Australian mammals disappearing at alarming rate

Australia is well-known for being the home of distinctive land mammals, including the wallaby. But four species of the bounding mammal have become extinct since Europeans settled on the continent in 1788. No longer to be seen are the kuluwarri, eastern hare-wallaby, toolache wallaby and crescent nailtail wallaby.

The 29 extinct Australian mammal species on the study's list comprise 35 percent of the world's modern mammal extinctions. The decline hasn't been across the board for all mammalian species, though. Along with marsupials, the hardest hit include rodents, like this hopping-mouse.

One of the most recent additions to the researchers' extinction list is the Bramble Cay melomys, a burrowing rodent that became extinct some time between 2006 and 2014.

Bat species have been pretty lucky, showing relatively low rates of decline over the past 20 years. But a couple still made the extinction list, including the Lord Howe Long-eared Bat.

On top of the extinct Australian land mammals, 21 percent of the continent's 273 land mammals are threatened. Scientists think the rate of loss - around one or two extinctions per decade - is likely to continue. Counterintuitively, much of the decline has occurred in areas only sparsely populated by humans.

Although gone from Australia, this egg-laying, milk-producing mammal escaped complete extinction from the face of the Earth. The Western Long-beaked Echidna survives in New Guinea, but is critically endangered.

In contrast, only one native land mammal in North America - the sea mink - became extinct during the same time period. The animal, prized for its reddish fur and bushy tail, was hunted to extinction, unlike his thriving cousin, the American Mink (pictured above).

Hunting, habitat loss and impacts of human development are most to blame for species extinction on other continents, especially where human populations are increasing.

But these factors don't apply in the Australian case, scientists believe, since most extinctions there occurred in remote areas - far from human population centers. Instead, scientists think the loss of Australian land mammals is primarily due to predation by introduced species, like the European red fox.

Another prolific killer is the feral cat, found in most habitats across Australia. The researchers believe that feral cats pose the highest threat to native mammal species. They contribute greatly to the disappearance of many ground-dwelling mammals on the mainland.

There's a bit of hope left in Australia's dismal numbers: Scientists say the country's marine mammals have fared better overall. But they've added a precaution: research has been impeded by a lack of information, since it's harder to collect data in water than on land.