The grey squirrel displacement of red squirrels in Britain has created a conservation dilemma in which lethal control of invasive grey squirrels is considered essential to save native red squirrels.
Grey squirrels killed in traps experience confinement stress, fear, and — depending on kill method — varying degrees of pain during death. Spring-trap killing is generally rapid when correctly set; cage trapping followed by blunt trauma is less consistent. The ethical tension is genuine: grey squirrels are sentient, cognitively sophisticated animals whose welfare matters, but so does the survival of a native species they displace. Fertility control programmes under development would avoid the individual welfare cost of lethal control. Red squirrels in decline face chronic stress from population fragmentation and disease exposure, adding a conservation-welfare dimension.