Threats to Australia’s rock-wallabies (Petrogale spp.) with key directions for effective monitoring

Rock-wallabies (Petrogale spp.) are one of Australia’s most speciose genera of mammals, irregularly distributed across much of the continent and its offshore islands. The 25 taxa in the genus Petrogale (17 species and 8 subspecies) have specialised ecological requirements that render them vulnerable to numerous threats. Many rock-wallaby populations have declined severely, and most species and subspecies are experiencing ongoing declines in population size, distribution and their conservation status. Despite an explicit recognition of the need for conservation management, some species are not monitored and a consensus on the most appropriate methods for ongoing population monitoring has proven elusive. We reviewed the available literature to understand the conservation issues and threats most relevant to Petrogale spp. We also reviewed rock-wallaby monitoring programs with the aim of identifying which are most informative of population trends, and most suitable for guiding better management responses. Major threats to rock-wallabies include predation by introduced cats and foxes, competition from introduced herbivores and overabundant native herbivores, changed fire regimes and loss of genetic diversity. There are synergisms that exacerbate these threats. While live-trapping gives comprehensive population data, camera traps have proven popular for collecting data over long periods, have minimal animal welfare impacts, and can simultaneously collect data on some significant co-occurring threats (feral predators and herbivores). A variety of rock-wallaby monitoring programs are current in Australia, but few adequately provide the range of data necessary for informed conservation. Monitoring programs should consider incorporating multiple methods to ensure the range of information necessary for successfully conserving rock-wallabies is obtained.