Removing invasive species restores ecosystems that support native animal welfare, but the methods used must be evaluated for the welfare costs imposed on the removed species.
Invasive species management creates a genuine welfare dilemma that conservation ethics cannot avoid. Stoats in New Zealand cause devastating welfare and conservation harm to native birds, yet stoats are themselves sentient animals capable of suffering during lethal control operations. Poison baiting causes prolonged deaths in target animals and non-target bycatch. Trap-kill methods cause suffering proportional to trap design and check frequency. The conservation case for invasive species removal is strong in isolated ecosystems where invasive predators are driving endemic species to extinction. The welfare minimum is to use the most humane effective method available, minimise non-target impacts, and invest in research into fertility control and immune-based approaches that might eventually replace lethal control.