Christmas Island Shrew Officially Extinct; 39 Australian Mammal Species Gone Since 1788, More Than In Any Other Nation

t’s official: the only Australian shrew is no more. The latest edition of the International Union for the Conservation of Nature’s Red List, the world’s most comprehensive global inventory on extinction risk, has declared the Christmas Island shrew is extinct. The news may not seem momentous. After all, most Australians know nothing of shrews and would be unaware this one species counted among our native fauna.

But the shrew’s extinction increases the tally of Australian mammals extinct since 1788 to 39 species. This is far more than for any other country. These losses represent about 10% of all Australia’s land mammal species before colonisation. It is a deplorable record of trashing an extraordinary legacy.

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Tens of thousands of years ago, a small family of shrews (or a pregnant female) rafted on floating vegetation, from islands of what is now Indonesia. Haphazardly, they landed on uninhabited Christmas Island, now an Australian territory about 1,500km west of the mainland. These lucky or reckless pioneers gave rise to Australia’s only shrew species. For many years the Christmas Island shrew prospered. When European naturalists first visited Christmas Island in the 1890s, at the time of its settlement, they remarked: "This little animal is extremely common all over the island, and at night its shrill shriek, like the cry of a bat, can be heard on all sides."

Change came quickly thereafter. In 1900, black rats were accidentally introduced, stowaways on hay bales. Worse, these rats were infested with trypanosomes, a cellular parasite. These trypanosomes spread rapidly to the island’s two species of native rats (and presumably the shrew). The long isolation of Christmas Island had cocooned its native mammals, leaving them with no resistance to new diseases. Within a year, island residents began seeing many dying rats stumbling across the forest floor.

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https://www.theguardian.com/environment/commentisfree/2025/oct/11/and-then-there-were-none-australias-only-shrew-declared-extinct