Giselle Owens

Efficiently finding rare species is a perennial challenge in conservation science. The orange-bellied parrot Neophema chrysogaster is a rare mobile bird that is difficult to locate using traditional field survey techniques with human observers. We harnessed recent advances in bioacoustic technology to create a survey framework that integrates passive acoustic surveys and semi-automated detection to increase monitoring capacity for the orange-bellied parrot. We developed a custom BirdNET classifier for the orange-bellied parrot and compared efficacy of acoustic and field surveys using an occupancy framework. We deployed autonomous recording units across the orange-bellied parrot breeding range in southwest Tasmania and concurrently undertook between three and six repeated point-count surveys at the same 48 sites using human observers. Our custom BirdNET classifier had high accuracy and discrimination abilities. Validation of model scores across a week (5,712 hours of audio) required 60 hours reviewing time and yielded a 95% confidence of a correct BirdNET prediction at scores over 0.998. Occupancy analysis showed that the detection probability of acoustic surveys (p = 0.80) was more than eleven times greater than field surveys by skilled ecologists familiar with the species (p = 0.07). We provide a template for how to implement monitoring of the orange-bellied parrot and recommendations for how our methods can be improved to optimise the classifier to account for other species and locations.

As biodiversity continues to decline amid the global extinction crisis, ex-situ management, including breeding animals in captivity for release, is becoming increasingly utilised. However, these programs represent significant investments, with no guarantee of success. It is often uncertain whether a conservation breeding program could effectively contribute to species recovery. We review two large, long-term conservation breeding programs to develop a population model for the critically endangered swift parrot ( Lathamus discolor ). We use a population viability analysis to construct a theoretical captive breeding program to investigate the role a breeding and release program might play in delaying the current extinction trajectory. We modelled how different sized programs could supply individuals for release to supplement the wild population to generate expectations on the timeframe, release numbers, and costs involved. The modelled programs could maintain the wild population of swift parrots at low levels (< 250 birds) while releases were ongoing. After releases ceased, unabated threats would cause the wild population to sharply decline, with most simulated populations becoming extinct within 10 years if threats to the in-situ population are not mitigated. Cost estimates for these modelled programs (including releases, captive husbandry, and salaries) ranged from $54–123 million. Although releases from captivity can delay extinction and buy time to facilitate in-situ conservation efforts, they represent a significant financial investment. Ex-situ management alone cannot recover threatened populations and must be considered in conjunction with in-situ conservation efforts.

Forest degradation is a major cause of habitat loss for species that rely on old forest features. Quantitative knowledge of forest degradation and deforestation in the breeding range of the critically endangered swift parrot (Lathamus discolor) is poor but essential to inform effective conservation planning. We provide the first quantitative analysis of forest degradation and deforestation across the swift parrot breeding range. We identify trends and drivers of anthropogenic loss to determine whether current forestry policy is aligned with targets to secure species recovery. We used global datasets of forest extent, change and loss to evaluate historic deforestation and forest dynamics since the year 2000. We applied our analysis at three spatial scales within the breeding range: potential, core, and Swift Parrot Important Breeding Areas (SPIBAs). We measured trends in fire and anthropogenic forest loss before and after forestry policy changes. Results informed a land use change analysis to identify major drivers of forest loss. Habitat loss has occurred in more than 50% of the swift parrots' breeding range. More than 37% of the breeding range was permanently deforested prior to the year 2000. Of remaining forest in the year 2000, approximately a quarter has been disturbed, degraded or permanently deforested. Degradation was 6.5 times that of deforestation, and production forestry was the major human driver of forest loss. Forest loss rates in SPIBAs have doubled since forestry policy change in 2014. Degraded forests are unlikely to provide habitat for swift parrots and urgent changes to forest policies and practices are needed to ensure the perpetuity of the species. We highlight the advantages of using publicly available remote-sensing datasets to quantify past and present habitat degradation, deforestation, and land use change at biologically meaningful scales relevant to the recovery of threatened species.

Monitoring threatened species is essential for understanding their conservation needs and developing effective recovery strategies. However, designing and implementing monitoring programs can be challenging in resource‐constrained environments, where conservation practitioners must balance the need for detailed information with limited resources. We present a case study focusing on the design of a range‐wide monitoring program for the Endangered rufous scrub‐bird (Atrichornis rufescens) in the mountain forests of eastern Australia. We first developed a ‘wish list’ of monitoring questions and then trialed the methods needed for answering them using sequence of pilot studies. We implemented a phased approach comprising (i) a study of whether individuals could be identified by their songs, (ii) identification of a ‘core range’ using species distribution models to refine the search area, and (iii) a trial of the efficacy of a preferred feasible monitoring approach. We offer a practical pathway for designing question‐driven monitoring programs for threatened species. Our study highlights the importance of clarifying explicit monitoring goals and tailoring methods to suit species' ecological and life history characteristics. By following this systematic approach, conservation efforts can obtain valuable information for effective management, even with limited resources and prevailing uncertainty about species ecology.

Detection of animals is influenced by species traits, environment, season and the methods used. Analytical techniques can address imperfect detection, such as false absences, but data limitations hinder accurate density estimation. Identifying field survey methods that optimize detectability is therefore a high research priority, especially for species of conservation concern. We consider a model species, the sugar glider Petaurus notatus, to evaluate how optimizing detections can affect survey outcomes. A literature meta‐analysis found little innovation in baiting approaches for sugar gliders over four decades. Honey‐based baits prevailed, despite emerging evidence of opportunistic carnivory. We compared sugar glider detection probabilities using honey and fish‐based baits in a spatially explicit capture‐recapture study. Fish bait increased detections 33‐fold, and density estimation (0.12 ha⁻¹) was only possible using the fish‐baited data – detections were too sparse using honey‐bait to facilitate analysis. Other factors that influence detectability include trap height and habitat connectivity, which were top moderators in our meta‐analysis, but these may be secondary to the bait or lure used. By using (i) species‐specific bait that accounts for the biology of the target species, and (ii) analytical tools to account for imperfect detection and heterogeneous movement of animals, we achieved good enough detection probabilities to undertake detailed analysis of the spatial ecology of sugar gliders. Compared to honey‐based baits (the prevailing approach of other studies on this species), the high detection probability attained with fish‐based baits provides an improvement on conventional practices. Our study is an important reminder that accounting for the biology of the target species during survey effort may mean the difference between collecting enough data for analysis or not. In the context of species conservation, optimizing detection likelihoods is critical for answering ecological questions about cryptic species, and our results demonstrate the need to reappraise generic approaches when better information is available.

Giselle Owens1,4, Ana Gracanin2, Joanne Potts3, Catherine M. Young1, Robert Heinsohn1, Philip Gibbons1, Dejan Stojanovic1Fenner School of Environment and Society, Australian National University, Canberra, AustraliaCentre for Sustainable Ecosystem Solutions, School of Earth, Atmospheric and Life Sciences, Faculty of Science, Medicine and Health, University of Wollongong Australia, New South Wales, AustraliaThe Analytical Edge Statistical Consulting, Hobart, AustraliaCorresponding author: giselle.owens@anu.edu.auRunning Head: Detection and density estimation for a cryptic speciesKey Words: detection probability, spatially explicit capture-recapture, SECR, meta-analysis, literature review, bait, lure, Petaurus notatus , sugar glider, density

Conservation assessments of threatened species are often limited by scarce data and parameter uncertainty. Predictive models, designed to incorporate this uncertainty, may be the only tool available to inform conservation assessments for data‐deficient species, but they are used surprisingly rarely for this purpose. The swift parrotLathamus discoloris the only critically endangered bird to be listed in Australia based on population viability analysis (PVA). We aimed to evaluate the accuracy of the 2015 conservation assessment, which used sparse information, by incorporating new detailed and long‐term data. First, we updated a range of life history parameter estimates, and then we repeated the same PVA as per the original conservation assessment. This process confirmed our earlier finding that swift parrot nests were more likely to survive in places with high mature forest cover. We identify that high forest landscape integrity and abundant hollow‐bearing trees best predict nest daily survival rates. Based on the updated PVA, we predict a 92.3% population decline over three generations (11 years). This supported the predictions of the original conservation assessment, and the main benefit of the additional data was improved confidence in projections (the magnitude and direction of the population decline were similar between the original and updated PVAs). Our results demonstrate that meaningful trends can be inferred for species with imperfect information about their life history. Using predictive models like PVAs can help managers identify which life history parameters impact most on demographic trends. This information can guide targeted data collection so that ‘draft’ models can be later updated to improve certainty around population predictions.

Lethal control of invasive mammalian predators can be controversial and is rarely a ‘silver bullet’ for conservation problems. Evaluating the efficacy of lethal control is important for demonstrating the benefits to threatened species are real and detecting unexpected perverse outcomes. We implemented a pilot study to evaluate if lethal control of introduced sugar gliders Petaurus breviceps can reduce the rate of nest predation on Tasmanian hollow nesting birds including swift parrots (Lathamus discolor). Using a before-after-control-impact design, we implemented a lethal control treatment whereby we attempted to remove sugar gliders from three treatment sites. In each time period across sites we monitored quail eggs in nest boxes to record predation, and used cameras to detect sugar gliders. We caught nine sugar gliders over three treatment sites. The model best supported by the data indicated an effect of site × time period on both egg survival and the rate of glider detection on cameras. There was no support for an effect of treatment on our data. We also recorded predation of a real swift parrot nest by sugar gliders at a treatment site where we recorded no predation of quail eggs. Our pilot study shows that at small scales, intensive lethal control of gliders yields low capture rates and no discernible effect on the metrics we measured. We conclude that alternative approaches to controlling the impact of sugar gliders, such as habitat protection, are critical in this study system before lethal control is widely implemented as a management tool.

Nest boxes are widely used for habitat restoration. Unfortunately, competitors of the target species may exploit nest boxes, creating perverse outcomes. Avoiding habitats preferred by nontarget species, while favoring those of the target species, requires an adaptive management approach if limited information about species preferences is available when deploying boxes. Using nest boxes intended for Swift Parrots Lathamus discolor, we identify factors associated with nontarget species occupancy (Common Starling Sturnus vulgaris and Tree Martin Petrochelidon nigricans) in newly deployed boxes in 2016, and then again after 3 years had elapsed in 2019. Box occupancy by different species depended on the interaction between distance of individual boxes to the forest edge and year. Although the target species exploited similar numbers of nest boxes in both years, competitors were the main beneficiaries of established boxes. A subordinate native nest competitor increased box occupancy likelihood at greater distances from forest edges in both years, but the relationship was stronger in 2019. Introduced Common Starlings S. vulgaris were most likely to occupy boxes close to forest edges, but the magnitude of this relationship was much greater for established than newly deployed boxes. We suggest that permanent box deployments for Swift Parrots may produce perverse outcomes by increasing nesting habitat for Common Starlings. We suggest that for species that only use cavities for part of their life cycle, managers should limit access to boxes outside of critical times to reduce the likelihood that pest populations can exploit restoration efforts and create new problems.