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Vertebrate management - commissioned reports

Date: 2007
Title: Assessing the risk of encroachment of grey squirrels into red squirrel forest reserves
Author: Peter Lurz, John Gurnell and Steve Rushton
Full report: PDF

UK red squirrel (Sciurus vulgaris) has disappeared from much of mainland Britain with its geographical range now restricted mainly to the north of England and Scotland and parts of Wales (Gurnell & Pepper, 1993). The decline of the red squirrel has been attributed to competition from introduced North American grey squirrels (Sciurus carolinensis) that have replaced red squirrels throughout much of their range. However, more recently a lethal epidemic disease has been identified as a contributing factor. The disease results from infection of red squirrels by a squirrelpox virus (SQPV) that is carried by grey squirrels. The transmission of the virus is a function of encounter rates within and between red and grey squirrels, but we do not know how the virus is transmitted from one individual to another or if the production and deployment of a vaccine is possible. Thus, there is an urgent need for well-targeted grey squirrel control to minimise spread and incursion of grey squirrels into designated red squirrel reserves in the North of England to reduce the risk of virus transmission