Development and application of survey methods to determine habitat use in relation to forest management and habitat characteristics of the endangered numbat (Myrmecobius fasciatus) in the Upper Warren region, Western Australia

Anke Seidlitz

Effective detection methods and knowledge on habitat requirements is key for successful wildlife monitoring and management. The numbat (Myrmecobius fasciatus) is an endangered, Australian-endemic marsupial that has experienced major population declines since European settlement. The Upper Warren region (UWR) in south-western Australia contains one of the two remaining natural populations. A lack of effective survey methods has caused a paucity of information regarding this population. This PhD project aimed to develop robust survey methods and determine habitat requirements for the numbat in the UWR. Given the perceived advantages of camera trap technology in wildlife research, camera trap trials were conducted to optimise camera methodologies for numbat detection. Swift 3C wide-angle camera traps positioned at ~25 cm above ground increased numbat detections by 140% compared to commonly used Reconyx PC900 camera traps. Elevated, angled cameras were suitable for numbat individual identification. As numbats are difficult to catch, three non-invasive methods for numbat detection were field tested (Sign surveys, driven surveys and camera trapping). Sign surveys (searching for diggings and scats) were more successful and cost effective than driven observational surveys or camera trapping. Sign surveys are appropriate to investigate changes in occupancy rates over time, which could serve as a metric for long-term numbat monitoring. Since camera traps are an attractive tool for wildlife detection, field trials were conducted to increase camera trap detection rates for numbats and other species. Detection rates from stationary Reconyx PC900/HC600 (40° detection angle) were compared to paired, periodically repositioned Reconyx PC900/HC600 and Swift 3C wide-angle camera traps (110° detection angle). Swift 3C wide-angle camera traps had significantly higher animal detection rates compared to Reconyx PC900/HC600 camera trap models. Stationary and periodically repositioned Reconyx camera traps performed similarly, although there were significant differences for some species including the numbat. Sign surveys that were conducted concurrently with the above camera trap field trials showed that autumn sign surveys detected significantly more numbat signs than spring sign surveys. Even though numbat detection rates by camera traps improved by using periodically repositioned Swift 3C wide-angle camera traps, sign surveys that were conducted at the same time and at the same sites were more successful. Sign surveys were applied to determine how forest management activities (prescribed fuelreduction burns, timber harvesting, introduced predator control intensity) affect numbat habitat use. Numbat signs were found at 83% of 78 survey sites, indicating that numbats in the UWR are habitat generalists. Log number was the only important determinant of numbat habitat use. Logs provide numbats with refuge from predators and hollows for resting and nesting. This project made valuable discoveries on monitoring and protecting numbats in the UWR. At present, the most effective method for monitoring the species is by using sign surveys to estimate occupancy. High habitat occupancy rates indicate that current forest management is suitable for this species provided that sufficient logs are retained in managed areas.

Development and application of survey methods to determine habitat use in relation to forest management and habitat characteristics of the endangered numbat (Myrmecobius fasciatus) in the Upper Warren region, Western Australia

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