Western Shield, managed by Western Australia's Department of Environment and Conservation, is a nature conservation program, safeguarding Western Australia's animals and rescuing them from extinction. Set out in 1996, it is the largest and most successful wildlife conservation program ever undertaken in Australia, as of 2009.
Between the 1920s and 1950s scientists synthetically developed a poison called sodium fluoroacetate (commonly called 1080 poison), for use in biological warfare. Subsequently it was found that sodium fluoroacetate occurred naturally in many plants of the south-west of Western Australia and many of the native mammalian herbivore fauna of the region had evolved with a natural tolerance to the poison. The plants, in the genus Gastrolobium, are commonly called "poison pea"; farmers often suffer livestock fatalities due to wandering animals that unfortunately encounter and graze the deadly plants.
During the late 1980s a conservation program relating to fox control - Fox Glove - commenced using dried meat baits and sausages laced with 1080 poison. Fox Glove was very effective in allowing native species' populations to increase. This was due to the local eradication of introduced predators, namely foxes and feral cats, although the control of feral cats is much more difficult, as the cats favor live prey. Poison coated oats and carrots are occasionally used to control herbivorous invasive species, including the rabbit and rats.
Since 1996 when Western Shield was initiated, a Beechcraft Baron flies 55,000 km every three months, to drop the 770,000 1080 poison baits. They cover an area greater than half the size of Tasmania as they deliver bait into most national parks, nature reserves and state forest of the south-west of Western Australia.
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The baiting primarily targeted foxes but was effective across the spectrum of introduced predators. This led to a huge increase in native species populations in the 1990s. For example, trap success rates for medium-sized mammals (particularly Woylies) in the Jarrah forest of Kingston Block, near Manjimup, revealed a sevenfold increase in native mammals in the five years after baiting began in 1993. Complementing the natural rebound of populations, additional measures included reintroductions and translocations, i.e. returning native species into ecosystems where they were previously found but later went locally extinct. Western Shield either reintroduced animals from breeding programs or directly relocated the animal from high self-sustaining populations elsewhere in the southwest. Western Shield has carried out many translocations to other DEC managed lands, to the privately owned conservation sanctuaries of the Australian Wildlife Conservancy, to other states' conservation lands, and even to islands.
Since 1996 over 80 translocations have taken place within Western Australia, with over 20 species (15 mammal species, 3 bird species, and a few reptile species) involved. The translocations have not only occurred in the southwest forests but also the Monte Bello Islands, the Pilbara, Kalbarri, Shark Bay, islands off of Adelaide., outback New South Wales, and the central deserts of Australia.
Species taken off the endangered species list
Western Shield has been so successful that three native mammal species have been taken off the list of Western Australia's list of threatened fauna – through the Wildlife Conservation Act 1950. The species taken off "Schedule 1 – Fauna that is rare or is likely to become extinct" were the Quenda (Isoodon obesulus), the Tammar Wallaby (Macropus eugenii) and the Woylie (Bettongia penicillata). The Woylie was also taken off the list of Australia’s threatened fauna – through the Environment Protection and Biodiversity Conservation Act 1999, it was demoted from the "Endangered" Category and is not even on the list any longer as it is not deemed in ‘danger of extinction’. The Woylie was also taken off the "IUCN Red List of the World’s Threatened Fauna" as "Endangered" and downgraded to "Lower Risk / Conservation Dependent". Western Shield’s success for having the Woylie de-listed as "Endangered" on the state, national, and international levels is a first for any species in the world to be taken off either the state, national, or international level of ‘Threatened Species’ due to successful wildlife conservation efforts.
Recent declines in native species
Unfortunately the success story of Western Shield program has been tarnished by more recent developments. The Woylie has been added back to WA’s list of threatened fauna due to the sharp declines since 2002, with some places having as much as a 95% decrease (including that locality near the Upper Warrer in Manjimup where the original ‘seven fold increase’ occurred). The Woylies population across all of Australia has declined, especially the DEC managed lands of the southwest forests. Wild populations that were replenished through translocations in South Australia have also mysteriously declined. In fact quite a few other species of the southwest forests have also declined and with no definite answers many studies are being undertaken, including through DEC’s ‘Saving our Species’ new initiative. Possible explanations include: disease, global warming, ground water losses, introduced predators building up a resistance to the poison in the baits, a natural population fluctuation, or possibly an increase in predation by native enemies such as Carpet Pythons and Chudicthes which are surviving well. A search for the cause is underway.
Gilbert's Potoroo significant recovery
Western Shield has saved many species from extinction, most notably the Gilbert's Potoroo which was ‘lost’ for over 100 years only to be rediscovered in 1994 in Two Peoples Bay Nature Reserve, near Albany. At that time the population consisted of probably less than 30 individuals. Western Shield’s Gilbert’s Potoroo subdivision, led by Dr. Tony Friend, now has a self-sustaining mainland wild population, a breeding centre ‘back up’ stock with a cross fostering program for Long-nosed Potoroos, and also an island paradise home to breeding animals on Bald Island. Although still below 40 animals, the critically endangered Gilbert’s Potoroo is in safe hands and hopefully on the road to recovery.
Although Western Shield’s early spectacular success has dimmed due to the decrease in some populations of native species in the latter 2000s, the program is still at the forefront in the conservation of Australian native species. It continues to conduct population studies and develop new tools for biodiversity protection and restoration. Future frontiers for Western Shield include efforts in the desert regions, the creation of an effective feral cat bait, and biological invasive species control, all aimed at reducing the number of endangered species and returning WA to the bio-diverse haven it was prior to European settlement.
- "Western Shield". Department of Environment and Conservation. Retrieved 2008-02-17.
- Possingham,Hugh; Jarman, Peter and Allen Kearns. (2004) A review of the Western Shield Program. Conservation science Western Australia, Vol.5, no.2 (Dec. 2004), entire issue.
- Bouncing back Landscope, Spring 1998, p. 28-35,