Home ranges and movements of an arboreal folivore after wildfire: comparing rehabilitated and non-rehabilitated animals in burnt and unburnt woodlands.

Background: Wildfires can have complex effects on wildlife populations. Understanding how post-fire conditions affect the movement ecology of threatened species can assist in better conservation and management, including informing the release of rescued and rehabilitated animals. The 2019-2020 megafires in Australia resulted in thousands of animals coming into care due to injury or concerns over habitat degradation.

Biodiversity impacts of the 2019-2020 Australian megafires.

With large wildfires becoming more frequent, we must rapidly learn how megafires impact biodiversity to prioritize mitigation and improve policy. A key challenge is to discover how interactions among fire-regime components, drought and land tenure shape wildfire impacts. The globally unprecedented 2019-2020 Australian megafires burnt more than 10 million hectares, prompting major investment in biodiversity monitoring.

Relationships between abiotic factors, foliage chemistry and herbivory in a tropical montane ecosystem.

Herbivore-plant interactions are fundamental processes shaping ecosystems, yet their study is challenged by their complex connections within broader ecosystem processes, requiring a nuanced understanding of ecosystem dynamics. This study investigated the relationship between nutrient availability and insect herbivory in the Australian Wet Tropics. Our objectives were threefold.

Warmer ambient temperatures reduce protein intake by a mammalian folivore.

The interplay between ambient temperature and nutrition in wild herbivores is frequently overlooked, despite the fundamental importance of food. We tested whether different ambient temperatures (10°C, 18°C and 26°C) influenced the intake of protein by a marsupial herbivore, the common brushtail possum (). At each temperature, possums were offered a choice of two foods containing different amounts of protein (57% versus 8%) for one week.

Health Assessments of Koalas after Wildfire: A Temporal Comparison of Rehabilitated and Non-Rescued Resident Individuals.

Many koalas () required rehabilitation after the 2019/20 Australian megafires. Little is known about how the post-release health of rehabilitated koalas compares to non-rescued resident koalas. We evaluated health parameters in rehabilitated koalas and resident koalas in burnt and unburnt habitat in southern New South Wales, Australia.

Fundamental dietary specialisation explains differential use of resources within a koala population.

The diets of individual animals within populations can differ, but few studies determine whether this is due to fundamental differences in preferences or capacities to eat specific foods, or to external influences such as dominance hierarchies or spatial variation in food availability. The distinction is important because different drivers of dietary specialisation are likely to have different impacts on the way in which animal populations respond to, for example, habitat modification. We used a captive feeding study to investigate the mechanisms driving individual dietary specialisation in a population of wild koalas (Phascolarctos cinereus) in which individuals predominantly ate either Eucalyptus viminalis or Eucalyptus obliqua foliage.

Food intake: an overlooked driver of climate change casualties?

Reduced voluntary food intake is a common response of endotherms to warmer temperatures. However, the implications of this are rarely considered for wild animals exposed to higher temperatures caused by climate change. We provide a conceptual model to demonstrate the potential consequences of elevated temperatures on food intake and survival.

The distribution and abundance of an unusual resource for koalas (Phascolarctos cinereus) in a sodium-poor environment.

Environmentally available sodium tends to decrease with increasing elevation, and sodium resources in these sodium-poor environments are critical for the survival of herbivores. Eucalypt leaves in the subalpine Monaro region of NSW, Australia contain much less sodium than eucalypt leaves at lower elevations, and subalpine koalas obtain this much needed resource by eating the bark from some Eucalyptus mannifera trees. To better understand the availability of salty-barked trees, we searched for evidence of koala bark chewing at 100 randomly generated locations in the region.

Faecal inoculations alter the gastrointestinal microbiome and allow dietary expansion in a wild specialist herbivore, the koala.

Background: Differences between individuals in their gastrointestinal microbiomes can lead to variation in their ability to persist on particular diets. Koalas are dietary specialists, feeding almost exclusively on Eucalyptus foliage but many individuals will not feed on particular Eucalyptus species that are adequate food for other individuals, even when facing starvation. We undertook a faecal inoculation experiment to test whether a koala's gastrointestinal (GI) microbiome influences their diet.

New approaches to tannin analysis of leaves can be used to explain in vitro biological activities associated with herbivore defence.

Although tannins have been an important focus of studies of plant-animal interactions, traditional tannin analyses cannot differentiate between the diversity of structures present in plants. This has limited our understanding of how different mixtures of these widespread secondary metabolites contribute to variation in biological activity. We used UPLC-MS/MS to determine the concentration and broad composition of tannins and polyphenols in 628 eucalypt (Eucalyptus, Corymbia and Angophora) samples, and related these to three in vitro functional measures believed to influence herbivore defence: protein precipitation capacity, oxidative activity at high pH and capacity to reduce in vitro nitrogen (N) digestibility.

Occurrence and distribution of unsubstituted B-ring flavanones in Eucalyptus foliage.

A group of plant specialised metabolites (PSMs) collectively known as unsubstituted B-ring flavanones (UBFs) have previously been found in the foliage of some species from the genus Eucalyptus L'Hér. (Myrtaceae), specifically from the subgenus Eucalyptus (monocalypts). Captive feeding studies using artificial diets suggest that these compounds may potentially influence the feeding preferences of marsupial folivores, such as koalas.

Intraspecific Variation in Nutritional Composition Affects the Leaf Age Preferences of a Mammalian Herbivore.

Ecologists have long been interested in how the nutritional composition of leaves changes as they age, and whether this affects herbivore feeding preferences. As a consequence, the literature abounds with reports that younger leaves contain higher concentrations of nitrogen and plant secondary metabolites (PSMs) than do older leaves. Most of these studies, however, base their conclusions on average values that often mean little to herbivores.

Correction to: Oxidizable Phenolic Concentrations Do Not Affect Development and Survival of Paropsis Atomaria Larvae Eating Eucalyptus Foliage.

Ian Wallis was inadvertently omitted as an author in this study. Ian Wallis assisted with the collection of the leaf samples that were used in this study, and built the chambers that the insects were housed in.

Genus-wide variation in foliar polyphenolics in eucalypts.

Many studies quantify total phenolics or total tannins, but understanding the ecological role of polyphenolic secondary metabolites requires at least an understanding of the diversity of phenolic groups present. We used UPLC-MS/MS to measure concentrations of different polyphenol groups - including the four most common tannin groups, the three most common flavonoid groups, and quinic acid derivatives - in foliage from 628 eucalypts from the genera Eucalyptus, Angophora and Corymbia. We also tested for phylogenetic signal in each of the phenolic groups.

A hot lunch for herbivores: physiological effects of elevated temperatures on mammalian feeding ecology.

Mammals maintain specific body temperatures (T ) across a broad range of ambient temperatures. The energy required for thermoregulation ultimately comes from the diet, and so what animals eat is inextricably linked to thermoregulation. Endothermic herbivores must balance energy requirements and expenditure with complicated thermoregulatory challenges from changing thermal, nutritional and toxicological environments.

Oxidizable Phenolic Concentrations Do Not Affect Development and Survival of Paropsis Atomaria Larvae Eating Eucalyptus Foliage.

Insect folivores can cause extensive damage to plants. However, different plant species, and even individuals within species, can differ in their susceptibility to insect attack. Polyphenols that readily oxidize have recently gained attention as potential defenses against insect folivores.

The Use of Polyethylene Glycol in Mammalian Herbivore Diet Studies: What Are We Measuring?

Polyethylene glycol (PEG) has been used to study the intake and digestion of tannin-rich plants by mammalian herbivores because it preferentially binds to tannins. However, it is not clear whether the responses of herbivores to dietary PEG is due to increased protein availability from the release of tannin-bound protein, amelioration of tannin effects, or whether PEG also may bind to other compounds and change their activity in the gut. We used three native New Zealand tree species to measure the effect of PEG on the amount of foliage eaten by invasive common brushtail possums (Trichosurus vulpecula) and on in vitro digestible nitrogen (available N).

From Leaf Metabolome to In Vivo Testing: Identifying Antifeedant Compounds for Ecological Studies of Marsupial Diets.

Identifying specific plant secondary metabolites that influence feeding behavior can be challenging, but a solid understanding of animal preferences can guide efforts. Common brushtail possums (Trichosurus vulpecula) predominantly eat Eucalyptus species belonging to the subgenus Symphyomyrtus, and avoid eating those belonging to the Monocalyptus subgenus (also called subgenus Eucalyptus). Using an unbiased (1)H NMR metabolomics approach, a previous study identified unsubstituted B ring flavanones in most species of monocalypts examined, whereas these compounds were absent from symphyomyrtles.

Extraction of pinocembrin from leaves of different species of Eucalyptus and its quantitative analysis by qNMR and HPTLC.

Pinocembrin, a flavanone with a variety of biological activities was isolated from Eucalyptus sieberi leaves and quantified in several other Eucalyptus species using qNMR and HPTLC densitometry. The effect of different extraction procedures on the extraction of the compound from Eucalyptus sieberi was also studied. The methods were validated in terms ofselectivity, specificity, linearity, recovery, precision and repeatability.

Four species of arboreal folivore show differential tolerance to a secondary metabolite.

The marsupials that eat Eucalyptus in south-eastern Australia provide an example of animals with similar niche requirements occurring sympatrically. They certainly differ in size, ranging from about 1 kg in the greater glider (Petauroides volans) and the closely related common ringtail possum (Pseudocheirus peregrinus), to 4 kg (common brushtail possum, Trichosurus vulpecula) and up to 15 kg in the koala (Phascolarctos cinereus). All species, however, may eat considerable amounts of eucalypt foliage, often favouring the same species, and thus appear to compete for food.

Feeding rates of a mammalian browser confirm the predictions of a 'foodscape' model of its habitat.

Adequate nutrition is a fundamental requirement for the maintenance and growth of populations, but complex interactions between nutrients and plant toxins make it difficult to link variation in plant quality to the ecology of wild herbivores. We asked whether a 'foodscape' model of habitat that uses near-infrared spectroscopy to describe the palatability of individual trees in the landscape, predicted the foraging decisions of a mammalian browser, the koala (Phascolarctos cinereus). Specifically, we considered four behavioural decision points at which nutritional quality may influence an animal's decision.

Whole-body protein turnover reveals the cost of detoxification of secondary metabolites in a vertebrate browser.

The detoxification limitation hypothesis predicts that the metabolism and biotransformation of plant secondary metabolites (PSMs) elicit a cost to herbivores. There have been many attempts to estimate these costs to mammalian herbivores in terms of energy, but this ignores what may be a more important cost-increases in protein turnover and concomitant losses of amino acids. We measured the effect of varying dietary protein concentrations on the ingestion of two PSMs (1,8 cineole-a monoterpene, and benzoic acid-an aromatic carboxylic acid) by common brushtail possums (Trichosurus vulpecula).

A metabolomic approach to identifying chemical mediators of mammal-plant interactions.

Different folivorous marsupials select their food from different subgenera of Eucalyptus, but the choices cannot be explained by known antifeedants, such as formylated phloroglucinol compounds or tannins, or by nutritional quality. Eucalypts contain a wide variety of plant secondary metabolites so it is difficult to use traditional methods to identify the chemicals that determine food selection. Therefore, we used a metabolomic approach in which we employed (1)H nuclear magnetic resonance spectroscopy to compare chemical structures of representatives from the two subgenera and to identify chemicals that consistently differ between them.

Behavioural contributions to the regulated intake of plant secondary metabolites in koalas.

In a given period of time, herbivores often eat less as dietary plant secondary metabolite (PSM) concentrations increase. This reduction in total food intake is interpreted as a need for the herbivore to regulate PSM ingestion in order to avoid toxication. However, regulation of PSM ingestion involves more than the reduction of total intake; it involves an alteration of meal patterns, through a reduction in the number and/or the size of the meals eaten.

Conflicting demands on detoxification pathways influence how common brushtail possums choose their diets.

Most herbivores eat more and survive better when they have access to a variety of foods. One explanation involves the detoxification of plant secondary metabolites (PSMs). By feeding from a variety of plants that contain different classes of PSMs, animals can use multiple detoxification pathways and presumably consume more food.