The effects of exclusion fencing on the yellow-footed rock-wallaby (Petrogale xanthopus celeris)

The effects of exclusion fencing on the yellow-footed rock-wallaby (Petrogale xanthopus celeris)

Many land managers have recently constructed exclusion fences around their properties in an effort to increase the productivity of sheep (Ovis aries) farming in central-western Queensland, Australia. These fences (known as cluster fences when they enclose more than one property) are used to exclude dingoes (Canis familiaris) from grazing properties and thereby eliminate livestock predation. The fences are also used by land managers as a tool to better manage total grazing pressure on their properties, usually through the removal of pest herbivores such as feral goats (Capra hircus) and red kangaroos (Osphranter rufus). While these fences are considered highly effective in this goal, what is less known is whether they have substantial impacts on other extant wildlife. This thesis aimed to elucidate this issue through an examination of positive and negative effects of pest cluster fences on a non-target wildlife species. First, potential positive effects were explored by investigating where threatened species distributions overlap with the cluster fencing in central western Queensland. Where species distributions did overlap with cluster fencing, threats to those species were checked against the proposed management of pest species within fences. From this examination, the yellow-footed rock-wallaby (YFRW; Petrogale xanthopus celeris) was identified as one species whose range and threats suggested it may benefit from pest species management within cluster fencing. As such, several potential effects of cluster fences (identified in a literature review) were also investigated for the species. From habitat scoring and camera trapping data, we found that YFRW habitat use and behaviour were similar both inside and outside the fences, although diel activity was considerably different. These data also revealed extensive spatial and temporal overlap between goats and YFRW, suggesting potential benefits to YFRW might accrue should goats be removed within fences. Finally, a genetic assessment of YFRW tissue samples collected at several colonies revealed that, whilst infrequent, YFRW do move between colonies over large distances. This aspect of the study indicated that fence placement may genetically isolate some colonies, which has the potential to create negative genetic consequences for the affected colonies in the long term. The project as a whole was limited by a lack of pre-fence data, and reliable data on predators. Despite these limitations, my research concluded that both positive and negative effects on non-target wildlife are likely to arise following the erection of cluster fences, but net effects remain unclear. I therefore propose that (1) non-target species be taken into account before and after exclusion fences are constructed, (2) at-risk species within the system be monitored to ensure negative effects do not exceed acceptable thresholds, and (3) mitigation strategies be employed if necessary to ensure negative outcomes do not outweigh the potential benefits of exclusion fencing to non-target species.