There are at least 69 species of wild mammals living in and around Britain and another 29 migratory species (bats and marine mammals), which occasionally visit. After the last ice age – 15,000 years ago – our native mammals crossed the land bridge attaching us to the continent before this was cut off by sea level rise. Some have already become extinct, including the beaver, brown bear and wolf. More recently, others have been deliberately (For example, grey squirrel and fallow deer) or accidentally (for example, mink) introduced to Britain by humans. The result is a mammal heritage formed from a unique mixture of species.
Britain and Ireland have two thirds of the world’s grey seals, probably half of Europe’s otters and important populations of badgers and horseshoe bats. Mammals are vital for the survival of other species. For example, the barn owl feeds almost entirely on small mammals and will only thrive where they are abundant. Mammals indicate that our own local environment is healthy; the survival of otters, for instance, suggests that our rivers are clean. But many species have suffered declines including pine martins, dormouse, most species of bat, brown hare, wild cat, water vole and polecat.
There are eight major groups that mammals can be divided into:
- Insectivores – characterised by their long snouts and sharp teeth adapted to their preferred diet of insects, worms, snails and other invertebrates. They include the mole, hedgehog and shrews.
- Bats – highly specialised insectivores, with wing membranes which make them the only mammals capable of flying. There are 16 species found in Britain.
- Lagomorphs – hare and rabbit – ground living vegetarians.
- Rodents – have large front teeth for gnawing and include squirrels, rats, mice and voles.
- Cetaceans – marine mammals – whales, dolphins and porpoises.
- Carnivores – flesh eating mammals such as the fox, otter, stoat and weasel.
- Seals – marine mammals that come ashore. Grey and common seals.
- Hoofed mammals – whose wild representatives are deer species.
Devon has 43 recorded breeding mammals living in the wild as well as 10 regular marine visitors. All 16 species of British bat have been recorded in Devon. The somewhat rare dormouse still has a stronghold in the County, as do otters, and Devon also has a healthy population of badgers. Unfortunately, it is thought that the once common water vole is now extinct in the County, or nearly so.
To help mammals and other wildlife survive, national and local nature reserves have been established and there are also many successful mammal-related initiatives such as, in Devon, Operation Otter and the Greater Horseshoe Bat Project. The protection of caves and old mines and buildings means that some bats now have secure roosting sites.
Simple ways to help mammals
- Clear up litter – every year thousands of small mammals die trapped in bottles and cans. Plastic bags and cartons can be swallowed by deer and prove fatal. Plastic rings for holding cans are also potentially fatal to animals such as hedgehogs.
- Don’t be too tidy in your garden or public spaces – leave an area to go ‘wild’. Areas of rough grass should be left to provide habitat for small mammals. Piles of leaves are good for hibernating hedgehogs and log or rock piles are good for small mammals to hide in.
- A piece of corrugated iron or similar material left in a grassy spot can create a nesting place for voles and wood mice.
- Avoid using chemicals in the garden to control pests such as slugs and aphids as small mammals can die eating poisoned prey and hedgehogs are poisoned by slug pellets.
- In dry spells of weather, turn over the compost heap to unearth moisture-loving creatures such as worms and slugs – badgers, foxes, hedgehogs and shrews will feed on them.
- Build bat boxes – at least 7 species of bat will use bat boxes. In a garden the boxes can be fitted to a tree or wall. Boxes fitted at different heights will attract different bats. At about 1.5m above ground they may be used by long-eared or pipistrelle bats whereas at 5m they may be used by large, high flying bats such as noctules.
- Dormouse boxes can be erected in suitable habitat, such as large hedgerows, scrub areas and coppiced woodland. For more information on dormice see the Woodland section.
- Many smaller mammals feed under bird feeders. You can place a paving slab on bricks and put some bird seed on it to attract voles and wood mice. Squirrels will feed on bird feeders so make sure they are robust enough to withstand their gnawing!
- Support organisations that are working for mammal conservation, particularly The Mammal Society and Devon Wildlife Trust.
Helping marine mammals
- Buy line-caught fish – purse trawling is responsible for the death of many dolphins and porpoises that are washed up on Devon’s coastline.
- Responsible boating – if dolphins and seals are present in the waters watch them from a distance rather than chasing them to get a closer look.