Articoli di riviste: "Koala habitat"

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Lunney, Daniel, Stephen Phillips, John Callaghan e Dionne Coburn. "Determining the distribution of Koala habitat across a shire as a basis for conservation: a case study from Port Stephens, New South Wales". Pacific Conservation Biology 4, n. 3 (1998): 186. http://dx.doi.org/10.1071/pc980186.

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The Australian National Koala Conservation Strategy recognizes the importance of conserving Koalas in their existing habitat, particularly through the integration of Koala conservation into local government planning (ANZECC 1998). The aim of this study was to define, rank and map the distribution of Koala habitat in Port Stephens Shire, New South Wales. The procedure was to merge the results of two independent survey techniques, each of which was interpreted using a vegetation map specifically prepared for this study. A field survey used a plot-based sampling protocol to determine tree species preferences based on the presence/absence of Koala faecal pellets. Data were obtained on 8 764 trees comprising 19 eucalypt and 12 non-eucalypt species. A high-profile community survey obtained 2 756 Koala records. Koala habitat maps from both survey methods were examined as overlapping GIS layers. Combined Koala habitat categories were then devised, ranked and mapped across the Shire. This study provides a practical and repeatable means of identifying and conserving Koala habitat in existing remnant vegetation over which local government has planning jurisdiction.

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Reckless, Hailee J., Michael Murray e Mathew S. Crowther. "A review of climatic change as a determinant of the viability of koala populations". Wildlife Research 44, n. 7 (2017): 458. http://dx.doi.org/10.1071/wr16163.

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The koala (Phascolarctos cinereus) occupies a broad range of eastern and southern Australia, extending over tropical coastal, semiarid inland and temperate regions. In many areas koala populations are under threat, in particular from the direct and indirect effects of ongoing habitat destruction due to increased urbanisation and other anthropogenic processes. Climate change presents additional threats to the integrity of koala habitats because many species of food and non-food trees have narrow climate envelopes and are unable to adapt to altered temperatures and rainfall. Climate extremes also produce physiological stresses in koalas that may increase the likelihood of outbreaks of chlamydiosis and other diseases. Climate change–related increases in the relative content of toxic chemicals in leaves are further stresses to the koala after ingestion. In addition, populations that originated from a small number of founder individuals are at potential risk due to their relatively low genetic diversity. Strategies that maintain residual habitat fragments and promote the construction of new refugia are now being formulated. Modelling of the impact of habitat metrics on koala distribution is providing important information that can be used in the rehabilitation of koala refugia. In future these models could be augmented with metrics that describe koala homeostasis to inform local conservation strategies. These considerations are also relevant for the maintenance of other taxa in the wider ecosystem that are also at risk from habitat destruction and climate change.

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Masters, Pip, Toni Duka, Steve Berris e Graeme Moss. "Koalas on Kangaroo Island: from introduction to pest status in less than a century". Wildlife Research 31, n. 3 (2004): 267. http://dx.doi.org/10.1071/wr03007.

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In less than a century the ecological profile of koalas on Kangaroo Island has shifted from that of a species introduced for conservation purposes to one of pest status. Between 1923 and 1925, 18 koalas were released on Kangaroo Island. Their numbers increased rapidly and in 1997 a population-control program was implemented based on a population estimate of 5000 koalas. During the course of this program, it became clear that the koala population on Kangaroo Island was much greater and more widely distributed than previously thought, hence a more comprehensive population survey was carried out.In 2000–01 the koala population size was calculated using a stratified sampling approach based on five 'catchment units' and three habitat classifications that were known to support koalas. The koala population was estimated to be ~27 000 koalas in 2001. There were substantial differences in koala density in the low-, medium- and high-quality habitat within each catchment unit, and therefore large differences in the spatial distribution of koalas across Kangaroo Island. This revised population estimate has substantial ramifications for the Kangaroo Island Koala Management Program that was set in place in 1997.

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Menkhorst, Peter, David Ramsey, Tim O'Brien, Emily Hynes e Desley Whisson. "Survival and movements of koalas translocated from an over-abundant population". Wildlife Research 46, n. 7 (2019): 557. http://dx.doi.org/10.1071/wr19090.

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Abstract Context At some sites in southern Victoria, browsing pressure caused by high-density koala populations can result in defoliation of preferred browse trees. In extreme cases, this over-browsing can lead to widespread tree death and starvation of koalas. To reduce the potential for mortality of trees and koalas, a management strategy that includes fertility control of females and translocation of healthy individuals (male and female) has been adopted. AimsTo compare the short- to medium-term survival and body condition of koalas translocated from over-browsed habitat and released into unoccupied (or nearly so) habitat with that of koalas left in situ in compromised habitat. Methods We monitored survival and body condition of 36 translocated koalas for 4–5 months after translocation relative to that of a control group (24 animals) left in situ. Koalas were recaptured and body condition measured (as a scaled body-mass index) ~40 and 137 days after translocation. Additionally, GPS loggers were used to investigate patterns of koala movement. Key resultsSurvival rates of translocated koalas were not different from those of controls and females in both groups showed slightly higher survival rates than did males. After 137 days, control animals had lower scaled body mass, whereas translocated animals, after an initial reduction, had mostly regained, or increased their scaled body mass. Translocated females regained their original scaled body mass faster than did translocated males. Male koalas in both control and translocated groups had higher rates of movement than did females, and translocated koalas had slightly higher rates of movement than did control koalas. Translocated koalas moved farther from their release location than control koalas. ConclusionsOn the basis of the scaled body-mass index, translocated koalas fared better than those left in situ in compromised habitat, even though the density of koalas in the over-browsed habitat had been reduced by a wider salvage translocation program. The process used to identify potential release sites, including a spatial koala-habitat index, accurately predicted suitable koala habitat. ImplicationsThe current management strategy of translocating koalas out of over-browsed habitat is supported and could be more widely applied.

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Smith, Andrew G., Clive McAlpine, Jonathan Rhodes, Leonie Seabrook, Daniel Lunney e Greg Baxter. "Are there habitat thresholds in koala occupancy in the semiarid landscapes of the Mulgalands Bioregion?" Wildlife Research 40, n. 5 (2013): 413. http://dx.doi.org/10.1071/wr13010.

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Context Habitat thresholds are the critical point(s), below which the probability of occurrence of a species declines. Identifying thresholds assists land managers to decide how much habitat is needed to conserve a species. However, for any given species, a threshold may not exist, or might occur at one scale but not at others, and it may differ across regions. The use of critical habitat thresholds can negatively affect populations if simplified conservation targets for habitat retention are prescribed. This problem is relevant to the koalas where there is evidence of habitat thresholds in mesic regions, but no studies of thresholds in semiarid regions. Aims The aim of the present study was to investigate whether a threshold exists between the occupancy of a site by koalas and habitat variables at both the site and at four landscape scales in the semiarid Mulgalands Bioregion of Queensland, Australia. Methods We modelled habitat relationships using standard and piece-wise logistic regression, and an information-theoretic approach, to determine whether the best model that explained the occupancy–habitat relationships was linear or had a distinct threshold. The site-scale variable was the percentage of primary eucalypt species. The landscape-scale variables included the amount of primary and secondary habitat, and an interaction between them. Key findings There was a threshold relationship between the occurrence of koalas and the percentage of primary trees at the site scale. At the landscape scale, most threshold models failed to converge, and evidence pointed to a linear relationship between habitat amount and koala occupancy. Conclusions Conservation actions for koalas in the Mulgalands Bioregion should concentrate on protecting the primary tree resource for koalas, namely, river red gums (E. camaldulensis). However, the maintenance or restoration of primary and secondary habitat to distances of 1000 m from the creek is important because of the linear relationship between koala presence and habitat amount. Implications As habitat is lost in the semiarid Mulgalands Bioregion, koala occupancy declines. If known thresholds from mesic regions are used to define a minimum amount of habitat to be retained for koalas, conservation of local koala populations may well fail.

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Callaghan, John, Clive McAlpine, David Mitchell, Jane Thompson, Michiala Bowen, Jonathan Rhodes, Carol de Jong, Renee Domalewski e Alison Scott. "Ranking and mapping koala habitat quality for conservation planning on the basis of indirect evidence of tree-species use: a case study of Noosa Shire, south-eastern Queensland". Wildlife Research 38, n. 2 (2011): 89. http://dx.doi.org/10.1071/wr07177.

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Context Mapping the habitat and distribution of a species is critical for developing effective conservation plans. Koala (Phascolarctos cinereus, Phascolarctidae) distribution is constrained by the nutritional and shelter requirements provided by a relatively small number of key tree species in any given area. Identifying these key species provides a practical foundation for mapping koala habitat and prioritising areas for conservation. Aims To determine key tree species for koalas in Noosa Shire (south-eastern Queensland, Australia) as a basis for mapping koala habitat quality. Methods We applied a faecal-pellet survey methodology in 1996/97 to assess evidence of use by koalas of 4031 trees from 96 randomly stratified survey sites across different eucalypt-forest and woodland communities. Results were compared with those from a later survey undertaken in 2001/02 involving 5535 trees from 195 sites that were distributed across broadly similar areas with the aim to investigate aspects of koala landscape ecology. Key results A total of 66.7% of the 1996/97 survey sites contained koala faecal pellets, recorded under 953 eucalypt trees (14 species) and 1670 non-eucalypt trees (27 species). The proportion of trees at a given survey site that had koala faecal pellets at the base ranged from 2.2% to 94.7% (mean = 31.13 ± 2.59% s.e.). For the 2001/02 dataset, koala pellets were found at 55.4% of sites, from 794 eucalypt and 2240 non-eucalypt trees. The proportion of trees with pellets ranged from 3% to 80% (mean = 21.07 ± 1.77% s.e.). Both the 1996/97 and 2001/02 surveys identified the same three tree species (forest red gum, Eucalyptus tereticornis, swamp mahogany, E. robusta, and tallowwood, E. microcorys) as the highest-ranked for koala use in the study area. Three additional species (red mahogany, E. resinifera, small-fruited grey gum, E. propinqua, and grey ironbark, E. siderophloia) were identified in the 1996/97 surveys as key eucalypt species. Of the non-eucalypts in the 1996/97 dataset, coast cypress pine (Callitris columellaris) and broad-leaved paperbark (Melaleuca quinquenervia) ranked highest for use by koalas, followed by pink bloodwood (Corymbia intermedia) and brush box (Lophostemon confertus). White bottlebrush (Callistemon salignus), hard corkwood (Endiandra sieberi), M. quinquenervia and C. intermedia ranked highest in the 2001/02 dataset. The findings showed significantly greater use of larger eucalypts (i.e. 300-mm to >600-mm diameter at breast height). Conclusions The identified key eucalypt species, being the critical limiting resource for koalas, were used to assign koala habitat-quality classes to mapped regional ecosystem types to create a Koala Habitat Atlas (KHA) for Noosa Shire. The combined two highest quality classes based on abundance of the key eucalypt species comprised only 15.7% of the total land area of the Shire. Implications The KHA approach provides a practical and repeatable method for developing koala habitat-suitability mapping for national-, regional- and local-scale conservation and recovery planning purposes.

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Dique, David S., Harriet J. Preece, Jim Thompson e Deidré L. de Villiers. "Determining the distribution and abundance of a regional koala population in south-east Queensland for conservation management". Wildlife Research 31, n. 2 (2004): 109. http://dx.doi.org/10.1071/wr02031.

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Koala surveys were used to determine the distribution and abundance of a threatened regional koala population in south-east Queensland to assist with the development of effective conservation management programs. Daytime systematic searches of strip transects were conducted twice yearly from 1996 to 1999 to determine koala density at a number of sites in urban, remnant bushland and bushland strata. Mean density estimates for 27 survey sites ranged from 0.02 to 1.26 koalas ha–1. Koala densities were generally higher in large tracts and remnant patches of eucalypt bushland towards the centre of the region with lower but significant densities in urban areas. Two estimates of population size were obtained: 7230 (±1668, 95% confidence limit) and 6246 (±1444, 95% confidence limit). The estimate of 6246 was considered to provide a better indication of actual population size as it reduced the variation within strata and took into account the distribution of koalas across the region. It is likely that determining habitat areas for conservation based on where koalas actually occur rather than identifying distributions of 'preferred' tree species or community reports, as has been promoted in other studies, is a better indicator of the conservation significance of remnant habitat areas. Future koala-management programs should ensure that the significance of eucalypt bushland areas towards the centre of the study area is not compromised by future urban development and associated threats to koalas.

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Ellis, William, Sean FitzGibbon, Alistair Melzer, Robbie Wilson, Steve Johnston, Fred Bercovitch, David Dique e Frank Carrick. "Koala habitat use and population density: using field data to test the assumptions of ecological models". Australian Mammalogy 35, n. 2 (2013): 160. http://dx.doi.org/10.1071/am12023.

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In principle, conservation planning relies on long-term data; in reality, conservation decisions are apt to be based upon limited data and short-range goals. For the koala (Phascolarctos cinereus), frequently reliance is made on the assumption that indirect signs can be used to indicate behavioural preferences, such as diet choice. We examined the relationship between the use of trees by koalas and the presence of scats beneath those trees. Tree use was associated with scat presence on 49% of occasions when koalas were radio-tracked in both central Queensland (n = 10 koalas) and south-east Queensland (n = 5 koalas), increasing to 77% of occasions when trees were rechecked the following day. Koala densities were correlated with scat abundance at sites with koala density between ~0.2 and 0.6 koalas per hectare. Our results confirm that scat searches are imprecise indicators of tree use by koalas, but demonstrate that these searches can be used, with caveats, to estimate koala population densities. We discuss how errors in estimating or applying predictive model parameters can bias estimates of occupancy and show how a failure to validate adequately the assumptions used in modelling and mapping can undermine the power of the products to direct rational conservation and management efforts.

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Seabrook, Leonie, Clive McAlpine, Greg Baxter, Jonathan Rhodes, Adrian Bradley e Daniel Lunney. "Drought-driven change in wildlife distribution and numbers: a case study of koalas in south west Queensland". Wildlife Research 38, n. 6 (2011): 509. http://dx.doi.org/10.1071/wr11064.

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Context Global climate change will lead to increased climate variability, including more frequent drought and heatwaves, in many areas of the world. This will affect the distribution and numbers of wildlife populations. In south-west Queensland, anecdotal reports indicated that a low density but significant koala population had been impacted by drought from 2001–2009, in accord with the predicted effects of climate change. Aims The study aimed to compare koala distribution and numbers in south-west Queensland in 2009 with pre-drought estimates from 1995–1997. Methods Community surveys and faecal pellet surveys were used to assess koala distribution. Population densities were estimated using the Faecal Standing Crop Method. From these densities, koala abundance in 10 habitat units was interpolated across the study region. Bootstrapping was used to estimate standard error. Climate data and land clearing were examined as possible explanations for changes in koala distribution and numbers between the two time periods. Key results Although there was only a minor change in distribution, there was an 80% decline in koala numbers across the study region, from a mean population of 59 000 in 1995 to 11 600 in 2009. Most summers between 2002 and 2007 were hotter and drier than average. Vegetation clearance was greatest in the eastern third of the study region, with the majority of clearing being in mixed eucalypt/acacia ecosystems and vegetation on elevated residuals. Conclusions Changes in the area of occupancy and numbers of koalas allowed us to conclude that drought significantly reduced koala populations and that they contracted to critical riparian habitats. Land clearing in the eastern part of the region may reduce the ability of koalas to move between habitats. Implications The increase in hotter and drier conditions expected with climate change will adversely affect koala populations in south-west Queensland and may be similar in other wildlife species in arid and semiarid regions. The effect of climate change on trailing edge populations may interact with habitat loss and fragmentation to increase extinction risks. Monitoring wildlife population dynamics at the margins of their geographic ranges will help to manage the impacts of climate change.

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Dique, David S., Jim Thompson, Harriet J. Preece, Guy C. Penfold, Deidré L. de Villiers e Ros S. Leslie. "Koala mortality on roads in south-east Queensland: the koala speed-zone trial". Wildlife Research 30, n. 4 (2003): 419. http://dx.doi.org/10.1071/wr02029.

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In 1995, the Queensland Parks and Wildlife Service, the Queensland Department of Main Roads and Redland Shire Council initiated the Koala Speed Zone Trial in the Koala Coast, south-east Queensland. The aim of the trial was to assess the effect of differential speed signs on the number of koalas (Phascolarctos cinereus) hit by vehicles in the Koala Coast from 1995 to 1999. On the basis of information collected by the Queensland Parks and Wildlife Service 1407 koalas were hit by vehicles in the Koala Coast during the five-year study (mean 281 koalas per year, range 251–315). Monitoring of vehicle speeds by the Queensland Department of Main Roads suggested that there was no significant reduction in vehicle speed during the trial period from August to December. Consequently, there was no evidence to suggest that a reduction in the number of koalas hit by vehicles occurred during the trial. Approximately 70% of koalas were hit on arterial and sub-arterial roads and approximately 83% did not survive. The location of each koala hit was recorded and the signed speed limit of the road was noted. Most koalas that were hit by vehicles were young healthy males. Pooling of data on koala collisions and road speed limits suggested that the proportion of koalas that survived being hit by vehicles was slightly higher on roads with lower speed limits. However, vehicle speed was not the only factor that affected the number of koalas hit by vehicles. It is suggested that habitat destruction, koala density and traffic volume also contribute to road-associated koala mortality in the Koala Coast.

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Lunney, Daniel, Carol Esson, Chris Moon, Murray Ellis e Alison Matthews. "A Community-based Survey of the Koala, Phascolarctos cinereus, in the Eden Region of South-eastern New South Wales". Wildlife Research 24, n. 1 (1997): 111. http://dx.doi.org/10.1071/wr94034.

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A community-based postal survey (questionnaire and map) was undertaken in the Eden region of south-eastern New South Wales in 1991–92 to help determine the local distribution of koalas and to obtain information on which to base a regional plan of management for koalas. The 1198 replies from the II 600 households in the region represented all parts of the area surveyed. The survey responses suggest that koalas are rare in the Eden region, and that the number of koalas has been constantly low for the last four decades. The records are scattered both chronologically and geographically. National Parks and Nature Reserves have never been the stronghold of local koala populations, and freehold land, particularly farmland, is not a major reservoir of koalas. Most koalas reported were in, or adjacent to, State Forests, particularly Murrah–Berrnagui and Tantawangalo–Glenbog–Yurammie. These areas appear to contain the core of the surviving koala population of the region. An assessment of the vegetation where koalas were sighted indicated that dry forest is the preferred habitat. The once abundant and widespread local koala population of late last century has been reduced by habitat loss and fragmentation to a few small, isolated populations. This regional survey, which was undertaken by use of a carefully constructed questionnaire, revealed an invaluable source of records and contributed 70% of the records in the database used for this study. This study also laid a basis for assessing koala management options in south-eastern New South Wales.

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Dennison, S., G. J. Frankham, L. E. Neaves, C. Flanagan, S. FitzGibbon, M. D. B. Eldridge e R. N. Johnson. "Population genetics of the koala (Phascolarctos cinereus) in north-eastern New South Wales and south-eastern Queensland". Australian Journal of Zoology 64, n. 6 (2016): 402. http://dx.doi.org/10.1071/zo16081.

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Habitat loss and fragmentation are key threats to local koala (Phascolarctos cinereus) populations. Broad-scale management is suboptimal for koalas because distribution models are not easily generalised across regions. Therefore, it is imperative that data relevant to local management bodies are available. Genetic data provides important information on gene flow and potential habitat barriers, including anthropogenic disturbances. Little genetic data are available for nationally significant koala populations in north-eastern New South Wales, despite reported declines due to urbanisation and habitat loss. In this study, we develop 14 novel microsatellite loci to investigate koala populations in north-eastern New South Wales (Port Macquarie, Coffs Harbour, Tyagarah, Ballina) and south-eastern Queensland (Coomera). All locations were significantly differentiated (FST = 0.096–0.213; FʹST = 0.282–0.582), and this pattern was not consistent with isolation by distance (R2 = 0.228, P = 0.058). Population assignment clustered the more northern populations (Ballina, Tyagarah and Coomera), suggesting contemporary gene flow among these sites. For all locations, low molecular variation among (16%) rather than within (84%) sites suggests historical connectivity. These results suggest that koala populations in north-eastern New South Wales and south-eastern Queensland are experiencing contemporary impediments to gene flow, and highlight the importance of maintaining habitat connectivity across this region.

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Quigley, Bonnie L., e Peter Timms. "Helping koalas battle disease – Recent advances in Chlamydia and koala retrovirus (KoRV) disease understanding and treatment in koalas". FEMS Microbiology Reviews 44, n. 5 (18 giugno 2020): 583–605. http://dx.doi.org/10.1093/femsre/fuaa024.

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ABSTRACT The iconic Australian marsupial, the koala (Phascolarctos cinereus), has suffered dramatic population declines as a result of habitat loss and fragmentation, disease, vehicle collision mortality, dog attacks, bushfires and climate change. In 2012, koalas were officially declared vulnerable by the Australian government and listed as a threatened species. In response, research into diseases affecting koalas has expanded rapidly. The two major pathogens affecting koalas are Chlamydia pecorum, leading to chlamydial disease and koala retrovirus (KoRV). In the last eight years, these pathogens and their diseases have received focused study regarding their sources, genetics, prevalence, disease presentation and transmission. This has led to vast improvements in pathogen detection and treatment, including the ongoing development of vaccines for each as a management and control strategy. This review will summarize and highlight the important advances made in understanding and combating C. pecorum and KoRV in koalas, since they were declared a threatened species. With complementary advances having also been made from the koala genome sequence and in our understanding of the koala immune system, we are primed to make a significant positive impact on koala health into the future.

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de Oliveira, S. M., P. J. Murray, D. L. de Villiers e G. S. Baxter. "Ecology and movement of urban koalas adjacent to linear infrastructure in coastal south-east Queensland". Australian Mammalogy 36, n. 1 (2014): 45. http://dx.doi.org/10.1071/am12046.

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In Redland City, koalas (Phascolarctos cinereus) are in rapid decline as they are exposed to anthropogenic threats such as habitat clearing, dog attacks, vehicle collisions and disease. This study investigated the influence of linear infrastructure on the movement and habitat use of urban koalas. Seven koalas were tracked for up to 28 weeks during the breeding season. Home ranges were calculated for 95% Minimum Convex Polygon (MCP95%) and 95% fixed Kernel Density (FK95%). Koalas responded to the landscape in different ways. Linear infrastructure did not restrict the movements of most koalas. Home ranges varied from 1.1 to 31.5 ha MCP95% and from 5 to 55 ha for FK95%. Koalas mainly used Eucalyptus tereticornis throughout the study site. A variety of non-regionally endemic and regionally endemic trees in urban and remnant vegetation areas were used, suggesting that all trees are potentially koala habitat. At the completion of the study, four koalas remained alive, two were killed by trains and one died from a dog attack. Despite the small sample size and short duration, our results suggest that koalas are able to navigate linear infrastructure; however, the high rates of mortality associated with these movements puts the long-term viability of urban koala populations in doubt.

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Adams-Hosking, Christine, Hedley S. Grantham, Jonathan R. Rhodes, Clive McAlpine e Patrick T. Moss. "Modelling climate-change-induced shifts in the distribution of the koala". Wildlife Research 38, n. 2 (2011): 122. http://dx.doi.org/10.1071/wr10156.

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Context The impacts of climate change on the climate envelopes, and hence, distributions of species, are of ongoing concern for biodiversity worldwide. Knowing where climate refuge habitats will occur in the future is essential to conservation planning. The koala (Phascolarctos cinereus) is recognised by the International Union for Conservation of Nature (IUCN) as a species highly vulnerable to climate change. However, the impact of climate change on its distribution is poorly understood. Aims We aimed to predict the likely shifts in the climate envelope of the koala throughout its natural distribution under various climate change scenarios and identify potential future climate refugia. Methods To predict possible future koala climate envelopes we developed bioclimatic models using Maxent, based on a substantial database of locality records and several climate change scenarios. Key results The predicted current koala climate envelope was concentrated in south-east Queensland, eastern New South Wales and eastern Victoria, which generally showed congruency with their current known distribution. Under realistic projected future climate change, with the climate becoming increasingly drier and warmer, the models showed a significant progressive eastward and southward contraction in the koala’s climate envelope limit in Queensland, New South Wales and Victoria. The models also indicated novel potentially suitable climate habitat in Tasmania and south-western Australia. Conclusions Under a future hotter and drier climate, current koala distributions, based on their climate envelope, will likely contract eastwards and southwards to many regions where koala populations are declining due to additional threats of high human population densities and ongoing pressures from habitat loss, dog attacks and vehicle collisions. In arid and semi-arid regions such as the Mulgalands of south-western Queensland, climate change is likely to compound the impacts of habitat loss, resulting in significant contractions in the distribution of this species. Implications Climate change pressures will likely change priorities for allocating conservation efforts for many species. Conservation planning needs to identify areas that will provide climatically suitable habitat for a species in a changing climate. In the case of the koala, inland habitats are likely to become climatically unsuitable, increasing the need to protect and restore the more mesic habitats, which are under threat from urbanisation. National and regional koala conservation policies need to anticipate these changes and synergistic threats. Therefore, a proactive approach to conservation planning is necessary to protect the koala and other species that depend on eucalypt forests.

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Lee, Tristan, Kyall R. Zenger, Robert L. Close e David N. Phalen. "Genetic analysis reveals a distinct and highly diverse koala (Phascolarctos cinereus) population in South Gippsland, Victoria, Australia". Australian Mammalogy 34, n. 1 (2012): 68. http://dx.doi.org/10.1071/am10035.

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Population genetics can reveal otherwise hidden information involving a species’ history in a given region. Koalas were thought to have been virtually exterminated from the Australian state of Victoria during the koala fur trade of the late 1800s. Koalas in the South Gippsland region of Victoria were examined using microsatellite markers to infer population structure and gene flow and to locate a possible remnant gene pool. The results indicate that the South Gippsland koala population had higher genetic diversity (A = 5.97, HO = 0.564) than other published Victorian populations, and was genetically distinct from other koala populations examined. South Gippsland koalas, therefore, may have survived the population reductions of the koala fur trade and now represent a remnant Victorian gene pool that has been largely lost from the remainder of Victoria. This paper illustrates that historic anthropogenic impacts have had little effect on reducing the genetic diversity of a population in the South Gippsland region. However, the South Gippsland population is now subject to threats such as logging and loss of habitat from housing and agriculture expansion. Our results suggest that the South Gippsland koalas require an alternative conservation management program.

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Rhind, Susan G., Murray V. Ellis, Martin Smith e Daniel Lunney. "Do Koalas Phascolarctos cinereus use trees planted on farms? A case study from north-west New South Wales, Australia." Pacific Conservation Biology 20, n. 3 (2014): 302. http://dx.doi.org/10.1071/pc140302.

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Biodiversity benefits are routinely cited as an outcome of planting trees on farms but there has been too little information to properly substantiate such claims. This study is among the first to examine the use of plantings by arboreal mammals. We examined an important inland koala population and its use of farm revegetation to determine: (1) if koalas use planted trees; (2) patch characteristics correlated with use/non-use by koalas; and, (3) contextual characteristics correlated with use/non-use. Surveys of koala dung, also known as scats or faecal pellets, were conducted under trees in 19 plantings. Fourteen showed signs of koalas and their pellets were recorded under 16 of the 25 tree taxa examined. All sizes and ages of trees were used, including the youngest plantings (six years). Considerable koala activity occurred in the various Eucalyptus species, but some tree species were not used. Koalas made substantial use of inland ironbark species, which are not listed as ‘koala food trees’ in government policy documents. Proximity to potential source populations of koalas was the strongest predictor of a planting being used, but this was further improved by including the age of the planting. There is extensive public funding available for restoration and land care activities. This study demonstrates that certain trees rapidly provide koala habitat when planted on farms and that the first priority should be restoring sites in close proximity to known koala populations. Tree species used should include local recognized food trees, as well as ironbarks and non-eucalyptus species that offer shelter.

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Jiang, Alex, Andrew Tribe, Clive J. C. Phillips e Peter J. Murray. "Do Livestock Injure and Kill Koalas? Insights from Wildlife Hospital and Rescue Group Admissions and an Online Survey of Livestock–Koala Conflicts". Animals 11, n. 9 (13 settembre 2021): 2684. http://dx.doi.org/10.3390/ani11092684.

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Abstract (sommario):

Koala populations in Australia are declining due to threats such as chlamydiosis, wild dog predation and vehicle collision. In the last decade, grazing livestock emerged anecdotally as a threat to koala survival in areas where koala habitat and livestock grazing land overlap. This is the first study investigating the significance of livestock-inflicted injuries and deaths in koala populations over a large spatial and temporal scale. We investigated the outcome, scale, and frequency of livestock–koala incidents via an online survey and analysed koala admission records in Queensland wildlife hospitals and a wildlife rescue group (Wildlife Victoria) in Victoria. The results provide evidence of both livestock-inflicted injuries and deaths to koalas, especially as these have been confirmed by witness statements. The outcomes for the koala victims of the incidents were severe with a 75% mortality rate. The reported frequency of livestock–koala incidents was low but increasing, with 72 cases (0.14% out of 50,873 admissions) in Queensland wildlife hospitals during 1997–2019, and 59 cases (0.8% of 7017 rescue records) in Wildlife Victoria during 2007–2019. These incidents were likely to be under-reported due to the remoteness of the incident location, possible mis-diagnoses by veterinarians and the possible reluctance of farmers to report them. Future research is encouraged to explore the mechanics and causes of livestock–koala incidents and to develop management strategies to minimise the livestock threat to koalas.

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Lunney, Daniel, Eleanor Stalenberg, Truly Santika e Jonathan R. Rhodes. "Extinction in Eden: identifying the role of climate change in the decline of the koala in south-eastern NSW". Wildlife Research 41, n. 1 (2014): 22. http://dx.doi.org/10.1071/wr13054.

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Abstract (sommario):

Context Reviews of climate change in Australia have identified that it is imposing additional stresses on biodiversity, which is already under threat from multiple human impacts. Aims The present study aimed to determine the contributions of several factors to the demise of the koala in the Eden region in south-eastern New South Wales and, in particular, to establish to what extent climate change may have exacerbated the decline. Methods The study built on several community-based koala surveys in the Eden region since 1986, verified through interviews with survey respondents. Historical records as far back as the late 19th century, wildlife databases and field-based surveys were used to independently validate the community survey data and form a reliable picture of changes in the Eden koala population. Analysis of the community survey data used a logistic model to assess the contribution of known threats to koalas, including habitat loss measured as changes in foliage projective cover, fire, increases in the human population and climate change in the form of changes in temperature and rainfall, to the regional decline of this species. Key results We found a marked, long-term shrinkage in the distribution of the koala across the Eden region. Our modelling demonstrated that a succession of multiple threats to koalas from land use (human population growth and habitat loss) and environmental change (temperature increase and drought) were significant contributors to this decline. Conclusions Climate change, particularly drought and rising temperatures, has been a hitherto hidden factor that has been a major driver of the decline of the koala in the Eden region. Implications Development of strategies to help fauna adapt to the changing climate is of paramount importance, particularly at a local scale.

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20

Kavanagh, Rodney P., Matthew A. Stanton e Traecey E. Brassil. "Koalas continue to occupy their previous home-ranges after selective logging in Callitris - Eucalyptus forest". Wildlife Research 34, n. 2 (2007): 94. http://dx.doi.org/10.1071/wr06126.

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Abstract (sommario):

The koala (Phascolarctos cinereus) is a charismatic, high-profile species whose conservation needs are commonly perceived to be incompatible with logging. However, koala biology and the results of chronosequence studies elsewhere suggest that this species may tolerate a degree of habitat alteration caused by logging. In this study, 30 koalas, five in each of six areas available for logging within a mixed white cypress pine (Callitris glaucophylla)–Eucalyptus forest in north-western New South Wales, were radio-tracked for one year during 1997–1998 to determine their movements, home-range sizes and tree preferences. Five months after the study began, three of these areas were logged selectively for sawlogs and thinnings of the white cypress pine, a tree that is important to koalas for daytime shelter. This removed about one-quarter of the stand basal area, but the eucalypt component was unaffected. The remaining three areas were left undisturbed as controls. Radio-tracking continued in all six areas for another seven months. Koalas continued to occupy all or part of their previous home-ranges after selective logging, and home-range sizes remained similar between logged and unlogged areas. Home-ranges for both sexes overlapped and were ~12 ha for males and 9 ha for females. Koala survival and the proportions of breeding females were similar in logged and unlogged areas. The principal food trees of the koala were red gums, mainly Eucalyptus blakelyi and E. chloroclada, and the pilliga box (E. pilligaensis), none of which were logged in this study. These results suggest that selective logging for white cypress pine does not appear to adversely affect koala populations and that koalas may not be as sensitive to logging as previously thought. Further work is required to determine thresholds in the level of retention of koala food trees in logging operations.

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Lunney, Danial, Shaan Gresser, Lisa E. O'neill, Alison Matthews e Jonathan Rhodes. "The impact of fire and dogs on Koalas at Port Stephens, New South Wales, using population viability analysis". Pacific Conservation Biology 13, n. 3 (2007): 189. http://dx.doi.org/10.1071/pc070189.

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Abstract (sommario):

The Port Stephens Koala Phascolarctos cinereus population has been regarded as one of the strongholds for Koalas in New South Wales. This study applied population viability analysis to investigate the impact of fire and predation by dogs on the viability of the local population. The rapid decline of the modelled Koala population under basic assumptions throws the assumed security of such large populations into question. In all the modelled management scenarios, reducing mortality had more influence than any other factor. Reducing the severity and frequency of large catastrophic fires improved the probability of survival for the population, though the modelled population size still declined sharply. Any management action to improve Koala survival must be accompanied by a reduction in mortality from dog attacks. Fires and dogs will have an ever greater impact on Koala populations as coastal forests become more fragmented and isolated by urban development, and their combined control will be needed to complement land-use planning measures to address habitat loss and fragmentation.

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Barth, Benjamin J., Sean I. FitzGibbon, Amber Gillett, Robbie S. Wilson, Beth Moffitt, Geoffrey W. Pye, Dalene Adam, Harriet Preece e William A. Ellis. "Scattered paddock trees and roadside vegetation can provide important habitat for koalas (Phascolarctos cinereus) in an agricultural landscape". Australian Mammalogy 42, n. 2 (2020): 194. http://dx.doi.org/10.1071/am18031.

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Abstract (sommario):

Habitat loss and fragmentation threaten the survival of koalas in Queensland. In rural landscapes, remaining koala habitat is often in the form of scattered paddock trees, patches of vegetation and roadside vegetation. The aims of this study were to (1) quantify the use of these three habitat types; (2) determine whether there is an increased use of scattered trees during the breeding season; and (3) describe the movement characteristics (daily step-length and turning angle) of koalas in different habitat types. To do this, koalas were caught and fitted with global positioning system (GPS) loggers that recorded their daily locations. We found koalas utilised all three habitat types in both breeding and non-breeding seasons, but roadside vegetation and scattered trees were utilised significantly more than expected based on their availability within the landscape. We found no significant difference in step-length or turning angles in scattered trees compared with patches of vegetation. We conclude that scattered trees are a critical element of habitat in this rural landscape. This work provides evidence that retaining or planting scattered trees within the rural landscape would likely complement or possibly enhance the conservation value of rural landscapes for koalas.

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23

Phillips, Stephen. "Differing mortality rates in two concurrently radio-tracked populations of koala (Phascolarctos cinereus)". Australian Mammalogy 40, n. 2 (2018): 198. http://dx.doi.org/10.1071/am16047.

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Abstract (sommario):

Radio-tracking studies enable insights into factors that contribute to koala mortality. Two radio-tracking studies investigating the impacts of disturbance events on koalas were undertaken in different areas over the same period. Both studies employed similar techniques for koala capture, processing and monitoring. In one study, none of nine koalas died during a 5-month monitoring program following their translocation into a new habitat area, while in the second study 6 of 11 koalas died over the same period during an in situ impact-monitoring study. The two populations differed morphologically and genetically: that with the higher mortality rate notable for a smaller head and neck circumference and lower genetic diversity. Differing outcomes from the two studies lend support to a hypothesis that inbreeding and the loss of genetic information may predispose some individuals and/or populations of koalas to an elevated stress response and/or increased susceptibility to disease, the expression of which may become exacerbated in the presence of ongoing disturbance or novel stressors that can include research activities. If this is the case, the endocrinology and genetic structure of free-ranging koala populations needs to be afforded greater consideration in terms of predicting a given population’s immunological response to potential isolation and/or disturbance events.

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24

Sullivan, B. J., G. S. Baxter, A. T. Lisle, L. Pahl e W. M. Norris. "Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. IV. Abundance and conservation status". Wildlife Research 31, n. 1 (2004): 19. http://dx.doi.org/10.1071/wr02037.

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Abstract (sommario):

Urban encroachment on dense, coastal koala populations has ensured that their management has received increasing government and public attention. The recently developed National Koala Conservation Strategy calls for maintenance of viable populations in the wild. Yet the success of this, and other, conservation initiatives is hampered by lack of reliable and generally accepted national and regional population estimates. In this paper we address this problem in a potentially large, but poorly studied, regional population in the State that is likely to have the largest wild populations. We draw on findings from previous reports in this series and apply the faecal standing-crop method (FSCM) to derive a regional estimate of more than 59 000 individuals. Validation trials in riverine communities showed that estimates of animal density obtained from the FSCM and direct observation were in close agreement. Bootstrapping and Monte Carlo simulations were used to obtain variance estimates for our population estimates in different vegetation associations across the region. The most favoured habitat was riverine vegetation, which covered only 0.9% of the region but supported 45% of the koalas. We also estimated that between 1969 and 1995 ~30% of the native vegetation associations that are considered as potential koala habitat were cleared, leading to a decline of perhaps 10% in koala numbers. Management of this large regional population has significant implications for the national conservation of the species: the continued viability of this population is critically dependent on the retention and management of riverine and residual vegetation communities, and future vegetation-management guidelines should be cognisant of the potential impacts of clearing even small areas of critical habitat. We also highlight eight management implications.

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Santamaria, Flavia, Rupert Palme, Rolf Schlagloth, Edith Klobetz-Rassam e Joerg Henning. "Seasonal Variations of Faecal Cortisol Metabolites in Koalas in South East Queensland". Animals 11, n. 6 (31 maggio 2021): 1622. http://dx.doi.org/10.3390/ani11061622.

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Abstract (sommario):

The Koala (Phascolarctos cinereus) is an endemic marsupial inhabiting four states of Australia. Urbanisation, declining habitat, drought and fires are threatening the survival of this flagship species. These threats may cause acute and chronic stress in koalas, which might also be associated with occurrence of infectious diseases in koala populations. Stress may induce an increase in cortisol reflected in increased faecal cortisol metabolite (FCM) values. To be able to use faecal cortisol metabolites to measure stress levels in this species, our aim was to determine baseline values for males and females during breeding and non-breeding season. A total of 351 defecations were collected fortnightly, twice a day, for 12 months from koalas at a wildlife facility in South East Queensland. Samples were analysed with three different enzyme immunoassays (EIAs): a cortisol, 5α-pregnane-3β,11β,21-triol-20-one (37e) and tetrahydrocorticosterone (50c) EIA. The latter, which also reacts with tetrahydrocortisol, the main metabolite in koala faeces, was found to have the highest biological sensitivity and, therefore, is the most suitable EIA to measure stress levels in koalas. Utilising this EIA, we found significant differences (p < 0.05) in FCM values between males and females, breeding and non-breeding season, and between morning and evening samples. Values of faecal cortisol metabolites established in stress-free koalas in this study can serve as a reference for future studies in koalas.

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Peel, Emma, Yuanyuan Cheng, Julianne T. Djordjevic, Denis O’Meally, Mark Thomas, Michael Kuhn, Tania C. Sorrell, Wilhelmina M. Huston e Katherine Belov. "Koala cathelicidin PhciCath5 has antimicrobial activity, including against Chlamydia pecorum". PLOS ONE 16, n. 4 (14 aprile 2021): e0249658. http://dx.doi.org/10.1371/journal.pone.0249658.

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Abstract (sommario):

Devastating fires in Australia over 2019–20 decimated native fauna and flora, including koalas. The resulting population bottleneck, combined with significant loss of habitat, increases the vulnerability of remaining koala populations to threats which include disease. Chlamydia is one disease which causes significant morbidity and mortality in koalas. The predominant pathogenic species, Chlamydia pecorum, causes severe ocular, urogenital and reproductive tract disease. In marsupials, including the koala, gene expansions of an antimicrobial peptide family known as cathelicidins have enabled protection of immunologically naïve pouch young during early development. We propose that koala cathelicidins are active against Chlamydia and other bacteria and fungi. Here we describe ten koala cathelicidins, five of which contained full length coding sequences that were widely expressed in tissues throughout the body. Focusing on these five, we investigate their antimicrobial activity against two koala C. pecorum isolates from distinct serovars; MarsBar and IPTaLE, as well as other bacteria and fungi. One cathelicidin, PhciCath5, inactivated C. pecorum IPTaLE and MarsBar elementary bodies and significantly reduced the number of inclusions compared to the control (p<0.0001). Despite evidence of cathelicidin expression within tissues known to be infected by Chlamydia, natural PhciCath5 concentrations may be inadequate in vivo to prevent or control C. pecorum infections in koalas. PhciCath5 also displayed antimicrobial activity against fungi and Gram negative and positive bacteria, including methicillin-resistant Staphylococcus aureus (MRSA). Electrostatic interactions likely drive PhciCath5 adherence to the pathogen cell membrane, followed by membrane permeabilisation leading to cell death. Activity against E. coli was reduced in the presence of 10% serum and 20% whole blood. Future modification of the PhciCath5 peptide to enhance activity, including in the presence of serum/blood, may provide a novel solution to Chlamydia infection in koalas and other species.

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Wu, Huiying, Noam Levin, Leonie Seabrook, Ben Moore e Clive McAlpine. "Mapping Foliar Nutrition Using WorldView-3 and WorldView-2 to Assess Koala Habitat Suitability". Remote Sensing 11, n. 3 (22 gennaio 2019): 215. http://dx.doi.org/10.3390/rs11030215.

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Abstract (sommario):

Conservation planning and population assessment for widely-distributed, but vulnerable, arboreal folivore species demands cost-effective mapping of habitat suitability over large areas. This study tested whether multispectral data from WorldView-3 could be used to estimate and map foliar digestible nitrogen (DigN), a nutritional measure superior to total nitrogen for tannin-rich foliage for the koala (Phascolarctos cinereus). We acquired two WorldView-3 images (November 2015) and collected leaf samples from Eucalyptus woodlands in semi-arid eastern Australia. Linear regression indicated the normalized difference index using bands “Coastal” and “NIR1” best estimated DigN concentration (% dry matter, R2 = 0.70, RMSE = 0.19%). Foliar DigN concentration was mapped for multi-species Eucalyptus open woodlands across two landscapes using this index. This mapping method was tested on a WorldView-2 image (October 2012) with associated koala tracking data (August 2010 to November 2011) from a different landscape of the study region. Quantile regression showed significant positive relationship between estimated DigN and occurrence of koalas at 0.999 quantile (R2 = 0.63). This study reports the first attempt to use a multispectral satellite-derived spectral index for mapping foliar DigN at a landscape-scale (100s km2). The mapping method can potentially be incorporated in mapping and monitoring koala habitat suitability for conservation management.

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Lollback, Gregory W., J. Guy Castley, Alexa C. Mossaz e Jean-Marc Hero. "Fine-scale changes in spatial habitat use by a low-density koala population in an isolated periurban forest remnant". Australian Mammalogy 40, n. 1 (2018): 84. http://dx.doi.org/10.1071/am16036.

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Abstract (sommario):

Koala (Phascolarctos cinereus) populations in south-east Queensland are in decline. Although various studies have looked at broad-scale tree preference and habitat quality, there has been little attempt to quantify fine-scale activity shifts from one year to the next or examination of activity at the mesoscale. This study quantified koala activity levels in a 909-ha forest patch at Karawatha Forest Park, in south Brisbane. The Spot Assessment Technique was used to quantify activity and tree selection on 33 long-term monitoring plots in 2009 and 2010. In total, 843 trees were searched and koala pellets were found underneath 34 and 47 trees in 2009 and 2010, respectively. A higher proportion of pellets was found underneath Eucalyptus tindaliae and E. fibrosa and there was weak selection for larger trees. A low occurrence of revisits and a minor shift in activity distribution from 2009 to 2010 indicate that the koala population exists at a low density. Rapid declines in koala populations are occurring in primary habitats. Hence, stable low-density koala populations are important for maintaining genetic diversity and connectivity in fragmented urban landscapes.

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Joyce, Briony A., Michaela D. J. Blyton, Stephen D. Johnston, Paul R. Young e Keith J. Chappell. "Koala retrovirus genetic diversity and transmission dynamics within captive koala populations". Proceedings of the National Academy of Sciences 118, n. 38 (7 settembre 2021): e2024021118. http://dx.doi.org/10.1073/pnas.2024021118.

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Abstract (sommario):

Koala populations are currently in rapid decline across Australia, with infectious diseases being a contributing cause. The koala retrovirus (KoRV) is a gammaretrovirus present in both captive and wild koala colonies that presents an additional challenge for koala conservation in addition to habitat loss, climate change, and other factors. Currently, nine different subtypes (A to I) have been identified; however, KoRV genetic diversity analyses have been limited. KoRV is thought to be exogenously transmitted between individuals, with KoRV-A also being endogenous and transmitted through the germline. The mechanisms of exogenous KoRV transmission are yet to be extensively investigated. Here, deep sequencing was employed on 109 captive koalas of known pedigree, housed in two institutions from Southeast Queensland, to provide a detailed analysis of KoRV transmission dynamics and genetic diversity. The final dataset included 421 unique KoRV sequences, along with the finding of an additional subtype (KoRV-K). Our analysis suggests that exogenous transmission of KoRV occurs primarily between dam and joey, with evidence provided for multiple subtypes, including nonendogenized KoRV-A. No evidence of sexual transmission was observed, with mating partners found to share a similar number of sequences as unrelated koala pairs. Importantly, both distinct captive colonies showed similar trends. These findings indicate that breeding strategies or antiretroviral treatment of females could be employed as effective management approaches in combating KoRV transmission.

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Tucker, G., A. Melzer e W. Ellis. "The development of habitat selection by subadult koalas". Australian Journal of Zoology 55, n. 5 (2007): 285. http://dx.doi.org/10.1071/zo07035.

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Abstract (sommario):

Dispersal by subadults is the principal source of gene flow between groups of koalas in Queensland, so understanding the behaviour of these immature animals is a priority for understanding the ecology of the species. Recent reports postulate that dispersing young koalas may inherit maternal tree selection, but avoid competing with adults. We compared the tree use and diet of adult female koalas with that of their offspring on St Bees Island, Queensland, using radio-tracking and faecal cuticle analysis, to examine this prediction. Koalas at St Bees Island used both fodder and non-fodder species during daytime, moving into fodder species at night. Koala diets were dominated by Eucalyptus tereticornis with E. platyphylla and Corymbia intermedia also represented. Utilisation of daytime tree species was diverse, but at night koalas were found almost exclusively in those species present in their diet. Use of trees during daytime by natal young and young adult koalas were similar to that of maternal adults, but tree use by intermediate stages (independent and dispersing young) during daytime varied from that of the mothers. This resource separation indicates that if tree utilisation for resting is learned from the mother, young animals are excluded from preferred trees while dispersing.

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Gallahar, Nicole, Kellie Leigh e David Phalen. "Koala tree selection in a mixed-tenure landscape and post-fire implications". Wildlife Research 48, n. 8 (2021): 737. http://dx.doi.org/10.1071/wr20206.

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Abstract (sommario):

Abstract ContextThe more frequent and intense bushfires predicted under climate change are likely to heavily impact koalas living inside protected areas and intact forests, which makes koala habitat in asset protection zones more important. Understanding how koalas use different habitats in a mixed-tenure landscape can inform effective conservation management. AimsThe aims of this study were to determine (1) the species and size of trees used by koalas, (2) whether choice of daytime trees was affected by available proportions of tree species and sizes in koala home ranges, and (3) whether developed land was used as frequently as native forest. MethodsTree use by koalas was determined by radio-tracking 10 koalas for an average of 12 months and recording the species and diameter of trees they occupied. To compare the proportions of tree species used by koalas with those available, tree availability was measured using random quadrats in the home ranges of five koalas that used forested areas extensively. The habitats used by 10 koalas were classified as native forest or developed land to investigate the importance of human-modified areas. Key resultsEucalyptus punctata was a preferred tree species, but each individual used four to nine species. Tree species were not chosen solely on the basis of available proportions; some species were selected preferentially. Half of the koalas used more developed land than native forest. Koalas preferentially used trees with larger diameters than the mean of available trees, and selected larger trees in developed areas than in native forest and when re-using trees. ConclusionsDespite the higher availability of trees in protected native forest at the site, 70% of the koalas used developed land in and around asset protection zones. Koalas whose home ranges were geographically close, but had different soil types and vegetation communities, were able to utilise different tree species. ImplicationsKoalas would benefit from protection of remnant native forests containing preferred trees on shale cap soil and conservation of native vegetation corridors along fence lines and in paddocks in developed areas because they are valuable resources and connect patchy landscapes. Protecting koalas on developed land improves their likelihood of surviving bushfires, allowing recolonisation of surrounding protected areas.

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Melzer, Alistair, Romane Cristescu, William Ellis, Sean FitzGibbon e Gabriella Manno. "The habitat and diet of koalas (Phascolarctos cinereus) in Queensland". Australian Mammalogy 36, n. 2 (2014): 189. http://dx.doi.org/10.1071/am13032.

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Abstract (sommario):

Descriptions of koala (Phascolarctos cinereus) habitat and diet from 11 sites across Queensland are presented. Koala activity was recorded from 49 regional ecosystems across nine land zones and five bioregions. Thirty-four tree species were identified from an examination of leaf cuticle fragments in faecal pellets. Although the species were from three families and seven genera, 44% of browse species (15) belonged to the myrtaceous subgenus Symphomyrtus. Eleven of these contributed most of the koala diet across all sites. However, most species were present in minor or trace dietary elements. There was also a large number of unidentified species or dietary elements, all of which were usually present in trace amounts. The importance of these minor and trace components is not known. Diet at some sites was founded on a single eucalypt species. Here the likelihood of those sites’ browse resources being lost or degraded by stochastic events, as climate variability increases, raises questions about the persistence of the resident koala populations.

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Lunney, Daniel, Martin Predavec, Indrie Miller, Ian Shannon, Mark Fisher, Chris Moon, Alison Matthews, John Turbill e Jonathan R. Rhodes. "Interpreting patterns of population change in koalas from long-term datasets in Coffs Harbour on the north coast of New South Wales". Australian Mammalogy 38, n. 1 (2016): 29. http://dx.doi.org/10.1071/am15019.

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Abstract (sommario):

We examined a long-term, repeat dataset for the koala population within Coffs Harbour Local Government Area. Analyses of these data have led to the conclusion that, following a perceived population decline in the 1980s, the koala population of Coffs Harbour has endured between 1990 and 2011 and showed no evidence of a precipitous decline during this period. Rather, the population change is best characterised as stable to slowly declining. This conclusion appears to contradict a common view of recent koala population declines on the north coast of New South Wales. There are four possible explanations for the population’s apparent stability: that conservation efforts and planning regulations have been effective; that surviving adults are persisting in existing home ranges in remnant habitat; that the broader Coffs Harbour population is operating as a ‘source and sink’ metapopulation; and/or that the standard survey methods employed are not sufficiently sensitive to detect small population changes. These findings do not mean there is no need for future conservation efforts aimed at koalas in Coffs Harbour; however, such efforts will need to better understand and account for a koala population that can be considered to be stable to slowly declining.

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Goldingay, Ross L., e Barbara Dobner. "Home range areas of koalas in an urban area of north-east New South Wales". Australian Mammalogy 36, n. 1 (2014): 74. http://dx.doi.org/10.1071/am12049.

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Abstract (sommario):

Conserving wildlife within urban areas requires knowledge of habitat requirements and population processes, and the management of threatening factors. The koala (Phascolarctos cinereus) is one species that is adversely affected by urban development. Sick and injured koalas in the Lismore urban area are regularly taken into care. We radio-tracked koalas released from care in order to estimate home-range areas and to determine their fate. Koalas were tracked for periods of 90–742 days; 7 of 10 survived for a period of at least one year. Home ranges defined by the minimum convex polygon (MCP100%) were large (mean ± s.e. = 37.4 ± 8.2 ha). Analysis using the 95% Fixed Kernel revealed home-range areas of 8.0 ± 1.7 ha. Analysis of the habitat composition of each MCP home range showed that they included 4.3 ± 0.9 ha of primary habitat (dominated by their primary food trees). These home ranges contained 27.6 ± 6.8 ha of non-habitat (cleared or developed land). Koalas crossed roads within their home ranges at least 5–53 times; one crossed the Bruxner Highway near a roundabout at least 32 times over his 2-year tracking period. Future management should include strategic food tree planting that enhances habitat connectivity and minimises the risk of car strike or dog attack.

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Ellis, Murray V., Susan G. Rhind, Martin Smith e Daniel Lunney. "Changes in the distribution of reports of the koala (Phascolarctos cinereus) after 16 years of local conservation initiatives at Gunnedah, north-west New South Wales, Australia". Pacific Conservation Biology 23, n. 1 (2017): 63. http://dx.doi.org/10.1071/pc16004.

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Abstract (sommario):

In the early 1990s the koala became the mascot for a revegetation program to control salinity on agricultural land around Gunnedah in New South Wales, and a snapshot of the koala’s distribution in the shire was collected at that time, mainly via a mail survey. After the success of tree plantings in the 1990s, the koala population of the Liverpool Plains became a focus of increasing local conservation efforts, as well as research to explain koala population dynamics. This included a repeat mail survey conducted in 2006, which enabled the comparison of the reported distributions to be undertaken. These two citizen science surveys had different response rates but both produced extensive datasets. By 2006, koalas were reported from a wider extent than in 1990, particularly to the north and east of the town, and in more developed agricultural areas, but with highest densities in areas with more than 25% wooded vegetation. In 1990, koalas were reported mostly from locations that were surrounded by more than 40% wooded vegetation with the core of the distribution being on the basalt hills south of the town of Gunnedah. Koalas were also reported with increased relative frequency in the town, and this formed the core of the reported sightings at that time. There were still no reports from many of the vegetated hilly margins of the shire. The observed changes in the pattern of reporting reflects the actual distribution of koalas intersected with the likelihood of observation and the willingness of people to report koalas, and also identify the areas that may be under-sampled to determine the true habitat breath of koalas in the area.

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Madani, G. F., K. R. Ashman, V. S. A. Mella e D. A. Whisson. "A review of the 'noose and flag' method to capture free-ranging koalas". Australian Mammalogy 42, n. 3 (2020): 341. http://dx.doi.org/10.1071/am19064.

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Abstract (sommario):

The capture of free-ranging individuals is often needed for research, population management and health assessment. Because of its iconic and threatened species status, methods to capture koalas (Phascolarctos cinereus) receive disproportionate scrutiny. We collated data on koala capture frequency, duration held by noose and incidents from six studies of koalas in Victoria and New South Wales that all used the ‘noose and flag’ method as the primary method of capture. Adverse events occurred in less than 1% of all captures (7 of 1236). Mean capture time in three of four locations recording duration held by noose was less than five minutes, minimising the duration of distress to the koala while allowing researchers to maintain control over the animal. The exception to this was a study in far south-west Victoria where trees were tall and koalas were relatively unresponsive to flagging, resulting in a longer mean duration held by noose (11.2 minutes). The reviewed capture data of the ‘noose and flag’ method suggest that this is an effective and safe capture method, allowing for capture of multiple individuals in a short period, and suitable for most habitat types and situations.

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Briscoe, Natalie J., Kathrine A. Handasyde, Stephen R. Griffiths, Warren P. Porter, Andrew Krockenberger e Michael R. Kearney. "Tree-hugging koalas demonstrate a novel thermoregulatory mechanism for arboreal mammals". Biology Letters 10, n. 6 (giugno 2014): 20140235. http://dx.doi.org/10.1098/rsbl.2014.0235.

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How climate impacts organisms depends not only on their physiology, but also whether they can buffer themselves against climate variability via their behaviour. One of the way species can withstand hot temperatures is by seeking out cool microclimates, but only if their habitat provides such refugia. Here, we describe a novel thermoregulatory strategy in an arboreal mammal, the koala Phascolarctos cinereus. During hot weather, koalas enhanced conductive heat loss by seeking out and resting against tree trunks that were substantially cooler than ambient air temperature. Using a biophysical model of heat exchange, we show that this behaviour greatly reduces the amount of heat that must be lost via evaporative cooling, potentially increasing koala survival during extreme heat events. While it has long been known that internal temperatures of trees differ from ambient air temperatures, the relevance of this for arboreal and semi-arboreal mammals has not previously been explored. Our results highlight the important role of tree trunks as aboveground ‘heat sinks’, providing cool local microenvironments not only for koalas, but also for all tree-dwelling species.

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Bentley, P. D., e T. D. Penman. "Is there an inherent conflict in managing fire for people and conservation?" International Journal of Wildland Fire 26, n. 6 (2017): 455. http://dx.doi.org/10.1071/wf16150.

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Wildfires are a natural disturbance in many ecosystems, creating challenges for land management agencies who need to simultaneously reduce risk to people and maintain ecological values. Here we use the PHOENIX RapidFire fire behaviour simulator to compare fuel treatment strategies that meet the twin objectives of reducing wildfire risk to human settlements and a fire sensitive endangered species, the koala (Phascolarctos cinereus) in south-eastern Australia. The local koala population is in decline and a conservation management plan is being prepared to exclude wildfire for a 10-year period to assist with population recovery. Twelve scenarios developed by the land management agencies were compared using four indicators: wildfire size; burn probability; impact from exposure to fire; and treatment cost. Compared with the current risk setting, three treatment scenarios were found to reduce wildfire size and burn probability concurrently to both people and koalas. These strategies worked by increasing the landscape area treated, which came with increased financial cost. However, the impact from exposure to fire for both property and koala habitat remains high. Additional complementary strategies beyond landscape fuel reductions are needed to reduce impact from exposure in the event of a wildfire.

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Munks, SA, R. Corkrey e WJ Foley. "Characteristics of Arboreal Marsupial Habitat in the Semi-Arid Woodlands of Northern Queensland." Wildlife Research 23, n. 2 (1996): 185. http://dx.doi.org/10.1071/wr9960185.

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The distribution of the koala (Phascolarctos cinereus) and the common brushtail possum (Trichosurus vulpecula) within the Prairie-Torrens Creek Alluvials province of the Desert Upland region of north-western Queensland was examined. The optimum habitat for each species as indicated by the occurrence of faecal pellet groups was found to be that associated with creek-lines. However, other land types were also used by each species to varying degrees. The relationship between various habitat variables and pellet group counts was investigated using Multiple regression and a Generalised linear model. Proximity to creek-bed, total basal area of trees, species richness and Acacia basal area (negative) best explained the occurrence of koalas. Proximity to creek-bed, Acacia basal area (negative), total basal area of trees, and available water (negative) best explained the occurrence of brushtail possums. In contrast to studies of arboreal species in the moist-south-eastern forests of Australia no relationship was found between foliar nutrient concentrations and the occurrence of koalas or brushtail possums. However, a significant relationship was found between leaf water concentration and the occurrence of koalas. It is suggested that water availability is the paramount factor defining preferred arboreal habitat in arid and semi-arid woodlands.

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40

Mitchell, Dave L., Mariela Soto-Berelov e Simon D. Jones. "Regional Variation in Forest Canopy Height and Implications for Koala (Phascolarctos cinereus) Habitat Mapping and Forest Management". Forests 12, n. 11 (29 ottobre 2021): 1494. http://dx.doi.org/10.3390/f12111494.

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Previous research has shown that the Koala (Phascolarctos cinereus) prefers larger trees, potentially making this a key factor influencing koala habitat quality. Generally, tree height is considered at regional scales which may overlook variation at patch or local scales. In this study, we aimed to derive a set of parameters to assist in classifying koala habitat in terms of tree height, which can then be used as an overlay for existing habitat maps. To determine canopy height variation within a specific forest community across a broad area in eastern Australia, we used freely available Airborne Laser Scanning (ALS) data and adopted a straightforward approach by extracting maximum-height ALS returns within a total of 288 30 m × 30 m “virtual” ALS plots. Our findings show that while maximum tree heights generally fall within published regional-scale parameters (mean height 33.2 m), they vary significantly between subregions (mean height 28.8–39.0 m), within subregions (e.g., mean height 21.3–29.4 m), and at local scales, the tree heights vary in response to previous land-use (mean height 28.0–34.2 m). A canopy height dataset useful for habitat management needs to recognise and incorporate these variations. To examine how this information might be synthesised into a usable map, we used a wall-to-wall canopy height map derived from ALS to investigate spatial and nonspatial clustering techniques that capture canopy height variability at both intra-subregional (100s of hectares) and local (60 hectare) scales. We found that nonspatial K-medians clustering with three or four height classes is suited to intra-subregional extents because it allows for simultaneous assessment and comparison of multiple forest community polygons. Spatially constrained clustering algorithms are suited to individual polygons, and we recommend the use of the Redcap algorithm because it delineates contiguous height classes recognisable on a map. For habitat management, an overlay combining these height classification approaches as separate attributes would provide the greatest utility at a range of scales. In addition to koala habitat management, canopy height maps could also assist in managing other fauna; identifying forest disturbance, regenerating forest, and old-growth forest; and identifying errors in existing forest maps.

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Dahlhausen, Katherine E., Guillaume Jospin, David A. Coil, Jonathan A. Eisen e Laetitia G. E. Wilkins. "Isolation and sequence-based characterization of a koala symbiont: Lonepinella koalarum". PeerJ 8 (20 ottobre 2020): e10177. http://dx.doi.org/10.7717/peerj.10177.

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Koalas (Phascolarctos cinereus) are highly specialized herbivorous marsupials that feed almost exclusively on Eucalyptus leaves, which are known to contain varying concentrations of many different toxic chemical compounds. The literature suggests that Lonepinella koalarum, a bacterium in the Pasteurellaceae family, can break down some of these toxic chemical compounds. Furthermore, in a previous study, we identified L. koalarum as the most predictive taxon of koala survival during antibiotic treatment. Therefore, we believe that this bacterium may be important for koala health. Here, we isolated a strain of L. koalarum from a healthy koala female and sequenced its genome using a combination of short-read and long-read sequencing. We placed the genome assembly into a phylogenetic tree based on 120 genome markers using the Genome Taxonomy Database (GTDB), which currently does not include any L. koalarum assemblies. Our genome assembly fell in the middle of a group of Haemophilus, Pasteurella and Basfia species. According to average nucleotide identity and a 16S rRNA gene tree, the closest relative of our isolate is L. koalarum strain Y17189. Then, we annotated the gene sequences and compared them to 55 closely related, publicly available genomes. Several genes that are known to be involved in carbohydrate metabolism could exclusively be found in L. koalarum relative to the other taxa in the pangenome, including glycoside hydrolase families GH2, GH31, GH32, GH43 and GH77. Among the predicted genes of L. koalarum were 79 candidates putatively involved in the degradation of plant secondary metabolites. Additionally, several genes coding for amino acid variants were found that had been shown to confer antibiotic resistance in other bacterial species against pulvomycin, beta-lactam antibiotics and the antibiotic efflux pump KpnH. In summary, this genetic characterization allows us to build hypotheses to explore the potentially beneficial role that L. koalarum might play in the koala intestinal microbiome. Characterizing and understanding beneficial symbionts at the whole genome level is important for the development of anti- and probiotic treatments for koalas, a highly threatened species due to habitat loss, wildfires, and high prevalence of Chlamydia infections.

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Hewson, Michael, Flavia Santamaria e Alistair Melzer. "Field Testing Satellite-Derived Vegetation Health Indices for a Koala Habitat Managers Toolkit". Remote Sensing 14, n. 9 (28 aprile 2022): 2119. http://dx.doi.org/10.3390/rs14092119.

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A Central Queensland University (CQU) partnership with the Queensland Government National Park management agency has developed a koala (Phascolarctos cinereus) habitat managers’ toolkit for vegetation health assessment. Private and public landholders use the field-based toolkit to assess habitat suitability or monitor conservation outcomes for the koala—an iconic Australian arboreal herbivorous marsupial. The toolkit was upgraded recently with instructions to process European Space Agency (ESA) Sentinel-2 multispectral satellite-derived selected vegetation maps for areal vegetation health trend monitoring. A field campaign sought to validate the relatively coarse spatial resolution derived indices (photosynthetic health, leaf area index and leaf water content) to verify their suitability for the habitat management decision-support toolkit. Other user requirement-driven criteria for including remote sensing in the toolkit were imagery and associated processing software costs and ease of map production for habitat managers without cost-effective access to spatial science skills. Despite moderate-to-low field and image vegetation proxy correlations, discussing the results with stakeholders indicates that, at a landscape scale, the use of cost-free, suitable temporal resolution, 10-m spatial resolution imagery is satisfactory when aligned with the design outcomes of a habitat health toolkit.

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Phillips, Stephen, John Callaghan e Valerie Thompson. "The tree species preferences of koalas (Phascolarctos cinereus) inhabiting forest and woodland communities on Quaternary deposits in the Port Stephens area, New South Wales". Wildlife Research 27, n. 1 (2000): 1. http://dx.doi.org/10.1071/wr98054.

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An assessment of the tree species preferences of koalas inhabiting forest and woodland communities growing on Quaternary deposits in the Port Stephens area, New South Wales, was undertaken between November 1994 and March 1996. Using a plot-based methodology, 3847 trees were sampled, comprising 15 Eucalyptus species and 17 species of non-eucalypt. Evidence of tree use by koalas, specifically the presence of koala faecal pellets, was recorded from beneath 10 Eucalyptus species and 9 species of non-eucalypt. Tree species preferences were determined by analyses of log- likelihood ratios derived from data based on the presence/absence of koala faecal pellets, rather than on gross counts. This approach confirmed significant variation in the levels of utilisation amongst and between different tree species, and that two in particular – swamp mahogany (E. robusta) and drooping red gum (E. parramattensis) – were most preferred. Increases in the levels of use of other tree species were also positively associated with the presence of E. robusta and/or E. parramattensis. Levels of utilisation of E. robusta and E. parramattensis did not alter significantly in response to changes in their respective densities, suggesting that the relative abundance of both was important in terms of understanding the carrying capacity of vegetation communities utilised by koalas. The results have established the success with which an enumerative approach to the interpretation of faecal pellet data can be utilised to clarify the tree species preferences of koalas. Application of the approach for habitat assessment and mapping purposes is also discussed.

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Hynes, E. F., K. A. Handasyde, Geoff Shaw e Marilyn B. Renfree. "Levonorgestrel, not etonogestrel, provides contraception in free-ranging koalas". Reproduction, Fertility and Development 22, n. 6 (2010): 913. http://dx.doi.org/10.1071/rd09253.

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Management of high-density koala (Phascolarctos cinereus) populations is essential because of the browsing damage they inflict on their habitat. We have tested two types of gestagen implant, namely levonorgestrel and etonogestrel, as contraceptives for koalas. Free-ranging female koalas were given either a control, levonorgestrel (70 mg) or etonogestrel (34 or 68 mg) implant before the breeding season. Koalas were monitored every 4–12 weeks for births. Plasma progesterone was measured and a cytological smear of the urogenital sinus was taken. Fertility was high in the control group and the two etonogestrel-treated groups, with approximately 90% of females giving birth. In contrast, no levonorgestrel-treated female produced young during the study. Removal of levonorgestrel implants from six females reversed the contraceptive effect in the next breeding season, whereas the eight females in which the levonorgestrel implants were left in remained infertile for six breeding seasons. Vaginal cytology showed evidence of oestrous cycles during the breeding season in all females from all groups and there was no difference seen in the prevalence of cornified epithelial cells in the oestrous smears. This indirectly suggests that levonorgestrel does not prevent follicular development and oestrous cycling. Plasma progesterone in levonorgestrel-treated females remained low all year, but rose in controls concurrent with the onset of the breeding season. This suggests that levonorgestrel prevents pregnancy by blocking ovulation. Etonogestrel had absolutely no contraceptive effect at the two doses delivered and so is not suitable for controlling koala populations. In contrast, levonorgestrel was effective as a long-term, reversible contraceptive in wild koalas.

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Sullivan, B. J., G. S. Baxter e A. T. Lisle. "Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. III. Broad-scale patterns of habitat use". Wildlife Research 30, n. 6 (2003): 583. http://dx.doi.org/10.1071/wr02036.

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To date there have been few quantitative studies of the distribution of, and relative habitat utilisation by, koalas in the mulgalands of Queensland. To examine these parameters we applied habitat-accessibility and relative habitat-utilisation indices to estimates of faecal pellet density sampled at 149 sites across the region. Modelling the presence of pellets using logistic regression showed that the potential range of accessible habitats and relative habitat use varied greatly across the region, with rainfall being probably the most important determinant of distribution. Within that distribution, landform and rainfall were both important factors affecting habitat preference. Modelling revealed vastly different probabilities of finding a pellet under trees depending on the tree species, canopy size, and location within the region.

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Knott, Tiffany, Daniel Lunney, Dionne Coburn e John Callaghan. "An ecological history of Koala habitat in Port Stephens Shire and the Lower Hunter on the Central Coast of New South Wales, 1801-1998". Pacific Conservation Biology 4, n. 4 (1998): 354. http://dx.doi.org/10.1071/pc980354.

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This paper describes the vegetation of Port Stephens Shire and environs at the time of European settlement, defines the sequence of vegetation clearance since that time, and estimates the extent to which the pre-European vegetation represented Koala habitat. A study of historical records, newspapers, documents and reports was undertaken in conjunction with interviews with long-standing Port Stephens residents. The historical records show that Koalas were widespread and common during early settlement. Reconstruction of the original vegetation was based on descriptions by early explorers and settlers from the early 1800s, when settlement commenced. Most of the land on either side of the Hunter River was vegetated by Shrubby Tall Open Forest intermingling with either Open Swamp Forest, or VineFern Closed Forest, or cedar brush. The first area to be settled was the alluvial land on the banks of the rivers where the soil was fertile and well watered. Settlement proceeded rapidly in the western part of the Shire from the early 1800s, concentrating on the Lower Hunter and Williams Rivers, but not progressing to the east until much later (mid to late 1800s). The historical record was sufficiently detailed to allow reconstruction of Koala habitat distribution at the time of settlement. Ecological history is now emerging as a discipline that has far more than curiosity value. It can provide the essential framework for conserving and restoring those landscapes exploited in the first century of European settlement.

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Cork, Steven J., Ian D. Hume e William J. Foley. "Improving Habitat Models and Their Utility in Koala Conservation". Conservation Biology 14, n. 3 (giugno 2000): 660–68. http://dx.doi.org/10.1046/j.1523-1739.2000.99389.x.

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David, Patricia, Sharyn Rundle-Thiele, Bo Pang, Kathy Knox, Joy Parkinson e Felix Hussenoeder. "Engaging the Dog Owner Community in the Design of an Effective Koala Aversion Program". Social Marketing Quarterly 25, n. 1 (13 gennaio 2019): 55–68. http://dx.doi.org/10.1177/1524500418821583.

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Introduction: This article outlines a dog owner–focused social marketing pilot program implemented in 2017, which aimed to reduce koala and domestic dog interactions in one local city council in Australia. Literature: Dog attacks and predation are the third most common cause of death in koalas after habitat loss and vehicle strikes. Programs aiming to reduce wildlife and domestic pet interactions frequently neglect human dimensions, and social sciences have been called upon to complement conservation efforts. Methods: Developed in consultation with dog training experts and the local regional council Leave It was based on input from 41 dog owners. Leave It was a 4-week training program priced at AUD$150 that was delivered by local dog trainers who had previously received specialized koala aversion training. Findings: Co-design results indicated that the social marketing pilot program needed to emphasize training, be positive, and be dog and not koala-focused. A fun, positive dog-focused event, supported by dog retailers, entertainers, and food service providers, was held in June 2017 to launch the Leave It program. Outcome evaluations for Leave It indicated a statistically significant increase in wildlife aversion–related behaviors (stay, come back every time/some of the time, and stay quiet on command). Process evaluation indicated that people enjoyed the dog-focused event and the opportunity to seek training and obedience advice. Conclusions: Co-designing the program with dog owners in the local council area engaged community members, making them contributors rather than program participants. The program had a dog focus rather than wildlife focus as recommended by dog owners.

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Mitchell, Dave L., Mariela Soto‐Berelov, William T. Langford e Simon D. Jones. "Factors confounding koala habitat mapping at multiple decision‐making scales". Ecological Management & Restoration 22, n. 2 (16 marzo 2021): 171–82. http://dx.doi.org/10.1111/emr.12468.

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Bryan, Brett Anthony. "A Generic Method for Identifying Regional Koala Habitat using GIS". Australian Geographical Studies 35, n. 2 (luglio 1997): 125–39. http://dx.doi.org/10.1111/1467-8470.00014.

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