Australia’s endangered species: Christmas Island shrew

Australia may not have any more shrews. Australia has only one representative, who is based on remote Christmas Island, closer to Java than anywhere else in Australia, and who has made his way into Australian politics.

Shrew These strange creatures, mostly tiny placental insectivores, are found in Europe, Africa, Asia, and the Americas, with nearly 400 species. In folklore, they have an unwelcome reputation that is largely undeserved and sometimes downright bizarre: they consort with witches, turn wine sour, and have violent tempers.

They look like mice with long noses and small eyes, but are not related to rodents. They weigh 2 grams, Etruscan shrew The smallest mammals in the world. On the Australian mainland, they have ecological counterparts, the unrelated marsupials planigales, ningauis, dunnarts and Wombat.

Christmas Island shrew (Hairy-tailed crocodile) was long thought to be a variant or subspecies of a more widespread Asian species. However, a recent genetic study by Mark Eldridge et al., based on a small number of now-deceased individual specimens, suggests that it is (or was) a distinct species restricted to Christmas Island. For a shrew that was presumably extinct, it may be very comforting to have its distinctiveness now confirmed.

status

Little is known about the Christmas Island shrew. Most of what is known about it comes from a few observations when it was discovered in the 1890s. After 1902, it has only been reported four times, twice in 1958, once in 1984, and once in 1985. It was feared to be extinct in 1908 and was thought to be extinct in the 1940s.

Its intermittent reappearance shows that extinction can be surprisingly difficult to prove, especially for small and cryptic species. Pessimists now conclude that it will not return; optimists cling to the shaky belief that a few individuals may still be surviving in the rainforest. Given Christmas Island’s relatively small size (135 square kilometers),²), its existence is a puzzle that should be solvable.

Christmas Island shrews were once common. In 1898, shortly after Christmas Island was first settled, the distinguished naturalist Charles Andrews was commissioned to conduct a comprehensive baseline survey of Christmas Island, documenting the survey’s impact:

It has hitherto been impossible to observe in detail the direct effects of the immigration of civilized people—and the animals and plants that came with them—on the material conditions and the local flora and fauna of an isolated oceanic island.

In 1900, Andrews described shrews as follows:

This little animal is very common on the island, and at night its shrill, bat-like cry can be heard on all sides. It lives in rock holes and at the roots of trees, and seems to feed mainly on small beetles.

Since then, no one has made any substantial additions to these two sentences.

threaten

The settlement is unusually large on Christmas Island Endemic species: Three of the other four endemic mammals are now extinct, and the last (the flying fox) is threatened. The five endemic reptiles are not much better off.

Andrews visited the island again in 1908 to monitor the environment and found that the island had changed dramatically: the shrews had disappeared, as had two endemic rat species that had been unusually abundant on the island before, and the introduction of black rats brought a disease (trypanosomiasis) that led to the disappearance of rats (and possibly shrews). The native rats have never appeared since. But a few shrews apparently survived, and a small group of them survived until at least the 1980s.

strategy

How do you protect a species that may or may not exist? Oddly, given that many endangered species known to be in need of recovery do not have recovery plans, the Christmas Island shrew has been the subject of two recovery plans, in 1997 and 2004. These could also be written for the Ironic, Angel, or Unicorn.

However, they did prompt some targeted surveys using traps, remote cameras, and bat detectors (on the assumption that these might record the shrews’ high-pitched screams).

So far the search has been in vain; current management is based on the hope that perhaps someone will turn up unexpectedly, or form a quixotic quest for zoology.

in conclusion

Christmas Island is now uninhabitable for many native species, with supercolonies of crazy ants, high densities of feral cats and black rats, and ongoing mining causing ecological changes. In his 2002 book The Future of Life, zoologist EO Wilson described a twilight of existence, “from critically endangered to the living dead to the thin edge of oblivion.” This may well be the fate of the Christmas Island shrew.

The Conversation is publishing a series of articles on Australia’s endangered species. View here.