Grey squirrel  (Sciurus carolinensis)

This species is a serious pest in Britain, and its habit of removing tree bark is extremely damaging. In addition to out-competing red squirrels, it also carries a disease called parapox virus, which affects the native species (5).

No conservation measures are in place for this introduced and now common species. Grey squirrels are controlled to protect trees and in areas where red squirrels persist (6). The eradication of grey squirrels for conservation reasons is unlikely; the costs involved would be enormous, and the species is very popular with the public (6).