SIR, — I suspect that in last week's article headlined 'Trapped grey squirrel was carrying pox', Norris Atthey means that the blood sample from the trapped grey squirrel contained antibodies showing that it had resisted squirrel-pox virus (SQPV) rather than being an active carrier.
His view that grey squirrels can only transmit squirrel-pox virus to reds and ignoring that reds can transmit it to other reds, is based on a flawed and prejudicial agenda.
In fact, it is known that the disease characteristics are similar to other poxvirus infections and that most are resistant to drying.
This can allow infected lesions or crusts to remain infected for a long time thus allowing the spread of the disease throughout the forest environment by almost any creature that comes into contact with it.
Indeed, Scottish Natural Heritage admits it does not know the route of transmission and that 'possibilities include being passed by ectoparasites, fleas, lice, ticks and mites which may transfer from animal to animal in the dreys'. They also acknowledge the virus may be airborne spread.
Research by McInnes et al in 2006 acknowledges 'the possibility that the virus is endemic to the UK and that other rodent species inhabiting the same woodland environment could be harbouring the virus'.
In Merseyside, a buffer zone has been in place for a number of years where grey squirrels are routinely killed.
However, increased human exploitation of red squirrels for tourism and the frequent intrusion by conservationists for monitoring population levels was always likely to lead to stress and loss of condition of the red squirrel, resulting in an increased susceptibility to disease.
The recent announcement that the red squirrel population has declined by 90 percent in the past two years is hardly surprising.
In short, fewer grey squirrels with more conservation and tourist intrusion have resulted in a massive decline in the red squirrel population — definitely not the predicted outcome.
Perhaps it's conservation that needs culled.