The Values of Eradicating Invasive Predators

A feral cat catches and eats a crimson rosella bird

Island conservation often requires evaluating one species against another. Cat versus seabird, rat versus reptile, mouse versus invertebrate. Although scientists can document the evidence of impacts, e.g. the staggering rates of declines in native species enacted by introduced predators, conservation biologists must arbitrate what the moral course of action is. In a paper accepted this week in the journal Conservation Biology, myself and an international consortium of conservation biologists grapple precisely with these complex moral and ethical issues in invasive species eradication on islands.

A feral cat catches and eats a crimson rosella bird in Australia (Photo by Department of the Environment, C. Potter)

Whether to support eradication of an introduced species from an island is based on a number of important judgements. The evidence of impact from the introduced predator must be high, such that its eradication would almost certainly create conservation gains. We must also accept that humans as agents of the original introduction of the predators are responsible for mitigating those impacts. This essentially means that we distinguish native from introduced species, and accept that doing nothing is itself a conscious course of action, i.e. a judgement call on the fate of species on the island.

A feral mouse eats another mouse during a plague outbreak in New Zealand (Photo by Sylvain Dromzee)

These value judgements must consider the suffering, of both the invasive predator, and also the native species upon which they are depredating. Lethal control of an invasive predator has important welfare concerns, but these must be weighed against the predation of introduced predators on naïve insular native species (e.g. mice on seabirds). “As conservation practitioners, we can have a say in how humane any deaths may be”. When the invasive predator is present on over 80% of the world’s island —> Read More