Extinct: Bramble Cay melomys

By Lauren Smith June 15, 2016
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Australia’s latest world-first is a heartbreaking one – we can now claim the first mammalian extinction thought to be primarily attributable to global warming.

WITH NO SIGHTINGS since 2009, experts have officially recommended that the Bramble Cay melomys (Melomys rubicola, also known as the mosaic-tailed rat) be declared extinct.

Known only from Bramble Cay, in the Torres Strait, the melomys has long been considered one of the most threatened mammals in Australia. A survey in 2004 found it likely that fewer than 50 individuals remained, occupying the 2.2ha vegetated patch of the tiny coral island.

Ian Gynther, Senior Conservation Office at the Department of Environment and Resource Management, led a team in a survey of the island in 2014, measuring the island dimensions and vegetation and counting animal populations. The report of that survey has just been published, concluding that there are no more melomys’ on the island.

Cause “almost certainly ocean indundation”

Researchers from the University of Queensland have concluded  that the main cause of the extinction is human-induced climate change. They affirmed that “The key factor responsible for the extirpation of this population was almost certainly ocean inundation of the low-lying cay, very likely on multiple occasions, during the last decade, causing dramatic habitat loss and perhaps also direct mortality of individuals.”

The researchers also found that that the vegetated area on the island, which had once provided food and shelter for the rodent, had declined from 2.43ha in July 1998 to 0.19ha in September 2014.

The report highlights the link between rising sea levels and dramatic weather events and human-led climate change, and notes that tidal gauge and satellite data from the Torres Strait indicates that the mean sea level has risen 6mm a year between 1993 and 2010 for the region, a figure that is around twice the global average.

Following the report, nominations are being prepared to amend the conservation status of the Bramble Cay melomys to extinct in the wild under both Queensland and Commonwealth legislation.

Possible Papua New Guinea population

The authors of the report do note that there is a slight chance that there’s an as-yet-unknown population of the species in Papua New Guinea around the Fly River delta area, and that until that area is adequately surveyed, the Bramble Cay melomys should have the tag  ‘Possibly Extinct’ added to the IUCN Red listing.

WWF-Australia spokesperson Darren Grover said that the melomys’ extinction is a sad reminder of Australia’s extinction crisis and that State and Federal governments must act fast to turn the situation around.

“Australia’s species extinction crisis is not something that occurred hundreds of years ago, it’s happening right now. Australia officially has the worst rate of mammal extinction in the world,” he said.

“Unless state governments and the next Australian Government commit significant amounts of funding towards protecting Australia’s threatened species, we can expect to see more native critters go extinct on our watch.”