Sterilisation plan for grey squirrels

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Scientists are planning a mass sterilisation programme to halt the

growth of Britain's grey squirrel population which is now feared to

have reached five million.

 

Killing squirrels - no bombing or arrows

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Teams in Britain and America are working against the clock to develop

a method of rendering the pests infertile using treated bait.

 

Grey squirrels carry squirrelpox virus which does not harm them but

kills reds squirrels

Some estimates put the number of greys in Britain at five million and

it is feared the local red population could die out within two

decades unless dramatic steps are taken to curb their bigger,

stronger rivals.

 

As well as forcing out red squirrels, greys destroy trees by

stripping bark and have taken their toll on songbird populations by

taking eggs. They also steal food from garden bird tables and infest

loft spaces.

 

The problem of the burgeoning grey population was highlighted by the

Daily Telegraph in an article by associate editor Simon Heffer which

prompted a flood of letters and emails from readers. He called for a

cull to stop them damaging the countryside.

 

Government scientists are working on a two-year programme

commissioned by the Department for Environment, Food and Rural

Affairs to find an effective oral contraceptive for grey squirrels.

 

They are also trying to pinpoint the best way of giving it to the

rodents without affecting other animals. If successful, the treatment

could be adopted in around five to 10 years.

 

Brenda Mayle, who is leading the research, said sterilisation

injections had already proved successful in horses and deer in the US.

 

" If it eats part of the bait and leaves the rest it is a risk to non-

target species. We are looking for a food package that the squirrel

will eat in its entirety and not cache, which it does with acorns, "

said Ms Mayle, who is research programme manager for Forest Research –

part of the Forestry Commission – in Surrey.

 

The contraceptive would work by attacking the immune system of the

squirrel, suppressing its fertility. Scientists are desperate to find

ways of tackling the grey squirrel threat before it causes more

damage to the red population.

 

Greys have been found to carry a disease called squirrelpox virus

(SQPV) which does not harm them but kills reds.

 

It is spreading through Britain and has recently been found as far

north as Lowland Scotland.

 

Ms Mayle said: " It's very important that we do find something to

reduce the rate of their spread, particularly because we are seeing

the squirrelpox virus spreading north in Scotland now. "

 

But she added: " It's not an alternative to culling. It will become

another tool in our ability to manage wildlife populations but it's

not an alternative to lethal methods. "

 

A spokesman for Defra ruled out a national cull, saying it had been

considered but would be too expensive with no guarantee of success.

 

" The Government is committed to preventing the further spread of grey

squirrels, however, eradication is considered impracticable at

national level. Some local programmes of control are under way,

particularly in areas where grey squirrels are threatening remaining

populations of reds or to protect forestry, " she said.

 

Grey squirrels were introduced to Britain from America in the

Victorian era but swiftly pushed out red squirrels, which are now

only found in the Isle of Wight, Brownsea Island, western Wales,

northern England and parts of Scotland.