Suchergebnisse

Abstract Context Determining the most efficient detection method for a target species is key for successful wildlife monitoring and management. Driven transects and sign surveys are commonly used to monitor populations of the endangered numbat (Myrmecobius fasciatus). Camera trapping is being explored as a new method. These methods were unevaluated for efficacy and cost for numbat detection. Aims To compare efficacy and costing of driven transects, sign surveys and camera trapping for detecting numbats in the Upper Warren region, Western Australia. Methods Seven repeat sign surveys and driven transects, as well as 4 months of camera trapping, were conducted concurrently at 50 sites along three transects. Numbat detection rates and costing of the three techniques were compared, and detection probabilities were compared between sign surveys and camera trapping. Key results Numbat signs were detected during 88 surveys at 39 sites, exceeding camera trapping (26 detections at 13 sites) and driven transects (seven detections near five sites). The estimated probability for detecting a numbat or a sign thereof (at a site where numbats were present) ranged from 0.21 to 0.35 for a sign survey, and 0.02 to 0.06 for 7 days of camera trapping. Total survey costs were lowest for driven transects, followed by camera trapping and sign surveys. When expressed as cost per numbat detection, sign surveys were cheapest. Conclusions Comparative studies of survey methods are essential for optimal, cost-effective wildlife monitoring. Sign surveys were more successful and cost effective than camera trapping or driven transects for detecting numbats in the Upper Warren region. Together with occupancy modelling, sign surveys are appropriate to investigate changes in occupancy rates over time, which could serve as a metric for long-term numbat monitoring. Implications There is no 'best' method for wildlife surveys. Case-specific comparison of animal detection methods is recommended to ensure optimal methods. For the numbat population in the Upper Warren region, further studies are needed to improve numbat detection rates from camera trapping, and to test sign surveys in autumn (March to May), when surviving juvenile numbats have established their own territory and assumptions regarding population closure are less likely to be violated.

Context Invasive predators are major drivers of global biodiversity loss. Red foxes (Vulpes vulpes) and feral cats (Felis catus) have contributed to the decline and extinction of many native species in Australia. The deployment of poison baits to control fox populations is a widespread conservation tool, but the effects of baiting intensity, rainfall and prey abundance on baiting effectiveness remain poorly understood. Aims We aimed to understand what influences the association between fox baiting intensity, red fox activity and feral cat activity, to provide inferences about what might affect the effectiveness of fox baiting in reducing fox activity. Methods We used generalised linear models to assess how fox and cat activity changes in relation to fox baiting intensity, rainfall, native prey availability and distance to agricultural land over a 6-year period (2006–13) in the forest ecosystems of the Upper Warren region of south-western Australia. Key results We found that fox activity was negatively associated with rainfall in the previous 12 months and positively associated with prey abundance and fox baiting intensity. We also found an interaction between fox baiting and prey abundance, with fox activity increasing with prey activity in areas of low and moderate baiting intensity, but remaining constant in areas of high baiting intensity. Feral cat activity was positively associated with prey abundance and fox baiting intensity. We found no clear relationship between fox and cat activity. Conclusions The drivers of the association between fox baiting and fox activity are unclear because intense fox baiting was targeted at areas of known high fox abundance. However, our results indicate that intense fox baiting may be effective at decoupling the positive association between fox activity and prey abundance. Our results also suggest a positive association between fox baiting intensity and feral cat activity, thus supporting the case for integrated fox and cat management. Implications We caution interpretation of our results, but note that management of invasive predators could be improved by adjusting the intensity of management in response to changes in environmental conditions and local context (e.g. strategically conducting intense predator management where prey abundance is highest). Improved understanding of these associations requires a monitoring program with sufficient replication and statistical power to detect any treatment effects.