Why are koalas endangered now in 2011?

The conservation status of koalas varies from region to region in Australia, but in no state are they legislated as "endangered".

Due to farming and land clearing, native koalas were eradicated from Western Australia and South Australia in the last century, but moves have been made to reestablish new colonies in both states. Currently, koalas are thriving on Kangaroo Island in SA, and in other isolated colonies.

Koalas are still listed as "common" in most parts of Queensland, but there are calls to list them as vulnerable in southeast Queensland, where koala numbers have dropped by about 60% in the last decade.

The NSW Government listed the koala as "rare and vulnerable" in 1992, and following protective measures which have seen koala populations regenerate, this has been changed to "vulnerable". The koala is, however, all but gone from the NSW central coast.

In Victoria, the koala is not on the threatened species list at all, and in some protected and remote regions, there is actually an overpopulation problem. They are considered to be "secure" in Victoria.

The chief threat to the koala is habitat loss. Koalas inhabit prime land which man has decided is better used for housing developments. Not only do the koalas lose their sources of shelter and food, they are subject to dog attacks and being hit by cars as suburbia extends further outwards. A prime example of this is southeast Queensland, where koala numbers have dropped to 60% less than what they were a decade ago, entirely due to increased development - and where they now face extinction by 2020.

Koalas are territorial, and they live in complex social communities where each member has a certain number of trees within its territory. When access to these trees is cut off by new roads, the koalas will still try to cross the road, and risk being hit. Relocation of koalas is rarely successful because their territorial and social habits are largely misunderstood.

Another significant factor is predation by introduced species such as dogs and foxes. Dogs have the instinct to hunt and kill these defenceless creatures, and a great deal of damage is done by such unsupervised pets.

Koalas are also subject to the disease chlamydia, which affects the koalas' fertility, and eventually leads to their death. Currently, there is no cure for this disease. At the best of times, the koala is a slow breeder, usually producing just one joey a year.