It's only just been recognised, but has Australia already lost its newest mammal species?

The Christmas Island shrew is a small, long-nosed, insectivorous mammal (5-6g) whose high pitched shrieks were once characteristic of the Christmas Island forest at night. Although shrews are widespread and common in Eurasia and Africa, Christmas Island, an Australian territory in the Indian Ocean, is the only place in Australia where shrews occur.

Christmas Island Shrew
Christmas Island Shrew Image: Created by Max Orchard
© Max Orchard

First discovered in 1888, the Christmas Island shrew was once highly abundant on the island, but declined within decades of its discovery and by 1909 was thought to be extinct. Then amazingly, in the 1980s, two shrews were captured on Christmas Island.

Were these shrews the species thought extinct, or were they recent invaders? Did the enigmatic Christmas Island Shrew still survive? With colleagues at the Australian Museum and the NSW Department of Primary Industries we began a study to find out. Using DNA sequences from museum specimens from Britain and Australia we sequenced fragments of DNA and have confirmed that the 1980s specimens were genuine Christmas Island shrews. In addition, although long thought of as only a subspecies of a widespread Asian shrew species, we discovered that the Christmas Island shrew is actually a distinct species very different from all other shrews.

Our research shows that the species, now known as Crocidura trichura, was able to survive for about 80 years without being detected. Our finding raises hope that the Christmas Island shrew, Australia’s only shrew species, may still survive. However, things are not looking good, with Christmas Island facing an ecological collapse brought about by multiple introduced species. Of the five mammal species known from Christmas Island, three are already extinct (2 rat species and a small insectivorous bat). It seems that there is only limited time to find and conserve this newly recognised Australian species.

More information:

Eldridge, M.D.B., Meek, P.D., & Johnson, R.N. (2013) Taxonomic Uncertainty and the Loss of Biodiversity on Christmas Island, Indian Ocean. Conservation Biology.Early View. Abstract