Fears grow as Australian native mouse remains unseen

A rare Australian native mouse could be in much more trouble than previously thought, with researchers reporting that it has not been detected in one of its main habitats since 2003.

Fears that the New Holland mouse (Pseudomys novaehollandiae) may already be extinct in the state of Victoria’s heavily forested Otways region have peaked, as researchers reveal that a physical and photographic trapping program between 2013 and 2017 failed to locate a single specimen.

This suggests that a trial program releasing captive-bred mice into the area in 2002 has failed. 

There has been little research into the New Holland mouse in the decade prior to 2013. However, in 2010 the species was listed as critically endangered, because available data indicated that it had disappeared from six known habitats and its total distribution had shrunk by 45%.

The latest research, led by Barbara Wilson of Deakin University in Melbourne, and published in the journal Australian Mammology, found that historically the New Holland mouse tended to live in small, isolated populations. 

Groupings existed for between one and six years before dying out. Populations tended to increase in periods of above-average rainfall, but fell precipitously during more frequent periods of drought or as a result of bushfires. Even at the best of times, Wilson and her colleagues note, New Holland mouse colonies are “extinction prone”.

And the research reveals that for the rodents these are absolutely not the best of times. 

The detection regime was extensive. The physical trapping program covered 42 sites, including nine in which the mouse had been recorded before 2003. The traps operated for the equivalent of 6378 nights. Camera traps were set up in up to 20 sites each year.

Not a single mouse was found.

“While the New Holland mouse is considered to be critically endangered in Victoria, it may be more precarious than previously estimated,” the researchers conclude. “The recent trapping confirming the loss of this species from known locations means that regional extinction cannot be ruled out.”

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