http://www.wildlifeonline.me.uk/questions_answers_squirrels.html#vulgarisdec

Ultimately humans are responsible for the demise of the red (and any number of other species) through first releasing the grey, then removing large areas of habitat in favour of less useful habitats such as Sitka Spruce plantations (a species of tree of little use to the red Link:http://www.forestry.gov.uk/forestry/INFD-5MJLGM )and finally through poor agricultural and land management techniques.
Thankfully some are now looking for positive ways to help – simply killing (or cleansing i think it is sometimes known as??!) one species to keep it in check or promote another smacks a little of some of the worst traits of the human race and i feel is not something to replicate or endorse.
Instead its pleasing to see that work like the vaccine for SQPV has shown some promising results – although as the link:
http://naturalengland.etraderstores.com/NaturalEnglandShop/product.aspx?ProductID=3e3f4c98-3163-4391-836a-dd75bed6303e
points out in the research information notes by natural England.
‘Work completed since this contract has illustrated the significance of this viral disease in the demise of the red squirrel and emphasised the need to reduce its impact. The development of a vaccine could be an important tool in tackling this problem, but the costs of developing a vaccine with no commercial potential are very significant and well beyond the reach of the conservation agencies alone’
New fund raiser for red squirrel vaccine anyone?