In strict numerical terms, the koala (Phascolarctos cinereus) is not in danger. Some population estimates count 100,000 to 300,000 animals still in the wild. But the health of various populations, many of which are isolated, has wildlife conservation groups concerned.
Other groups point to the overpopulated islands off the coast of South Australia and Victoria as reason not to list the koala as threatened or even vulnerable. Some would even have the koala continue to be considered a pest species in certain areas. An assessment of the status of all Australian koala populations is needed to develop an appropriate management and protection plan for this charismatic species.
Koala Island Translocations at Center of Wildlife Conservation Controversy
On Kangaroo Island, there are more koalas than the area can support, resulting in habitat destruction and threats to some endemic island species. To make matters worse, the koala is not native to the island. It was brought there at a time when hunting koalas for fur was decimating populations in Victoria and ultimately resulted in their extirpation in the state of South Australia. Remnant populations were moved to offshore islands to prevent their extinction.
Returning Island Koalas to the Mainland May Not be the Best Solution
Today, koalas from those remnant populations on Kangaroo and some other islands, are being used to repopulate mainland areas. But genetic anomalies are showing up in these animals, raising concerns about the long term viability of the reintroduced koalas. Seymour et al (2001) have linked these developmental abnormalities with inbreeding.
Most of the reintroduced koalas also exist in isolated populations on the mainland. That isolation means breeding between populations doesn’t occur which only adds to the lack of genetic diversity. Mainland populations are also exposed to Chlamydia, a viral disease that affects reproduction.
Even in areas where koalas have not been reintroduced, human activities as a result of development in prime koala habitat, result in heavy losses to local populations every year. In those areas, local government is working to increase protection for koalas and reduce the level of habitat fragmentation. But local efforts are unlikely to be effective in maintaining a healthy koala population in Australia.
What Can be Done to Help Australia’s Koalas
In Queensland a major effort is underway to help the koalas in the south east of the state where their strongest population is being affected by the ever increasing human population. New South Wales is also taking steps to protect their koala populations. Koala rescue and rehabilitation efforts in Victoria and other states also contribute by caring for victims of bushfires, road traffic accidents and other threats to the species.
The inbreeding situation points to the importance of providing wildlife corridors in urban and suburban areas to allow the koalas to travel between populations, increasing genetic diversity. But the wildlife corridors would need to be implemented with care until the full extent of disease and genetic anomalies in various koala populations is understood.
In the long term, a full survey of all koala populations in Australia will be needed to understand which populations lack genetic diversity, which are isolated and which are at risk of becoming isolated. The link between Chlamydia, which may have been present in koalas for many years, and stress or overcrowding also needs to be better understood in order to control outbreaks of this deadly disease.
In a best case scenario, wildlife conservationists, scientists and state and national government personnel would meet to develop a plan that takes into account all the threats to the species and ways in which the various organizations can cooperate to reduce these threats. Without a coordinated effort, a healthy, wild koala population continues to be at risk.
Resources:
Seymour et al.2001. High effective inbreeding coefficients correlate with morphological abonormalities in populations of South Australian koalas (Phascolarctos cinereus). Animal Conservation 4:3:211-219. Zoological Society of London
Dawn M. Smith - A vet nurse, Dawn has worked in wildlife rehabilitation and conservation around the world in addition to her veterinary hospital ...
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