Programs to control invasive species often involve killing millions of animals, creating genuine ethical tensions between ecosystem restoration and individual animal welfare.
Invasive species control programs pit the welfare of individual animals against the survival of entire native species and ecosystems. Rats stoats and possums causing extinctions of endemic birds are themselves sentient animals capable of suffering. Welfare science demands that control methods minimize suffering where possible, that alternatives are developed, and that the ethical costs are honestly acknowledged rather than dismissed.