Threatened Species - The Brush-tailed Bettong in South Australia - From Extinct to Indicator Species
Pre European Status
The Brush-tailed Bettong, Bettongia penicillata Gray 1837, is grouped with potoroos and other bettongs into the family Potoroidae within the super family Macropodoidea (Strahan 1995). The species formerly ranged across southern Australia, where it occurred in suitable habitat from southwest Western Australia, through to the Mt Lofty Ranges in South Australia and eastward to the Great Dividing Range. In addition to its former southern distribution, the species also once ranged over much of the Great Victoria Desert of Western Australia and South Australia, the Great Sandy and Gibson Deserts in Western Australia and into the Tanami Desert of the Northern Territory (Burbidge et al. 1988). A population also persisted on St Francis Island, South Australia. Historic accounts of Brush-tailed Bettongs in South Australia suggest that they were an extremely abundant species in some parts of the State. Around 1900, dealers near Adelaide did a great trade in selling them by the dozen at ninepence a head for coursing (Jones 1924). The DeclineBy the early 1900s, Brush-tailed Bettongs had become extinct in South Australia (including St Francis Island) and from the remainder of its former known range, except for small areas in the southwest of Western Australia. A combination of factors including habitat clearance and introduced predators/competitors were considered responsible for extinction of the species in South Australia and in other parts of its former range. Recovery of the Species in South AustraliaAs a major part of the Brush-tailed Bettong former range was in South Australia, an important component of its recovery was to re-establish the species in this state. In an attempt to re-establish the species in South Australia, a small colony of animals was obtained from Perth Zoo in 1975 and these were bred successfully at Para Wirra Recreation Park near Adelaide (Nelson et al. 1992). The small population increased rapidly as the species breeds readily in captivity and is highly foecund. Para Wirra and additional captive breeding facilities were then able to provide stock for re-establishment programs throughout South Australia.
With introduced predators/competitors believed responsible for much of the Brush-tailed Bettongs' decline, consideration was given to the re-establishment of the species on the mainland in areas protected by vermin proof fences. However, construction costs and maintenance were considered too great at the time and it was decided to establish bettongs on offshore islands free of foxes, rabbits and cats (Delroy et al. 1986). Starting in 1979, small islands (including 1- Bird Club I. [2 ha], Pt Augusta, 2- Island ‘A’ [15 ha], Venus Bay, and 3- Bairds Bay I. [13 ha], Bairds Bay) were used to assess the feasibility of direct releases of captive bred stock to the wild. Although predation by dogs and foxes (on Bird Club and Bairds Bay Islands respectively) caused the termination of 2 island trials, the long-term survival and successful breeding outcomes demonstrated the suitability of captive bred stock in direct release exercises. After the preliminary trials on smaller offshore islands, an attempt to create larger, self-sustaining populations became a management priority. The first large offshore island to receive bettongs was St Francis Island (809 ha) in 1980. By 1987, a total of 128 individuals were released onto the island. However, the rapid decline of the population in subsequent years resulted in the unfortunate failure of this reintroduction attempt. Although the exact cause of failure is not known, theories range from excessive competition with bandicoots to predation by Carpet Pythons. Successful introduction programs that began on Wedge Island (947 ha) in 1983 and St Peter Island (3 439 ha) in 1989 have created the first viable wild populations in the State. New genetic stock were obtained from Western Australia and released onto Venus Bay Peninsula. This population also flourished due to the ecological restoration program (with introduced predator control being a focus) initiated at the site. The first bettong reintroduction to a fenced mainland site in South Australia occurred in 1991, at Earth Sanctuaries ‘Yookamurra’ property in the Murray Mallee. Yookamurra and other private/community based programs, such as the recent bettong introduction to Katarapko Island in the Riverland, all assist in raising community awareness about endemic native fauna. The successful establishment of bettong populations in South Australia, coupled with similar successes experienced in Western Australia, resulted in the species being down listed from Endangered to Lower Risk (conservation dependent) in 1996. Key Locations Relating to theRecovery of Brush-tailed Bettongs in South Australia Key
locations relating to the recovery of Brush-tailed Bettongs in South
Australia. Summary Information Relating to Key Brush-tailed Bettong Populations in South Australia
The Brush-tailed Bettong as an Indicator Species in Ecological Restoration ProgramsWith the successful de-listing of the species from State and Commonwealth Threatened Species Schedules, the focus of Brush-tailed Bettong recovery in South Australia has now become the trial reintroduction of the species to areas of its former range that are not geographical isolates. At these sites, Brush-tailed Bettongs are being used to demonstrate the effectiveness of intensive introduced predator/competitor management. In this phase of the bettong recovery program, animals were reintroduced to both Lincoln and Flinders Ranges National Parks in 1999. In both locations, the bettongs have persisted and are providing information useful for ongoing programs. References
Program Support
Authors Jason van Weenen, Scientific Officer, Threatened Species, ContactJason van Weenen, Scientific Officer, Threatened Species, Department for Environment and Heritage |
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