Palm-size marsupials may face extinction from wild ‘house’ cats

After surviving Australian bushfires, the Kangaroo Island dunnart faces hungry predators

someone holds a Kangaroo Island dunnart on a piece of cloth

This Kangaroo Island dunnart — caught in 2022 during routine monitoring of the island’s wildlife— easily fits in the palm of a hand. Not counting its tail, it’s just 7.5 centimeters (3 inches) long.

Pat Hodgens

Marsupials are those mammals with pouches to carry their young. Few of these animals have gone from miraculous survival to the brink of extinction as quickly as the Kangaroo Island dunnart.

In 2019 and 2020, devastating fires burned nearly 100,000 square kilometers (38,600 square miles) of southeastern Australia. (That’s an area roughly the size of Indiana or Virginia and almost as big as Taiwan or Switzerland.) Wildfire flames threatened hundreds of species with extinction. But the Kangaroo Island dunnart (Sminthopsis aitkeni) seemed to defy that concern. And that was even though its population numbered fewer than 500 before the fires.

But now these rare creatures may be more at risk than ever. That’s the finding of a June 16 study in Scientific Reports. The big threat for these animals: being eaten by a cat.

Cats are mighty predators. As of 2008, feral cats had contributed to more than one in every eight species extinctions worldwide.

Cats are not native to Kangaroo Island. In fact, they’re viewed as an invasive species. Many of these animals have become part of the island’s wildlife. That’s one reason the government has been culling cats on Kangaroo Island for years. The scientists who conducted the dunnart study knew all this. But when they studied the remains of cats euthanized in 2020, the researchers were still surprised by what they saw. Seven out of every 86 cats had recently dined on dunnarts.

“We were not expecting to find so many,” says Louis Lignereux. He’s a field researcher in Australia at the University of Adelaide School of Animal and Veterinary Science. And these gut contents were only a snapshot of the cats’ risk to dunnarts. Those meal data reflected only what these animals had eaten in the last day and a half. Taking that into account, those seven cats alone could have eaten enough dunnarts to wipe out the Kangaroo Island population within a few months. These studied cats, of course, were now dead. But hundreds more still roam the island.

The dunnart’s small habitat makes this animal especially vulnerable. It’s like putting all your eggs in one basket, Lignereux says. Since the fires, the Kangaroo Island dunnart is thought to now live in an area about a tenth the size of the New York borough of Manhattan.

“If something happened to this spot,” Lignereux warns, “then [the dunnart] is gone forever.”

Asa Stahl is the 2022 AAAS Mass Media fellow with Science News. He is a 5th year Astrophysics Ph.D. student at Rice University, where his research focuses on detecting and characterizing young stars and planets.

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