger). These colour variations depend on the amount of melanin (a natural substance that gives colour (pigment) to hair and skin) in the badgers’ hairs and is controlled genetically.

It has been suggested that the black and white stripes are a warning to other animals that the badger is capable of looking after itself and will defend its territory.

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The Water Vole

Best known as "Ratty" in the Wind in the Willows, the mammal is declining faster than any other in Britain.

Once common on all of Durham's rivers the water vole has suffered a catastrophic decline in numbers and distribution in County Durham, as it has throughout most of the UK. Today the water vole is restricted to a few small colonies in County Durham mostly in our urban areas or in places not yet reached by the American Mink.

Water vole numbers have been dropping since 1900, but in the last 20 years the decline has accelerated alarmingly. National surveys have shown that water voles have been lost from more than 89% of sites that they inhabited sixty years ago, this makes them the fastest declining mammal in the UK. Predictions for the water voles future are bleak, based on current population declines it is possible that the water vole may become extinct in the UK by 2006.

Their disappearance appears to be a classic case of habitat loss and then fragmentation. This leaves small isolated populations that are vulnerable to other threats such as flooding and pollution incidents. The water vole is easy prey for the American Mink, which has spread throughout the country, the arrival of this new predator able to hunt the voles both in the water and in their burrows has lead to the systematic eradication of many of these small water vole populations.

Typical water vole habitat includes slow-flowing watercourses with tall, luxuriant bankside vegetation. Water voles favour grasses and sedges as a food source and will eat the bark of certain trees such as willow during the winter. Water voles also need steep sided earth banks where they can excavate their burrow systems.

The water vole is listed in the UK Action Plan on Biodiversity, published by the Government in 1994. The BAP sets out strategies and targets for conserving species and habitats for the next twenty years. Durham Wildlife Trust has undertaken a water vole survey of North Durham and South Tyne and Wear as well as managing its nature reserves for the benefit of water vole populations.

Water voles are a priority species for conservation at Durham Wildlife Trust who are eager to receive any reports or sightings of water voles.

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Bats (All Species)

Current factors causing loss or decline in the bat population nationwide are the damage and fragmentation of woodland foraging habitat, old hedgerows and tree lines, and other appropriate habitat.

The lesser horseshoe bat was originally a cave-roosting bat, although most summer maternity colonies now use buildings, particularly old large houses and farm buildings. Most still hibernate in underground sites such as caves.

Females forage within 2-3 km of the maternity roost, feeding on insects taken in flight in mixed woodland, hedgerows and treelines.

In Britain, the lesser horseshoe bat is now found only in south-west England and Wales. It was formerly present in south-east England and the Midlands. Current estimates suggest a UK population of 14,000 divided equally between Wales and England. About 230 summer (or all-year) roosts are known and about 480 hibernation roosts.

Of the latter, only 20% are used by more than 10 bats. The lesser horseshoe bat is widespread throughout central and southern Europe, but has undergone severe decline in the northern part of its range.

This species is included in Appendix II of the Bonn Convention (and its Agreement on the Conservation of Bats in Europe) and Appendix II of the Bern Convention (and Recommendation 36 on the Conservation of Underground Habitats). It is also listed on Annexes II and IV of the EC Habitats and Species Directive.

It is protected under Schedule 2 of the Conservation (Natural Habitats, etc.) Regulations 1994 (Regulation 38) and Schedule 5 of the Wildlife and Countryside Act 1981. The 1996 IUCN Red list of Threatened Animals classifies this species as Vulnerable (VU A2c).

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