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Small Australian Marsupials in Sudden Decline

Animals such as the bandicoot, quoll and tree possum are in dramatic decline in the country's north, and feral cats could be the cause.

Small, furry marsupials such as the bandicoot, quoll and tree possums are in dramatic decline in Australia's north and feral cats could be the cause, according to analysis reported Wednesday.

Chris Johnson, a wildlife conservation professor from the University of Tasmania, said small mammal species were at risk of extinction across the continent, but the changes in the north were marked.

"There's a pretty clear picture and it shows that lots of species have declined dramatically," Johnson told AFP.

Dino-Era India, Australia and Antarctica Mapped

"Where we can infer the timing of decline, it's been fairly recent and there are now large areas where small mammals are either very rare or don't exist but the habitat looks like it should support small mammals."

Johnson said while scientists discussed the changes as a "new wave of decline" it was not clear how sudden it was except that it became very noticeable in the early 1990s, particularly in places such as Kakadu National Park, a conservation area in the Northern Territory.

About 20 small native mammals have disappeared from Kakadu in recent decades including rat-like bandicoots, northern quolls, tree possums, and the weasel-like phascogale, he said, adding that similar declines had occurred elsewhere.

New analysis from a database of current mammal populations reported to a meeting of experts in Canberra Wednesday has allowed researchers to compare the current wave of extinction across different species, with those in the past, Johnson said, adding it revealed some common factors.

"First, the extinctions are occurring mainly in ground-dwelling animals of small body-size which live in open, dry habitat. This points the finger of suspicion strongly at an introduced predator -- the cat," he said.

"We have seen similar extinction patterns driven by predators like foxes in southern Australia -- so the big question was: 'Is history repeating itself, or is it something new?'"

Australia's Great Barrier Reef On Watch

He said the declines were in species eaten by cats, an animal believed to have been introduced with European settlement in the late 1700s.

"Where there are no cats there have been no declines," he said.

He said because cats had been around for so long and the declines were more recent, the question was what had changed to make them such a damaging predator.

Johnson said the use of fire by graziers seemed to have played a role as well, given there had been no significant land clearing or evidence of disease in northern Australia.

"It is probably no one thing, but the data points to a combination of several effects -- all of which tend to favour the hunting style adopted by cats which places small ground-dwelling animals at greater risk," he said.

A spotted quoll is seen in its enclosure at Taronga Zoo in Sydney on May 7, 2014. Small, furry marsupials such as the bandicoot, quoll and tree possum are in dramatic decline in Australia's north and feral cats could be the cause.

A pair of Common reef cuttlefish (Sepia latimanus) hovers above a patch of hard coral located on the Far Northern part of the Great Barrier Reef. With the ocean warming, rising, and becoming more acidic, coupled with land runoff, marine pollution and coastal development -- life in Australia's Great Barrier Reef is threatened from all sides and may be placed on the "in danger" designation for UNESCO World Heritage Sites. Can Australia meet the challenge to do a better job of protection by 2014? Here's some photos of what's at risk.

Clownfish protect their eggs hidden in a sea anemone on the Great Barrier Reef.

The most-loved Heart Reef among the Whitsunday Islands in the Great Barrier Reef is part of the protected off-limits areas to SCUBA divers and snorklers.

Three sea turtles in the Great Barrier Reef.

A flying gurnard (Dactyloptena orientalis), spreads out large pectorals to scare away enemies on the Great Barrier Reef, Australia.

A ribbon eel in the Great Barrier Reef.

The poisonous blue-ringed octopus (Hapalochlaena lunulata) stalks prey among the coral.

The size isn't intimidating, but the deadly poison is; divers wear gloves to hold the blue-ringed octopus.

A black-blotched moray eel at home in the Great Barrier Reef off the coast of Australia.

Christmas tree tube worms on the Great Barrier Reef.

The polyps on this stalk of Acropora echinata, a type of Staghorn coral, show vividly colored tips.

Many reefs around the world are threatened by bleaching, as sea temperatures become too warm and stress the corals. The high temperatures kill the colorful polyps, and leave a reef cemetery of coral skeletons.

Staghorn Coral release eggs and sperm in a mass spawning event on the Great Barrier Reef.

The head of a whale shark (Rhincodon typus), near Ningaloo Reef in West Australia - Indian Ocean. Whale sharks feed on the eggs and sperm released from coral during massive spawning events a few days after the full moon between October and December.

What goes in must come out. A sea cucumber (Thelnota ananas) leaves a trail of waste as it processes its food.

An olive sea snake explores Alcyonarian coral.

The head of an Ocellated Epaulette shark (Hemiscyllium ocellatum), in the Great Barrier Reef, Australia.

Sea level rise poses a real threat to many parts of Australia. Already increased coastal erosion as a result of sea level rise is evident, as here where trees have been undercut and toppled by erosion on Green Island off Cairns in Queensland, Australia.

A rusting anchor chain rests amid the skeletons of pieces of hard coral in the Great Barrier Reef. Marine pollution comes in many different forms, but always from human hands. Greater protection and awareness of human impact on the reef is critical.