Rock Wallaby Reintroduction
To breed and reintroduce brush-tailed rock wallabies into their former range in Australia
In the early 1900s the brush-tailed rock-wallaby, Petrogale penicillata, numbered in the millions throughout rocky habitats of eastern Victoria, but were regarded as extinct in Victoria by 1916. They were subsequently rediscovered at two sites in Victoria in the mid 1900s. A combination of predation, competition, habitat modification and degradation, hunting, disease, climatic changes and stochastic events have contributed to the decline in numbers. Captive breeding using cross-fostering has been used to increase animal numbers with subsequent reintroduction into part of their former range.
There are currently three known wild colonies of Victorian brush-tailed rock wallaby in the southern Ecological Significant Unit (ESU), all are located in East Gippsland. Combined across the three sites, the wild population is currently estimated at 21, inclusive of one captive-bred male released in 2005 (a second male released at the same time was found dead six months post-release). These sites are monitored regularly by members of the Victorian Brush-Tailed Rock-wallaby Recovery Team.
As part of the National Recovery Program, a captive breeding program started in 1996 in order to increase numbers for reintroduction to the wild. The first joey was born at the Adelaide Zoo in 1998 and 116 animals have been born since, with the current captive population standing at 36 after the first reintroduction.
Cross-fostering, a technique refined by the staff of the Adelaide Zoo, has been optimised and used to maximise births and recruitment into the captive brush-tailed rock wallaby population. Pouch young of approximately 10-14 days old are transferred to the pouch of a yellow-footed rock wallaby, P. x. xanthopus, or tammar wallaby, Macropus eugenii, that have young at a similar stage of lactation, and are of similar age and size. These surrogate mothers then raise the joeys through the energy and time intensive lactation period, freeing the brush-tailed rock wallaby mother up to give birth to another joey a month later. The use of this technique can see females give birth to up to 8 young in the time they would normally invest into a single young.
With multiple institutions participating in this program, pouch young have come not only from the adults at the Adelaide Zoo, but also flown from Healesville Sanctuary, Tidbinbilla Nature Reserve and Waterfall Springs. Many research projects have been conducted in cross-fostering to determine how to best apply it. This research has provided information on how to get young to attach to a teat, techniques for transporting joeys, growth rates, breeding success, through to species recognition.
With a growing captive population, a reintroduction site needed to be selected. Extensive site evaluations saw a site in the Grampians National Park identified as a suitable location for the release of Victorian brush-tailed rock-wallabies. A long-term baiting program aimed at reducing fox numbers at the reintroduction site was undertaken and Dunkeld Pastoral Company established a large pre-release ‘hardening off' enclosure where wallabies are housed prior to release. The first reintroduction of ten animals occurred at Moora Moora Creek on the 12th November, 2008, with 3 deaths known to have occurred in the first 6 months, while the remaining animals have settled in well and are being monitored twice weekly.
WAZA Conservation Project 09011 is implemented by the Victorian brush-tailed rock wallaby recovery team and is supported by Conservation Ark - Zoos SA, Tidbinbilla Nature Reserve, Healesville Sanctuary, Waterfall Springs Wildlife Park, Victorian brush-tailed rock wallaby recovery team, Parks Victoria, Department for Sustainability and Environment, Dunkeld Pastoral Company Ltd - Funding, Genetic Technologies - Funding, Ian Potter Foundation - Funding, Myer Foundation - Funding, R.E. Ross Trust - Funding, The Nature Conservancy - Funding, Bristol Myers Squibb - Funding, Wildlife Unlimited Ltd, Friends of the Grampians, Friends of the Cobbras, Royal Mail Hotel - Funding, Mt Sturgeon Merino - Funding, Dunkeld Sandstone - Funding.
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