Rebecca West’s research while affiliated with UNSW Sydney and other places

Context Fenced conservation reserves are an effective management tool for the conservation of many threatened species. However, conservation fencing is known to inadvertently affect non-target species, ranging from barrier effects to direct mortality. There is a paucity of information on the negative impacts of fencing on reptiles. Aims Using the woma python, a species of conservation significance, this research aimed to improve our knowledge of how reptiles interact with fences. Methods The spatial ecology of womas was explored in relation to fencing at the Wild Deserts project partnership site, a rabbit-, cat- and fox-proof fenced area of Sturt National Park in arid Australia. A 6-year dataset of opportunistic observations of womas at the study site were analysed for demographic, spatial and temporal patterns in woma fence interactions. Nine adult pythons were radiotracked over a year to assess space use in relation to fencing. Key results Twenty-two per cent of all opportunistic woma observations at the site were mortalities associated with entanglements. All 20 entanglement deaths were in 30-mm netting despite 50-mm netting comprising lower segments of 21% of the fence network. Fencing encounters were greatest in dune habitats and during summer and autumn. Fence crossings were infrequent among telemetered pythons and most encounters did not result in entanglement, with four of the nine individuals recorded to have crossed the fence successfully, despite one mortality. Conclusions Thirty-millimetre netting, particularly in areas of netting overlap, represents an entanglement risk to womas. Implications This research is applicable to the management of conservation fences and can be extended to other large snake and reptile species. The impacts of small-aperture netting on large snakes and other non-target species should be considered in the planning phases for conservation fencing and mitigation strategies should be sought in the planning phases where possible. Large-aperture netting is preferable to 30-mm netting for pythons, where exclusion of rabbits is not necessary. However, larger netting apertures may disproportionately affect other non-target species such as bearded dragons.

A combined multiscale approach using ground, drone and satellite surveys can provide accurate landscape scale spatial mapping and monitoring. We used field observations with drone collected imagery covering 70 ha annually for a 5‐year period to estimate changes in living and dead vegetation of four widespread and abundant arid zone woody shrub species. Random forest classifiers delivered high accuracy (> 95%) using object‐based detection methods, with fast repeatable and transferrable processing using Google Earth Engine. Our classifiers performed well in both dominant arid zone landscape types: dune and swale, and at extremes of dry and wet years with minimal alterations. This highlighted the flexibility of the approach, potentially delivering insights into changes in highly variable environments. We also linked this classified drone vegetation to available temporally and spatially explicit Landsat satellite imagery, training a new, more accurate fractional vegetation cover model, allowing for accurate tracking of vegetation responses at large scales in the arid zone. Our method promises considerable opportunity to track vegetation dynamics including responses to management interventions, at large geographic scales, extending inference well beyond ground surveys.

The density and abundance of arid‐dwelling taxa often change significantly in response to precipitation fluctuations and the abundance of their predators. The survival and density of burrowing arthropods and their burrows in arid environments following prolonged dry periods and subsequent rains is poorly understood, as is the potential influence of reintroductions of their predators, such as fossorial mammals. The persistence of these arthropods and their burrows may be important for other species that rely on them for food or use their burrows for shelter. In this study, we examined the density of burrowing and ground‐nesting arthropods and their burrows in Australia's Strzelecki Desert over two years between 2019 and 2021. This period spanned the tail‐end of the worst drought on record and subsequent drought‐breaking rains. We employed a Before‐After Control‐Impact (BACI) study design to examine the short‐term effects of a fossorial mammal reintroduction of the greater bilby ( Macrotis lagotis ) into predator‐free fenced exclosures and used an inspection camera to detect the presence of spiders and other taxa within individually marked burrows. We observed the largest changes in arthropod abundance and burrow density between a period that encompassed a third consecutive summer in drought and the commencement of drought‐breaking rains, with some taxa declining by as much as 77% ( p < 0.001). While the density of harvester ant middens erupted over this time, the density of tarantulas, trapdoor spiders and scorpions declined significantly. The greater bilby reintroduction had no short‐term effect on the densities of the arthropods or their burrows, but their arrival may have implications on their post‐drought recovery. Further studies are needed to determine if the significant declines in arthropod populations and burrows are reflective of normal boom‐bust population dynamics due to the poor natural history knowledge of the arthropods we examined.

Harnessing natural selection to improve conservation outcomes is a recent concept in ecology and evolutionary biology and a potentially powerful tool in species conservation. One possible application is the use of natural selection to improve antipredator responses of mammal species that are threatened by predation from novel predators. We investigated whether long‐term exposure of an evolutionary naïve prey species to a novel predator would lead to phenotypic changes in a suite of physical and behavioral traits. We exposed a founder population of 353 burrowing bettongs (Bettongia lesueur) to feral cats (Felis catus) over 5 years and compared the physical and behavioral traits of this population (including offspring) to a control (non‐predator exposed) population. We used selection analysis to investigate whether changes in the traits of bettongs were likely due to phenotypic plasticity or natural selection. We also quantified selection in both populations before and during major population crashes caused by drought (control) and high predation pressure (predator‐exposed). Results showed that predator‐exposed bettongs had longer flight initiation distances, larger hind feet, and larger heads than control bettongs. Trait divergence began soon after exposure and continued to intensify over time for flight initiation distance and hind foot length relative to control bettongs. Selection analysis found indicators of selection for larger hind feet and longer head length in predator‐exposed populations. Results of a common garden experiment showed that the progeny of predator‐exposed bettongs had larger feet than control bettongs. Results suggest that long‐term, low‐level exposure of naïve prey to novel predators can drive phenotypic changes that may assist with future conservation efforts.

Eyrean Grasswrens Amytornis goyderi have generally been considered habitat specialists associated with Sandhill Canegrass Zygochloa paradoxa on the dunes of inland Australian deserts in the Lake Eyre Basin. Following above-average rainfall in 2020–2022 and an associated vegetation response in the Strzelecki Desert, Eyrean Grasswrens were observed at 39 locations south-east of their known distribution, with sites up to 11 km inside New South Wales, well beyond the extent of previous easterly records on the New South Wales–South Australia border. Further, two sites were north of the New South Wales–Queensland border, confirming the species 380 km south of previous Queensland records. Nine sites were within feral-free exclosures at the Wild Deserts project site in Sturt National Park, New South Wales. Repeated observations between May 2021 and August 2022 suggest persistence for at least 16 months in ephemeral vegetation on sand dunes supporting no Sandhill Canegrass. Two instances of breeding were recorded, with juvenile birds and feeding by an adult male observed. We explore possible drivers for this apparent range expansion and future scenarios around persistence inside landscape-scale exclosures, within which theorised threats from feral predators and overabundant herbivores are absent, presenting an opportunity to assess the relevancy of these drivers on the ecology of Eyrean Grasswrens.