Island populations of red squirrels serve as vital refuges from grey squirrel competition and squirrelpox, making island conservation a cornerstone of red squirrel recovery strategy.
Red squirrels on the mainland face a constant welfare threat from squirrelpox virus, which causes fatal illness characterised by skin lesions, eye discharge, and progressive debilitation before death. The suffering from squirrelpox is prolonged and severe. Island populations that remain grey squirrel-free are protected from this threat and support healthier, longer-lived individuals. Conservation of island refuges directly prevents the welfare harm of squirrelpox mortality in resident populations and maintains the genetic diversity needed for long-term population health.