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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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. 

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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.

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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.

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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.

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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.

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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.

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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. 

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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.

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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.

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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.  

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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.

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