Zoology - Theses
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ItemHistory, habitat and management: considerations in the selection of potential reintroduction and translocation sites for the brush-tailed rock-wallaby, Petrogale penicillata, in East Gippsland Victoria( 2002)Currently, there are estimated to be no more than 25 Brush-tailed Rock-wallabies, Petrogale penicillata, of Victorian origin remaining, with half of these in captivity as part of a breeding program. The decline of Brush-tailed Rock-wallabies has been attributed to several factors including hunting, predation, competition and stochastic events such as wildfire and disease. In Victoria, rock-wallabies have continued to decline in number, even after the cessation of hunting and implementation of an intensive predator control program. Without the intervention of captive-breeding and reintroduction or translocation programs, this critically endangered species will soon become extinct in Victoria. Reintroduction and translocation are becoming increasingly popular in the recovery of endangered species, however, many past attempts have had unknown or poor success rates. Conditions influencing the success of reintroduction and translocation programs are not well understood and for the most part, past efforts have been conducted in an ad hoc manner with little monitoring and documentation. One of the factors considered important in success is identification and selection of sites with high habitat quality, as unfavourable habitat is likely to result in the loss of animals through dispersal, predation or lack of other essential requirements. In addition to Wakefield (1961) and Short's (1980) observations of Brush-tailed Rock-wallabies occupying restricted habitat, presumably in response to the introduction of the Red Fox, Vulpes vulpes, this study found that there has been further restrictions in habitat use in East Gippsland, Victoria since the 1960s. Extant Brush-tailed Rock-wallabies sites were found to be larger than unoccupied sites, face predominantly north to north-east, have a general slope greater than 45° and a greater number of ledges per 100m of transect. It was also found that rock-wallabies preferred larger refuges with more than one entrance, low exposure to weather and another refuge or ledge within 10m. Preferred ledges were also large, faced predominantly north to east and within 10m of another refuge or ledge. The advantages these characteristics offer in the selection of future reintroduction and translocation sites are discussed. However, habitat suitability is not the only factor important to the selection of reintroduction or translocation sites. The selection of release sites will need to consider the ability to effectively undertake monitoring and management activities, and balance these requirements with the ecological requirements. This study also investigated past and current management (e.g., burning and predator control) of the study area and found that there has been a substantial change in land use that may have contributed to the persistence of Brush-tailed Rock-wallabies at the current sites in East Gippsland. This knowledge offers clues to future management. Other factors influencing site management are also discussed, and release sites with secure land tenure, which are easily accessible throughout the year and have a good network of vehicle tracks are considered favourable for reintroduction and translocation. In addition, release sites should not be in areas that conflict with visitor activities and should have strong community support.