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Considerable funding and effort is dedicated to the conservation and recovery of threatened species in Australia. We describe a series of five iterative steps that will improve the effectiveness of programmes for threatened species management. These steps are best integrated using Population Viability Analysis (PVA) in an approach to management where the key stages are completed concurrently. In this way management actions for the conservation of threatened species can be regularly assessed and upgraded as more information and improved computer simulation models become available.

We review current knowledge of the diet and predator-prey relationships of the feral cat (Felis catus), fox (Vulpes vulpes) and dingo (Canis familiaris dingo) (including wild dogs), and consider how forest fragmentation by roads may influence the use of native forest ecosystems by these species and the significance of this for native fauna. The cat, fox and dingo are significant predators in Australia that interact with native fauna in various ways, including predation, competition for resources, and transmission of disease. On the basis of current knowledge, it is clear that the nature and impact of predation by the cat, fox and dingo on native fauna are primarily determined by prey availability, although there are exceptions to this rule. Generally, dingoes prey upon large to medium-sized prey species (e.g. wallabies, common wombats and possums), foxes prey upon medium-sized to small prey (e.g. possums and rats) and consume a significant component of scavenged material and vegetation, while cats also prey upon medium-sized to small prey, but may have a greater proportion of reptiles and birds in their diet. The cat is generally considered to be an opportunistic predator and to have contributed to the demise of a number of mammals. The fox is considered more of a threat to small native mammals than is the cat and it has been asserted that all species of mammals that fall within the critical weight range (CWR) of 120-5000 g are at risk of local extinction when the fox is present. The severity of the impact of the dingo upon the native fauna is considered to be minimal, at least in comparison with the impact that the cat and fox can have on populations. The dingo is not considered a threat to CWR mammals in undisturbed environments. The fox, feral cat and dingo are all considered to have the ability to selectively prey upon species and, to some extent, individual sexes and age-classes of a number of larger prey species.Although many of Australia's forested areas are relatively heavily fragmented by roads, there are no published studies specifically investigating the use of roads by feral predators. Information on the distribution and abundance of foxes, cats and dingoes in these ecosystems, their ecology and their impact on native fauna is particularly limited. Further, the extent to which roads influence the distribution and abundance of these species and the consequences of these for native fauna are poorly known. Given this, we suggest that one of the most important research needs is to establish the relative impact that exotic predators may have on native fauna under varying degrees of road construction within native forests. For example, are areas with and without roads in forests used differently by exotic predators and what is the significance of this in terms of the potential impact on fauna? The extent to which feral predators forage away from roads needs further investigation, as does the rates of predation within edges, because this may have several consequences for the design, location and siz...

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Geographic variation iri body size and sexual dimorphism, as determined by measurements of condylo-basal length, was investigated in the sugar glider (Petaurus breviceps) and the squirrel glider (P. norfolcensis). Correlation and multiple regression analyses were employed to determine whether geographic or climatic variables accounted for more of this size variation. The effects of age and sex were removed from analyses prior to applying statistical techniques. Numerous geographic and climatic variables were correlated with size variation in both species. Both species followed a clinal change in body size consistent with Bergmann's rule (i.e. both species were larger in the south of their ranges where temperatures are colder). One geographic variable, latitude, and three climatic variables representing temperature, precipitation and seasonality, were then selected for multiple regression analyses. Latitude accounted for more of this size variation (20-28%) in P. breviceps than climatic variables in four multiple regression models (considering two age and two sex classes). This result indicated that an isolation-by-distance model was operating in this species which was attributed to the oceanic barriers between the Australian mainland and New Guinea and Tasmania, causing genetic differentiation between isolated populations. Once latitude was removed from the analyses, temperature accounted for more of the variation (18-24%) in body size in three regressions, whilst precipitation (11%) contributed significantly to the remaining model. This result was interpreted as an adaptation to ambient temperature following Bergmann's rule. When using both geographic and climatic variables, latitude accounted for more size variation (47-69%) than climatic variables in two regressions for P. norfolcensis, whilst seasonality accounted for more variation (26-46%) in the remaining two regressions. When latitude was excluded From the analyses, seasonality (body size decreases with increasing seasonality) accounted for more variation in size in three of four regressions (26-46%), whilst precipitation (60%) accounted for the most variation in the fourth regression. These findings for P. norfolcensis suggested that large body size may be an advantage in aseasonal environments where climates and therefore foods are less predictable. Latitude and precipitation both contributed significantly to the degree of sexual dimorphism exhibited across the range of P. breviceps, suggesting that an isolation-by-distance model and primary productivity account for some of the change in sexual dimorphism in this species. Both these variables were more important than temperature and average sexual dimorphism was greater in the tropics. The relationship with primary productivity implies that in areas where food is more abundant, males attempt to grow larger in order to enhance fighting ability for access to food and mates. In contrast, females channel extra energy towards offspring production, not body size, in order to minimise energy costs during reproduction. Character displacement did not appear to influence body size variation in the two Petaurus species.