Much of modern theory posits change as a positive force. Societies, cultures and even religious ideas must be capable of evolving and keeping pace, to remain relevant for the modern era. In some cases, however, such evolution of fundamentals may reverse a principle into its opposite. One example seen in modern Buddhism, for example, is killing in the name of conservation. Australian environmental Buddhists are confronted by this issue of accommodating philosophical change and determining whether and where environmentalism crosses the Buddhist boundaries. Cane toads, an introduced species, threaten the survival of a variety of native reptiles, amphibians and mammals. In the chaos of climate change debates and responsible activism, Australian Buddhists are asked—‘Is it justifiable to kill one species to protect another?’ A range of Buddhist precepts and ethical dilemmas arise in the subsequent decision process.