Invasive Species Denialism Gets Demolished
In 2025, Dr. Arian Wallach of Queensland University of Technology and Dr. Erick Lundgren published a paper in BioScience that made a remarkable claim: there is "little evidence" that cats and foxes caused Australian mammal extinctions. They argued that habitat loss, not introduced predators, was the real driver.
Twenty-five of Australia's leading conservation scientists read the paper, found it indefensible, and published a detailed rebuttal in the same journal.
What Wallach and Lundgren Claimed
The original paper argued that the timeline of mammal declines did not match the arrival of cats and foxes. They presented data suggesting other factors — land clearing, altered fire regimes, drought — were more plausible explanations. The implication: maybe the billions of dollars spent on feral cat control were wasted.
Cat advocacy groups shared the paper widely. It confirmed what they wanted to believe.
What 25 Scientists Found Wrong
The rebuttal, led by Professor John Woinarski of Charles Darwin University, identified fundamental errors:
Wallach and Lundgren "misinterpreted their own data." Every case of population decline in their dataset occurred after cat arrival — not before, not independent of it. The timeline actually supported the predation hypothesis.
The original authors ignored the most powerful natural experiment available: predator-free havens. In fenced reserves and islands where cats and foxes have been removed, mammal populations increased 680% between 2000 and 2017. In areas with cats and foxes present, populations declined 80% over the same period.
That is not a subtle difference. That is a 760-percentage-point divergence.
Biodiversity Council: Leading Scientists Refute Invasive Species Denialism
The Numbers Australia Lives With
Australia has lost more mammals to extinction than any other continent — approximately 40 species since European colonization. Cats contributed to at least 22 of those extinctions. They currently threaten 124+ additional species. Feral cats kill an estimated 1.7 billion native animals per year.
These are not debatable figures. They come from decades of fieldwork, gut content analysis, camera trapping, and exclusion experiments.
UNSW: Yes, Feral Cats and Foxes Really Have Driven Australian Mammals to Extinction
Why This Matters Beyond Australia
Invasive species denialism is not new. It follows a pattern familiar from climate denial: find a credentialed contrarian, publish in a reputable journal, generate media coverage, and create the impression of scientific uncertainty where none exists.
The cat predation question is not uncertain. Cats have contributed to the extinction of 63 species worldwide, including 14% of all island bird, mammal, and reptile extinctions. They prey on 2,083 species across the globe. When you remove cats, populations recover. When you don't, they collapse.
Two academics tried to muddy those waters. Twenty-five corrected them. The correction should be louder than the original claim.
BioScience: Rebuttal to Invasive Species Denialism Paper
Last edited: