Red squirrels have been displaced from most of Britain by the introduced grey squirrel, and welfare-conscious grey squirrel control is central to red squirrel conservation in remaining refugia.
Grey squirrel control raises direct welfare questions about lethal management of introduced species. Spring trapping, when properly set and checked daily as required by law, kills instantly and is considered humane. Poisoning (secondary poison via grey squirrel reproductive bait) raises different welfare concerns through the mode of death. Red squirrel welfare is affected both by squirrelpox (which causes rapid weight loss and death within 2 weeks of infection) and by food competition that reduces body condition and winter survival probability. The welfare trade-off between humanely controlled grey squirrel killing and the unchecked spread of squirrelpox among red squirrels — for whom infection is invariably fatal — underlies the management ethics of this conservation intervention.