Suchergebnisse

Context Introduced sambar deer (Cervus unicolor) are increasing in south-eastern Australia, and both volunteer and contract ground-based shooters are being used by management agencies to control their undesirable impacts. However, little is known about the effectiveness and costs of volunteer and contract shooters for controlling deer populations in Australia. Aims We evaluated the effectiveness and costs of volunteer and contract ground-based shooters for controlling sambar deer and their impacts in a 5-year management program conducted in and around alpine peatlands in Alpine National Park, Victoria. Methods Ground-based shooting operations were organised in two blocks. Within each block, four ~4200-ha management units were delimited, of which two were randomly assigned as treatment (ground-based shooting) and two as non-treatment (no organised ground-based shooting). In the treatment units, ground-based shooting was conducted using either volunteers or contractors. Each shooting team recorded their effort and the numbers of deer seen and shot, and used a GPS to record their track log and the time and locations of deer shot. Key costs were recorded for both shooter types. Key results The catch per unit effort of contract shooters was four times greater than that of volunteer shooters. Both shooter types were most effective during the first half of the night and prior to sunrise, and when using a vehicle with a spotlight or walking with thermal-vision equipment. During the day, the use of gundogs to indicate deer significantly increased the success rate of volunteer shooters. Both volunteer and contract shooters used roads and tracks to move in the landscape, but contractors covered more ground than did volunteers. After accounting for key operational costs, the cost per deer killed was 10.1% higher for contract than volunteer shooters. Conclusions The effectiveness of ground-based shooters is increased by operating at night using vehicles, spotlights and thermal-vision equipment. Contract shooters kill sambar deer at a faster rate, but are slightly more expensive per deer killed, than are volunteer shooters. Implications Ground-based shooting is likely to be most effective when conducted at night with thermal-vision equipment, and in areas with a high density of roads and tracks.

Context Of the six species of non-native deer present in Australia, the sambar deer is the largest and has been identified as a major threat to high-elevation peatlands in south-eastern Australia. However, little is known about sambar deer activity in high-elevation peatlands. Aims The aims of this study were to quantify sambar deer activity (including wallowing) seasonally and daily in response to biotic and abiotic variables, and how activity was impacted by ground-based shooting. Methods To estimate sambar deer activity, camera traps were continuously deployed for 4 years in two ~4300-ha areas in Alpine National Park, Victoria, south-eastern Australia. One area was subject to management operations using ground-based shooting to target deer and the other was not. Monthly activity of sambar deer was modelled using biotic (woody vegetation cover), abiotic (snow depth, aspect, slope, distance to water, road and peatland) and management (treatment versus non-treatment) covariates. Additional camera traps were deployed to monitor sambar deer activity at wallows. Key results Sambar deer activity decreased when snow depth increased (between July and September), and was highest in easterly and northerly aspects with dense woody vegetation close to high-elevation peatlands and roads. During our 4-year study, sambar deer activity decreased in the treatment area but increased in the non-treatment area. Sambar deer exhibited a crepuscular diel cycle, with greatest activity around sunset. Only male sambar deer were observed to wallow, with most wallowing occurring in the afternoon during October–June. Conclusions Sambar deer utilised high-elevation peatlands during October–June. Daily activity was crepuscular and was greatest in dense tree cover close to roads. Ground-based shooting reduced sambar deer activity in and around high-elevation peatlands. Implications Control operations targeting sambar deer at high elevations in south-eastern Australia should be conducted during October–June. Outside this period sambar deer appear to use lower-elevation habitats. The effectiveness of ground-based shooting could be improved by focusing this control action around sunset (when sambar deer are most active) and in places with dense vegetation close to roads and high-elevation peatlands.

Deer are among the world's most successful invasive mammals and can have substantial deleterious impacts on natural and agricultural ecosystems. Six species have established wild populations in Australia, and the distributions and abundances of some species are increasing. Approaches to managing wild deer in Australia are diverse and complex, with some populations managed as 'game' and others as 'pests'. Implementation of cost-effective management strategies that account for this complexity is hindered by a lack of knowledge of the nature, extent and severity of deer impacts. To clarify the knowledge base and identify research needs, we conducted a systematic review of the impacts and management of wild deer in Australia. Most wild deer are in south-eastern Australia, but bioclimatic analysis suggested that four species are well suited to the tropical and subtropical climates of northern Australia. Deer could potentially occupy most of the continent, including parts of the arid interior. The most significant impacts are likely to occur through direct effects of herbivory, with potentially cascading indirect effects on fauna and ecosystem processes. However, evidence of impacts in Australia is largely observational, and few studies have experimentally partitioned the impacts of deer from those of sympatric native and other introduced herbivores. Furthermore, there has been little rigorous testing of the efficacy of deer management in Australia, and our understanding of the deer ecology required to guide deer management is limited. We identified the following six priority research areas: (i) identifying long-term changes in plant communities caused by deer; (ii) understanding interactions with other fauna; (iii) measuring impacts on water quality; (iv) assessing economic impacts on agriculture (including as disease vectors); (v) evaluating efficacy of management for mitigating deer impacts; and (vi) quantifying changes in distribution and abundance. Addressing these knowledge gaps will assist the development and prioritisation of cost-effective management strategies and help increase stakeholder support for managing the impacts of deer on Australian ecosystems.