Red squirrels have been almost entirely displaced from England and Wales by the grey squirrel, with conservation efforts focused on strongholds in Scotland and some islands.
Red squirrels displaced by grey squirrels experience the loss of habitat and food resources, increasing competition stress and starvation risk. Individuals contracting squirrelpox suffer acute disease causing facial lesions, lethargy, and death within weeks. Conservation management that controls grey squirrel populations in red squirrel habitat prevents this suffering at the individual level while addressing population-level decline. The development of oral vaccines represents a potential welfare-positive breakthrough.