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Ecology

Details: Category: Population dynamics

A dangerous idea: that Koala densities can be low without the populations being in danger

Close, R, Ward, S, & Phalen, D 2017, Australian Zoologist, vol. 38, no. 3, pp. 272-280.

In New South Wales, many local koala populations are considered threatened under the state’s legislation, either due to their declining population statuses or their low densities. Through assessing historical evidence from pre-European settlement and present data from previous tracking and translocation studies, it was observed that koala populations in the Sydney basin area existed in low densities prior to European settlement, and that koalas possess great dispersal abilities that allow them to persist in healthy, small, widely-distributed populations, allowing them to remain functional and sustainable.

Details: Category: Biogeography

A preliminary investigation of the distribution of koalas and their potential habitat in the Tweed Shire, and implications for management

Faulks, J 1991, Australian Zoologist, vol. 27, no. 1 & 2, pp. 1-13.

The author of this review used historical information, past surveys, personal interviews and relevant literature to determine the distribution of koalas in the Tweed Shire Council region, an area dominated by natural habitat with prime agricultural land throughout, and consequently make recommendations about habitat management in the region.

Details: Category: Threatening processes

A survey of koala road kills in New South Wales

Canfield, PJ 1991, Journal of Wildlife Diseases, vol. 27, no. 4, pp. 657-660.

With increasing fragmentation of remnant forest along Australia’s east coast, motor vehicle accidents have become a significant cause of injury and death in koala populations. In a survey of koala road kills conducted in the northern coast of New South Wales between 1984 and 1990, 75 koalas were found to have died from injuries relating to motor vehicle accidents. After analysis, it was identified that healthy, young to middle-aged male koalas were more prone to vehicular incidents, especially during the mating period.

Details: Category: Habitat

A survey of pesticide accumulation in a specialist feeder, the koala (Phascolarctos cinereus)

Marschner, C, Higgins, DP & Krockenberger, MB 2017, Bulletin of Environmental Contamination and Toxicology, vol. 99, no. 1, p. 303-307.

This study is the first to examine exposure to and effects of pesticides in koalas. In all tissue samples from koalas that inhabited areas impacted by horticultural, agricultural or urban development, pesticide levels were consistently below the limit of detection. This finding suggests that, for these koalas, chronic ongoing or acute exposure to pesticides was unlikely.

Details: Category: Habitat

A survey of ticks (Acari: Ixodidae) from an over-abundant koala (Phascolarctos cinereus) population in south eastern Australia, with an overview of the ticks and mites of koalas

Kwak, ML & Reed, J 2017, Experimental & Applied Acarology, vol. 73, pp. 109-114.

Koala health surveys undertaken at Cape Otway in Victoria in 2016 revealed that ticks are prevalent in this over-abundant koala population. A total of 1036 ticks (of the species Ixodes tasmani) were found on 159 female koalas, and every sampled female was found to have ticks present. The average infestation intensity was estimated to be 6.6 ticks per animal and there was, in general, more female ticks than male ticks found on the host. None of the animals exhibited signs of health stress or anaemia, suggesting I. tasmani may not have adverse health effects on the koalas in this region.

Details: Category: Threatening processes

Assessing the significance of endemic disease in conservation – koalas, chlamydia, and koala retrovirus as a case study

McCallum, H, Kerlin, DH, Ellis, W & Carrick, F 2017, Conservation Letters, e12425.

The value of disease management as a tool for biological conservation is often contested. The koala presents an ideal case study for examining this debate. Endemic diseases, most notably chlamydiosis and koala retrovirus (KoRV), are highly prevalent throughout koala populations. The extent to which disease contributes to population decline, however, is not agreed upon.

Details: Category: Threatening processes

Aversive behaviour by koalas (Phascolarctos cinereus) during the course of a music festival in northern New South Wales, Australia

Phillips, S 2016, Australian Mammalogy, vol. 38, pp. 158-163.

By monitoring changes in movement and behaviour of a resident koala population, this study investigated the extent of disturbance caused by a five-day musical festival in northern New South Wales. Seven koalas were monitored over a period of 6 months, whereby three koalas demonstrated extreme aversive behaviour in response to the festival, evacuating their known ranging areas. Three other koalas displayed aversive responses, but remained within known ranging areas.

Details: Category: Habitat

Bark chewing reveals a nutrient limitation of leaves for a specialist folivore

Au, J, Youngentob, KN, Clark, RH, Phillips, R & Foley, WJ 2017, Journal of Mammalogy, vol. 98, no. 4, pp. 1185-1192.

Koalas of the subalpine Monaro region in New South Wales appear to have developed the unusual adaptation of chewing the sodium-rich bark of Eucalyptus mannifera to meet their nutritional requirements within a landscape that is otherwise lacking in the mineral micronutrient.

Details: Category: Threatening processes

Bearing up well? Understanding the past, present and future of Australia's koalas

Black, KH, Price, GJ, Archer, M & Hand, SJ 2014, Gondwana Research, vol. 25, pp. 1186-1201.

Evidence from fossil records of the family Phascolarctidae indicates that these specialist folivores, of which the modern koala Phascolarctos cinereus is the last surviving member, are particularly sensitive to climate change. Knowledge about the nature and rate of change in previous palaeocommunities of phascolarctids together with data relating to the responses of modern koala populations to historic climatic extremes indicate that the future survival of the species is under threat.

Details: Category: Threatening processes

Behavioural determination of visual function in the koala (Phascolarctos cinereus)

Schmid, LM, Schmid, KL & Brown, B 1991, Wildlife Research, vol. 18, no. 3, pp. 367-374.

Reduction of vision in koalas was found here to result in significant behavioural changes. Maintaining a minimum level of vision appears necessary for koalas to be able to locate and climb trees, as with severely obstructed vision, captive koalas were not able to reach or climb a nearby tree.

Details: Category: Behaviour & communication

Behavioural determination of visual function in the koala (Phascolarctos cinereus)

Schmid, LM, Schmid, KL & Brown, B 1991, Wildlife Research, vol. 18, no. 3, pp. 367-374.

Reduction of vision in koalas was found here to result in significant behavioural changes. Maintaining a minimum level of vision appears necessary for koalas to be able to locate and climb trees, as with severely obstructed vision, captive koalas were not able to reach or climb a nearby tree.

Details: Category: Population dynamics

Breeding dynamics of koalas in open woodlands

Ellis, WA, Hale, PT & Carrick, FN 2002, Wildlife Research, vol. 29, pp. 19-25.

This study aimed to increase current knowledge on the breeding behaviours of koalas by using radio tracking and genetic analyses to investigate the spatial and breeding dynamics of koalas at Blair Athol, Queensland. Authors reported that ‘resident’ males possessed no parental advantage compared to ‘transient’ males. Furthermore, the genetic differences among the four regional populations studied increased with distance from one another, supporting a model of isolation by distance.

Details: Category: Biogeography

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

Ellis, MV, Rhind, SG, Smith, M & Lunney, D 2017, Pacific Conservation Biology, vol. 23, no. 1, pp. 63-70.

The results of two community surveys of the koala population in the Gunnedah region in New South Wales taken in 1990 and 2006 were compared. The survey of 1990 was initiated after the charismatic marsupial became a mascot for a tree planting program to address the problem of salinity on agricultural land in the area. As koalas were later reported to be using these planted trees, another survey was conducted in 2006 at a broader geographical scale. Although the surveys employed different methodologies, these two datasets allowed some broad conclusions to be made about changes in the region’s koala population over time.

Details: Category: Biogeography

Characteristics of arboreal marsupial habitat in the semi-arid woodlands of northern Queensland

Munks, SA, Corkrey, R, & Foley, WJ 1996, Wildlife Research, vol. 23, pp. 185-195.

Koalas and common brushtail possums utilise a range of different land types in the semi-arid woodlands of northern Queensland but exhibit higher preferences for habitats characterised by high tree basal area and nearness to creek-lines. It appears, therefore, that foliar moisture rather than foliar nutrients has a high influence on arboreal marsupials’ habitat preferences in semi-arid woodlands.

Details: Category: Habitat

Characteristics of arboreal marsupial habitat in the semi-arid woodlands of northern Queensland

Munks, SA, Corkrey, R, & Foley, WJ 1996, Wildlife Research, vol. 23, pp. 185-195.

Koalas and common brushtail possums utilise a range of different land types in the semi-arid woodlands of northern Queensland but exhibit higher preferences for habitats characterised by high tree basal area and nearness to creek-lines. It appears, therefore, that foliar moisture rather than foliar nutrients has a high influence on arboreal marsupials’ habitat preferences in semi-arid woodlands.

Details: Category: Biogeography

Chemosensory discrimination of identity and familiarity in koalas

Charlton, BD 2015, Behavioural Processes, vol. 119, no. 1, pp. 38-43.

Male koalas can differentiate between the scent gland secretions of familiar and unfamiliar individuals. The koalas spent more time sniffing scents from unknown males than familiar males, demonstrating that they can discriminate between members of their species with regards to their familiarity. These results suggest koalas use chemical cues to figure out the identity and familiarity of other koalas.

Details: Category: Threatening processes

Conserving koalas: A review of the contrasting regional trends, outlooks and policy challenges

McAlpine, C, Lunney, D, Melzer, A, Menkhorst, P, Phillips, S, Phalen, D, Ellis, W, Foley, W, Baxter, G, de Villiers, D, Kavanagh, R, Adams-Hosking, C, Todd, C, Whisson, D, Molsher, R, Walter, M, Lawler, I & Close, R 2015, Biological Conservation, vol. 192, pp. 226-236.

The koala has suffered a 50% decline in its distribution since European colonisation began in Australia, and consequently its conservation has become a national priority. The purpose of this review was to synthesise current knowledge of koala populations and their threats to identify a way forward for their conservation.

Details: Category: Threatening processes

Consistent patterns of vehicle collision risk for six mammal species

Visintin, C, van der Ree, R & McCarthy, MA 2017, Journal of Environmental Management, vol. 201, no. 1, pp. 397-406.

The authors of this study developed a quantitative risk model framework for evaluating the extent to which the variables of species occurrence, road speed and traffic volume influence the risk of wildlife-vehicle collision for a section of road. The framework was applied to examine the risk of wildlife-vehicle collisions on Victorian roads for six species including the koala.

Details: Category: Habitat

Current approaches to modelling the environmental niche of eucalypts: implication for management of forest biodiversity

Austin, MP & Meyers, JA 1996, Forest Ecology and Management, vol. 85, pp. 95-106.

Due to cost, time and other constraints, forest managers cannot have optimum knowledge of all the species distributed throughout the ecosystem they administer. One of the next best options is having access to spatial models to predict the area’s biodiversity and its distribution. This paper, in the context of nine species of eucalyptus trees across 8377 sites in south-eastern Australia, examined the performance of two modelling techniques: Generalised Linear Modelling (GLM) and Generalised Additive Modelling (GAM). The authors chose trees to study because of their size and immobility, and their value in predicting the distribution of some other biota, including koalas. Results pertaining to seven environmental predictors (including temperature, nutrients and light) for one species, Eucalyptus cypellocarpa, are provided.

Details: Category: Threatening processes

Decline causes of koalas in south east Queensland, Australia: a 17-year retrospective study of mortality and morbidity

Gonzalez-Astudillo, V, Allavena, R, McKinnon, A, Larkin, R & Henning, J 2017, Scientific Reports, vol. 7, 42587.

South-east Queensland koala populations have been in decline for several decades. The authors of this study examined a comprehensive database of 20,250 koala admissions into wildlife hospitals in the region between 1997 and 2013 to identify the causes of morbidity and mortality that have contributed to this decline. The results suggest that chlamydiosis, motor vehicle trauma and wasting are the most frequent conditions observed and that they frequently co-occur within individuals.

Details: Category: Threatening processes

Decline of the urban koala (Phascolarctos cinereus) population in Warringah Shire, Sydney

Smith, P & Smith J 1990, Australian Zoologist, vol. 26, nos. 3-4, pp. 109-129.

Koala populations within Warringah Shire, Sydney have rapidly declined over the last 50 years. Initial declines can be attributed to habitat loss, as primary koala habitat was converted to urban area from the 1970s onwards. Surviving populations are now restricted to two main areas: Barrenjoey Peninsula and Ku-ring-gai Chase National Park, with only rare sightings in other areas of the Shire.

Details: Category: Habitat

Dental microwear texture analysis of extant koalas: clarifying causal agents of microwear

Hedberg, C & DeSantis, LRG 2016, Journal of Zoology, vol. 301, no. 1, pp. 206-214.

The dental microwear of the koala is consistent with that of other tough object feeders and reflects its dietary composition and behaviours. The most likely factors influencing microwear patterns in the koala are the properties of food consumed, abrasion during mastication and the ingestion of grit.

Details: Category: Biogeography

Determining the distribution and abundance of a regional koala population in south-east Queensland for conservation management

Dique, DS, Preece, HJ, Thompson, J & de Villiers, DL 2004, Wildlife Research, vol. 31, pp. 109-117.

Integrating strip-transect surveys and landcover classification, this study identifies the distribution and abundance of a regionally threatened koala population in the Koala Coast, south-east Queensland. Koala densities were found to be greatest in remnant patches and large areas of eucalypt bushland, especially towards the region’s centre. Urban areas possessed lower, but significant densities.

Details: Category: Habitat

Development and field validation of a regional, management-scale habitat model: A koala Phascolarctos cinereus case study

Law, B, Caccamo, G, Roe, P, Truskinger, A, Brassil, T, Gonaslves, L, McConville, A & Stanton, M 2017, Ecology and Evolution, vol. 7, no. 1, pp. 7475-7489.

Predictive habitat suitability modelling based on environmental predictor variables can accurately identify areas of koala occupancy. Using the koala as a case study, the value of regional-level distribution modelling as a tool for conservation and land management in relation to threatened, rare or cryptic species is demonstrated.

Details: Category: Habitat

Dietary specialisation and Eucalyptus species preferences in Queensland koalas (Phascolarctos cinereus)

Higgins, AL, Bercovitch, FB, Tobey, JR & Hamlin Andrus, C 2011, Zoo Biology, vol. 30, no. 1, pp. 52-58.

Koalas appear to demonstrate individual dietary preferences for different species of Eucalyptus and an overall preference for particular species; however, the factors driving these preferences are not yet understood.

Details: Category: Behaviour & communication

Discrimination of sex and reproductive state in koalas, Phascolarctos cinereus, using chemical cues in urine

Charlton, BD 2014, Animal Behaviour, vol. 91, no. 1, pp. 119-125.

Koalas can determine both the sex and oestrous stage of other individuals by detecting unique chemical cues in their urine. During their breeding season, male and oestrus female koalas at Lone Pine Koala Sanctuary demonstrated a higher interest in the urine of males than did nonoestrus females, which avoided male urine. Male koalas investigated the urine of an oestrus female, but not that of a nonoestrus female.

Details: Category: Behaviour & communication

Disentangling the mechanisms of mate choice in a captive koala population

Brandies, PA , Grueber, CE, Ivy, JA, Hogg, CJ & Belov, K 2017, PeerJ Preprints (Not Peer Reviewed).

Successful captive breeding is a major contributor to the conservation of many threatened species; however, the sustainability of several captive breeding programs is limited by pair incompatibility. If captive breeding is to be both successful and sustainable, an understanding of the behavioral and genetic drivers of pair incompatibility is essential. To determine what behavioral and genetic drivers influence pair incompatibility of captive koalas, analyses of 28 years of pairing data from the studbook for the San Diego Zoo koala colony and genetic analyses of 70 banked koala DNA samples from the same colony were performed. Both behavioral and genetic determinants were found to contribute to captive koala mating success.

Details: Category: Biogeography

Dispersal patterns in a regional koala population in south-east Queensland

Dique, DS, Thompson, J, Preece, HJ, de Villiers, DL & Carrick, FN 2003, Wildlife Research, vol. 30, pp. 281-290.

Between 1996 and 2000, koala dispersal was monitored in a population within the Koala Coast. A total of 195 koalas were radio-tracked, of which 40 dispersed, five made exploratory movements and 150 remained within the same natal home range. Significantly more males than females dispersed from their natal range.

Details: Category: Habitat

Distribution of foliar formylated phloroglucinol derivatives amongst Eucalyptus species

Eschler, BM, Pass, DM, Willis, R & Foley, WJ 2000, Biochemical Systematics and Ecology, vol. 28, no. 1, pp. 813-824.

Formylated phloroglucinol compounds (FPCs) are an important feeding deterrent in Eucalyptus foliage, with samples of 27 out of 41 Eucalyptus species found to have masses characteristic of FPCs. The subgenus Monocalyptus lacked any known FPCs, while the most commonly identified FPC group was the sideroxylonals.

Details: Category: Habitat

Do ecosystems need top predators? A review of native predator-prey imbalances in south-east Australia

Yugovic, J 2014, The Victorian Naturalist, vol. 132, no. 1, pp. 4-11.

This review assesses the capacity of top predators in south-east Australia to control mesopredators and herbivores and in turn, manage local terrestrial ecosystems. In particular, the ecological imbalances associated with Eucalyptus over-browsing by koalas is examined. With the large-scale loss of top native predators, namely the dingo (Canis lupus dingo), introduced mesopredators such as the red fox and cat have overtaken this apex ecological function, regulating herbivore populations in local areas.

Details: Category: Habitat

Ecological example of conditioned flavor aversion in plant-herbivore interactions: effect of terpenes of Eucalyptus leaves on feeding by common ringtail and brushtail possums

Lawler, IR, Stapley, J, Foley, WJ & Eschler, BM 1999, Journal of Chemical Ecology, vol. 25, no. 2, pp. 401-415.

The avoidance of Eucalyptus terpenes by common ringtail and brushtail possums is found here to be due to a conditioned flavour aversion. The possums avoid terpenes due to them acting as an indication of toxic diformylaphloroglucinol compounds (DFPCs), rather than due to being toxic themselves.

Details: Category: Habitat

Effects of fire on the structure and composition of open eucalypt forests

Spencer, R & Baxter, GS 2006, Austral Ecology, vol. 31, pp. 638-646.

Fires can result in dramatic changes to habitat structure and complexity. This study showed that frequent fires on Fraser Island influenced habitat structure and led to a decrease in diversity due to an increase in the dominance of certain plant species. A change in habitat structure is likely to have negative effects on species that depend on certain plants or structural layers in an environment for habitat, shelter or food.

Details: Category: Behaviour & communication

Estimating the active space of male koala bellows: propagation of cues to size and identity in a Eucalyptus forest

Charlton, BD, Reby, D, Ellis, WAH, Brumm, J & Tecumseh Fitch, W 2012, PLoS ONE, vol. 7, no. 9, e45420.

The acoustic cues that most reliably distinguish the bellow of one male koala from another can be transmitted across a distance of up to 50 metres in a eucalypt forest. The acoustic features that indicate the size of a male, however, can be reliably communicated over a longer distance of up to 150 metres in the typical habitat of the koala.

Details: Category: Threatening processes

Failure to respond to food resource decline has catastrophic consequences for koalas in a high-density population in southern Australia

Whisson, DA, Dixon, V, Taylor, ML & Melzer, A 2016, PLoS One, vol. 11, no. 1, pp. 1-12.

Between September 2011 and November 2013, the growth and consequent collapse of a koala population resulting from a decline in key food trees was documented. During the study, population density grew from 10.1 to 18.4 koalas/ha, with a significant decline in manna gum (Eucalyptus viminalis) canopy condition taking place as a consequence of high browsing pressure. Individuals were shown to remain in small home ranges (0.4-1.2ha), regardless of the severity of food tree defoliation.

Details: Category: Biogeography

Far Western New South Wales occurrence of a koala Phascolarctos cinereus

Ellis, M, Sheppard, N & Gall, K 1997, Australian Zoologist, vol. 30, no. 3, pp. 327-328.

In July of 1994, a grazier 30 kilometres north of Wilcannia reported sighting a male koala. Prior to this there had only been occasional sightings of koalas in the western plains of New South Wales, mainly concentrated around Ivanhoe and the along the Darling River. This new observation suggests that koala dispersal or colonisation may be promoted by their use of the Darling River corridor.

Details: Category: Behaviour & communication

Female koalas prefer bellows in which lower formants indicate larger males

Charlton, BD, Ellis, WAH, Brumm, J, Nilsson, K & Fitch, WT 2012, Animal Behaviour, vol. 84, no. 1, pp 1565-1571.

Formants, the frequencies produced by vibrating air in the vocal tract, are acoustic cues that female koalas can use to evaluate the size of a bellowing male. Oestrus female koalas at Lone Pine Koala Sanctuary looked significantly more towards and spent significantly more time in close proximity to speakers broadcasting bellows with lower formant values, indicating a large male caller, than to speakers broadcasting higher formant values produced by a smaller male.

Details: Category: Habitat

Four new species of Telanepsia Turner (Lepidoptera: Oecophoridae) with larvae feeding on koala and possum scats

Common, IFB & Horak, M 1994, Invertebrate Systematics, vol. 8, pp. 809-828.

Four new Telanepsia moth species (Lepidoptera: Oecophoridae) have been found in koala and possum scats in southern Australia. The new species have been named T. stockeri, T. scatophilia, T. tidbinbilla and T. coprobora. The terminology and morphological ratios of T. stockeri, T. scatophilia, T. tidbinbilla and T. coprobora are examined in this study.

Details: Category: Threatening processes

Foxes in trees: a threat for Australian arboreal fauna?

Mella, VSA, McArthur, C, Frend, R & Crowther, M 2018, Australian Mammalogy, vol. 40, no. 1, pp. 103-105.

For the first time in Australia, researchers have observed red foxes (Vulpes vulpes) climbing trees. It is not yet known whether such behaviour is common or if red foxes can prey upon arboreal species; however, this surprising behaviour may have negative consequences for koalas.

Details: Category: Behaviour & communication

Free-ranging male koalas use size-related variation in formant frequencies to assess rival males

Charlton, BD, Whisson, DA & Reby, D 2013, PLoS ONE, vol. 8, no. 7, e70279.

Male koalas detect acoustic cues in the bellows of their competitors to the caller’s body size and change their own vocal response accordingly. When exposed to a bellow from a large, as opposed to a small, caller during the breeding season, male koalas produce a delayed bellow of greater duration.

Details: Category: Behaviour & communication

Heterosexual and homosexual behaviour and vocalisations in captive female koalas (Phascolarctos cinereus)

Feige, S, Nilsson, K, Phillips, CJC & Johnston, SD 2007. Applied Animal Behaviour Science, vol. 103, no. 1, pp 131-145.

Female koalas in captive environments engage in both homosexual and heterosexual interactions, although only heterosexual interactions have been recorded in nature. In captivity, female koalas also produce acoustic bellows, a sexual behaviour typically only observed in males. This study of koalas in Lone Pine Koala Sanctuary revealed that homosexual interactions between females comprised the same component behaviours and vocalisations as, but were shorter in duration than, heterosexual interactions.

Details: Category: Habitat

Honeyeater plucks koala for nest material

Cody, ML 1991, EMU, vol. 91, pp. 125-126.

This report describes an observation of a single yellow-faced honeyeater repeatedly plucking fur from a koala and incorporating it into its nest in Fairyland, southeast Queensland. This interaction is thought to be the first observed between honeyeaters and koalas, although similar plucking and nesting habits have been previously described between honeyeaters and cows, humans and some other marsupial species.

Details: Category: Habitat

Improving habitat models and their utility in koala conservation

Cork, SJ, Hume, ID & Foley, WJ 2000, Conservation Biology, vol. 14, no. 3, pp. 660-668.

Conservation efforts and decision-making for the protection of koalas are often dependent on sufficient koala habitat models, which identify geographic distributions of the species and show changes in habitat use in response to different variables over time. A review of models showed that there is a need to improve the accuracy and authority of such models for meaningful use in the decision-making process.

Details: Category: Threatening processes

Individuals matter: predicting koala road crossing behaviour in south-east Queensland

Dexter, CE, Appleby, RG, Scott, J, Edgar, JP & Jones, DN 2018, Australian Mammalogy, vol. 40, no. 1, pp. 67-75.

An investigation into the factors influencing the movements of koalas has revealed that, within a population, not all koalas are equally likely to cross a road. Road mitigation strategies that target those individuals most at risk of vehicle strike are likely to deliver greater benefits for koalas than strategies that do not account for these inter-individual differences.

Details: Category: Habitat

Influence of insect herbivory on the decline of black box (Eucalyptus largiflorens)

Stone, C & Bacon, PE 1995, Australian Journal of Botany, vol. 43, pp. 555-564.

A study of the influence of insect herbivory on the dieback of black box (Eucalyptus largiflorens) was undertaken in southern central New South Wales in 1993. Insecticide was applied to half of the tree samples to investigate the relationship between insect herbivory and different tree characteristics. Insecticide treatment, together with reduced rainfall, reduced insect herbivory damage greatly. The least trunk diameter increment was measured in trees that suffered the highest level of insect herbivory. There was surprisingly little evidence to show a consistent relationship between herbivory and crown condition. Moreover, two distinct foliage morphologies, both broad- and narrow-lanceolate, were observed in adjacent trees, as opposed to having only narrow-lanceolate foliage which is typically described for the species. Trees with broader foliage were found to be more susceptible to insect herbivory.

Details: Category: Habitat

Ingestion and excretion of Eucalyptus punctata D. C. and its essential oil by the koala, Phascolarctos cinereus (Goldfuss)

Eberhard, IH, McNamara, J, Pearse, RJ & Southwell, IA 1975, Australian Journal of Zoology, vol. 23, pp. 169-179.

This study describes a feeding trial during which ingestion and excretion by four captive koalas fed an exclusive diet of Eucalyptus punctata punctata was examined. Findings showed that 60% of leaf dry matter was digestible and of the volatile oil ingested, an insignificant proportion was excreted, with 7-30% passing through to the faeces and 1% in the urine.

Details: Category: Habitat

Insects associated with the faecal pellets of the koala, Phascolarctos cinereus Goldfuss

Melzer, A, Schneider, MA & Lamb, D 1994, Australian Entomologist, vol. 21, no. 3, pp. 69-70.

In koala faecal pellets collected near Springsure, Queensland, insects that causing pellet damage and decomposition were identified. One beetle species (Ptinus sp.), two moth species (Argyrotoxa pompica and Blastobasis sp.) and four wasp species (Pycnobracon sp., Choeras sp., Diaulomorpha sp. and a pteromalid) were recovered from the faecal pellets.

Details: Category: Habitat

Koalas continue to occupy their previous home-ranges after selective logging in Callitris-Eucalyptus forest

Kavanagh, RP, Stanton, MA, & Brassil, TE 2007, Wildlife Research, vol. 34, pp- 94-107.

Tree logging is one of the many processes that contribute to habitat loss for a variety of arboreal marsupials; however, sensitivity to logging may vary amongst different species. Koalas, for instance, do not require old trees for breeding or nesting as other arboreal marsupials do, but require certain tree species for food. The authors of this study investigated how selective logging affects the koalas in the Pilliga forests in north-western New South Wales, and found that tree preferences, home range sizes, home range overlap between individuals, movements, fidelity, fecundity and mortality of the koalas did not differ between logged and unlogged sites. These results suggest that selective logging does not necessarily adversely impact the conservation of koalas in the Pilliga forests.

Details: Category: Population dynamics

Low genetic diversity and inbreeding depression in Queensland koalas

Worthington-Wilmer, JM, Melzer, A, Carrick, F, & Moritz, C, 1993, Wildlife Research, vol. 20, pp. 177-188.

Analysis of mitochondrial DNA (mtDNA) of two Queensland koala populations reveals that genetic variation within and between these population is extremely low, though the variation appears to be structured geographically. Furthermore, the analysis also shows inbreeding levels in a captive colony in one of these populations to be moderate and high, but koalas within this colony do not show strong evidence of inbreeding depression apart from the male-biased sex ratio.

Details: Category: Habitat

Low-density koala (Phascolarctos cinereus) populations in the mulgalands of south-west Queensland. II. Distribution and diet

Sullivan, BJ, Norris, WM & Baxter, GS 2003, Wildlife Research, vol. 30, pp. 331-338.

In the mulgalands of south-west Queensland, the distribution of a local koala population and their food tree preferences were established through a combination of belt transect and faecal pellet surveys. Findings indicated that distribution is strongly associated with annual rainfall, with greatest abundances in northern and easterly regions of the study area. Faecal pellet analyses showed that the vast majority of the koalas’ diets in the mulgalands was comprised of five different Eucalyptus species.

Details: Category: Biogeography

Modeling Species’ Distributions to Improve Conservation in Semiurban Landscapes: Koala Case Study

Rhodes, JR, Wiegand, T, McAlpine, CA, Callaghan, J, Lunney, D, Bowen, M & Possingham, HP 2006, Conservation Biology, vol. 20, no. 2, pp. 449-459.

Logistic regression models can be used to show the distribution of koalas in response to the quality of natural habitat and anthropogenic impacts, and consequently to predict changes in populations in response to these variables over time. Here, this modelling approach in combination with distribution mapping techniques showed that natural habitat availability was the most important factor determining koala presence; however, anthropogenic impacts are an increasing threat to the existence of koalas in some areas, particularly at a local scale.

Details: Category: Threatening processes

Modelling climate-change-induced shifts in the distribution of the koala

Adams-Hosking, C, Grantham, HS, Rhodes, JR, McAlpine, C & Moss, PT 2011, Wildlife Research, vol. 38, pp. 122-130.

Climate change is resulting in shifting distributions of koala populations throughout Australia as a direct result of increased temperatures and decreased rainfall. Bioclimatic models based on current koala localities and several climate change scenarios were used in this study to predict future climatic envelopes of koala populations. Results showed a likely progressive movement eastwards and southwards in Queensland, New South Wales and Victoria.

Details: Category: Biogeography

Modelling climate-change-induced shifts in the distribution of the koala

Adams-Hosking, C, Grantham, HS, Rhodes, JR, McAlpine, C & Moss, PT 2011, Wildlife Research, vol. 38, pp. 122-130.

Climate change is resulting in shifting distributions of koala populations throughout Australia as a direct result of increased temperatures and decreased rainfall. Bioclimatic models based on current koala localities and several climate change scenarios were used in this study to predict future climatic envelopes of koala populations. Results showed a likely progressive movement eastwards and southwards in Queensland, New South Wales and Victoria.

Details: Category: Biogeography

Modelling distributions of arboreal and ground-dwelling mammals in relation to climate, nutrients, plant chemical defences and vegetation structure in the eucalypt forests of southeastern Australia

Cork, SJ & Catling, PC 1996, Forest Ecology and Management, vol. 85, pp. 163-175.

This paper reviews numerous studies investigating how both arboreal and ground-dwelling mammal distributions respond to changes in climate, leaf nutrients, plant chemical defences and vegetation structure, using the temperate Eucalyptus forests of southeastern and northeastern New South Wales as case studies.

Details: Category: Threatening processes

Modelling mammalian extinction and forecasting recovery: koalas at Iluka (NSW, Australia)

Lunney, D, O’Neill, L, Matthews, A & Sherwin, WB 2002, Biological Conservation, vol. 106, pp. 101-113.

The authors of this study modelled the effects of several population-boosting scenarios to evaluate the factors likely to be most important in the extinction and recovery of the koala population at Iluka, New South Wales. Improvements in neither mortality nor fertility rates reversed extinction risk. Only metapopulation planning to facilitate immigration into the koala population combined with increased fertility was found to restore the population to its initial size.

Details: Category: Threatening processes

Morbidity and Mortality in the Koala (Phascolarctos cinereus)

Backhouse, TC & Bolliger, A 1961, Australian Journal of Zoology, vol. 9, no.1, pp. 24-37.

Of 28 koalas autopsied in 1960, pneumonia was the leading cause of death in this mortality study, which also presented as a comorbidity with trauma. Other significant causes of death were hepatitis, yeast infections of the species Cryptococcus neoformans, leukaemia and anaemia. Ovarian cysts were observed in a number of the koalas, but it was only the cause of death for koalas whose cysts had become infected. Finally, senility-associated diseases such as cardiac failure were seen at a low level.

Details: Category: Biogeography

Movement patterns of koalas in remnant forest after fire

Matthews, A, Lunney, A, Gresser, S & Maitz, W 2016, Australian Mammalogy, vol. 38, pp. 91-104.

With greater fragmentation of remnant, fire-prone forest across eastern Australia, prevailing koala populations are becoming increasingly susceptible to disturbance events. This study investigated the dispersal of koalas after a large wildfire on the central coast of New South Wales. Radio-tracking over three years revealed a wide variety of patterns, with rehabilitated and unburnt koalas demonstrating both localised and long-range movement exceeding 20km.

Details: Category: Behaviour & communication

Perception of male caller identity in koalas (Phascolarctos cinereus): acoustic analysis and playback experiments

Charlton, BD, Ellis, WAH, McKinnon, AJ, Brumm, J, Nilsson, K & Tecumseh Fitch, W 2011, PLoS ONE, vol. 6, no. 5, e20329.

The bellow of a male koala is unique from that of other koalas to the extent that bellows can be consistently discriminated between and identified to individuals. Both male and female koalas that were familiar with the bellow of a particular male dishabituated in response to the bellow of an unfamiliar male and displayed comparatively greater interest in the novel stimulus.

Details: Category: Behaviour & communication

Perception of size-related formant information in male koalas (Phascolarctos cinereus)

Charlton, BD, Ellis, WAH, Larkin, R & Tecumseh Fitch, W 2012, Animal Cognition, vol. 15, no. 1, pp. 999-1006.

This report is the first to document evidence of male koalas being able to perceive variations in formant spacing in the bellows of other males that convey the caller’s body size.

Details: Category: Threatening processes

Post-fire survival and reproduction of rehabilitated and unburnt koalas

Lunney, D, Gresser, SM, Mahon, PS & Matthews, A 2004, Biological Conservation, vol. 120, pp. 567-575.

Comparisons of koalas rehabilitated after sustaining burn injuries following a fire event against uninjured koalas found no significant difference in post-release survival and reproductive success between the two groups, indicating human intervention and rehabilitation efforts can be beneficial to conservation efforts following fire.

Details: Category: Habitat

Relationship between chemical function groups on Eucalyptus secondary metabolites and their effectiveness as marsupial antifeedants

Lawler, IR, Eschler, BM, Schliebs, DM & Foley, WJ 1999, Journal of Chemical Ecology, vol. 25, no. 11, pp. 2561-2573.

Significant variation in the type and concentration of diformylphloroglucinol compounds (DFPCs) is observed within species of Eucalyptus, which contributes to their resistance against foliage consumption by marsupials. Jensenone was used as a model DFPC and compared to structural variants to determine the functional group causing the deterrent activity, with the aldehyde on the aromatic ring determined to reduce ringtail possum food intake.

Details: Category: Threatening processes

Skeletal fluorosis in marsupials: a comparison of bone lesions in six species from an Australian industrial site

Death, C, Coulson, G, Kierdorf, U, Kierdorf, H, Ploeg, R, Firestone, SM, Dohoo, I & Hufschmid, J 2017, Science of the Total Environment, vol. 584-585, no. 1, pp. 1198-1211.

Koalas and other marsupials living in high-fluoride environments are at risk of developing skeletal fluorosis. The severity of skeletal lesions in an affected animal is positively associated with bone fluoride levels. Of the six species studied here, all exhibited either localised or generalised periosteal hyperostosis but the distribution of lesions varied according to the animal’s mastication and gait.

Details: Category: Behaviour & communication

Subharmonics increase the auditory impact of female koala rejection calls

Charlton, BD, Watchorn, DJ & Whisson, DA 2017, Ethology, vol. 123, no. 1, pp. 571-579.

Subharmonics in female koala vocalisations made when rejecting a mating attempt create an unpredictable acoustic pattern that may serve to attract a higher-quality mate.

Details: Category: Behaviour & communication

The acoustic structure and information content of female koala vocal signals

Charlton, BD 2015, PLoS ONE, vol. 10, no. 10, e0138670.

Female koalas produce distinct categories of vocalisations that differ in acoustic structure. Some of these vocalisations contain acoustic cues to the caller’s identity, age and sex, which is likely of great adaptive significance to male koalas.

Details: Category: Behaviour & communication

The association of tooth wear with sociality of free-ranging male koalas (Phascolarctos cinereus Goldfuss)

Logan, M & Sanson, GD 2002, Australian Journal of Zoology, vol. 50, no. 1, pp. 621–626.

This study found that tooth wear is associated with the reproductive efforts of male koalas. Koalas with very low and high tooth wear were found to have decreased reproductive efforts, while koalas with intermediate tooth wear were found to exert higher reproductive effort.

Details: Category: Threatening processes

The causes and prognoses of different types of fractures in wild koalas submitted to wildlife hospitals

Henning, J, Hannon, C, McKinnon, A, Larkin, R & Allavena, R 2015, Preventative Veterinary Medicine, vol. 122, pp. 371-378.

Fractures, whether caused by cars, dog attacks or falls from trees, regularly result in the death or euthanasia of wild koalas. It is, therefore, important for koala conservation and management to identify patterns and risk factors regarding the prevalence of fractures. Within this study, data collected from over 2000 wild koalas with fractures admitted to south-east Queensland wildlife hospitals were analysed. Head fractures and vehicle collisions were the most common type and cause of fractures respectively.

Details: Category: Habitat

The effect of exotic pasture development on floristic diversity in central Queensland, Australia

Fairfax, RJ & Fensham, RJ 2000, Biological Conservation, vol. 94, pp. 11-21.

The establishment of exotic pasture following tree clearance can negatively impact the floristic composition of vegetation in brigalow (Acacia harpophylla), gidgee (A. cambagei) and eucalypt (Eucalyptus populnea, E. melanophloia) dominated woodlands and forests in semi-arid central Queensland.

Details: Category: Behaviour & communication

The effects of tooth wear on the activity patterns of free-ranging koalas (Phascolarctos cinereus Goldfuss)

Logan, M & Sanson, GD 2002, Australian Journal of Zoology, vol. 50, pp. 281–292.

This study found that increased tooth wear affects adult koalas in multiple ways. Koalas with significant tooth wear spend less time sleeping and being inactive than those without. They also spend less time moving about and stay within smaller areas. On the other hand, they spend more time feeding and have more spaced out feeding times, thus becoming less nocturnal.

Details: Category: Habitat

The importance of forest area and configuration relative to local habitat factors for conserving forest mammals: A case study of koalas in Queensland, Australia

McAlpine, CA, Rhodes, JR, Callaghan, JG, Bowen, ME, Lunney, D, Mitchell, DL, Pullar, DV & Possingham, HP 2006, Biological Conservation, vol. 132, pp. 153-165.

Koalas were used as a model species in this study to represent forest-dependent mammals particularly affected by forest clearing and fragmentation. The study was conducted in south-east Queensland and compared the importance of forest area and configuration with nine fine-scale habitat features for koala occurrence. Results found that koala occurrence was positively associated with the area of forest habitat, habitat patch size and the proportion of primary eucalypt species. In contrast, forest patch density, mean nearest neighbour distance (between forest patches) and road density had a negative relationship with koala occurrence.

Details: Category: Biogeography

The spatial and temporal distribution of koala faecal pellets

Ellis, WAH, Sullivan, BJ, Lisle, A & Carrick, FN 1998, Wildlife Research, vol. 25, pp. 663-668.

Faecal pellet counting is a convenient tool to determine the habitat use of vertebrate species, and particularly how individual koalas utilise trees. This study investigates the relationship between koala activity and the temporal and spatial patterns of pellet production by koalas. The authors reported that koala pellet production was at its peak between 6pm and midnight, and that there was a significant relationship between the average length of time spent in a tree by a koala and the time of day at which the koala arrived in the tree.

Details: Category: Biogeography

The use of corridors by mammals in fragmented Australian eucalypt forests

Downes, SJ, Handasyde, KA & Elgar, MA 1997, Conservation Biology, vol. 11, no. 3, pp. 718-726.

The composition and density of mammalian assemblages utilising forest patches, corridors and pasture in fragmented forest landscapes vary between species, generally depending on individual species characteristics. This study highlights the importance of corridors, particularly for arboreal mammal species such as the koala, as they provide resident habitat and functional pathways in a fragmented forest system.

Details: Category: Threatening processes

Time-delayed influence of urban landscape change on the susceptibility of koalas to chlamydiosis

McAlpine, C, Brearley, G, Rhodes, J, Bradley, A, Baxter, G, Seabrook, L, Lunney, D, Liu, Y, Cottin, M, Smith, AG & Timms, P 2017, Landscape Ecology, vol. 32, no. 3, pp. 1-17.

The effects of changes in landscape or climate on the prevalence of chlamydiosis in koalas may not manifest until several years after the initial change occurred. Disease prevalence and body condition of koalas in southeast Queensland were quantified to determine both the spatial factors that affect these variables and the time delay, if any, of the effect. For landscapes in which the area of suitable habitat increased, koalas had high body condition scores but also high disease prevalence three years later. Alternatively, when the extent of urbanisation in a landscape increased, koala populations exhibited an increased prevalence of chlamydiosis four years later and decreased body condition one year later. An increase in annual rainfall was associated with immediately improved body condition and reduced disease prevalence after two years.

Details: Category: Habitat

Time-delayed influence of urban landscape change on the susceptibility of koalas to chlamydiosis

McAlpine, C, Brearley, G, Rhodes, J, Bradley, A, Baxter, G, Seabrook, L, Lunney, D, Liu, Y, Cottin, M, Smith, AG & Timms, P 2017, Landscape Ecology, vol. 32, no. 3, pp. 1-17.

The effects of changes in landscape or climate on the prevalence of chlamydiosis in koalas may not manifest until several years after the initial change occurred. Disease prevalence and body condition of koalas in southeast Queensland were quantified to determine both the spatial factors that affect these variables and the time delay, if any, of the effect. For landscapes in which the area of suitable habitat increased, koalas had high body condition scores but also high disease prevalence three years later. Alternatively, when the extent of urbanisation in a landscape increased, koala populations exhibited an increased prevalence of chlamydiosis four years later and decreased body condition one year later. An increase in annual rainfall was associated with immediately improved body condition and reduced disease prevalence after two years.

Details: Category: Habitat

Tree species preferences of koalas (Phascolarctos cinereus) in the Campbelltown area south-west of Sydney, New South Wales

Phillips, S & Callaghan, J 2000, Wildlife Research, vol. 27, pp. 509-516.

In the Campbelltown Local Government Area, the quality of habitat being utilised by a small koala population was assessed, with particular attention paid to food tree species preferences. Forty-five different field sites were examined, revealing that grey gum (Eucalyptus punctata) and blue-leaved stringybark (E. agglomerata) were the most preferred species. However, tree preferences were shown to depend on soil substrate, derived either from shale or sandstone.

Details: Category: Threatening processes

Tree use by koalas (Phascolarctos cinereus) after fire in remnant coastal forest

Matthews, A, Lunney, D, Gresser, S & Maitz, W 2007, Wildlife Research, vol. 34, pp. 84-93.

Resource depletion as a result of wildfire has a short-term impact on koala populations in remnant forests. The present study revealed that koala populations at Port Stephens in New South Wales returned to utilising burnt trees shortly after intense wildfires that occurred in 1994, and some koalas were even observed using burnt trees exclusively. Furthermore, the authors noticed differences in the preferences and uses of tree species between the sexes, breeding and non-breeding females, day time and night time, as well as between seasons.

Details: Category: Habitat

Tree use, diet and home range of the koala (Phascolarctos cinereus) at Blair Athol, central Queensland

Ellis, WAH, Melzer, A, Carrick, FN & Hasegawa, M 2002, Wildlife Research, vol. 29, pp. 303-311.

In the area of Blair Athol Coal Mine, central Queensland, daytime tree use, home range and diet was monitored in free-ranging koalas. During the observation period, male and female koalas occupied, on average, 93 and 56 trees respectively and home ranges of 135 and 101 ha. Koalas rarely returned to the same daytime roosting tree and proportional species representation in diet did not reliably reflect tree-roosting behaviour.

Details: Category: Behaviour & communication

Tree-hugging behavior beats the heat

Briscoe, NJ 2015, Temperature, vol. 2, no. 1, pp. 33-35.

Koalas change their behaviour to use temperature variation in microclimates to cool themselves down by hugging cool tree surfaces during hot weather to increase heat loss. They were observed to minimise evaporative water loss through spending more time in shaded areas and hugging trunks of trees of the species Acacia mernsii, which has a cool trunk temperature.

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