The Values of Eradicating Invasive Predators

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
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 groups, but a native species may be surviving on one last island, we must also consider the rights of populations, species, or even ecosystems which rely on keystone natives to function (e.g. seabirds). This means the debate on invasive predator control is not just about animal ethics, but more broadly about environmental ethics.

If anyone would like to read the full text of our paper please contact me for a copy.

Read All Posts by James Russell

Conservation biologist Dr. James Russell works throughout the world on remote islands and other sites to provide conservation solutions by applying a combination of scientific methods. Follow James on National Geographic voices for regular updates on his own work or other exciting developments in island conservation.
  • Kerry Brown

    Bring on the debate. Well done. Please send me a copy of your Conservation Biology article.

  • TNR Researcher

    If you truly care about the well-being of animals then destroying free-roaming cats is the most humane thing to do of all options available (even for the cats themselves). Destroy any one invasive species cat = save the lives of thousands of native animals. That’s the true suffering-animal-equation. Saving them from being tortured to death by being disemboweled-alive or skinned-alive and left to suffer to death, or their offspring left to starve to death after the parents are killed or after cats have destroyed all of their ONLY food-sources — and all done to NATIVE animals that actually belong here by just ONE cat.

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