Koalas on Australian Islands

Koalas on Australian Islands | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Koalas on Australian Islands Mitchell Jacob Eddie, William Anthony Ellis, Salit Kark This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6300594/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 01 Sep, 2025 Read the published version in Biodiversity and Conservation → Version 1 posted 10 You are reading this latest preprint version Abstract Despite substantial conservation and research investments, populations of the endemic and iconic koala (Phascolarctos cinereus) continue to decline across much of their Australian range, resulting in their Endangered status. Island refugia may offer a crucial strategy for koala conservation but also have the potential to become ecological traps, leading to further population declines across the species’ range. Despite this, systematic efforts to map and record koala occurrences across Australian islands are lacking. This has left significant gaps in understanding the status, origin, and distribution of island koala populations, the factors influencing their persistence, and the extent of threats they face. This study aimed to address these gaps by creating the first comprehensive database of koalas on Australian islands, characterising their distribution, status, and history of occurrence. We integrated this database with spatial mapping software to analyse the geographic distribution and extent of anthropogenic and environmental threats across Australian island. Additionally, we applied path analysis to model the effects of abiotic, biotic, and anthropogenic factors on island koala persistence. We found records of koalas (historical and/or current) on 37 Australian islands, spanning subtropical to temperate climates, with > 15 islands currently supporting koala populations. Among the threats to extant island koala populations analysed, anthropogenic land use and overbrowsing exhibited a consistent spatial trend, both being more pronounced at lower latitudes. These findings can inform conservation and management actions by identifying islands where threat mitigation is required and highlighting those that may serve as suitable refuges for future translocation and koala conservation efforts. Conservation status threats refuges translocation Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Introduction The koala (Phascolarctos cinereus) is an endemic iconic marsupial restricted to the eucalypt forest and woodland communities of southern, eastern and south-eastern Australia (Melzer et al. 2000 ). Owing to their endearing appearance and unique natural history, koalas hold significant ecological and cultural importance in Australia and attract international attention. While substantial research and management efforts have focused on koalas on the Australian mainland, systematic documentation of koala occurrences on islands is lacking, leaving the status, origin and long-term trajectories of these populations largely unstudied. A few well-known islands, such as Kangaroo Island and North Stradbroke Island (Minjerribah), have been relatively well-documented, but they represent only a fraction of the species’ broader island distribution. Australia has over 9,200 islands spanning tropical to subantarctic climates, some of which support koalas as part of their native range. Other islands host introduced koala populations, that were marooned for various purposes, including to serve as reservoirs for restocking depleted mainland populations (Danaher et al. 2023 ; Menkhorst 2008 ; Lewis 1934 ) Compared to mainland environments, islands are often isolated from anthropogenic threats and disease, making them ideal refuges in some cases (Cristescu et al. 2012 ; Whittaker and Fernández-Palacios 2006 ). This is particularly relevant in Australia, where human population density is concentrated on the mainland (Australian Bureau of Statistics 2024b ). Islands also offer enclosed areas where exotic species and disease can be eliminated (Moro et al. 2018 ). Island refuges have been successfully used in modern conservation efforts, such as on Maria Island off the coast of Tasmania, which supported Tasmanian devil reproduction, due to its isolation from disease that devastated mainland populations (Hogg and Wise 2022 ) . Islands can also become ecological traps. Their isolation and relatively small area compared to the mainland can hinder species dispersal in response to environmental or anthropogenic pressures. Additionally, small population sizes and low genetic diversity increase susceptibility to such pressures, increasing the risk of local extinction (Moro et al. 2018 ). The disappearance of koala populations from some islands has been attributed to ecological entrapment through land clearing, hunting, and human interference (Green 2016 ; Jackson 2007 ; Allen n.d.). Some of these island populations, such as on Quoin and Coochiemudlo, are believed to have been of natural origin and may have harboured unique genetic diversity now lost. Despite significant investments in koala conservation, including a recent 50 million AUD federal funding allocation over four years (WWF 2022), koalas are listed as endangered under the Australian Commonwealth Environment Protection and Biodiversity Conservation (EPBC) 1999 for populations in the Australian states of New South Wales, Queensland, and the Australian Capital Territory (Department of Climate Change, Energy, the Environment and Water 2023 ). In contrast, South Australian and Victorian populations are not EPBC-listed and are managed for overabundance through contraception and translocation (Menkhorst 2008 ). However, all koala populations remain classified as vulnerable on the International Union for Conservation of Nature’s (IUCN) Red List (Burbidge and Woinarski 2020 ) The conservation listings reflect persistent threats to mainland populations, such as anthropogenic land use, human population density, fire, disease and over browsing. Anthropogenic land uses tend to occur on high quality koala habitat. The associated habitat loss displaces koalas to peri-urban or degraded habitats where they are exposed to threats from the human population (Department of Environmental Science 2023 ; Januchowski et al. 2008 ; Lesslie and Mewett, 2013 ; Crowther 2009 ). Wildfires impact koala survival directly through burns and indirectly through tree mortality (Armenteras et al. 2013 ; Phillips et al. 2021 ; National Parks and Wildlife Service South Australia 2020 ). Overabundant koala populations have been found to over-browse, destroying habitats, depleting resources and leading to koala starvation (Jackson 2007 ; Whisson and Shimmin 2006 ). Diseases, largely manifestations of chlamydial infections, are the largest contributor to mortality and are responsible for up to 57% of female infertility in some koala populations (Hanger et al. 2017 ; Rhodes et al. 2011 ). The spatial patterns and severity of these threats has not been described across islands with extant koala populations. There is also a paucity of research on the drivers influencing koala persistence on islands. We hypothesize that geographic, biotic, and human-mediated factors influencing island koala persistence include anthropogenic land use, fire, translocation effort, island area, climate, and isolation (distance to the mainland). Land use and fire were identified as factors that can contribute to koala population declines (and thus persistence) (Lunney et al. 2017 ; McAlpine et al. 2015 ; Melzer et al. 2000 ). Native and introduced island koala populations have both received varying degrees of translocation effort. Notably, translocation effort has a positive correlation with persistence and introduction success of other species (Hossack et al. 2022 ). The island biogeography theory attempts to explain how organisms are distributed amongst islands, and suggests that the strongest correlates are island area and island isolation (Guo 2015 ; Mologni and Burns 2023 b). Climate, which is strongly related with latitude, is a known determinant of species distribution, and despite having a geographic range spanning various latitudes, koala distributions can still be influenced by climate factors (Shabani et al. 2019 ). To address current knowledge gaps, we collated a novel database which we named ‘ Koalas on Australian Islands ’. This is the first database of its kind for koalas in Australia. We aimed to identify koala status and origin across all islands with recorded occurrences, explore the distribution and extent of environmental and anthropogenic threats to extant island koala populations, and investigate key factors shaping koala persistence on islands. This may help to mitigate threats and clarify the role of islands with koala occurrences as refuges or ecological traps, contributing to koala conservation. Methods Forming the ‘ Koalas on Australian Islands ’ database We collated data on koala status, origin, translocation history, fire intensity, land use, overbrowsing history, chlamydial prevalence, island latitude, island area and distance to mainland for all islands where there was historically documented koala occupancy, forming the ‘ Koalas on Australian Islands ’ database. Koala status for each island was designated as “present”, “absent”, or “unknown” and origin was designated as “natural”, “introduced” or “unknown”. For islands that were found to have extant populations, chlamydial infection status was recorded as “positive”, “negative”, or “unknown”. Additionally, islands were classified as either historically overbrowsed or not. Data for these variables were sourced from the Island Occurrences of Threatened Australian Species (IOTAS) database (Baxter et al. 2021), published and unpublished research, literature and reports, newspapers and journals, open-access databases, expert correspondence, departmental archives, anecdotal accounts, local knowledge, and books related to the islands of interest. To maximize resource retrieval, search terms included historical synonyms for koalas, such as “native monkey”, “monkey bear”, “bear” and “kul-la”. Islands with conflicting evidence regarding koala status or origin were classified as unknowns. Islands lacking reported sightings within the species' maximum lifespan (beyond 18 years) were also categorized as unknown (Gordon 1991). Koala status was classified as “absent” only if the following criteria were met; 1) no evidence of koala presence in over 50 years, 2) a significant human footprint (such as frequent tourism or greater than 100 permanent residents) and 3) no environmental surveys (such as fauna surveys on other species or habitat assessments). All islands with designated “absent” koala populations were corroborated by peer reviewed literature, though absence was often inferred in these accounts. The quality of koala occurrence data for each island was assessed on a scale from 0 to 4, with 0 being the lowest and 4 the highest (definitions provided in Table 1). Sources scoring 0 were excluded from analysis. Islands where koala persistence is widely acknowledged received a credibility score of 4 and were assigned a last record date of 2024. A full list of sources is provided in Table 2 and Table A.1. Table 1 Definitions and examples of the criteria for the four source credibility ratings. Credibility Score Definition 0 Inferred – Inferences drawn from personal communications but never explicitly stated, or the nature of the record is undefined (i.e., unknown if the recorder inferred presence or witnessed live specimens). 1 Anecdotal – Verbal accounts and second-hand information explicitly reporting koala occurrences. 2 Written information – firsthand record in popular press, book or website. 3 Technical reports – environmental impact statements, government or in house reports, unpublished data. 4 Peer reviewed documents and material – skulls, artifacts, scats, peer reviewed journals. Table 2 The ‘Koalas on Australian Islands database’ . This database shows the status (present or absent) and origin (introduced or natural) of koalas across all coastal and inland Australian Islands with a recorded koala occurrence. The sources of information this data was drawn from, and the combined credibility of these sources are also shown. References corresponding to source numbers are shown in Table A.1. Island Name State Origin Status Last Record Credibility Source Brampton Island Queensland Introduced Present 2017 4 1–6 Bribie Island Queensland Natural Absent 1965 4 1,4,6–9 Chinaman Island Victoria Introduced Unknown 1964 (2024?) 4 10–18 Churchill Island Victoria Introduced Absent 1980 2 4 Clairview Island Queensland Natural Present 2022 3 1,19 Coochiemudlo Island Queensland Natural Absent “Several decades ago” 4 1,4,6 Curtis Island Queensland Natural Absent 1934 3 1,5,20 Fraser Island Queensland Natural Absent 1913–1922 1 1,21–23 French Island Victoria Introduced Present 2024 4 4,8,10–13,24–29 Great Keppel Island Queensland Natural Absent 1960 3 1,5,30–32 Hallstrom Island New South Whales Introduced Absent 1962 3 4,11,12 Kangaroo Island South Australia Introduced Present 2024 4 11,12,33 Keswick Island Queensland Unknown Unknown ? 4 6 King Island Tasmania Introduced Absent < 1968 2 34 Little Snake Island Victoria Introduced Unknown 1967 3 8,10,26 Magnetic Island Queensland Introduced Present 2024 4 1,5,35 Goat Island South Australia Introduced Absent 1976 3 4,10,12,36 Newry Island Queensland Natural Present 2009 4 1,2,4,6,37,38 North Minjerribah Queensland Unknown Present 2024 4 2,6,39–42 Outer Newry Island Queensland Natural Unknown 1947 4 1,43 Pental Island Victoria Introduced Unknown 1990 4 4,11,44 Phillip Island Victoria Introduced Present 2024 4 4,6,24,26,28,45,46 Quail Island Victoria Introduced Present 2024 4 11,13–15,18,24,47 Quoin Island Queensland Natural Absent 1965 4 48–51 Rabbit Island Queensland Natural Present 2008 3 2,4,6,37,38 Raymond Island Victoria Introduced Present 2024 4 6,52,53 Rita Island Queensland Natural Absent 1931 2 1,54–56 Rotamah Island Victoria Natural Present “Last 12 months” 1 4,57–59 Snake Island Victoria Introduced Present 2024 4 11,12,26,60,61 South Minjerribah Queensland Unknown Absent ? 0 39,41,62 St Bees Island Queensland Introduced Present 2022 4 2,3,5,63,64 St Margaret Island Victoria Introduced Unknown 1977 4 4,6,65–67 Sunday Island Victoria Introduced Unknown 1977–1978 4 65,67,68 Three Hummock Island Tasmania Introduced Absent < 1947 1 4,8,10,69,70 Ulupna Island Victoria Introduced Present 2021 4 4,6,71 Wartook Island Victoria Introduced Absent 1965 3 4,12,72 Whitsunday Island Queensland Natural Absent ? 1 1,73 For all islands with recorded koala occurrence, we obtained data for island area, distance to the mainland, and island latitude using the ‘Islands of Australia’ shapefile and ‘Australian mainland’ shapefile, as well as the ‘Calculate Field’ and ‘Near’ tools in ArcGIS Pro (Commonwealth of Australia 2015; Australian Bureau of Statistics 2024a; Esri 2023). Latitudes were extracted from island polygon centroids. We obtained land use data from the ‘Catchment scale land use of Australia and commodities – Update December 2023’(Australian Bureau of Agricultural Resource Economics and Sciences (ABARES) 2023). This dataset classifies an areas primary land use. Land use classified as ‘production from dryland agriculture and plantation,’ ‘production from irrigated agriculture and plantations,’ and ‘intensive use’ involve large scale clearing of native vegetation or replacement with introduced species and will be collectively termed ‘anthropogenic land use’ throughout the remainder of this report. Both the percentage and proportion of island area allocated to anthropogenic land use was measured on each island with historical koala occupancy for the subsequent threat and path analysis respectively. We obtained fire data from Digital Earth Australia’s ‘Historic Hotspots’ dataset (Commonwealth of Australia Geoscience Australia 2024). This dataset was chosen to quantify the mean fire intensity, measured as Fire Radiative Power in Megawatts (MW), of all islands with recorded koala occurrences. The mean fire intensity experienced by each island was calculated by spatially joining each hot spot to the island they intersected and then using the summary statistics by group tool in ArcGIS Pro. Data on the human population of each island with extant koala populations was obtained from the Australian population grid 2023 in ESRI Grid format (Australian Bureau of Statistics 2023b). The zonal statistics as table tool on ArcGIS Pro was used to estimate the total population for each island. We used the collated data for the status and origin of island koala populations to produce Table 2. Additionally, we used ArcGIS Pro software and the ‘Islands of Australia’ and ‘Australian mainland’ data to visualise the spatial distribution of the status and origin of island koala populations to produce Fig. 1. The data for fire intensity, Chlamydia status, overbrowsing history, land use and human population were used to estimate the magnitude and presence of threats on islands with extant koala populations in Table 3. The summary statistics of these variables by Australian State are presented in Fig. 2 and compared to examine spatial trends (note that South Australia is not included as summary statistics cannot be calculated from a single value). Fire intensity, human population size and land use are also visually represented and spatially mapped for each island with extant koala populations using ArcGIS Pro software in Fig. 3. Table 3 Threats present on coastal and inland islands that are thought to currently support koala populations. Quantitative magnitudes have been rounded to two decimal places. Sources for data on disease and over browsing include; (Jackson, 2007; Lee et al., 2013; Menkhorst, 2008; Whisson & Ashman, 2020). Island Name Historically over browsed Disease- Chlamydia pecorum Area Under Anthropogenic land use (%) Approximate Human Population Mean Fire Intesnity (MW) Australian State Brampton Island No Positive 4.26% 0 0 Queensland Clairview Island No Unknown 5.64% 0 9.83 Queensland French Island Yes Negative 32.96% 130 24.03 Victoria Kangaroo Island Yes Negative 49.28% 4481 60.29 South Australia Magnetic Island No Positive 11.20% 2144 11.65 Queensland Newry Island No Unknown 0% 0 4.83 Queensland North Minjerribah No Positive 6.10% 1953 26.87 Queensland Phillip Island Yes Positive 82.59% 13270 4.92 Victoria Quail Island Yes Positive 0% 0 0 Victoria Rabbit Island No Unknown 0% 0 3.29 Queensland Raymond Island Yes Positive 52.05% 460 12.7 Victoria Rotamah Island No Unknown 0% 0 0 Victoria Snake Island Yes Positive 2.47% 0 13.18 Victoria St Bees Island No Positive 0% 0 10.56 Queensland Ulupna Island No Unknown 49.44% 16 17.49 Victoria Data Analysis We used path analysis to examine the effect size and significance of a) fire intensity, b) proportion of island area under anthropogenic land use, c) latitude, d) translocation effort, e) island area and f) isolation (distance to mainland) on koala persistence on islands. This approach tests multiple direct and indirect relationships between variables within a system of causal regression pathways. Unlike standard regression, path analysis enables inclusion of multiple dependent variables and accounts for the possibility that a variable can act as both a predictor and an outcome. Path analysis is ideal for studying ecological systems where variables influence each other directly but also through mediating variables. A pathway diagram was produced to show the hypothesised direct and indirect relationships between variables (Fig. 4; Table A.2). Each island was assigned a value for koala persistence and a value for each variable hypothesised to influence koala persistence from the data sources above. The path analysis was conducted by fitting a structural equation model using the ‘lavaan’ package in RStudio. The model was adjusted until fit indices were satisfactory. In the final path model, all variables were scaled using the “scale” function in R to reduce issues with skewed distributions and variance when running the model. Distance to mainland was log transformed to address linearity issues, which were checked using the “DHARMa” package. Translocation effort was treated as an ordered categorical variable, as count data are not supported by the lavaan package. Translocation effort was therefore grouped into three categories “no effort”, “low effort” and “high effort” consisting of zero, one to two and three or more translocations each. Assumptions for the ordered logistic regression of this pathway were checked using the “brant” package and cumulative log odds plots in RStudio. The output of the path analysis is shown in Fig. 5. We excluded some islands with recorded koala occurrences from the path analysis (Table A.3). Islands where koalas were intentionally removed or introduced with only females (e.g., Churchill Island) were excluded from the analysis, as the reasons for the absence of these populations are apparent and independent of environmental factors. Islands assigned a credibility rating of 0 were also excluded, as these records were considered unreliable. Finally, islands with unknown koala population status were excluded, leaving a total sample size of 26 islands for analysis. Results Status and origin of koala populations on islands We found records of koala occurrence on 37 islands across five Australian states. These included 18 islands in Queensland, one in New South Wales, 14 in Victoria, two in South Australia, and two in Tasmania (Table 2 ; Fig. 1 ). As of 2024 Koalas currently persist on 15 of these islands across a range of latitudes, including seven in Queensland, seven in Victoria and one in South Australia. The status of documented koala populations on 7 islands has been designated as unknown and koalas have disappeared from 15 islands they once occupied (Fig. 1 ) Natural (rather than human introduced) koala populations persist on 4 out of 15 Islands. Three of these islands occur in Queensland, including Clairview, Rabbit and Newry Island (Fig. 1 ). The last koala records on Rabbit Island and Newry Island were 16 and 15 years ago, respectively, and therefore these islands narrowly meet the 18-year threshold set earlier in this report to still be considered present (Table 2 ). Rotamah Island is the only Victorian island with a natural population. It is believed to have been colonised naturally from nearby mainland translocations (Jackson 2007 ). The status of the natural population on Queensland’s Outer Newry Island is unknown. Koalas are introduced to 21 out of the 37 islands that they have been recorded on, possibly more. Only three of these introductions occurred on Queensland islands. The origin of the koala populations on three islands remains unknown (Table 2 ; Fig. 1 ). Spatial patterns of threats to koalas on islands The average human population size, fire intensity and percentage of island area under anthropogenic land use across all Australian islands with extant koala populations was 1497 ± 903, 13.31 (MW) ± 3.98 (MW) and 19.73% ± 6.85%, respectively (mean ± standard error; Fig. 2 ). The relatively high standard errors indicate substantial variability in threat severity across the islands. Phillip Island has the largest human population (13,270 residents) and the greatest percentage of anthropogenic land use (82.59% of the island’s area) (Table 3 ). All other islands have less than 53% of their area dedicated to anthropogenic land use and only three other islands—North Stradbroke Island (Minjerribah), Kangaroo Island and Magnetic Island—have relatively high human populations compared to the remaining 11 islands. Kangaroo Island has a high mean fire intensity (60.29 MW) relative to all other islands. In contrast, eight islands—Brampton, Clairview, Newry, Quail, Rabbit, Rotamah, Snake, and St Bees—have consistently low values for the analysed threats, with mean fire intensities below 15 MW, anthropogenic land usage under 10% of each island’s area, and human populations below 100 residents (Table 3 ). The islands with the highest percentages of land dedicated to anthropogenic use are concentrated at lower latitudes, particularly in Victoria and on Kangaroo Island, South Australia, rather than in Queensland (Fig. 3 ). This pattern is reflected in the data presented in Fig. 2 , where Queensland islands have an average of 3.89% ± 1.60% of their area dedicated to anthropogenic land use, compared to Victorian islands, where the average is 31.36% ± 12.13%. Aside from outliers—Kangaroo Island in South Australia and Phillip Island in Victoria—there are no notable differences in fire intensity or human population size between Victorian and Queensland islands (Fig. 3 ). While there is a relatively large difference in the mean human population of Queensland and Victorian islands (585 and 1982 respectively), the substantial overlap in standard error (Fig. 2 ) suggests that there is no significant spatial difference in the magnitude of these threats between Queensland and Victoria. The high average human population size of Victorian islands is largely driven by the disproportionately high population of Phillip Island, which also inflates the sample standard error. Eight islands had documented incidents of Chlamydia sp. in individuals of the population, four in Queensland and four in Victoria (Table 3 ). Only French and Kangaroo Islands have no documented incidence of Chlamydia . The disease status is unknown for five islands (Table 3 ). Four of these (Rotamah, Clairview, Rabbit and Newry) were identified as having low values for fire intensity, percentage of anthropogenic landuse and human population. These four islands have also never had documented incidence of over browsing. Overbrowsing has never been documented on Queensland islands, and only two Victorian islands (Ulupna and Rotamah island) appear to have been free of over browsing (Table 3 ). Drivers of koala persistence on islands The path analysis revealed that translocation effort was the only direct interaction that significantly affected koala persistence (p < 0.01) (Fig. 5 ). This suggests that for each unit increase in translocation effort, there is a 0.767 (± 0.202 SE) increase in the log-odds of koala persistence. That is, as translocation effort increases, so does koala persistence. Koala persistence did not have detected significant interactions with anthropogenic land use (p > 0.05), mean fire power (p > 0.05), island area (p > 0.05), isolation (p > 0.05) or latitude (p > 0.05) (Fig. 5 ). There was a marginally significant indirect interaction with latitude and island koala persistence through translocation effort as a mediating variable (p = 0.053) (Fig. 5 ). The negative coefficient suggests that for every 1 standard deviation increase in latitude the log odds of an island having a higher category of translocation effort decreases by -0.943 ± 0.487 (Fig. 5 ). There were no other significant indirect interactions through mediating variables. Neither of the pathways with mean fire intensity and proportion of anthropogenic land use as the outcome variable produced a significant interaction. The CFI, TLI, SPMR, RMSEA and scaling correction factor indices indicate that the structural equation model is an excellent fit to the data (see Fig. 5 for index explanations) Discussion We created the first comprehensive database for koala status and origin across all Australian islands with a known record of occurrence. The spatial trends and magnitude of threats to islands with extant koala populations were characterised and investigated, and the key drivers of koala persistence on islands were also investigated. With koala populations persisting on some islands and becoming locally extinct on others (Fig. 1 ; Table 2 ), islands have functioned as both refuges and ecological traps for the species. Our threat analysis identified eight islands with relatively low anthropogenic land use, fire intensity, and human populations, indicating that they have served—or have the potential to serve—as refuges. Among these, Rotamah, Rabbit, Newry, and Clairview have unknown chlamydial status and no recorded incidence of overbrowsing. If these islands are Chlamydia -free, they may be invaluable for conserving and supporting the broader koala species amid ongoing mainland threats. In contrast some islands with extant koala populations face ongoing challenges that may lead to ecological entrapment where sustaining a wild viable koala population will be challenging. For example, Phillip Island has exceptionally high anthropogenic land use and human population size, even relative to the upper range of other islands and the remnant wild koala population is reportedly fewer than 20 individuals (Hunt 2011 ). Addressing the risk of ecological entrapment is becoming increasingly urgent as human activity and environmental pressures continue to accelerate on island environments (Braje et al. 2017 ; Mologni and Burns 2023 ). Implications of koalas for other island species The broad latitudinal range of historical koala occupancy on islands, spanning from Central Queensland to the Bass Strait, reflects a combination of natural dispersal and human-mediated introductions (Table 2 ; Fig. 1 ). On some islands, introduced koalas have led to significant degradation of ecosystems (Whisson and Ashman 2020 ). Islands, which harbor 37% of all critically endangered species while occupying only 5.3% of the land area globally (Tershy et al. 2015 ), are particularly vulnerable to the impacts of introduced species (Bellard et al. 2017 ; Spatz et al. 2017 ). Islands with introduced koala populations should be closely monitored to mitigate potential impacts on endemic and threatened island biodiversity. However, it is also important to consider that, as a flagship and umbrella species, conservation efforts focused on koalas may provide broader benefits for other ecologically significant and endemic island species. Natural koala populations only persist on Rabbit, Newry, and Rotamah Islands. It is crucial to prevent ecological entrapment on these islands or to investigate their populations further, as they may harbor unique genetic diversity. The designated origin for some island koala populations contradicts other literature. The defunct population on Quoin Island (Queensland) was thought to be of an introduced origin (Danaher et al. 2023 ; Jackson 2007 ; Lee et al. 2013 ). This assumption arose from the interest of a former island owner, Mr. Lewis Allen, in receiving koalas from Mr. Claude Reid at the Lone Pine Koala Sanctuary in Brisbane for his tourism ventures (Koala Colony Near Gladstone 1953 ). However, Lew Allen’s own accounts detail how he first encountered koalas on the island following a cyclone that defoliated many eucalypt trees in 1945 (Allen n.d.). This was corroborated by Max Allen, Lew Allen’s son, who confirmed that the koalas they had in captivity were native to the island (M. Allen personal communication 2024). The koala population on North Minjerribah is widely accepted to be naturally occurring (Abbott and Burbidge 1995 ; Danaher et al. 2023 ; Durbidge and Covacevich 1981 ; Jackson 2007 ). However, conflicting evidence exists, and the origin of koalas on this island was classified as "unknown" in this study. For instance, a Mr. Meston published the following statement in the Queenslander newspaper on October 9, 1920 (Meston 1920 ): “ A. H. Chisholm. The Ornithological society secretary writes to the courier expressing his enthusiasm over the reservation of Stradbroke as a sanctuary. A. H Chisholm informs the Queenslander that ‘possums, bears, ducks, pigeons and quails will be protected. The weak spot here lies in the fact that there are no bears or possums on any part of Stradbroke and never have been, at least not for the last hundred years.’ As there are no dingoes on the island, it forms an ideal spot as a sanctuary on which to place cinus, opossums, bears and various other interesting fauna ." Genetic evidence regarding the origin of the koala population on North Stradbroke Island (Minjerribah) is also contested, with some sources suggesting a native origin and others indicating an introduced origin (Lee et al. 2008; Cristescu et al. 2011; Danaher et al. 2023 ). Despite this controversy, North Minjerribah was still included in the statistical analysis and was attributed zero known translocations, which is appropriate given the lack of explicit evidence detailing any koala translocations to the island. Islands where the full history of koala occurrences remains unknown—particularly whether populations are native or introduced, such as North Stradbroke Island (Minjerribah)—require further investigation Managing threats to extant island koala populations As islands of lower latitudes exhibit a higher anthropogenic land use, Victoria’s authorities should prioritize habitat restoration and the conservation of remaining natural areas. In contrast, fire intensity and human population size show no clear spatial trends, suggesting that these threats are highly variable across latitudes. This variability suggests that mitigation efforts may be best approached on a case-by-case basis, tailored to the specific threat levels on each island. Alternatively, a broader-scale strategy could involve mitigating each threat across the koala’s entire latitudinal range. For instance, setting targets to expand protected areas on koala-inhabited islands could provide consistent management of land use. If mitigating threats across multiple islands is logistically or economically unfeasible, efforts may be more effectively directed toward safeguarding the eight islands previously highlighted as ideal refuge candidates. Overbrowsing has been documented exclusively on islands in Victoria and South Australia, despite the routine implementation of population regulation strategies, such as translocation. This persistent issue suggests that these islands may be unsuitable as long-term koala refuges (Gray 2010 ; Menkhorst 2008 ). The impact of koalas on other endemic fauna remains poorly understood but warrants investigation, as their presence may pose a significant ecological threat. Characterizing these interactions is essential for future research, as preserving koalas at the expense of other endemic island species could be counterproductive. Given these challenges, management resources may be more effectively allocated toward the complete removal of koalas from Victorian islands, rather than sustaining populations that are ultimately unviable. Persistence of island koala populations Translocation effort emerged as a key factor influencing koala persistence on islands as the only direct significant interaction in the path analysis. This reflects the ability of translocations to increase population size and genetic diversity and aligns with previous successes in using translocations as a conservation tool for koalas (Melzer et al. 2000 ; Menkhorst 2008 ; Parker 2008 ; Weeks et al. 2011 ). This also suggests there may be a need for ongoing intervention to sustain some populations, and in particular designated refuges. Surprisingly, island area did not significantly affect koala persistence, despite the environmental constraints of smaller islands, such as limited resources, lower carrying capacity, and reduced genetic diversity (Furlan et al. 2012 ). This suggests that koalas are resilient across a range of island sizes, potentially due to their flexible home range size (Davies et al. 2013 ; Ellis et al. 2002 ; Tucker 2008 ), inbreeding avoidance mechanisms like sex-biased dispersal (Schultz et al. 2020 ), and predisposition to outbreeding (Ellis et al. 2002 ; Ellis et al. 2015 ). However, as smaller islands generally support fewer individuals (White and Searle 2007 ), their long-term value as koala refuges warrants careful evaluation. Similarly, fire intensity showed no significant effect on koala persistence, possibly due to the presence of unburnt refuges that allow populations to recover. Available fire intensity data only spans from 2008, which restricts its utility for explaining earlier koala declines (Commonwealth of Australia (Geoscience Australia) 2024 ). More static measures, such as fire regimes, could provide a clearer understanding of long-term fire patterns, but these remain largely unavailable for most islands due to insufficient vegetation data. The non-significant effect of anthropogenic land use on persistence was unexpected, as it challenges the widely accepted understanding that habitat loss is a primary driver of koala declines (Melzer et al. 2000 ). While habitat loss has been implicated in past island extinctions (Green 2016 ; Jackson 2007 ), the absence of a clear relationship in this study may reflect incomplete historical records or the variability in land use intensity across islands. Distance to the mainland was hypothesized to influence koala persistence by facilitating immigration and gene flow, given that koalas are capable of swimming between islands (The beauty of Newry Island 1947 ; Platt 2017 ) yet no significant effect was detected. This suggests that dispersal events are either too rare or insufficient to meaningfully shape population dynamics. Alternatively, the potential risks of proximity, such as increased exposure to mainland threats (Pretto et al. 2012 ), may offset any benefits of connectivity. While latitude did not directly influence persistence, its marginally significant effect on translocation effort aligns with the higher frequency of translocations in Victoria compared to Queensland, driven by historical management strategies (Hrdina and Gordon 2004 ; Menkhorst 2008 ). The absence of a direct latitudinal effect on persistence suggests that koalas are adaptable to a range of climatic conditions, despite recent evidence of distribution shifts driven by climate change (Shabani et al. 2019 ). While this study examined the factors influencing koala persistence on islands, the drivers of koala population trends on islands, such as declines or increases, remain unknown. To better understand these dynamics, islands should be surveyed to characterize relevant metrics, such as species abundance. This approach provides greater insight than a binary presence-absence indicator, as it can better reflect the condition and viability of island populations. The islands with unknown koala occupancy status should be investigated urgently to determine whether they offer conservation benefits or require management intervention. Expanding knowledge of these islands will also increase sample size for future analyses. Confirming koala presence is particularly important for islands that historically supported native populations, as this information will help guide conservation decisions within the species’ natural range. Our database and analyses address critical knowledge gaps regarding island koala populations and establish a baseline for future conservation efforts. This provides a valuable tool for spatially prioritising islands based on their conservation value and exposure to threats. This framework can help identify islands capable of supporting resilient koala populations as refuges, as well as those facing severe threats and trending toward ecological entrapment. Declarations Acknowledgements We thank Noam Levin for access to data and guidance, Simon Blomberg for statistical advice Peter Menkhorst for assisting with accessing koala records, and the many people who provided personal accounts, mainly Stephen Jackson, Emma Hickingbotham, Alex Stroud, Mary, Brent Smith, Max Allen, Barry Howlett, Parks Victoria, Queensland Parks and Wildlife and the Kangaroo Island Landscape Board, The Biodiversity Research Group for their feedback and support and Craig Eddie and Alex Stroud for support in undertaking field surveys. Author contributions Mitchell Eddie: Writing - original draft, writing - review and editing, methodology, data curation, formal analysis, investigation, conceptualization, visualization, project administration, resources, validation, software. William Ellis: Supervision, funding acquisition, writing - review and editing, project administration, validation. Salit Kark: Supervision, conceptualization, planning, data, writing - review and editing, validation. Funding statement and competing interests This project received travel support from The San Diego Zoo Wildlife Alliance. The authors have no relevant financial or non-financial interests to disclose. Data statement Our research data is presented in Table 2 and is accompanied by the sources in Table A.1. The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request. References Abbott I, Burbidge A (1995) The occurrence of mammal species on the islands of Australia: A summary of existing knowledge. CALMScience 1:259–324 Allen L (n.d.) Birth of a Hermit. Giria Allen Armenteras D, González TM, Retana J (2013) Forest fragmentation and edge influence on fire occurrence and intensity under different management types in Amazon forests. 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Supplementary Files Appendices.docx Cite Share Download PDF Status: Published Journal Publication published 01 Sep, 2025 Read the published version in Biodiversity and Conservation → Version 1 posted Editorial decision: Revision requested 19 May, 2025 Reviews received at journal 19 May, 2025 Reviewers agreed at journal 14 May, 2025 Reviewers agreed at journal 14 May, 2025 Reviews received at journal 12 May, 2025 Reviewers agreed at journal 12 May, 2025 Reviewers invited by journal 12 May, 2025 Editor assigned by journal 05 Apr, 2025 Submission checks completed at journal 26 Mar, 2025 First submitted to journal 25 Mar, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6300594","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":455273156,"identity":"24421083-1960-4edf-b1d4-69ad1fddc79e","order_by":0,"name":"Mitchell Jacob Eddie","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA/klEQVRIiWNgGAWjYJACCR4DBjkwAy7EQ4QWYwY2sBYDYrUwMCQ2EK1Ft4H54I03BTbp8+f3GN74uOMPg8HxBMYHb9sY5A0OYNdidoAt2XKOQVruhmM8xpYzzxgwGJx5wGw4t43BcANOLTxm0jwGh3M3sAEZvG1ALTcS2IAMBkbcWvi/AbX8T5dvA2r5C9HC/huoxR6PLWxALQcSGI4BtTBCbWEGaknEqeUwmzHQL8mGG46lFVv2thnzSJ552Cw555xE8kxcWo43P7zx5o+dvHzz4Y03frbJyfEdTz744U2ZjW0fDi0MzGh8cBwxIKcEYkACSapHwSgYBaNg+AMABBhWLsXDtQAAAAAASUVORK5CYII=","orcid":"","institution":"The University of Queensland","correspondingAuthor":true,"prefix":"","firstName":"Mitchell","middleName":"Jacob","lastName":"Eddie","suffix":""},{"id":455273157,"identity":"801a28f7-c172-4882-9775-d0a7092f74b6","order_by":1,"name":"William Anthony Ellis","email":"","orcid":"","institution":"The University of Queensland","correspondingAuthor":false,"prefix":"","firstName":"William","middleName":"Anthony","lastName":"Ellis","suffix":""},{"id":455273158,"identity":"7c66f75f-cf17-4b1f-926f-7cd9b68ffdf4","order_by":2,"name":"Salit Kark","email":"","orcid":"","institution":"The University of Queensland","correspondingAuthor":false,"prefix":"","firstName":"Salit","middleName":"","lastName":"Kark","suffix":""}],"badges":[],"createdAt":"2025-03-25 06:23:07","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6300594/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6300594/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s10531-025-03115-9","type":"published","date":"2025-09-01T15:57:14+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":82798689,"identity":"22bb3606-2436-4c98-8cf9-3d3d58f77d13","added_by":"auto","created_at":"2025-05-15 10:52:16","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1318241,"visible":true,"origin":"","legend":"\u003cp\u003eThe distribution of Australian islands with recorded koala occurrences. Squares, circles, and triangles indicate the origin of koalas on each island: introduced, natural, or unknown, respectively. The colour coding reflects the current koala status: green for present, white for unknown, and red for absent. The known range of koalas is also shown by dots.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6300594/v1/0b8c20705d1bb9c5606429c2.png"},{"id":82799618,"identity":"bfcb2874-d7b9-4737-939a-6ec63897d4ab","added_by":"auto","created_at":"2025-05-15 11:00:15","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":82441,"visible":true,"origin":"","legend":"\u003cp\u003eDot and whisker plot depicting the mean ± standard error of three key threats to koala populations, across the 15 islands with extant koala populations. The threats shown are the mean human population size, the mean fire intensity (MW) and mean percentage of island area under anthropogenic land use. Plots are shown for all persisting island populations (gold) and persisting island populations in Queensland (maroon) and Victoria (blue) individually.\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6300594/v1/31840923bf0fc5f7d858c8ac.png"},{"id":82797448,"identity":"deaa32cb-aece-4851-9797-008cc75848f3","added_by":"auto","created_at":"2025-05-15 10:44:15","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":516775,"visible":true,"origin":"","legend":"\u003cp\u003eSeverity of three prominent threats to koala populations on Australian islands with extant koalas. Point symbols’ size is proportional to the quantity of the threat value for the island that they represent. Three threats are shown, mean fire intensity (green points – measured as fire radiative power in megawatts), human population size (blue points – measured as number of people) and percentage of anthropogenic landuse (purple – measured as the percentage of an islands area under anthropogenic landuse). The larger the symbol, the higher the associated threat value.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6300594/v1/53278324798b7bac94dcc57a.png"},{"id":82797444,"identity":"e9d8597c-acf4-4bdf-9e3a-bf37d2ba821c","added_by":"auto","created_at":"2025-05-15 10:44:15","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":198502,"visible":true,"origin":"","legend":"\u003cp\u003eHypothesised pathway diagram for causal interactions between geographic (blue) biotic (green) and human related (grey) factors on koala persistence. Anthropogenic land use represents a combination of a human impact and biotic factor (yellow)\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"floatimage6.png","url":"https://assets-eu.researchsquare.com/files/rs-6300594/v1/ac8efc83652efaacdf473204.png"},{"id":82797455,"identity":"f5be86ff-09e6-406e-b28c-5cb5caef2184","added_by":"auto","created_at":"2025-05-15 10:44:16","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":330548,"visible":true,"origin":"","legend":"\u003cp\u003ePathway diagram of regression between geographic (blue) biotic (green) and human related (grey) factors on koala persistence (n=26 islands). Anthropogenic land use represents both a human impact and biotic factor (yellow)\u003cstrong\u003e. \u003c/strong\u003eSignificant interactions are shown with red arrows. Labels display path coefficients representing the relative effect size of a predictor variable on a response variable and its associated P - value in brackets. The fit indices of the model are bolded in the bottom right corner. Six fit indices were produced to assess model fit and quality. The Comparative Fit Index (CFI): Compares the tested model to a baseline model, with values ≥ 0.95 indicating good fit. The Tucker-Lewis Index (TLI): Like CFI, penalizes model complexity, with values ≥ 0.95 considered good. The Root Mean Square Error of Approximation (RMSEA): Assesses how well the model fits per degree of freedom, with values ≤ 0.06 indicating close fit. The Standardized Root Mean Square Residual (SRMR): Measures the average difference between observed and predicted correlations, with values ≤ 0.08 considered acceptable. The Model baseline chi-square p-value: Tests overall model fit; p \u0026gt; 0.05 suggests the model fits well. The Scaling correction factor: Adjusts chi-square statistics for non-normality; values closer to 1 indicate minimal correction needed.\u003c/p\u003e","description":"","filename":"floatimage7.png","url":"https://assets-eu.researchsquare.com/files/rs-6300594/v1/483debf5b14ed40a279e405c.png"},{"id":90827986,"identity":"86058fd6-bcc8-48f1-a097-a942c0d15234","added_by":"auto","created_at":"2025-09-08 16:04:42","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":3345199,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6300594/v1/2b4646bf-9d1b-4207-a236-cf7367e7f555.pdf"},{"id":82797442,"identity":"16510a0e-6398-492a-98a5-58bee60fc99b","added_by":"auto","created_at":"2025-05-15 10:44:15","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":29278,"visible":true,"origin":"","legend":"","description":"","filename":"Appendices.docx","url":"https://assets-eu.researchsquare.com/files/rs-6300594/v1/12940cab73ed534c948387a2.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Koalas on Australian Islands","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThe koala \u003cem\u003e(Phascolarctos cinereus)\u003c/em\u003e is an endemic iconic marsupial restricted to the eucalypt forest and woodland communities of southern, eastern and south-eastern Australia (Melzer et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Owing to their endearing appearance and unique natural history, koalas hold significant ecological and cultural importance in Australia and attract international attention.\u003c/p\u003e \u003cp\u003eWhile substantial research and management efforts have focused on koalas on the Australian mainland, systematic documentation of koala occurrences on islands is lacking, leaving the status, origin and long-term trajectories of these populations largely unstudied. A few well-known islands, such as Kangaroo Island and North Stradbroke Island (Minjerribah), have been relatively well-documented, but they represent only a fraction of the species’ broader island distribution.\u003c/p\u003e \u003cp\u003eAustralia has over 9,200 islands spanning tropical to subantarctic climates, some of which support koalas as part of their native range. Other islands host introduced koala populations, that were marooned for various purposes, including to serve as reservoirs for restocking depleted mainland populations (Danaher et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Menkhorst \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Lewis \u003cspan citationid=\"CR39\" class=\"CitationRef\"\u003e1934\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eCompared to mainland environments, islands are often isolated from anthropogenic threats and disease, making them ideal refuges in some cases (Cristescu et al. \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2012\u003c/span\u003e; Whittaker and Fernández-Palacios \u003cspan citationid=\"CR66\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). This is particularly relevant in Australia, where human population density is concentrated on the mainland (Australian Bureau of Statistics \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e2024b\u003c/span\u003e). Islands also offer enclosed areas where exotic species and disease can be eliminated (Moro et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Island refuges have been successfully used in modern conservation efforts, such as on Maria Island off the coast of Tasmania, which supported Tasmanian devil reproduction, due to its isolation from disease that devastated mainland populations (Hogg and Wise \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2022\u003c/span\u003e) .\u003c/p\u003e \u003cp\u003eIslands can also become ecological traps. Their isolation and relatively small area compared to the mainland can hinder species dispersal in response to environmental or anthropogenic pressures. Additionally, small population sizes and low genetic diversity increase susceptibility to such pressures, increasing the risk of local extinction (Moro et al. \u003cspan citationid=\"CR47\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). The disappearance of koala populations from some islands has been attributed to ecological entrapment through land clearing, hunting, and human interference (Green \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Jackson \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Allen n.d.). Some of these island populations, such as on Quoin and Coochiemudlo, are believed to have been of natural origin and may have harboured unique genetic diversity now lost.\u003c/p\u003e \u003cp\u003eDespite significant investments in koala conservation, including a recent 50\u0026nbsp;million AUD federal funding allocation over four years (WWF 2022), koalas are listed as endangered under the Australian Commonwealth Environment Protection and Biodiversity Conservation (EPBC) 1999 for populations in the Australian states of New South Wales, Queensland, and the Australian Capital Territory (Department of Climate Change, Energy, the Environment and Water \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). In contrast, South Australian and Victorian populations are not EPBC-listed and are managed for overabundance through contraception and translocation (Menkhorst \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). However, all koala populations remain classified as vulnerable on the International Union for Conservation of Nature’s (IUCN) Red List (Burbidge and Woinarski \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e2020\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eThe conservation listings reflect persistent threats to mainland populations, such as anthropogenic land use, human population density, fire, disease and over browsing. Anthropogenic land uses tend to occur on high quality koala habitat. The associated habitat loss displaces koalas to peri-urban or degraded habitats where they are exposed to threats from the human population (Department of Environmental Science \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Januchowski et al. \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Lesslie and Mewett, \u003cspan citationid=\"CR38\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Crowther \u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e2009\u003c/span\u003e). Wildfires impact koala survival directly through burns and indirectly through tree mortality (Armenteras et al. \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Phillips et al. \u003cspan citationid=\"CR50\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; National Parks and Wildlife Service South Australia \u003cspan citationid=\"CR48\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Overabundant koala populations have been found to over-browse, destroying habitats, depleting resources and leading to koala starvation (Jackson \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Whisson and Shimmin \u003cspan citationid=\"CR64\" class=\"CitationRef\"\u003e2006\u003c/span\u003e). Diseases, largely manifestations of chlamydial infections, are the largest contributor to mortality and are responsible for up to 57% of female infertility in some koala populations (Hanger et al. \u003cspan citationid=\"CR29\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Rhodes et al. \u003cspan citationid=\"CR53\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). The spatial patterns and severity of these threats has not been described across islands with extant koala populations.\u003c/p\u003e \u003cp\u003eThere is also a paucity of research on the drivers influencing koala persistence on islands. We hypothesize that geographic, biotic, and human-mediated factors influencing island koala persistence include anthropogenic land use, fire, translocation effort, island area, climate, and isolation (distance to the mainland).\u003c/p\u003e \u003cp\u003eLand use and fire were identified as factors that can contribute to koala population declines (and thus persistence) (Lunney et al. \u003cspan citationid=\"CR41\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; McAlpine et al. \u003cspan citationid=\"CR42\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Melzer et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). Native and introduced island koala populations have both received varying degrees of translocation effort. Notably, translocation effort has a positive correlation with persistence and introduction success of other species (Hossack et al. \u003cspan citationid=\"CR31\" class=\"CitationRef\"\u003e2022\u003c/span\u003e). The island biogeography theory attempts to explain how organisms are distributed amongst islands, and suggests that the strongest correlates are island area and island isolation (Guo \u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Mologni and Burns \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003eb). Climate, which is strongly related with latitude, is a known determinant of species distribution, and despite having a geographic range spanning various latitudes, koala distributions can still be influenced by climate factors (Shabani et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eTo address current knowledge gaps, we collated a novel database which we named ‘\u003cem\u003eKoalas on Australian Islands\u003c/em\u003e’. This is the first database of its kind for koalas in Australia. We aimed to identify koala status and origin across all islands with recorded occurrences, explore the distribution and extent of environmental and anthropogenic threats to extant island koala populations, and investigate key factors shaping koala persistence on islands. This may help to mitigate threats and clarify the role of islands with koala occurrences as refuges or ecological traps, contributing to koala conservation.\u003c/p\u003e \u003c/div\u003e"},{"header":"Methods","content":"\u003cp\u003eForming the ‘\u003cem\u003eKoalas on Australian Islands\u003c/em\u003e’ database\u003c/p\u003e\n\u003cp\u003eWe collated data on koala status, origin, translocation history, fire intensity, land use, overbrowsing history, chlamydial prevalence, island latitude, island area and distance to mainland for all islands where there was historically documented koala occupancy, forming the ‘\u003cem\u003eKoalas on Australian Islands\u003c/em\u003e’ database.\u003c/p\u003e\n\u003cp\u003eKoala status for each island was designated as “present”, “absent”, or “unknown” and origin was designated as “natural”, “introduced” or “unknown”. For islands that were found to have extant populations, chlamydial infection status was recorded as “positive”, “negative”, or “unknown”. Additionally, islands were classified as either historically overbrowsed or not. Data for these variables were sourced from the Island Occurrences of Threatened Australian Species (IOTAS) database (Baxter et al. 2021), published and unpublished research, literature and reports, newspapers and journals, open-access databases, expert correspondence, departmental archives, anecdotal accounts, local knowledge, and books related to the islands of interest. To maximize resource retrieval, search terms included historical synonyms for koalas, such as “native monkey”, “monkey bear”, “bear” and “kul-la”.\u003c/p\u003e\n\u003cp\u003eIslands with conflicting evidence regarding koala status or origin were classified as unknowns. Islands lacking reported sightings within the species' maximum lifespan (beyond 18 years) were also categorized as unknown (Gordon 1991). Koala status was classified as “absent” only if the following criteria were met; 1) no evidence of koala presence in over 50 years, 2) a significant human footprint (such as frequent tourism or greater than 100 permanent residents) and 3) no environmental surveys (such as fauna surveys on other species or habitat assessments). All islands with designated “absent” koala populations were corroborated by peer reviewed literature, though absence was often inferred in these accounts.\u003c/p\u003e\n\u003cp\u003eThe quality of koala occurrence data for each island was assessed on a scale from 0 to 4, with 0 being the lowest and 4 the highest (definitions provided in Table 1). Sources scoring 0 were excluded from analysis. Islands where koala persistence is widely acknowledged received a credibility score of 4 and were assigned a last record date of 2024. A full list of sources is provided in Table 2 and Table A.1.\u003c/p\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 1\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eDefinitions and examples of the criteria for the four source credibility ratings.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCredibility Score\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDefinition\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eInferred – Inferences drawn from personal communications but never explicitly stated, or the nature of the record is undefined (i.e., unknown if the recorder inferred presence or witnessed live specimens).\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAnecdotal – Verbal accounts and second-hand information explicitly reporting koala occurrences.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWritten information – firsthand record in popular press, book or website.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTechnical reports – environmental impact statements, government or in house reports, unpublished data.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePeer reviewed documents and material – skulls, artifacts, scats, peer reviewed journals.\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cdiv\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 2\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eThe \u003cem\u003e‘Koalas on Australian Islands database’\u003c/em\u003e. This database shows the status (present or absent) and origin (introduced or natural) of koalas across all coastal and inland Australian Islands with a recorded koala occurrence. The sources of information this data was drawn from, and the combined credibility of these sources are also shown. References corresponding to source numbers are shown in Table A.1.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eIsland Name\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eState\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eOrigin\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eStatus\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eLast Record\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eCredibility\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSource\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBrampton Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2017\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1–6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBribie Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1965\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,4,6–9\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eChinaman Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1964 (2024?)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10–18\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eChurchill Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1980\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eClairview Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2022\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,19\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCoochiemudlo Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e“Several decades ago”\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,4,6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eCurtis Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1934\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,5,20\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFraser Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1913–1922\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,21–23\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFrench Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,8,10–13,24–29\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGreat Keppel Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1960\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,5,30–32\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eHallstrom Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNew South Whales\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1962\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,11,12\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eKangaroo Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSouth Australia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11,12,33\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eKeswick Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e?\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eKing Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTasmania\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt; 1968\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e34\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eLittle Snake Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1967\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8,10,26\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMagnetic Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,5,35\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eGoat Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSouth Australia\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1976\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,10,12,36\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNewry Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2009\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,2,4,6,37,38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNorth Minjerribah\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2,6,39–42\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eOuter Newry Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1947\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,43\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePental Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1990\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,11,44\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePhillip Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,6,24,26,28,45,46\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQuail Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11,13–15,18,24,47\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQuoin Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1965\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e48–51\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRabbit Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2008\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2,4,6,37,38\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRaymond Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6,52,53\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRita Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1931\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,54–56\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRotamah Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e“Last 12 months”\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,57–59\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSnake Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2024\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11,12,26,60,61\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSouth Minjerribah\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e?\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e39,41,62\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSt Bees Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2022\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2,3,5,63,64\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSt Margaret Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1977\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,6,65–67\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSunday Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1977–1978\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e65,67,68\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eThree Hummock Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eTasmania\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u0026lt; 1947\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,8,10,69,70\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUlupna Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePresent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2021\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,6,71\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWartook Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eIntroduced\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1965\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4,12,72\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eWhitsunday Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNatural\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eAbsent\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e?\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e1,73\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eFor all islands with recorded koala occurrence, we obtained data for island area, distance to the mainland, and island latitude using the ‘Islands of Australia’ shapefile and ‘Australian mainland’ shapefile, as well as the ‘Calculate Field’ and ‘Near’ tools in ArcGIS Pro (Commonwealth of Australia 2015; Australian Bureau of Statistics 2024a; Esri 2023). Latitudes were extracted from island polygon centroids.\u003c/p\u003e\n\u003cp\u003eWe obtained land use data from the ‘Catchment scale land use of Australia and commodities – Update December 2023’(Australian Bureau of Agricultural Resource Economics and Sciences (ABARES) 2023). This dataset classifies an areas primary land use. Land use classified as ‘production from dryland agriculture and plantation,’ ‘production from irrigated agriculture and plantations,’ and ‘intensive use’ involve large scale clearing of native vegetation or replacement with introduced species and will be collectively termed ‘anthropogenic land use’ throughout the remainder of this report. Both the percentage and proportion of island area allocated to anthropogenic land use was measured on each island with historical koala occupancy for the subsequent threat and path analysis respectively.\u003c/p\u003e\n\u003cp\u003eWe obtained fire data from Digital Earth Australia’s ‘Historic Hotspots’ dataset (Commonwealth of Australia Geoscience Australia 2024). This dataset was chosen to quantify the mean fire intensity, measured as Fire Radiative Power in Megawatts (MW), of all islands with recorded koala occurrences. The mean fire intensity experienced by each island was calculated by spatially joining each hot spot to the island they intersected and then using the summary statistics by group tool in ArcGIS Pro.\u003c/p\u003e\n\u003cp\u003eData on the human population of each island with extant koala populations was obtained from the Australian population grid 2023 in ESRI Grid format (Australian Bureau of Statistics 2023b). The zonal statistics as table tool on ArcGIS Pro was used to estimate the total population for each island.\u003c/p\u003e\n\u003cp\u003eWe used the collated data for the status and origin of island koala populations to produce Table 2. Additionally, we used ArcGIS Pro software and the ‘Islands of Australia’ and ‘Australian mainland’ data to visualise the spatial distribution of the status and origin of island koala populations to produce Fig. 1. The data for fire intensity, \u003cem\u003eChlamydia\u003c/em\u003e status, overbrowsing history, land use and human population were used to estimate the magnitude and presence of threats on islands with extant koala populations in Table 3. The summary statistics of these variables by Australian State are presented in Fig. 2 and compared to examine spatial trends (note that South Australia is not included as summary statistics cannot be calculated from a single value). Fire intensity, human population size and land use are also visually represented and spatially mapped for each island with extant koala populations using ArcGIS Pro software in Fig. 3.\u003c/p\u003e\n\u003ctable id=\"Tab5\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv\u003eTable 3\u003c/div\u003e\n \u003cdiv\u003e\n \u003cp\u003eThreats present on coastal and inland islands that are thought to currently support koala populations. Quantitative magnitudes have been rounded to two decimal places.\u003c/p\u003e\n \u003cdiv\u003e\n \u003cp\u003eSources for data on disease and over browsing include; (Jackson, 2007; Lee et al., 2013; Menkhorst, 2008; Whisson \u0026amp; Ashman, 2020).\u003c/p\u003e\n \u003c/div\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eIsland Name\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eHistorically over browsed\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eDisease-\u003cem\u003eChlamydia pecorum\u003c/em\u003e\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eArea Under Anthropogenic land use (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eApproximate Human Population\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean Fire Intesnity (MW)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eAustralian State\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eBrampton Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePositive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.26%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eClairview Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.64%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFrench Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNegative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32.96%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e130\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eKangaroo Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNegative\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e49.28%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4481\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e60.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSouth Australia\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMagnetic Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePositive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.20%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2144\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNewry Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNorth Minjerribah\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePositive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e6.10%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e1953\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e26.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePhillip Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePositive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e82.59%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e13270\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.92\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQuail Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePositive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRabbit Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRaymond Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePositive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e52.05%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e460\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eRotamah Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSnake Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eYes\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePositive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e2.47%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e13.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eSt Bees Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePositive\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eQueensland\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUlupna Island\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eNo\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eUnknown\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e49.44%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e17.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eVictoria\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cdiv\u003e\n\u003c/div\u003e\n\u003cdiv\u003e\n\u003c/div\u003e\n\u003ch2\u003eData Analysis\u003c/h2\u003e\n\u003cp\u003eWe used path analysis to examine the effect size and significance of a) fire intensity, b) proportion of island area under anthropogenic land use, c) latitude, d) translocation effort, e) island area and f) isolation (distance to mainland) on koala persistence on islands. This approach tests multiple direct and indirect relationships between variables within a system of causal regression pathways. Unlike standard regression, path analysis enables inclusion of multiple dependent variables and accounts for the possibility that a variable can act as both a predictor and an outcome. Path analysis is ideal for studying ecological systems where variables influence each other directly but also through mediating variables. A pathway diagram was produced to show the hypothesised direct and indirect relationships between variables (Fig. 4; Table A.2).\u003c/p\u003e\n\u003cp\u003eEach island was assigned a value for koala persistence and a value for each variable hypothesised to influence koala persistence from the data sources above. The path analysis was conducted by fitting a structural equation model using the ‘lavaan’ package in RStudio. The model was adjusted until fit indices were satisfactory. In the final path model, all variables were scaled using the “scale” function in R to reduce issues with skewed distributions and variance when running the model. Distance to mainland was log transformed to address linearity issues, which were checked using the “DHARMa” package. Translocation effort was treated as an ordered categorical variable, as count data are not supported by the lavaan package. Translocation effort was therefore grouped into three categories “no effort”, “low effort” and “high effort” consisting of zero, one to two and three or more translocations each. Assumptions for the ordered logistic regression of this pathway were checked using the “brant” package and cumulative log odds plots in RStudio. The output of the path analysis is shown in Fig. 5.\u003c/p\u003e\n\u003cp\u003eWe excluded some islands with recorded koala occurrences from the path analysis (Table A.3). Islands where koalas were intentionally removed or introduced with only females (e.g., Churchill Island) were excluded from the analysis, as the reasons for the absence of these populations are apparent and independent of environmental factors. Islands assigned a credibility rating of 0 were also excluded, as these records were considered unreliable. Finally, islands with unknown koala population status were excluded, leaving a total sample size of 26 islands for analysis.\u003c/p\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eStatus and origin of koala populations on islands\u003c/h2\u003e \u003cp\u003eWe found records of koala occurrence on 37 islands across five Australian states. These included 18 islands in Queensland, one in New South Wales, 14 in Victoria, two in South Australia, and two in Tasmania (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). As of 2024 Koalas currently persist on 15 of these islands across a range of latitudes, including seven in Queensland, seven in Victoria and one in South Australia. The status of documented koala populations on 7 islands has been designated as unknown and koalas have disappeared from 15 islands they once occupied (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e)\u003c/p\u003e \u003cp\u003eNatural (rather than human introduced) koala populations persist on 4 out of 15 Islands. Three of these islands occur in Queensland, including Clairview, Rabbit and Newry Island (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The last koala records on Rabbit Island and Newry Island were 16 and 15 years ago, respectively, and therefore these islands narrowly meet the 18-year threshold set earlier in this report to still be considered present (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Rotamah Island is the only Victorian island with a natural population. It is believed to have been colonised naturally from nearby mainland translocations (Jackson \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). The status of the natural population on Queensland\u0026rsquo;s Outer Newry Island is unknown. Koalas are introduced to 21 out of the 37 islands that they have been recorded on, possibly more. Only three of these introductions occurred on Queensland islands. The origin of the koala populations on three islands remains unknown (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eSpatial patterns of threats to koalas on islands\u003c/h3\u003e\n\u003cp\u003eThe average human population size, fire intensity and percentage of island area under anthropogenic land use across all Australian islands with extant koala populations was 1497\u0026thinsp;\u0026plusmn;\u0026thinsp;903, 13.31 (MW)\u0026thinsp;\u0026plusmn;\u0026thinsp;3.98 (MW) and 19.73% \u0026plusmn; 6.85%, respectively (mean\u0026thinsp;\u0026plusmn;\u0026thinsp;standard error; Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The relatively high standard errors indicate substantial variability in threat severity across the islands.\u003c/p\u003e \u003cp\u003ePhillip Island has the largest human population (13,270 residents) and the greatest percentage of anthropogenic land use (82.59% of the island\u0026rsquo;s area) (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). All other islands have less than 53% of their area dedicated to anthropogenic land use and only three other islands\u0026mdash;North Stradbroke Island (Minjerribah), Kangaroo Island and Magnetic Island\u0026mdash;have relatively high human populations compared to the remaining 11 islands. Kangaroo Island has a high mean fire intensity (60.29 MW) relative to all other islands.\u003c/p\u003e \u003cp\u003eIn contrast, eight islands\u0026mdash;Brampton, Clairview, Newry, Quail, Rabbit, Rotamah, Snake, and St Bees\u0026mdash;have consistently low values for the analysed threats, with mean fire intensities below 15 MW, anthropogenic land usage under 10% of each island\u0026rsquo;s area, and human populations below 100 residents (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eThe islands with the highest percentages of land dedicated to anthropogenic use are concentrated at lower latitudes, particularly in Victoria and on Kangaroo Island, South Australia, rather than in Queensland (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). This pattern is reflected in the data presented in Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, where Queensland islands have an average of 3.89% \u0026plusmn; 1.60% of their area dedicated to anthropogenic land use, compared to Victorian islands, where the average is 31.36% \u0026plusmn; 12.13%. Aside from outliers\u0026mdash;Kangaroo Island in South Australia and Phillip Island in Victoria\u0026mdash;there are no notable differences in fire intensity or human population size between Victorian and Queensland islands (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). While there is a relatively large difference in the mean human population of Queensland and Victorian islands (585 and 1982 respectively), the substantial overlap in standard error (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) suggests that there is no significant spatial difference in the magnitude of these threats between Queensland and Victoria. The high average human population size of Victorian islands is largely driven by the disproportionately high population of Phillip Island, which also inflates the sample standard error.\u003c/p\u003e \u003cp\u003eEight islands had documented incidents of \u003cem\u003eChlamydia sp.\u003c/em\u003e in individuals of the population, four in Queensland and four in Victoria (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Only French and Kangaroo Islands have no documented incidence of \u003cem\u003eChlamydia\u003c/em\u003e. The disease status is unknown for five islands (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). Four of these (Rotamah, Clairview, Rabbit and Newry) were identified as having low values for fire intensity, percentage of anthropogenic landuse and human population. These four islands have also never had documented incidence of over browsing. Overbrowsing has never been documented on Queensland islands, and only two Victorian islands (Ulupna and Rotamah island) appear to have been free of over browsing (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n\u003ch3\u003eDrivers of koala persistence on islands\u003c/h3\u003e\n\u003cp\u003eThe path analysis revealed that translocation effort was the only direct interaction that significantly affected koala persistence (p\u0026thinsp;\u0026lt;\u0026thinsp;0.01) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). This suggests that for each unit increase in translocation effort, there is a 0.767 (\u0026plusmn;\u0026thinsp;0.202 SE) increase in the log-odds of koala persistence. That is, as translocation effort increases, so does koala persistence. Koala persistence did not have detected significant interactions with anthropogenic land use (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), mean fire power (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), island area (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05), isolation (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) or latitude (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). There was a marginally significant indirect interaction with latitude and island koala persistence through translocation effort as a mediating variable (p\u0026thinsp;=\u0026thinsp;0.053) (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The negative coefficient suggests that for every 1 standard deviation increase in latitude the log odds of an island having a higher category of translocation effort decreases by -0.943\u0026thinsp;\u0026plusmn;\u0026thinsp;0.487 (Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). There were no other significant indirect interactions through mediating variables. Neither of the pathways with mean fire intensity and proportion of anthropogenic land use as the outcome variable produced a significant interaction. The CFI, TLI, SPMR, RMSEA and scaling correction factor indices indicate that the structural equation model is an excellent fit to the data (see Fig.\u0026nbsp;\u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e for index explanations)\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eWe created the first comprehensive database for koala status and origin across all Australian islands with a known record of occurrence. The spatial trends and magnitude of threats to islands with extant koala populations were characterised and investigated, and the key drivers of koala persistence on islands were also investigated. With koala populations persisting on some islands and becoming locally extinct on others (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e; Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), islands have functioned as both refuges and ecological traps for the species.\u003c/p\u003e \u003cp\u003eOur threat analysis identified eight islands with relatively low anthropogenic land use, fire intensity, and human populations, indicating that they have served\u0026mdash;or have the potential to serve\u0026mdash;as refuges. Among these, Rotamah, Rabbit, Newry, and Clairview have unknown chlamydial status and no recorded incidence of overbrowsing. If these islands are \u003cem\u003eChlamydia\u003c/em\u003e-free, they may be invaluable for conserving and supporting the broader koala species amid ongoing mainland threats.\u003c/p\u003e \u003cp\u003eIn contrast some islands with extant koala populations face ongoing challenges that may lead to ecological entrapment where sustaining a wild viable koala population will be challenging. For example, Phillip Island has exceptionally high anthropogenic land use and human population size, even relative to the upper range of other islands and the remnant wild koala population is reportedly fewer than 20 individuals (Hunt \u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). Addressing the risk of ecological entrapment is becoming increasingly urgent as human activity and environmental pressures continue to accelerate on island environments (Braje et al. \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Mologni and Burns \u003cspan citationid=\"CR46\" class=\"CitationRef\"\u003e2023\u003c/span\u003e).\u003c/p\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eImplications of koalas for other island species\u003c/h2\u003e \u003cp\u003eThe broad latitudinal range of historical koala occupancy on islands, spanning from Central Queensland to the Bass Strait, reflects a combination of natural dispersal and human-mediated introductions (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e; Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). On some islands, introduced koalas have led to significant degradation of ecosystems (Whisson and Ashman \u003cspan citationid=\"CR63\" class=\"CitationRef\"\u003e2020\u003c/span\u003e). Islands, which harbor 37% of all critically endangered species while occupying only 5.3% of the land area globally (Tershy et al. \u003cspan citationid=\"CR58\" class=\"CitationRef\"\u003e2015\u003c/span\u003e), are particularly vulnerable to the impacts of introduced species (Bellard et al. \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; Spatz et al. \u003cspan citationid=\"CR56\" class=\"CitationRef\"\u003e2017\u003c/span\u003e). Islands with introduced koala populations should be closely monitored to mitigate potential impacts on endemic and threatened island biodiversity. However, it is also important to consider that, as a flagship and umbrella species, conservation efforts focused on koalas may provide broader benefits for other ecologically significant and endemic island species. Natural koala populations only persist on Rabbit, Newry, and Rotamah Islands. It is crucial to prevent ecological entrapment on these islands or to investigate their populations further, as they may harbor unique genetic diversity.\u003c/p\u003e \u003cp\u003eThe designated origin for some island koala populations contradicts other literature. The defunct population on Quoin Island (Queensland) was thought to be of an introduced origin (Danaher et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Jackson \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2007\u003c/span\u003e; Lee et al. \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2013\u003c/span\u003e). This assumption arose from the interest of a former island owner, Mr. Lewis Allen, in receiving koalas from Mr. Claude Reid at the Lone Pine Koala Sanctuary in Brisbane for his tourism ventures (Koala Colony Near Gladstone \u003cspan citationid=\"CR36\" class=\"CitationRef\"\u003e1953\u003c/span\u003e). However, Lew Allen\u0026rsquo;s own accounts detail how he first encountered koalas on the island following a cyclone that defoliated many eucalypt trees in 1945 (Allen n.d.). This was corroborated by Max Allen, Lew Allen\u0026rsquo;s son, who confirmed that the koalas they had in captivity were native to the island (M. Allen personal communication 2024).\u003c/p\u003e \u003cp\u003eThe koala population on North Minjerribah is widely accepted to be naturally occurring (Abbott and Burbidge \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1995\u003c/span\u003e; Danaher et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Durbidge and Covacevich \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e1981\u003c/span\u003e; Jackson \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2007\u003c/span\u003e). However, conflicting evidence exists, and the origin of koalas on this island was classified as \"unknown\" in this study. For instance, a Mr. Meston published the following statement in the Queenslander newspaper on October 9, 1920 (Meston \u003cspan citationid=\"CR45\" class=\"CitationRef\"\u003e1920\u003c/span\u003e):\u003c/p\u003e \u003cp\u003e\u0026ldquo;\u003cem\u003eA. H. Chisholm. The Ornithological society secretary writes to the courier expressing his enthusiasm over the reservation of Stradbroke as a sanctuary. A. H Chisholm informs the Queenslander that \u0026lsquo;possums, bears, ducks, pigeons and quails will be protected. The weak spot here lies in the fact that there are no bears or possums on any part of Stradbroke and never have been, at least not for the last hundred years.\u0026rsquo; As there are no dingoes on the island, it forms an ideal spot as a sanctuary on which to place cinus, opossums, bears and various other interesting fauna\u003c/em\u003e.\"\u003c/p\u003e \u003cp\u003eGenetic evidence regarding the origin of the koala population on North Stradbroke Island (Minjerribah) is also contested, with some sources suggesting a native origin and others indicating an introduced origin (Lee et al. 2008; Cristescu et al. 2011; Danaher et al. \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). Despite this controversy, North Minjerribah was still included in the statistical analysis and was attributed zero known translocations, which is appropriate given the lack of explicit evidence detailing any koala translocations to the island. Islands where the full history of koala occurrences remains unknown\u0026mdash;particularly whether populations are native or introduced, such as North Stradbroke Island (Minjerribah)\u0026mdash;require further investigation\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eManaging threats to extant island koala populations\u003c/h3\u003e\n\u003cp\u003eAs islands of lower latitudes exhibit a higher anthropogenic land use, Victoria\u0026rsquo;s authorities should prioritize habitat restoration and the conservation of remaining natural areas. In contrast, fire intensity and human population size show no clear spatial trends, suggesting that these threats are highly variable across latitudes. This variability suggests that mitigation efforts may be best approached on a case-by-case basis, tailored to the specific threat levels on each island. Alternatively, a broader-scale strategy could involve mitigating each threat across the koala\u0026rsquo;s entire latitudinal range. For instance, setting targets to expand protected areas on koala-inhabited islands could provide consistent management of land use. If mitigating threats across multiple islands is logistically or economically unfeasible, efforts may be more effectively directed toward safeguarding the eight islands previously highlighted as ideal refuge candidates.\u003c/p\u003e \u003cp\u003eOverbrowsing has been documented exclusively on islands in Victoria and South Australia, despite the routine implementation of population regulation strategies, such as translocation. This persistent issue suggests that these islands may be unsuitable as long-term koala refuges (Gray \u003cspan citationid=\"CR26\" class=\"CitationRef\"\u003e2010\u003c/span\u003e; Menkhorst \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). The impact of koalas on other endemic fauna remains poorly understood but warrants investigation, as their presence may pose a significant ecological threat. Characterizing these interactions is essential for future research, as preserving koalas at the expense of other endemic island species could be counterproductive. Given these challenges, management resources may be more effectively allocated toward the complete removal of koalas from Victorian islands, rather than sustaining populations that are ultimately unviable.\u003c/p\u003e\n\u003ch3\u003ePersistence of island koala populations\u003c/h3\u003e\n\u003cp\u003eTranslocation effort emerged as a key factor influencing koala persistence on islands as the only direct significant interaction in the path analysis. This reflects the ability of translocations to increase population size and genetic diversity and aligns with previous successes in using translocations as a conservation tool for koalas (Melzer et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2000\u003c/span\u003e; Menkhorst \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Parker \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2008\u003c/span\u003e; Weeks et al. \u003cspan citationid=\"CR62\" class=\"CitationRef\"\u003e2011\u003c/span\u003e). This also suggests there may be a need for ongoing intervention to sustain some populations, and in particular designated refuges.\u003c/p\u003e \u003cp\u003eSurprisingly, island area did not significantly affect koala persistence, despite the environmental constraints of smaller islands, such as limited resources, lower carrying capacity, and reduced genetic diversity (Furlan et al. \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e2012\u003c/span\u003e). This suggests that koalas are resilient across a range of island sizes, potentially due to their flexible home range size (Davies et al. \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Ellis et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Tucker \u003cspan citationid=\"CR60\" class=\"CitationRef\"\u003e2008\u003c/span\u003e), inbreeding avoidance mechanisms like sex-biased dispersal (Schultz et al. \u003cspan citationid=\"CR54\" class=\"CitationRef\"\u003e2020\u003c/span\u003e), and predisposition to outbreeding (Ellis et al. \u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2002\u003c/span\u003e; Ellis et al. \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e2015\u003c/span\u003e). However, as smaller islands generally support fewer individuals (White and Searle \u003cspan citationid=\"CR65\" class=\"CitationRef\"\u003e2007\u003c/span\u003e), their long-term value as koala refuges warrants careful evaluation.\u003c/p\u003e \u003cp\u003eSimilarly, fire intensity showed no significant effect on koala persistence, possibly due to the presence of unburnt refuges that allow populations to recover. Available fire intensity data only spans from 2008, which restricts its utility for explaining earlier koala declines (Commonwealth of Australia (Geoscience Australia) \u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e2024\u003c/span\u003e). More static measures, such as fire regimes, could provide a clearer understanding of long-term fire patterns, but these remain largely unavailable for most islands due to insufficient vegetation data.\u003c/p\u003e \u003cp\u003eThe non-significant effect of anthropogenic land use on persistence was unexpected, as it challenges the widely accepted understanding that habitat loss is a primary driver of koala declines (Melzer et al. \u003cspan citationid=\"CR43\" class=\"CitationRef\"\u003e2000\u003c/span\u003e). While habitat loss has been implicated in past island extinctions (Green \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2016\u003c/span\u003e; Jackson \u003cspan citationid=\"CR34\" class=\"CitationRef\"\u003e2007\u003c/span\u003e), the absence of a clear relationship in this study may reflect incomplete historical records or the variability in land use intensity across islands.\u003c/p\u003e \u003cp\u003eDistance to the mainland was hypothesized to influence koala persistence by facilitating immigration and gene flow, given that koalas are capable of swimming between islands (The beauty of Newry Island \u003cspan citationid=\"CR59\" class=\"CitationRef\"\u003e1947\u003c/span\u003e; Platt \u003cspan citationid=\"CR51\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) yet no significant effect was detected. This suggests that dispersal events are either too rare or insufficient to meaningfully shape population dynamics. Alternatively, the potential risks of proximity, such as increased exposure to mainland threats (Pretto et al. \u003cspan citationid=\"CR52\" class=\"CitationRef\"\u003e2012\u003c/span\u003e), may offset any benefits of connectivity.\u003c/p\u003e \u003cp\u003eWhile latitude did not directly influence persistence, its marginally significant effect on translocation effort aligns with the higher frequency of translocations in Victoria compared to Queensland, driven by historical management strategies (Hrdina and Gordon \u003cspan citationid=\"CR32\" class=\"CitationRef\"\u003e2004\u003c/span\u003e; Menkhorst \u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2008\u003c/span\u003e). The absence of a direct latitudinal effect on persistence suggests that koalas are adaptable to a range of climatic conditions, despite recent evidence of distribution shifts driven by climate change (Shabani et al. \u003cspan citationid=\"CR55\" class=\"CitationRef\"\u003e2019\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWhile this study examined the factors influencing koala persistence on islands, the drivers of koala population trends on islands, such as declines or increases, remain unknown. To better understand these dynamics, islands should be surveyed to characterize relevant metrics, such as species abundance. This approach provides greater insight than a binary presence-absence indicator, as it can better reflect the condition and viability of island populations.\u003c/p\u003e \u003cp\u003eThe islands with unknown koala occupancy status should be investigated urgently to determine whether they offer conservation benefits or require management intervention. Expanding knowledge of these islands will also increase sample size for future analyses. Confirming koala presence is particularly important for islands that historically supported native populations, as this information will help guide conservation decisions within the species\u0026rsquo; natural range.\u003c/p\u003e \u003cp\u003eOur database and analyses address critical knowledge gaps regarding island koala populations and establish a baseline for future conservation efforts. This provides a valuable tool for spatially prioritising islands based on their conservation value and exposure to threats. This framework can help identify islands capable of supporting resilient koala populations as refuges, as well as those facing severe threats and trending toward ecological entrapment.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgements\u003c/p\u003e\n\u003cp\u003eWe thank Noam Levin for access to data and guidance, Simon Blomberg for statistical advice Peter Menkhorst for assisting with accessing koala records, and the many people who provided personal accounts, mainly Stephen Jackson, Emma Hickingbotham, Alex Stroud, Mary, Brent Smith, Max Allen, Barry Howlett, Parks Victoria, Queensland Parks and Wildlife and the Kangaroo Island Landscape Board, The Biodiversity Research Group for their feedback and support and Craig Eddie and Alex Stroud for support in undertaking field surveys. \u003c/p\u003e\n\n\u003cp\u003eAuthor contributions\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMitchell Eddie:\u003c/strong\u003e Writing - original draft, writing - review and editing, methodology, data curation, formal analysis, investigation, conceptualization, visualization, project administration, resources, validation, software. \u003cstrong\u003eWilliam Ellis:\u003c/strong\u003e Supervision, funding acquisition, writing - review and editing, project administration, validation. \u003cstrong\u003eSalit Kark: \u003c/strong\u003eSupervision, conceptualization, planning, data, writing - review and editing, validation.\u003c/p\u003e\n\n\u003cp\u003eFunding statement and competing interests\u003c/p\u003e\n\u003cp\u003eThis project received travel support from The San Diego Zoo Wildlife Alliance.\u003c/p\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\n\u003cp\u003eData statement\u003c/p\u003e\n\u003cp\u003eOur research data is presented in Table 2 and is accompanied by the sources in Table A.1. The datasets generated during and/or analysed during the current study are available from the corresponding author on reasonable request.\u003c/p\u003e\n"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAbbott I, Burbidge A (1995) The occurrence of mammal species on the islands of Australia: A summary of existing knowledge. CALMScience 1:259\u0026ndash;324\u003c/li\u003e\n\u003cli\u003eAllen L (n.d.) Birth of a Hermit. Giria Allen\u003c/li\u003e\n\u003cli\u003eArmenteras D, Gonz\u0026aacute;lez TM, Retana J (2013) Forest fragmentation and edge influence on fire occurrence and intensity under different management types in Amazon forests. Biological Conservation 159:73\u0026ndash;79. https://doi.org/10.1016/j.biocon.2012.10.026\u003c/li\u003e\n\u003cli\u003eAustralian Bureau of Agricultural Resource Economics and Sciences (ABARES) (2023) Catchment Scale Land Use of Australia \u0026ndash; Update December 2023 [Dataset]. 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Pacific Conservation Biology 23(3):277\u0026ndash;294. https://doi.org/10.1071/PC17008\u003c/li\u003e\n\u003cli\u003eMcAlpine C, Lunney D, Melzer A, Menkhorst P, Phillips S, Phalen D, Ellis W, Foley W, Baxter G, de Villiers D, Kavanagh R, Adams-Hosking C, Todd C, Whisson D, Molsher R, Walter M, Lawler I, Close R (2015) Conserving koalas: A review of the contrasting regional trends, outlooks and policy challenges. Biological Conservation 192:226\u0026ndash;236. https://doi.org/10.1016/j.biocon.2015.09.020\u003c/li\u003e\n\u003cli\u003eMelzer A, Carrick F, Menkhorst P, Lunney D, John BS (2000) Overview, Critical Assessment, and Conservation Implications of Koala Distribution and Abundance. Conservation Biology 14(3):Article 3. https://doi.org/10.1046/j.1523-1739.2000.99383.x\u003c/li\u003e\n\u003cli\u003eMenkhorst P (2008) Hunted, marooned, re-introduced, contracepted: A history of Koala management in Victoria. 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Oxford University Press. https://doi.org/10.1093/oso/9780198566113.001.0001\u003c/li\u003e\n\u003cli\u003eWWF Australia (2022) WWF welcomes $50 million in federal funding for koalas. WWF Australia. https://www.wwf.org.au/news/news/2022/wwf-welcomes-50-million-in-federal-funding-for-koalas#gs.gntxjb\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"biodiversity-and-conservation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bioc","sideBox":"Learn more about [Biodiversity and Conservation](https://www.springer.com/journal/10531)","snPcode":"10531","submissionUrl":"https://submission.nature.com/new-submission/10531/3","title":"Biodiversity and Conservation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Conservation, status, threats, refuges, translocation","lastPublishedDoi":"10.21203/rs.3.rs-6300594/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6300594/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eDespite substantial conservation and research investments, populations of the endemic and iconic koala \u003cem\u003e(Phascolarctos cinereus)\u003c/em\u003e continue to decline across much of their Australian range, resulting in their Endangered status. Island refugia may offer a crucial strategy for koala conservation but also have the potential to become ecological traps, leading to further population declines across the species\u0026rsquo; range. Despite this, systematic efforts to map and record koala occurrences across Australian islands are lacking. This has left significant gaps in understanding the status, origin, and distribution of island koala populations, the factors influencing their persistence, and the extent of threats they face. This study aimed to address these gaps by creating the first comprehensive database of koalas on Australian islands, characterising their distribution, status, and history of occurrence. We integrated this database with spatial mapping software to analyse the geographic distribution and extent of anthropogenic and environmental threats across Australian island. Additionally, we applied path analysis to model the effects of abiotic, biotic, and anthropogenic factors on island koala persistence. We found records of koalas (historical and/or current) on 37 Australian islands, spanning subtropical to temperate climates, with \u0026gt;\u0026thinsp;15 islands currently supporting koala populations. Among the threats to extant island koala populations analysed, anthropogenic land use and overbrowsing exhibited a consistent spatial trend, both being more pronounced at lower latitudes. These findings can inform conservation and management actions by identifying islands where threat mitigation is required and highlighting those that may serve as suitable refuges for future translocation and koala conservation efforts.\u003c/p\u003e","manuscriptTitle":"Koalas on Australian Islands","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-15 10:44:11","doi":"10.21203/rs.3.rs-6300594/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-19T04:32:59+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-19T04:25:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"65291874780800031588023325432053025842","date":"2025-05-15T02:20:38+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"222732888053634033646243690108146292467","date":"2025-05-14T20:19:04+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-12T10:07:11+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"263261503341203917571485324712932762835","date":"2025-05-12T06:33:08+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-05-12T06:10:12+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-04-05T07:57:53+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-03-26T15:02:48+00:00","index":"","fulltext":""},{"type":"submitted","content":"Biodiversity and Conservation","date":"2025-03-25T06:07:41+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"biodiversity-and-conservation","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bioc","sideBox":"Learn more about [Biodiversity and Conservation](https://www.springer.com/journal/10531)","snPcode":"10531","submissionUrl":"https://submission.nature.com/new-submission/10531/3","title":"Biodiversity and Conservation","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"b9fe2c5b-477d-464b-b109-e73660fbf379","owner":[],"postedDate":"May 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-09-08T16:01:41+00:00","versionOfRecord":{"articleIdentity":"rs-6300594","link":"https://doi.org/10.1007/s10531-025-03115-9","journal":{"identity":"biodiversity-and-conservation","isVorOnly":false,"title":"Biodiversity and Conservation"},"publishedOn":"2025-09-01 15:57:14","publishedOnDateReadable":"September 1st, 2025"},"versionCreatedAt":"2025-05-15 10:44:11","video":"","vorDoi":"10.1007/s10531-025-03115-9","vorDoiUrl":"https://doi.org/10.1007/s10531-025-03115-9","workflowStages":[]},"version":"v1","identity":"rs-6300594","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6300594","identity":"rs-6300594","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}