The Christmas Island shrew is no more. Australia’s only shrew species has officially been declared extinct in the latest update of the IUCN’s Red List of Threatened Species.
This little mammal, once common across the island, hasn’t been seen since 1985, and there have only been four sightings in the past 120 years.
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Lying south-east of Java in the Indian Ocean, Christmas Island was once annexed by Britain, later invaded by Japan, then managed by Singapore, and is now part of Australia – whose north-west mainland point is 1,500km away. Its remote location, and lack of human habitation until the late 1800s, means it is home to a variety of unique species that have evolved there, including its shrew.
Unfortunately, the accidental introduction of non-native black rats brought a non-native parasite that wiped out two of the native rat species, and potentially a high proportion of the shrew population as well. Additional factors may have contributed to the decline, including non-native cats and snakes also being introduced to the island.
A paper published in September 2023 calculated that a 96.3% likelihood of the shrew being extinct, and this was confirmed by the latest IUCN update.
“This is one of the most mysterious of extinctions,” says Professor John Woinarski at the Charles Darwin University, Australia, and lead author of the paper.
“This shrew persisted - but obviously in only very small numbers - long after it was initially thought extinct in 1908. But with only four records over the last 120-odd years, its status has been extremely challenging to resolve. Its loss highlights the disproportionate rate of extinctions of island biota, and their susceptibility to introduced plants, animals and disease.”
Three other Australian mammals – the marl, the south-eastern striped bandicoot, and the Nullarbor barred bandicoot – were assessed for the first time and entered into the Red List as extinct.
Alongside the Christmas Island shrew, other species reassessed and now deemed extinct include a cone snail, which has also not been seen since the 1980s, a tree in the ebony tree genus that hasn’t been recorded since the 1850s, and the slender-billed curlew, last recorded in 1995 in Morocco.
Top image: Christmas Island. Credit: Getty
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