Journal articles on the topic 'Koalas'
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1
Schmid, LM, KL Schmid, and B. Brown. "Behavioural determination of visual function in the Koala (Phascolarctos cinereus)." Wildlife Research 18, no. 3 (1991): 367. http://dx.doi.org/10.1071/wr9910367.
Abstract:
A behavioural estimate of the koala's dependence on vision was made using fabric hoods to degrade the vision of ten male koalas. Koalas were placed on the ground in a square enclosure, with a centrally placed 'tree'. With unobstructed vision, the koalas quickly travelled across the ground to the tree and climbed it. However, with severely reduced vision, the koalas would not search for or climb the tree. When their vision was obscured, the koalas tended to raise their forelegs when walking, taking high, reaching steps. The koala appears to require a certain minimum level of vision before climbing trees. Ocular chlamydial infection, which can cause a significant visual loss, may result in similar changes in behaviour and thus contribute to mortality.
2
Dahlhausen, Katherine E., Ladan Doroud, Alana J. Firl, Adam Polkinghorne, and Jonathan A. Eisen. "Characterization of shifts of koala (Phascolarctos cinereus) intestinal microbial communities associated with antibiotic treatment." PeerJ 6 (March 12, 2018): e4452. http://dx.doi.org/10.7717/peerj.4452.
Abstract:
Koalas (Phascolarctos cinereus) are arboreal marsupials native to Australia that eat a specialized diet of almost exclusively eucalyptus leaves. Microbes in koala intestines are known to break down otherwise toxic compounds, such as tannins, in eucalyptus leaves. Infections by Chlamydia, obligate intracellular bacterial pathogens, are highly prevalent in koala populations. If animals with Chlamydia infections are received by wildlife hospitals, a range of antibiotics can be used to treat them. However, previous studies suggested that koalas can suffer adverse side effects during antibiotic treatment. This study aimed to use 16S rRNA gene sequences derived from koala feces to characterize the intestinal microbiome of koalas throughout antibiotic treatment and identify specific taxa associated with koala health after treatment. Although differences in the alpha diversity were observed in the intestinal flora between treated and untreated koalas and between koalas treated with different antibiotics, these differences were not statistically significant. The alpha diversity of microbial communities from koalas that lived through antibiotic treatment versus those who did not was significantly greater, however. Beta diversity analysis largely confirmed the latter observation, revealing that the overall communities were different between koalas on antibiotics that died versus those that survived or never received antibiotics. Using both machine learning and OTU (operational taxonomic unit) co-occurrence network analyses, we found that OTUs that are very closely related to Lonepinella koalarum, a known tannin degrader found by culture-based methods to be present in koala intestines, was correlated with a koala’s health status. This is the first study to characterize the time course of effects of antibiotics on koala intestinal microbiomes. Our results suggest it may be useful to pursue alternative treatments for Chlamydia infections without the use of antibiotics or the development of Chlamydia-specific antimicrobial compounds that do not broadly affect microbial communities.
3
Kayesh, Mohammad Enamul Hoque, Md Abul Hashem, and Kyoko Tsukiyama-Kohara. "Toll-Like Receptor Expression Profiles in Koala (Phascolarctos cinereus) Peripheral Blood Mononuclear Cells Infected with Multiple KoRV Subtypes." Animals 11, no. 4 (April 1, 2021): 983. http://dx.doi.org/10.3390/ani11040983.
Abstract:
Toll-like receptors (TLRs), evolutionarily conserved pattern recognition receptors, play an important role in innate immunity by recognizing microbial pathogen-associated molecular patterns. Koala retrovirus (KoRV), a major koala pathogen, exists in both endogenous (KoRV-A) and exogenous forms (KoRV-B to J). However, the expression profile of TLRs in koalas infected with KoRV-A and other subtypes is yet to characterize. Here, we investigated TLR expression profiles in koalas with a range of subtype infection profiles (KoRV-A only vs. KoRV-A with KoRV-B and/or -C). To this end, we cloned partial sequences for TLRs (TLR2–10 and TLR13), developed real-time PCR assays, and determined TLRs mRNA expression patterns in koala PBMCs and/or tissues. All the reported TLRs for koala were expressed in PBMCs, and variations in TLR expression were observed in koalas infected with exogenous subtypes (KoRV-B and KoRV-C) compared to the endogenous subtype (KoRV-A) only, which indicates the implications of TLRs in KoRV infection. TLRs were also found to be differentially expressed in koala tissues. This is the first report of TLR expression profiles in koala, which provides insights into koala’s immune response to KoRV infection that could be utilized for the future exploitation of TLR modulators in the maintenance of koala health.
4
Ellis, Murray V., Susan G. Rhind, Martin Smith, and 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, no. 1 (2017): 63. http://dx.doi.org/10.1071/pc16004.
Abstract:
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.
5
Dique, David S., Jim Thompson, Harriet J. Preece, Guy C. Penfold, Deidré L. de Villiers, and Ros S. Leslie. "Koala mortality on roads in south-east Queensland: the koala speed-zone trial." Wildlife Research 30, no. 4 (2003): 419. http://dx.doi.org/10.1071/wr02029.
Abstract:
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.
6
Masters, Pip, Toni Duka, Steve Berris, and Graeme Moss. "Koalas on Kangaroo Island: from introduction to pest status in less than a century." Wildlife Research 31, no. 3 (2004): 267. http://dx.doi.org/10.1071/wr03007.
Abstract:
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.
7
Jiang, Alex Zijian, Andrew Tribe, Clive J. C. Phillips, and Peter J. Murray. "Insights from Koala–Cattle Interaction Experiments: Koalas and Cattle May See Each Other as a Disturbance." Animals 12, no. 7 (March 30, 2022): 872. http://dx.doi.org/10.3390/ani12070872.
Abstract:
Koalas are facing many threats and have now been officially listed as endangered. Recently, concerns were raised in anecdotal reports of koalas being killed by livestock, especially cattle. We investigated the significance of cattle as a threat to koala survival via two koala–cattle interaction experiments, from both the koala and cattle perspectives. In the first experiment, we recorded the ranging behaviour of free-ranging, radio-collared koalas prior to, during and after cattle grazed within their usual home range. Koalas decreased their distance travelled and the size of their home range when they shared space with cattle, compared with the period before cattle started grazing within their home range. In the second experiment, we recorded the reactions of cattle towards koalas that they encountered on the ground, using motorised animal models: a model koala mounted on a remote-controlled vehicle and a model dog mounted on the same vehicle, and the vehicle alone. The koala model elicited aggression and fear in cattle, similar to the dog model, whereas their reaction to the vehicle was significantly less aggressive. No actual attacks by the cattle were observed. The results provide experimental evidence that negative koala–livestock interactions occur and indicate that cattle and koalas may see each other as a disturbance.
8
Menkhorst, Peter, David Ramsey, Tim O'Brien, Emily Hynes, and Desley Whisson. "Survival and movements of koalas translocated from an over-abundant population." Wildlife Research 46, no. 7 (2019): 557. http://dx.doi.org/10.1071/wr19090.
Abstract:
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.
9
Marsh, Karen J., Ben D. Moore, Ian R. Wallis, and William J. Foley. "Continuous monitoring of feeding by koalas highlights diurnal differences in tree preferences." Wildlife Research 40, no. 8 (2013): 639. http://dx.doi.org/10.1071/wr13104.
Abstract:
Context It is difficult to measure feeding rates for most wild nocturnal mammalian herbivores. Thus, although koalas are a popular species to study, we have a poor understanding of their activity patterns and feeding ecology. Researchers often assume that the trees that koalas occupy during the day indicate feeding preferences, but they may better reflect preferred resting sites. Aims We recorded the activities of koalas, with an emphasis on their feeding, particularly when they fed, the trees that they fed from, the number of meals they consumed and the variability in these measurements. Methods We continuously monitored eight koalas by audio- and radio-telemetry for 14 consecutive 24-h periods each. We followed two koalas at a time and recorded the trees they visited, when, where and how long they fed, and the size and nutritional composition of the trees in the landscape. Key results Individual koalas varied in how many trees they visited, how many meals they ate and how long they spent feeding during each 24-h period. They preferred Eucalyptus globulus trees during the day, but fed mainly at night, with a preference for E. viminalis. The trees that koalas visited during the day were larger than those that they visited at night. Conclusions The trees that koalas occupied during the day were poor indicators of their diet preferences, whereas the daily feeding activities of individual koalas varied widely. Implications Predicting a koala’s diet from the trees it occupies during the day is fraught with error. Although the trees that koalas rest in are important in the species ecology for reasons other than feeding, we should refrain from using them to predict an animal’s diet. Because feeding activity is difficult to measure, it is probably best done indirectly by analysing leaf-cuticle fragments or waxes in faeces. The substantial day-to-day variation in koala activities also indicates that behavioural and physiological studies of koalas require long monitoring periods – a week or longer.
10
Stephenson, Tamsyn, Natasha Speight, Wai Yee Low, Lucy Woolford, Rick Tearle, and Farhid Hemmatzadeh. "Molecular Diagnosis of Koala Retrovirus (KoRV) in South Australian Koalas (Phascolarctos cinereus)." Animals 11, no. 5 (May 20, 2021): 1477. http://dx.doi.org/10.3390/ani11051477.
Abstract:
Koala retrovirus, a recent discovery in Australian koalas, is endogenised in 100% of northern koalas but has lower prevalence in southern populations, with lower proviral and viral loads, and an undetermined level of endogenisation. KoRV has been associated with lymphoid neoplasia, e.g., lymphoma. Recent studies have revealed high complexity in southern koala retroviral infections, with a need to clarify what constitutes positive and negative cases. This study aimed to define KoRV infection status in Mount Lofty Ranges koalas in South Australia using RNA-seq and proviral analysis (n = 216). The basis for positivity of KoRV was deemed the presence of central regions of the KoRV genome (gag 2, pol, env 1, and env 2) and based on this, 41% (89/216) koalas were positive, 57% (124/216) negative, and 2% inconclusive. These genes showed higher expression in lymph node tissue from KoRV positive koalas with lymphoma compared with other KoRV positive koalas, which showed lower, fragmented expression. Terminal regions (LTRs, partial gag, and partial env) were present in SA koalas regardless of KoRV status, with almost all (99.5%, 215/216) koalas positive for gag 1 by proviral PCR. Further investigation is needed to understand the differences in KoRV infection in southern koala populations.
11
Matthews, Alison, Daniel Lunney, Shaan Gresser, and Wendy Maitz. "Tree use by koalas (Phascolarctos cinereus) after fire in remnant coastal forest." Wildlife Research 34, no. 2 (2007): 84. http://dx.doi.org/10.1071/wr06075.
Abstract:
The aim of this study was to examine the effects of fire on resource use by a population of koalas in remnant coastal forest. Fifty-five koalas were monitored regularly by radio-tracking for up to 35 months. The attributes of each tree in which the koala was sighted were recorded, giving a total of 8390 records. Analyses were undertaken on a range of ecological information. Regeneration of the forest began immediately following the fires and within three months koalas were seen among the epicormic growth. From a total 4631 trees used by koalas, 3247 (70%) were burnt. Observations of koalas feeding included 53% in burnt trees. Koalas changed trees frequently; individual trees were used once only on 3555 occasions (42% of all observations). Of all the trees used, 95% were used by only one collared koala; no trees were used by more than three koalas. Swamp mahogany (Eucalyptus robusta) was the tree species most frequently used by koalas, particularly at night and by breeding females. Koalas preferred trees of larger diameter (>30 cm) and used significantly taller trees during summer. This study has shown that resource depletion from intense wildfire is short-term for koalas because they utilise burnt trees within months of the fire for both food and shelter.
12
Ellis, William, Sean FitzGibbon, Alistair Melzer, Robbie Wilson, Steve Johnston, Fred Bercovitch, David Dique, and Frank Carrick. "Koala habitat use and population density: using field data to test the assumptions of ecological models." Australian Mammalogy 35, no. 2 (2013): 160. http://dx.doi.org/10.1071/am12023.
Abstract:
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.
13
Chen, Chien-Jung, Stephen T. Anderson, Natasha Steiger, Allan McKinnon, Joerg Henning, and Rachel Allavena. "Bone biomarkers in koalas: validation of assays and preliminary analyses." Journal of Veterinary Diagnostic Investigation 32, no. 6 (September 11, 2020): 856–63. http://dx.doi.org/10.1177/1040638720957031.
Abstract:
Traumatic injury, including bone fracture, is, to date, one of the leading causes of koala mortality in the South East Queensland region of Australia. Further, the specialist diet of koalas, which is restricted to certain Eucalyptus spp., may impact their normal bone physiology. Considering the dramatic koala population decline and high incidence of trauma, a greater understanding of koala bone physiology may support conservation. We retrieved from GenBank the protein sequences of parathyroid hormone (PTH), osteocalcin (OCN), and tissue-nonspecific alkaline phosphatase (TNALP) in human, dog, cattle, horse, koala, and gray short-tailed opossum. After homology was determined, plasma samples from 13 koalas were analyzed with human PTH, OCN, and bone-specific ALP (BALP) assay kits. Although koala PTH exhibited relatively low sequence homology with placental mammals, high sequence homology between humans and koalas was observed for both OCN and TNALP, and successful cross-reactivity was achieved using human enzyme immunoassay kits for detection of OCN and BALP biomarkers in koala plasma. However, we identified no correlation between OCN and BALP concentrations of healthy and trauma-affected koalas ( p = 0.66 and p = 0.79, respectively). Further analysis of OCN and BALP in healthy and diseased koalas will allow a better understanding of bone physiology in this unique marsupial.
14
McINNES, L. M., A. GILLETT, J. HANGER, S. A. REID, and U. M. RYAN. "The potential impact of native Australian trypanosome infections on the health of koalas (Phascolarctos cinereus)." Parasitology 138, no. 7 (April 27, 2011): 873–83. http://dx.doi.org/10.1017/s0031182011000369.
Abstract:
SUMMARYWhole blood collected from koalas admitted to the Australian Zoo Wildlife Hospital (AZWH), Beerwah, QLd, Australia, during late 2006–2009 was tested using trypanosome species-specific 18S rDNA PCRs designed to amplify DNA fromTrypanosoma irwini, T. gillettiandT. copemani. Clinical records for each koala sampled were reviewed and age, sex, blood packed cell volume (PCV), body condition, signs of illness, blood loss, trauma, chlamydiosis, bone marrow disease, koala AIDS and hospital admission outcome (‘survival’ / ‘non-survival’) were correlated with PCR results. Overall 73·8% (439/595) of the koalas were infected with at least 1 species of trypanosome.Trypanosoma irwiniwas detected in 423/595 (71·1%),T. gillettiin 128/595 (21·5%) andT. copemaniin 26/595 (4·4%) of koalas. Mixed infections were detected in 125/595 (21%) with co-infections ofT. irwiniandT. gilletti(101/595, 17%) being most common. There was a statistical association between infection withT. gillettiwith lower PCV values and body condition scores in koalas with signs of chlamydiosis, bone marrow disease or koala AIDS. No association betweenT. gillettiinfection and any indicator of health was observed in koalas without signs of concurrent disease. This raises the possibility thatT. gillettimay be potentiating other disease syndromes affecting koalas.
15
Witt, Ryan R., Chad T. Beranek, Lachlan G. Howell, Shelby A. Ryan, John Clulow, Neil R. Jordan, Bob Denholm, and Adam Roff. "Real-time drone derived thermal imagery outperforms traditional survey methods for an arboreal forest mammal." PLOS ONE 15, no. 11 (November 16, 2020): e0242204. http://dx.doi.org/10.1371/journal.pone.0242204.
Abstract:
Koalas (Phascolarctos cinereus) are cryptic and currently face regional extinction. The direct detection (physical sighting) of individuals is required to improve conservation management strategies. We provide a comparative assessment of three survey methods for the direct detection of koalas: systematic spotlighting (Spotlight), remotely piloted aircraft system thermal imaging (RPAS), and the refined diurnal radial search component of the spot assessment technique (SAT). Each survey method was repeated on the same morning with independent observers (03:00–12:00 hrs) for a total of 10 survey occasions at sites with fixed boundaries (28–76 ha) in Port Stephens (n = 6) and Gilead (n = 1) in New South Wales between May and July 2019. Koalas were directly detected on 22 occasions during 7 of 10 comparative surveys (Spotlight: n = 7; RPAS: n = 14; and SAT: n = 1), for a total of 12 unique individuals (Spotlight: n = 4; RPAS: n = 11; SAT: n = 1). In 3 of 10 comparative surveys no koalas were detected. Detection probability was 38.9 ± 20.03% for Spotlight, 83.3 ± 11.39% for RPAS and 4.2 ± 4.17% for SAT. Effective detectability per site was 1 ± 0.44 koalas per 6.75 ± 1.03 hrs for Spotlight (1 koala per 6.75 hrs), 2 ± 0.38 koalas per 4.35 ± 0.28 hrs for RPAS (1 koala per 2.18 hrs) and 0.14 ± 0.14 per 6.20 ± 0.93 hrs for SAT (1 koala per 43.39 hrs). RPAS thermal imaging technology appears to offer an efficient method to directly survey koalas comparative to Spotlight and SAT and has potential as a valuable conservation tool to inform on-ground management of declining koala populations.
16
Lunney, Daniel, Carol Esson, Chris Moon, Murray Ellis, and Alison Matthews. "A Community-based Survey of the Koala, Phascolarctos cinereus, in the Eden Region of South-eastern New South Wales." Wildlife Research 24, no. 1 (1997): 111. http://dx.doi.org/10.1071/wr94034.
Abstract:
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.
17
de Oliveira, S. M., P. J. Murray, D. L. de Villiers, and G. S. Baxter. "Ecology and movement of urban koalas adjacent to linear infrastructure in coastal south-east Queensland." Australian Mammalogy 36, no. 1 (2014): 45. http://dx.doi.org/10.1071/am12046.
Abstract:
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.
18
Quigley, Bonnie L., and Peter Timms. "The Koala Immune Response to Chlamydial Infection and Vaccine Development—Advancing Our Immunological Understanding." Animals 11, no. 2 (February 3, 2021): 380. http://dx.doi.org/10.3390/ani11020380.
Abstract:
Chlamydia is a significant pathogen for many species, including the much-loved Australian marsupial, the koala (Phascolarctos cinereus). To combat this situation, focused research has gone into the development and refinement of a chlamydial vaccine for koalas. The foundation of this process has involved characterising the immune response of koalas to both natural chlamydial infection as well as vaccination. From parallels in human and mouse research, it is well-established that an effective anti-chlamydial response will involve a balance of cell-mediated Th1 responses involving interferon-gamma (IFN-γ), humoral Th2 responses involving systemic IgG and mucosal IgA, and inflammatory Th17 responses involving interleukin 17 (IL-17) and neutrophils. Characterisation of koalas with chlamydial disease has shown increased expression within all three of these major immunological pathways and monitoring of koalas’ post-vaccination has detected further enhancements to these key pathways. These findings offer optimism that a chlamydial vaccine for wider distribution to koalas is not far off. Recent advances in marsupial genetic knowledge and general nucleic acid assay technology have moved koala immunological research a step closer to other mammalian research systems. However, koala-specific reagents to directly assay cytokine levels and cell-surface markers are still needed to progress our understanding of koala immunology.
19
Ellis, William, Rachael Attard, Stephen Johnston, Peter Theileman, Allan McKinnon, and David Booth. "Faecal particle size and tooth wear of the koala (Phascolarctos cinereus)." Australian Mammalogy 36, no. 1 (2014): 90. http://dx.doi.org/10.1071/am13033.
Abstract:
We used computer-aided image analysis of leaf fragment particles found in faecal pellets of 45 koalas, representing the range of tooth wear in this species, to investigate how tooth wear in the koala influences faecal particle sizes. Although the range of sizes of particles produced did not vary between koalas across different tooth wear classes, with all koalas producing small, medium and large particles, koalas with advanced tooth wear produced a greater proportion of larger particles. This observation may prove useful for demographic population analyses based on scat surveys since the broad age class of individual koalas can be estimated from faecal pellet analysis. Older koalas produced faecal pellets containing a higher proportion of the largest-sized particle sizes (those greater than 0.59 mm2) than either young or mature koalas but there was no difference detected between mature and young koalas.
20
Quigley, Bonnie L., and Peter Timms. "Helping koalas battle disease – Recent advances in Chlamydia and koala retrovirus (KoRV) disease understanding and treatment in koalas." FEMS Microbiology Reviews 44, no. 5 (June 18, 2020): 583–605. http://dx.doi.org/10.1093/femsre/fuaa024.
Abstract:
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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Ashman, Kita R., and Desley A. Whisson. "Developing guidelines for the use of traps to capture koalas." Australian Mammalogy 42, no. 3 (2020): 380. http://dx.doi.org/10.1071/am20018.
Abstract:
Capture of wildlife is essential both for research and management, and minimising the amount of stress an animal experiences during capture is important. We examined the behavioural response of koalas to cage traps to improve protocols for trapping koalas. We used heat- and motion-sensing cameras to record the behaviour of koalas in traps, and the duration spent in traps. Behavioural responses were scored on a scale of 0 (no apparent response) to 3 (heightened response) from videos. We successfully trapped a koala in 19 of 21 attempts. For 12 occasions when traps were monitored with cameras, koalas spent 6.3–181.2min in traps and 8 of 12 koalas displayed heightened behavioural responses (score of ≥2). The frequency of response scores did not vary between males and females and was not influenced by trapped duration. We found that traps were effective for capturing koalas; however, to minimise overt behavioural responses by trapped koalas, trap-check intervals need to be as short as possible. We recommend the use of trap-trigger devices to alert personnel when a koala is trapped. The addition of such devices in trapping practices may reduce potential for adverse behavioural responses and improve the cost-efficacy of trapping.
22
Rhind, Susan G., Murray V. Ellis, Martin Smith, and 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, no. 3 (2014): 302. http://dx.doi.org/10.1071/pc140302.
Abstract:
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.
23
Lee, Tristan, Kyall R. Zenger, Robert L. Close, and David N. Phalen. "Genetic analysis reveals a distinct and highly diverse koala (Phascolarctos cinereus) population in South Gippsland, Victoria, Australia." Australian Mammalogy 34, no. 1 (2012): 68. http://dx.doi.org/10.1071/am10035.
Abstract:
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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Schmertmann, Laura J., Alex Kan, Valentina S. A. Mella, Cristina M. Fernandez, Mathew S. Crowther, George Madani, Richard Malik, Wieland Meyer, and Mark B. Krockenberger. "Prevalence of cryptococcal antigenemia and nasal colonization in a free-ranging koala population." Medical Mycology 57, no. 7 (January 12, 2019): 848–57. http://dx.doi.org/10.1093/mmy/myy144.
Abstract:
AbstractCryptococcosis, caused by environmental fungi in the Cryptococcus neoformans and Cryptococcus gattii species complexes, affects a variety of hosts, including koalas (Phascolarctos cinereus). Cryptococcal antigenemia and nasal colonization are well characterized in captive koalas, but free-ranging populations have not been studied systematically. Free-ranging koalas (181) from the Liverpool Plains region of New South Wales, Australia, were tested for cryptococcal antigenemia (lateral flow immunoassay) and nasal colonization (bird seed agar culture). Results were related to environmental and individual koala characteristics. Eucalypt trees (14) were also randomly tested for the presence of Cryptococcus spp. by bird seed agar culture. In sum, 5.5% (10/181) and 6.6% (12/181) of koalas were positive for antigenemia and nasal colonization, respectively, on at least one occasion. And 64.3% (9/14) of eucalypts were culture-positive for Cryptococcus spp. URA5 restriction fragment length polymorphism analysis identified most isolates as C. gattii VGI, while C. neoformans VNI was only found in one koala and one tree. Colonized koalas were significantly more likely to test positive for antigenemia. No associations between antigenemia or colonization, and external environmental characteristics (the relative abundance of Eucalyptus camaldulensis and season), or individual koala characteristics (body condition, sex, and age), could be established, suggesting that antigenemia and colonization are random outcomes of host-pathogen-environment interactions. The relationship between positive antigenemia status and a relatively high abundance of E. camaldulensis requires further investigation. This study characterizes cryptococcosis in a free-ranging koala population, expands the ecological niche of the C. gattii/C. neoformans species complexes and highlights free-ranging koalas as important sentinels for this disease.
25
Ellis, W. A. H., B. J. Sullivan, A. T. Lisle, and F. N. Carrick. "The spatial and temporal distribution of koala faecal pellets." Wildlife Research 25, no. 6 (1998): 663. http://dx.doi.org/10.1071/wr97028.
Abstract:
Faecal pellets were collected under trees used by free-ranging koalas in south-western, central and south-eastern Queensland to determine the spatial and temporal distribution of pellets with respect to the activity of koalas. Deposition of faecal pellets by koalas was analysed according to the time of day at which the tree was occupied. For free-ranging koalas, 47% of daily faecal pellet output was recovered using a collection mat of 8 × 8 m placed under a day-roost tree. The best predictor of pellet production was the presence of a koala in a tree between 1800 hours and midnight. For other periods, there was no relationship between period of tree occupancy and faecal pellet recovery. There was a significant relationship between the average length of tree occupancy and the time of day that a koala entered a tree.
26
White, Rhys T., Alistair R. Legione, Alyce Taylor-Brown, Cristina M. Fernandez, Damien P. Higgins, Peter Timms, and Martina Jelocnik. "Completing the Genome Sequence of Chlamydia pecorum Strains MC/MarsBar and DBDeUG: New Insights into This Enigmatic Koala (Phascolarctos cinereus) Pathogen." Pathogens 10, no. 12 (November 25, 2021): 1543. http://dx.doi.org/10.3390/pathogens10121543.
Abstract:
Chlamydia pecorum, an obligate intracellular pathogen, causes significant morbidity and mortality in livestock and the koala (Phascolarctos cinereus). A variety of C. pecorum gene-centric molecular studies have revealed important observations about infection dynamics and genetic diversity in both koala and livestock hosts. In contrast to a variety of C. pecorum molecular studies, to date, only four complete and 16 draft genomes have been published. Of those, only five draft genomes are from koalas. Here, using whole-genome sequencing and a comparative genomics approach, we describe the first two complete C. pecorum genomes collected from diseased koalas. A de novo assembly of DBDeUG_2018 and MC/MarsBar_2018 resolved the chromosomes and chlamydial plasmids each as single, circular contigs. Robust phylogenomic analyses indicate biogeographical separation between strains from northern and southern koala populations, and between strains infecting koala and livestock hosts. Comparative genomics between koala strains identified new, unique, and shared loci that accumulate single-nucleotide polymorphisms and separate between northern and southern, and within northern koala strains. Furthermore, we predicted novel type III secretion system effectors. This investigation constitutes a comprehensive genome-wide comparison between C. pecorum from koalas and provides improvements to annotations of a C. pecorum reference genome. These findings lay the foundations for identifying and understanding host specificity and adaptation behind chlamydial infections affecting koalas.
27
Wedrowicz, Faye, Jennifer Mosse, Wendy Wright, and Fiona E. Hogan. "Using non-invasive sampling methods to determine the prevalence and distribution of Chlamydia pecorum and koala retrovirus in a remnant koala population with conservation importance." Wildlife Research 45, no. 4 (2018): 366. http://dx.doi.org/10.1071/wr17184.
Abstract:
Context Pathogenic infections are an important consideration for the conservation of native species, but obtaining such data from wild populations can be expensive and difficult. Two pathogens have been implicated in the decline of some koala (Phascolarctos cinereus) populations: urogenital infection with Chlamydia pecorum and koala retrovirus subgroup A (KoRV-A). Pathogen data for a wild koala population of conservation importance in South Gippsland, Victoria are essentially absent. Aims This study uses non-invasive sampling of koala scats to provide prevalence and genotype data for C. pecorum and KoRV-A in the South Gippsland koala population, and compares pathogen prevalence between wild koalas and koalas in rescue shelters. Methods C. pecorum and KoRV-A provirus were detected by PCR of DNA isolated from scats collected in the field. Pathogen genetic variation was investigated using DNA sequencing of the C. pecorum ompA and KoRV-A env genes. Key results C. pecorum and KoRV-A were detected in 61% and 27% of wild South Gippsland individuals tested, respectively. KoRV-A infection tended to be higher in shelter koalas compared with wild koalas. In contrast with other Victorian koala populations sampled, greater pathogen diversity was present in South Gippsland. Conclusions In the South Gippsland koala population, C. pecorum is widespread and common whereas KoRV appears less prevalent than previously thought. Further work exploring the dynamics of these pathogens in South Gippsland koalas is warranted and may help inform future conservation strategies for this important population. Implications Non-invasive genetic sampling from scats is a powerful method for obtaining data regarding pathogen prevalence and diversity in wildlife. The use of non-invasive methods for the study of pathogens may help fill research gaps in a way that would be difficult or expensive to achieve using traditional methods.
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Gallahar, Nicole, Kellie Leigh, and David Phalen. "Koala tree selection in a mixed-tenure landscape and post-fire implications." Wildlife Research 48, no. 8 (2021): 737. http://dx.doi.org/10.1071/wr20206.
Abstract:
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.
29
Johnston, S. D., P. O'Callaghan, K. Nilsson, G. Tzipori, and J. D. Curlewis. "Semen-induced luteal phase and identification of a LH surge in the koala (Phascolarctos cinereus)." Reproduction 128, no. 5 (November 2004): 629–34. http://dx.doi.org/10.1530/rep.1.00300.
Abstract:
The koala ovulates in response to mating. The purpose of this study was to document the LH surge induced by copulation and to investigate the potential roles of mechanical stimulation of the urogenital sinus and deposition of semen in induction of the luteal phase. In experiment 1, serial blood samples from four koalas that underwent normal mating showed elevated concentrations of LH approximately 24–32 h post-coitus. There was no corresponding elevation in LH in koalas (n = 4) that were exposed to the presence of a male but received no physical contact. In experiment 2, koalas on day 2 of oestrus were exposed to one of the following treatments (n = 9 per group): artificial insemination with 1 ml 0.9% sterile saline (control group), insemination with 1 ml koala semen, stimulation of the urogenital sinus with a purposebuilt glass rod (designed to mimic the action of the penis during natural mating) and urogenital stimulation with the glass rod followed by insemination of 1 ml koala semen. Confirmation of a luteal phase was based on evidence of a prolonged return to oestrus, parturition and/or elevated progesterone concentrations. Insemination of saline (0/9) and urogenital stimulation (0/9) failed to induce a luteal phase. Insemination of semen without glass rod stimulation resulted in a luteal phase in 4/9 koalas, three of which gave birth. Insemination of semen in combination with urogenital stimulation produced a luteal phase in 7/9 koalas, four of which gave birth. Semen had a significant effect on induction of the koala luteal phase (P < 0.001) but glass rod stimulation had no such effect (P = 0.335). It was concluded that semen must be involved in the induction of a luteal phase in the koala. The results presented in this study will serve to improve optimal timing and induction of ovulation for artificial insemination in the koala.
30
Ellis, W. A. H., A. Melzer, F. N. Carrick, and M. Hasegawa. "Tree use, diet and home range of the koala (Phascolarctos cinereus) at Blair Athol, central Queensland." Wildlife Research 29, no. 3 (2002): 303. http://dx.doi.org/10.1071/wr00111.
Abstract:
Free-ranging koalas (Phascolarctos cinereus) were monitored by means of radio-relocation in the area of Blair Athol Coal Mine and surrounding properties. Daytime tree use, home range and diet of these koalas was determined in spring and autumn, as was the leaf moisture composition of potential fodder species. Koalas used on average 93 (male koalas) and 56 (female koalas) trees during the period of observation, occupying home ranges of 135 and 101 ha respectively. Mean sightings per tree were 1.19 for both males and females and home-range sizes were not significantly different between sexes or seasons. Koalas were observed returning to previously used daytime roosting trees infrequently (<12%). Although koalas were observed roosting in trees of the species that they ate, proportional species representation in the diet of these koalas during spring and autumn did not accurately reflect concurrent observations of their daytime tree-roosting behaviour. Koalas were observed to utilise non-fodder species for daytime roosting, and patterns of daytime tree use and diet selection varied between individuals inhabiting adjacent communities within the site. Leaf moisture of tree species represented in koala diets was greater in autumn than spring.
31
Santamaria, Flavia, Rupert Palme, Rolf Schlagloth, Edith Klobetz-Rassam, and Joerg Henning. "Seasonal Variations of Faecal Cortisol Metabolites in Koalas in South East Queensland." Animals 11, no. 6 (May 31, 2021): 1622. http://dx.doi.org/10.3390/ani11061622.
Abstract:
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.
32
Dique, David S., Harriet J. Preece, Jim Thompson, and Deidré L. de Villiers. "Determining the distribution and abundance of a regional koala population in south-east Queensland for conservation management." Wildlife Research 31, no. 2 (2004): 109. http://dx.doi.org/10.1071/wr02031.
Abstract:
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.
33
Eisenhofer, Raphael, Kylie L. Brice, Michaela DJ Blyton, Scott E. Bevins, Kellie Leigh, Brajesh K. Singh, Kristofer M. Helgen, et al. "Individuality and stability of the koala (Phascolarctos cinereus) faecal microbiota through time." PeerJ 11 (January 23, 2023): e14598. http://dx.doi.org/10.7717/peerj.14598.
Abstract:
Gut microbiota studies often rely on a single sample taken per individual, representing a snapshot in time. However, we know that gut microbiota composition in many animals exhibits intra-individual variation over the course of days to months. Such temporal variations can be a confounding factor in studies seeking to compare the gut microbiota of different wild populations, or to assess the impact of medical/veterinary interventions. To date, little is known about the variability of the koala (Phascolarctos cinereus) gut microbiota through time. Here, we characterise the gut microbiota from faecal samples collected at eight timepoints over a month for a captive population of South Australian koalas (n individuals = 7), and monthly over 7 months for a wild population of New South Wales koalas (n individuals = 5). Using 16S rRNA gene sequencing, we found that microbial diversity was stable over the course of days to months. Each koala had a distinct faecal microbiota composition which in the captive koalas was stable across days. The wild koalas showed more variation across months, although each individual still maintained a distinct microbial composition. Per koala, an average of 57 (±16) amplicon sequence variants (ASVs) were detected across all time points; these ASVs accounted for an average of 97% (±1.9%) of the faecal microbial community per koala. The koala faecal microbiota exhibits stability over the course of days to months. Such knowledge will be useful for future studies comparing koala populations and developing microbiota interventions for this regionally endangered marsupial.
34
Sullivan, B. J., W. M. Norris, and G. S. Baxter. "Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. II. Distribution and diet." Wildlife Research 30, no. 4 (2003): 331. http://dx.doi.org/10.1071/wr00032.
Abstract:
This study used faecal pellets to investigate the broadscale distribution and diet of koalas in the mulgalands biogeographic region of south-west Queensland. Koala distribution was determined by conducting faecal pellet searches within a 30-cm radius of the base of eucalypts on 149 belt transects, located using a multi-scaled stratified sampling design. Cuticular analysis of pellets collected from 22 of these sites was conducted to identify the dietary composition of koalas within the region. Our data suggest that koala distribution is concentrated in the northern and more easterly regions of the study area, and appears to be strongly linked with annual rainfall. Over 50% of our koala records were obtained from non-riverine communities, indicating that koalas in the study area are not primarily restricted to riverine communities, as has frequently been suggested. Cuticular analysis indicates that more than 90% of koala diet within the region consists of five eucalypt species. Our data highlights the importance of residual Tertiary landforms to koala conservation in the region.
35
Hanger, Jon J., Lindell D. Bromham, Jeff J. McKee, Tracy M. O'Brien, and Wayne F. Robinson. "The Nucleotide Sequence of Koala (Phascolarctos cinereus) Retrovirus: a Novel Type C Endogenous Virus Related to Gibbon Ape Leukemia Virus." Journal of Virology 74, no. 9 (May 1, 2000): 4264–72. http://dx.doi.org/10.1128/jvi.74.9.4264-4272.2000.
Abstract:
ABSTRACT A novel retrovirus, morphologically consistent with mammalian C-type retroviruses, was detected by electron microscopy in mitogen-stimulated peripheral blood mononuclear cell cultures from 163 koalas and in lymphoma tissue from 3 koalas. PCR amplified provirus from the blood and tissues of 17 wild and captive koalas, and reverse transcriptase-PCR demonstrated viral mRNA, viral genomic RNA, and reverse transcriptase activity in koala serum and cell culture supernatants. Comparison of viral sequences derived from genomic DNA and mRNA showed identity indicative of a single retroviral species—here designated koala retrovirus (KoRV). Southern blot analysis of koala tissue genomic DNA using labelled KoRV probes demonstrated banding consistent with an endogenous retrovirus. Complete and apparently truncated proviruses were detected in DNA of both clinically normal koalas and those with hematopoietic disease. KoRV-related viruses were not detected in other marsupials, and phylogenetic analysis showed that KoRV paradoxically clusters with gibbon ape leukemia virus (GALV). The strong similarity between GALV and KoRV suggests that these viruses are closely related and that recent cross-host transmission has occurred. The complete proviral DNA sequence of KoRV is reported.
36
Kayesh, Mohammad Enamul Hoque, Md Abul Hashem, Fumie Maetani, Atsushi Goto, Noriko Nagata, Aki Kasori, Tetsuya Imanishi, and Kyoko Tsukiyama-Kohara. "Molecular Insights into Innate Immune Response in Captive Koala Peripheral Blood Mononuclear Cells Co-Infected with Multiple Koala Retrovirus Subtypes." Pathogens 11, no. 8 (August 14, 2022): 911. http://dx.doi.org/10.3390/pathogens11080911.
Abstract:
Koala retrovirus (KoRV) exists in both endogenous and exogenous forms and has appeared as a major threat to koala health and conservation. Currently, there are twelve identified KoRV subtypes: an endogenous subtype (KoRV-A) and eleven exogenous subtypes (KoRV-B to -I, KoRV-K, -L, and -M). However, information about subtype-related immune responses in koalas against multiple KoRV infections is limited. In this study, we investigated KoRV-subtype (A, B, C, D, and F)-related immunophenotypic changes, including CD4, CD8b, IFN-γ, IL-6, and IL-10 mRNA expression, in peripheral blood mononuclear cells (PBMCs) obtained from captive koalas (n = 37) infected with multiple KoRV subtypes (KoRV-A to F) reared in seven Japanese zoos. Based on KoRV subtype infection profiles, no significant difference in CD4 and CD8b mRNA expression was observed in the study populations. Based on the different KoRV subtype infections, we found that the IFN-γ mRNA expression in koala PMBCs differs insignificantly (p = 0.0534). In addition, IL-6 and IL-10 mRNA expression also did not vary significantly in koala PBMCs based on KoRV subtype differences. We also investigated the Toll-like receptors (TLRs) response, including TLR2–10, and TLR13 mRNA in koala PBMCs infected with multiple KoRV subtypes. Significant differential expression of TLR5, 7, 9, 10, and 13 mRNA was observed in the PBMCs from koalas infected with different KoRV subtypes. Therefore, based on the findings of this study, it is assumed that co-infection of multiple KoRV subtypes might modify the host innate immune response, including IFN-γ and TLRs responses. However, to have a more clear understanding regarding the effect of multiple KoRV subtypes on host cytokines and TLR response and pathogenesis, further large-scale studies including the koalas negative for KoRV and koalas infected with other KoRV subtypes (KoRV-A to -I, KoRV-K, -L and -M) are required.
37
TAYLOR, ANDREA C., JENNY MARSHALL GRAVES, NEIL D. MURRAY, STEPHEN J. O'BRIEN, N. YUHKI, and BILL SHERWIN. "Conservation genetics of the koala (Phascolarctos cinereus): low mitochondrial DNA variation amongst southern Australian populations." Genetical Research 69, no. 1 (February 1997): 25–33. http://dx.doi.org/10.1017/s0016672397002607.
Abstract:
Koala (Phascolarctos cinereus) populations in southern Australia have a history of bottlenecks – earlier this century the species became extinct in South Australia, and almost so in Victoria. Subsequently large numbers of animals from island populations (founded from very few animals) have been translocated back to mainland sites and to other islands in the region. As part of a larger study of the genetic structure of koala populations in southern Australia, we have undertaken a survey of mitochondrial DNA restriction fragment length polymorphism (mtDNA-RFLP) variability. Genomic DNA from 91 koalas from five populations was examined using 23 restriction enzymes, and mtDNA fragments were detected using a domestic cat full-length mtDNA clone. Only one of the enzymes, TaqI, revealed polymorphism – a relatively low amount of variation compared with other mammals, although low mtDNA-RFLP variation has also been reported in Queensland koalas. French Island and populations established predominantly from French Island immigrant koalas, either directly or via other island populations, were indistinguishable by haplotype frequencies. The mtDNA data are thus consistent with the interpretation that the koala translocation programme has homogenized gene frequencies amongst those populations involved. South Gippsland is not recorded as having received translocated koalas directly, and has significantly different mtDNA-RFLP haplotype frequencies from all other populations examined. The fact that this distinction was not previously observed in nuclear gene frequencies may reflect predominantly male-mediated dispersal in koalas.
38
Dique, David S., Jim Thompson, Harriet J. Preece, Deidré L. de Villiers, and Frank N. Carrick. "Dispersal patterns in a regional koala population in south-east Queensland." Wildlife Research 30, no. 3 (2003): 281. http://dx.doi.org/10.1071/wr02043.
Abstract:
Koala dispersal was investigated as part of a detailed ecological study of a nationally significant koala population located 20 km south-east of Brisbane, Queensland. From 1996 to 2000, 195 koalas from three sites were captured and fitted with radio-collars. A total of 40 koalas (23 males and 17 females) dispersed from these sites. Most (93%) dispersing individuals were 20–36 months of age. Three adult females (more than 36 months old) dispersed and no adult males dispersed during the study. A significantly higher proportion of young males dispersed than females. Dispersal occurred between June and December, with most dispersal of males commencing in July and August and that of females commencing between September and November prior to, and early in, the annual breeding season. The mean straight-line distance between the natal and breeding home ranges for males and females was similar and was measured at 3.5 km (range 1.1–9.7 km) and 3.4 km (range 0.3–10.6 km) respectively. Dispersing males and females tended to successfully disperse south and west of their natal home ranges and were generally unable to successfully disperse to urban areas within the study area, as a high proportion of the mortality of dispersing koalas was associated with attacks by domestic dogs and with collisions with vehicles on roads. Information from other studies indicates that most young koalas disperse from their natal areas. It is likely that the social behaviour and mating systems of koala populations provide mechanisms for young koalas to disperse. The potential role of dispersal in the dynamics of regional koala populations is discussed.
39
Speight, Natasha, Daniel Colella, Wayne Boardman, David A. Taggart, Julie I. Haynes, and William G. Breed. "Seasonal variation in occurrence of oxalate nephrosis in South Australian koalas (Phascolarctos cinereus)." Australian Mammalogy 41, no. 1 (2019): 92. http://dx.doi.org/10.1071/am17038.
Abstract:
Many koalas (Phascolarctos cinereus) in the Mount Lofty Ranges, South Australia, are affected by oxalate nephrosis, in which renal calcium oxalate deposition occurs. In other species, suboptimal water intake increases the risk of urinary calcium oxalate crystal formation. Koalas principally rely on eucalypt leaf moisture content to maintain hydration but the Mount Lofty Ranges region has hot, dry summers. This study investigates the association between temperature, rainfall and eucalypt leaf moisture and the occurrence of oxalate nephrosis in this population of koalas. Koalas from the Mount Lofty Ranges population that had died or were euthanased between 2008 and 2016 were necropsied and oxalate nephrosis was determined by histopathology (n=50). Leaf moisture content of Mount Lofty eucalypts was determined seasonally. It was found that increased numbers of koalas with oxalate nephrosis died in the months following high mean maximal temperature and in the months following low rainfall. Eucalypt leaf moisture content was not significantly associated with koala deaths. These findings suggest that hot and dry summer/autumn periods contribute to an increased incidence of koala deaths due to oxalate nephrosis. This is probably due to the effects of evaporative water loss and/or lack of access to supplementary drinking water at this time.
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Phillips, Stephen. "Differing mortality rates in two concurrently radio-tracked populations of koala (Phascolarctos cinereus)." Australian Mammalogy 40, no. 2 (2018): 198. http://dx.doi.org/10.1071/am16047.
Abstract:
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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McLean, Natasha, and Kathrine A. Handasyde. "Sexual maturity, factors affecting the breeding season and breeding in consecutive seasons in populations of overabundant Victorian koalas (Phascolarctos cinereus)." Australian Journal of Zoology 54, no. 6 (2006): 385. http://dx.doi.org/10.1071/zo06015.
Abstract:
It is important to have knowledge of basic population parameters to understand how these vary geographically and temporally and how they contribute to population dynamics. This paper investigates three of these parameters in Victorian koala populations: sexual maturity, aspects of the breeding season, and the continuity of individuals’ breeding. The investigation was carried out in koalas of known-age in two free-living (Redbill Creek on French Island and Brisbane Ranges) and one semi-captive (the Koala Conservation Centre on Phillip Island) population as well as koalas of unknown age in four Victorian populations of overabundant koalas: Mt Eccles and Framlingham in south-west Victoria, French Island in Western Port and Snake Island in south Gippsland. At sexual maturity, female koalas had a mean age (±95% confidence interval) of 24.4 months (23.5–25.3 months), a mean head length of 125 mm (124–127 mm) and a mean body mass of 6.6 kg (6.3–6.8 kg). Only 7.4% of independent females (of unknown age) were carrying young when they weighed less than 6 kg. The breeding season was more restricted in the south-west populations. At Framlingham and Mt Eccles 85% and 91% of births, respectively, occurred between December and March. At Snake and French Islands only 46% and 53% of births, respectively, were recorded in the same period. In the Chlamydia-free population (Red Bill Creek) none of the koalas that were monitored stopped breeding and then resumed breeding in a subsequent season whereas many females from Chlamydia-infected populations (Brisbane Ranges and the Koala Conservation Centre) did so. This variation in reproductive patterns is likely to make an important contribution to the variation in the demography observed in different koala populations.
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Law, B., L. Gonsalves, R. Bilney, J. Peterie, R. Pietsch, P. Roe, and A. Truskinger. "Using Passive Acoustic Recording and Automated Call Identification to Survey Koalas in the Southern Forests of New South Wales." Australian Zoologist 40, no. 3 (January 2020): 477–86. http://dx.doi.org/10.7882/az.2019.033.
Abstract:
Cost-effective surveys of low density koala populations are challenging, but technological developments in the acoustics field offer great potential for landscape-scale surveys and monitoring. We assessed passive acoustic recording coupled with automated call identification as a survey method for koalas Phascolarctos cinereus . Surveys targeted areas of previously known koala activity based on scat surveys in southern forests of New South Wales where a low density of koalas is suspected. We set 24 Song Meters to record at night over a two week period (~3,696 hours) in the koala breeding season (October/November) in Murrah Flora Reserve. Recordings were scanned by a koala call recogniser and “matches” were manually verified. Across the 24 sites, 522 validated koala bellows were recorded at 21 sites (87.5 % detection rate). Three environmental variables had most influence on detection probability of koalas, including nightly rainfall (-ve), nightly temperature (-ve) and topographic position (lower on ridges). Calling activity peaked at midnight. Sustained site occupancy, at least in the short-term, was apparent as under optimal conditions (no rain) koalas were recorded, on average, for > 50 % of survey nights rather than for just a few nights. We suggest that only a modest survey effort (4–5 nights) in the breeding season, on nights with < 3 mm of rain, is required to achieve 90–95 % probability of koala call detection in an area of low koala density. Comparison with scat surveys at the same sites revealed that detection rates were more than three times greater with acoustic surveys. Technological advances will continue to provide improvements for wildlife survey, and perhaps most importantly, for collecting much needed long-term data to assess trends in occupancy or other population attributes over time.
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Rundle-Thiele, Sharyn. "A reflection on motivating community action to protect an endangered species using marketing." European Journal of Marketing 56, no. 9 (November 16, 2022): 2558–72. http://dx.doi.org/10.1108/ejm-03-2022-0146.
Abstract:
Purpose This paper aims to describe a case that has worked with community aiming to prevent koala deaths and injuries across known causes including dogs. Design/methodology/approach Over a 6½-year period, a project team has applied the Co-create–Build–Engage (CBETM) process initially delivering a proof-of-concept pilot programme for one threat faced by koalas, which was later scaled to citywide delivery. This approach is now being extended across 12 local government areas, and the author’s team is now working across all preventable threats faced by koalas’ regionwide. Leave It is now nested as one behaviour change project in a wider project delivered across Southeast Queensland, in partnership with Queensland Government, 12 local government areas, community groups and other organisations. Findings Underpinned by the pathway to impact and CBETM processes, this paper describes how the 3½-year Leave It project reduced koala deaths from dog attacks by 40% in the Redland City Council area. A reduction in koala deaths will contribute to a measurable increase in the local koala population across successive generations delivering lasting impact. Research limitations/implications This paper provides an overview of links between inputs, activities, outputs and outcomes to impact. Robust koala population data is needed to precisely measure impact over time. Practical implications One female koala joey saved equates to seven new koalas in the next generation and prevention of koala deaths can be achieved when people can be motivated to take action. Originality/value This paper reflects on 6½ years of experience applying marketing to deliver changes in people’s behaviour that protect koalas. A high-level overview of the strategic and operational marketing efforts that have been and continue to be applied is described.
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Zee, Y. P., C. Lopez-Fernandez, J. Gosalvez, W. V. Holt, and S. D. Johnston. "82 DNA FRAGMENTATION DYNAMICS OF KOALA SPERMATOZOA." Reproduction, Fertility and Development 21, no. 1 (2009): 141. http://dx.doi.org/10.1071/rdv21n1ab82.
Abstract:
Koala sperm chromatin has a tendency to relax following incubation and thawing but the background incidence and dynamics of DNA fragmentation during semen processing at 35°C and following chilled and frozen preservation has not been investigated. This study (n = 10) was designed to establish the fragmentation dynamics of koala sperm DNA at body temperature (35°C), after chilling (4°C) for upward of 16 days, and following a standard freeze–thaw protocol (Johnston SD et al. 2006 Cryobiology 53, 218–228). Sperm DNA fragmentation index (sDFI) was determined using a Halomax kit (ChromaCell SL, Madrid, Spain), which had been customized and validated for koalas (Johnston SD et al. 2007 J. Androl. 28, 891–899). All semen was assessed for sDFI over a 48-h incubation period (T0, T2, T6, T24, and T48) at 35°C. After incubation at 35°C for 48 h, the sDFI and rate of DNA degradation of freshly diluted spermatozoa were highly variable between individuals; the sDFI for 2 koalas remained consistently low (≤2%) whereas the other 8 had sDFI of 8 to 12% after incubation. Chilled storage increased sDFI in all animals, but the rate of increase and the time at which the DNA started to fragment also varied between koalas; sDFI for 1 koala increased immediately upon rewarming after being chilled for 4 h, whereas that of another koala did not increase until after 8 days of chilling and 24 h of incubation at 35°C. Animals also responded to cryopreservation differently; sDFI increased after thawing for 2 of the koalas but did not increase in the others. Subsequent evaluation of frozen–thawed spermatozoa from a greater number of captive koalas (n = 22), and under extended conditions of post-thaw incubation (up to 17 days at 35°C) permitted categorization of the koalas into 3 distinctive groups based on their DNA fragmentation dynamics and rate of DNA degradation. For 7 of the animals, sDFI remained close to the basal level when incubated at 35°C over 7 days, whereas 2 of the koalas had sDFI ranging from 40 to 70% after 24 h of incubation. This study confirmed the occurrence of inter-animal variability in the dynamics of DNA fragmentation, a finding that was apparent whether or not the spermatozoa had been subjected to chilling or cryopreservation.
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Matthews, Alison, Daniel Lunney, Shaan Gresser, and Wendy Maitz. "Movement patterns of koalas in remnant forest after fire." Australian Mammalogy 38, no. 1 (2016): 91. http://dx.doi.org/10.1071/am14010.
Abstract:
The increasing fragmentation of fire-prone forests of Australia has made the remaining populations of koalas (Phascolarctos cinereus) more vulnerable to extinction. We examined the movement patterns of koalas in remnant forest of Port Stephens following a major wildfire. Each koala (n = 55) was monitored regularly by radio-tracking for up to 35 months. The movements of koalas showed a wide variation in patterns, from highly localised movements to long-range dispersal over 20 km. Within the first 12 months, 35% of tracked koalas moved from their release location to new areas where they established home ranges. Daily movement distances of males (mean = 278.3 m) was higher than for females (141.0 m). Monthly displacement ranged from less than 10 m to more than 5 km, and was higher for koalas that subsequently died. Home ranges of males (95% kernel) were significantly larger than those of females (mean for males = 58.9 ± 10.5 ha; mean for females = 25.7 ± 8.6 ha), and this sex difference was also evident for core areas (50% kernel). There were no differences in the movement patterns or home-range sizes of rehabilitated koalas compared with wild koalas. This study has shown that resource depletion from wildfire is short term for koalas because their mobility allows rapid recolonisation of the burnt forest, and they can maintain home ranges within sites regenerating from fire. The reintroduction of rehabilitated koalas into burnt forest may also assist in the recovery of populations in fragmented and isolated habitat.
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Oliveira, Nidia M., Karen B. Farrell, and Maribeth V. Eiden. "In Vitro Characterization of a Koala Retrovirus." Journal of Virology 80, no. 6 (March 15, 2006): 3104–7. http://dx.doi.org/10.1128/jvi.80.6.3104-3107.2006.
Abstract:
ABSTRACT Recently, a new endogenous koala gammaretrovirus, designated KoRV, was isolated from koalas. The KoRV genome shares 78% nucleotide identity with another gammaretrovirus, gibbon ape leukemia virus (GALV). KoRV is endogenous in koalas, while GALV is exogenous, suggesting that KoRV predates GALV and that gibbons and koalas acquired the virus at different times from a common source. We have determined that subtle adaptive differences between the KoRV and GALV envelope genes account for differences in their receptor utilization properties. KoRV represents a unique example of a gammaretrovirus whose envelope has evolved to allow for its expanded host range and zoonotic potential.
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Smith, Andrew G., Clive McAlpine, Jonathan Rhodes, Leonie Seabrook, Daniel Lunney, and Greg Baxter. "Are there habitat thresholds in koala occupancy in the semiarid landscapes of the Mulgalands Bioregion?" Wildlife Research 40, no. 5 (2013): 413. http://dx.doi.org/10.1071/wr13010.
Abstract:
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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Kavanagh, Rodney P., Matthew A. Stanton, and Traecey E. Brassil. "Koalas continue to occupy their previous home-ranges after selective logging in Callitris - Eucalyptus forest." Wildlife Research 34, no. 2 (2007): 94. http://dx.doi.org/10.1071/wr06126.
Abstract:
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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Jiang, Alex Zijian, Peter Murray, Clive Phillips, Andrew Tribe, and William Ellis. "Movement of Free-Ranging Koalas in Response to Male Vocalisation Playbacks." Animals 12, no. 3 (January 24, 2022): 287. http://dx.doi.org/10.3390/ani12030287.
Abstract:
Effective conservation strategies rely on knowledge of seasonal and social drivers of animal behaviour. Koalas are generally solitary and their social arrangement appears to rely on vocal and chemical signalling. Male koala vocalisations, known as bellows, are believed to be closely related to their breeding behaviour. Previous research suggests that oestrous female koalas use bellows to locate unique males to mate with, and that males can similarly use bellows to evaluate the physical attributes of their peers. We tested the behavioural responses of 20 free ranging koalas to bellow recordings collected from small (<6 kg) and large (>8.5 kg) adult male koalas. Individual koala movement was reported by hourly-uploaded GPS coordinates. We report evidence of intra-male competition, with adult males approaching bellow playbacks, particularly those from small-sized males. In contrast, males under three years of age were averse to the playbacks. No patterns in the response of females were detected. Our results provide the strongest evidence yet that bellows are primarily a means by which males occupy and control space during the breeding season. Future studies are required to see if female response to bellows depends on their reproductive status.
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Middleton, David R., Bryan Walters, Peter Menkhorst, and Patrick Wright. "Fertility control in the koala, Phascolarctos cinereus: the impact of slow-release implants containing levonorgestrel or oestradiol on the production of pouch young." Wildlife Research 30, no. 3 (2003): 207. http://dx.doi.org/10.1071/wr02052.
Abstract:
Two hormone-based fertility-control treatments were trialed on free-ranging female koalas. Either levonorgestrel or oestradiol-17β was administered in a cylindrical, silastic, sub-dermal implant. Levonorgestrel was administered in a commercially produced implant (Norplant 2, Leiras). Two different doses of oestradiol were administered via custom-made implants of different length (1 cm and 0.5 cm). Treatments were randomly applied to 58 females (each koala receiving a single implant) and a control group of 27 female koalas received no implant. Fertility, as determined by the presence of pouch young, was recorded following capture and examination during June 1998, 1999, 2000 and 2001. Fertility was reduced in all treatment groups but remained high (90%) in the untreated group. Fertility was lowest in koalas that received levonorgestrel (0%) and longer oestradiol implants (5%). The results demonstrate that slow-release implants containing either of these two steroid hormones have the ability to significantly lower fertility of wild koalas for at least four breeding seasons following treatment. No adverse side effects were apparent in any of the treated individuals. Compared with the cost of current management strategies for over-abundant koala populations, their deployment on a large scale should be cost-effective.