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| | | Nature offers a window on global natural history, providing a unique insight into the natural world, the environment, and the magnificent creatures that inhabit it.
nhuradio@bbc.co.uk | | | | | LISTEN AGAIN 30 min | | | |
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"Nature is full of surprises, so the programme can investigate fascinating and challenging areas in
our relations with the natural world without being too technical or preachy. My job is brilliant because, as a link between the listener and the subject, I can discover new information and ideas which help people make up their own minds on important issues."
Paul Evans |
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|  | | | Contented or contentious? |
Paws for Reflection
In Nature this week, Paul Evans weighs up the evidence for and against the domestic cat.
There’s no doubt that we’re a nation of cat-lovers…between us we have 8 million of them, and there are a further 1 million living wild….but it seems that for every person who likes cats, there’s someone else who’s far from happy at the alleged effects cats are having on our wildlife. So who’s right? Paul talks to the biologists who’ve studied cat predation and to the defenders of the domestic moggy.
Paul gets to grips with why cats hunt and how they manage to live together in such large numbers when he talks to feline behaviourist Rachel Casey . She explains that cats were domesticated in Egypt some 4,000 years ago to deal with mice which attacked grain harvests. Large numbers of prey at grainstores led to unusually large concentrations of cats which tolerated each other because of the high levels of food.
Nowadays there are large numbers of cats in suburbia too. Stephen Harris from the Mammal Society has estimated 226 cats per square kilometre in his north Bristol study area, nearly 500 times the density of the Scottish wildcat, our only native feline. Those cats that do hunt are, he says, bound to have an impact on the animals that live in our gardens and countryside. The Mammal Society survey “What The Cat Brought In” conducted in 1997 sampled a thousand known hunters and the Society’s chairman Michael Woods reveals that they caught 4,000 mice, 2,000 voles and about half as many shrews between them. These figures may be under-estimates since they reflect only the prey brought home. Extrapolating the findings, gives a figure of 275 million mammals, birds, reptiles and amphibians taken by cats in the UK each year.
Birds are also taken in large numbers and Graham Appletom from the British Trust for Ornithology explains to Paul how recoveries of ringed birds can give us an idea of how significant cats are as controllers of bird numbers. For example, half of the ringed robins found dead in gardens are victims of cats, though this figure is biased by the fact that cats often bring their prey back home to their core territory where it can easily be found. Graham Appleton points out that although cats do kill large numbers of robins, the robin population in urban areas is increasing, so that the effects of cats are not necessarily limiting numbers. Where they are a more serious threat to birds, is in cases where the species is already declining. House sparrows and song thrushes are both decreasing and the addition of cats into the equation could affect populations which are already threatened.
One of the most vulnerable British animals to cat predation is the sand lizard, a rare reptile of southern heathland and the dunes of Lancashire. Keith Corbett of the Herpetological Conservation Trust explains that because the lizards live in small, often isolated populations and are predictable in their basking behaviour, they are easy for cats to pick off.
In many parts of the world , cats are a serious threat to endangered species and drastic measures are needed to remove them. Paul meets film-maker Peter Crawford who has recently travelled to Ascension Island in the South Atlantic. There, cats originally introduced by settlers have reduced seabird colonies by up to a half in 50 years or so. The solution, supported partly by the RSPB, has been to tag cats with known owners. Any non-tagged feral cats found in areas near seabird colonies have been poisoned and nearly all feral cats have now been eradicated.
This solution is obviously inappropriate for the British Isles, concludes Graham Madge of the RSPB, as we don’t have any globally threatened species living here for which cat predation is a major factor. However, if proof were available that some species , such as house sparrows and song thrushes were being affected by cats, then it is possible that cat curfews could be introduced in the future. Rachel Casey points out that many cats do not hunt and that the figure of 275 million creatures killed annually is an over-estimate, since the Mammal society survey targeted cats that were known hunters.
Paul concludes that 9 million cats must be having some effect on our wildlife, but that the exact figure is very difficult to quantify: more research is needed. | | |
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