Why British Mammals?
Because Mammals Matter
British mammals all play a vital role in maintaining a balanced ecosystem, on land, in water and air. Our mammals are keystone predator and prey items, indicators of habitat quality and shapers of our environment. Small mammals sustain our carnivores and birds of prey and bats control insect numbers, the otter and water vole indicate high water quality in our riparian habitats, and the harvest mouse and hedgehog imply diverse, connected landscapes.
Because the British Isles are a Special Place for Mammals
We form the north western limit to many species' ranges, separated from the continent, to provide a vital stronghold for many which are scarce or threatened elsewhere.
The Grey seal world population is estimated at only 250,000, with 101,500 living around the our coasts alone. Similarly we have nearly 30% of all Europe's Red deer, and the only thriving national badger population comprising larger family groups.
Cut off from the continent around 8,000 years ago, our native mammal fauna was fixed. It's important to understand the changes that have taken place since, and how species interact and impact on each other and their environment today. We can then accurately identify the issues for conservation, and advocate conservation policies that benefit mammals and the ecosystem as a whole. Today we have:
27 native terrestrial mammals
17 native bats
15 cetaceans found in and around our waters
4 additional island species (inc. 9 cetacenas in their waters)
14 introduced or naturalised species
11 vagrant species of bat and pinniped (found only occasionally)
4 feral species (not including pets & feral counterparts)
Losses and Gains
Persecution and hunting for meat and fur caused the extinction of the Wolf, Gray Whale, Brown Bear, Elk, Beaver, Aurochs, Wolverine, Wild Boar and Lynx, eradicating all large predators and most large herbivores and forever changing our landscape.
Introductions started with the import of sheep, goats, domestic cattle and pigs 5500 years ago. More recently the rabbit, house mouse, brown hare, edible dormouse, grey squirrel, American mink and several deer (Fallow, Sika, Chinese muntjac, Chinese water deer) arrived.
Some of our species, while abundant elsewhere, are of high conservation concern here, including the pine marten, limited to north England and Scotland, and the Scottish wildcat, a sub-species unique to us, numbers as few as 300 animals. Some species, including the polecat, otter and dormouse, have benefited hugely from conservation. Others are still vulnerable or thought to be declining, including the harvest mouse, brown hare, water vole, hedgehog and red squirrel. For other species we still know too little, such as the stoats and weasels, voles, and mole, which we are working to change.
Facing Modern Threats
Eradication of 'vermin' and pests of rural economies caused the decline of polecats and pine martens, and continue to threaten otters (in fisheries) and badgers (and bTB). We must also manage the impact of deer on forestry in the absence of natural predators
Introduced species impact upon farming and forestry, and compete with native species for space and food. Some also bring risks of hybridisation, disease transmission and predation, threatening native species such as red deer, red squirrel, water vole and wildcat.
Badgers, foxes, hedgehogs, polecats and deer are often casualties on roads.
Loss of habitat through land use change and agricultural intensification threatens many species. Recently brown hares appear less common on farmland, loss of hedgerows affects hedgehogs, and less connectivity affects dormice, bats and others.
Just A Numbers Game?
An important question for conservation management and a concern for some species impacts is often often about numbers e.g. rabbits and farming, deer and forestry, otters and fisheries, badgers and bovine tuberculosis.
Our estimate is about 285 million wild mammals in Britain; mostly Wood mouse (38 million), Field vole (71 million) and Common shrew (42 million). Bats are comparatively are; even the pipistrelle, if it is only one species, numbers no more than 2 million. Red deer number only 360,000.
However, size also matters when considering abundance. Our perception of some species as a pest of agriculture and forestry in made clear when considering their size. Compared to number dominant species, it is the rabbits and deer which largely dominate the biomass of wild mammals. It is their masses as much as their numbers which are supported by the vegetation they eat, and their impact on the rural economy is therefore considerable.
Even then, that's only 2% of total biomass. The 21 million sheep, 4 million cattle, 0.8 million pigs, 0.75 million horses account for 56% and of course 60 million adult humans, plus pets, for the other 42%. Further still, the biomass today is 33 times greater than 6000 years ago, demonstrating how have changed the ecology of the countryside. Grasslands, with or without fertilizer, produce more growth each year than woodland and as such support more animals and humans.