ORCID Profile
0000-0002-7867-414X
Current Organisation
University of Sydney
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Ecology | Wildlife and Habitat Management | Evolutionary Biology | Plant Biology | Nutrition And Physiology | Tree Improvement (Selection, Breeding And Genetic Engineering) | Plant Protection (Pests, Diseases And Weeds) | Wildlife And Habitat Management | Management And Environment | Agricultural Biotechnology | Terrestrial Ecology | Marine And Estuarine Ecology (Incl. Marine Ichthyology) | Terrestrial Ecology | Life Histories (Incl. Population Ecology) | Sociobiology And Behavioural Ecology | Conservation And Biodiversity | Behavioural Ecology | Environmental Science and Management | Ecological Applications | Forestry Sciences | Soil Chemistry | Plant Improvement (Selection, Breeding And Genetic Engineering) | Post Harvest Technologies | Evolutionary Impacts of Climate Change | Microbial Ecology | Host-Parasite Interactions | Life Histories | Plant Physiology | Ecological Impacts of Climate Change | Plant Physiology | Landscape Ecology | Animal Systematics and Taxonomy | Biological Adaptation
ANZSRC Socio-Economic Objective (SEO)
Forest and Woodlands Flora, Fauna and Biodiversity | Expanding Knowledge in the Biological Sciences | Integration of farm and forestry | Forestry | Primary products from plants | Field crops | Integrated (ecosystem) assessment and management | Hardwood plantations | Horticultural crops | Control of pests and exotic species | Softwood plantations | Urban and Industrial Flora, Fauna and Biodiversity | Flora, Fauna and Biodiversity of environments not elsewhere classified | Integrated (ecosystem) assessment and management | Pasture, browse and fodder crops | Health not elsewhere classified | Flora, Fauna and Biodiversity at Regional or Larger Scales | Farmland, Arable Cropland and Permanent Cropland Flora, Fauna and Biodiversity | Ecosystem Adaptation to Climate Change | Climate Change Adaptation Measures | Control of pests and exotic species | Living resources (flora and fauna) | Fodder crops |
Related Links
Publications
Links between riparian characteristics and the abundance of common wombat (Vombatus ursinus) burrows in an agricultural landscape
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/WR08071
Abstract: Agricultural riparian zones are often vulnerable to weed invasion and degradation of the physical streambank character through the tr ling of livestock. Riparian zone restoration seeks to improve habitat bio ersity, minimise streambank erosion and improve water quality. In order for this to be effective land managers need to broadly understand the connections between riparian systems and adjoining agricultural ecosystems and to understand the habitat requirements of wildlife species adapted to the evolving riparian landscape. Common wombats (Vombatus ursinus) are abundant in the riparian agricultural landscapes of south-eastern Australia, but there is concern about their persistence in other landscapes. To understand the importance of riparian characteristics for wombats, we examined five physical and five vegetative characteristics associated with abundance of wombat burrows in the riparian zone of an agricultural landscape in south-eastern New South Wales, using two independent datasets. The abundance of wombat burrows increased substantially with increasing shrub cover in both datasets. There was weaker but consistent support for an association between wombat burrows and stream order and vegetation width. There were more burrows per metre by high than low order streams and burrows were most abundant at an intermediate vegetation width. In one of the two datasets, burrow abundance declined as the proportion of native shrubs in the shrub layer increased. As wombats are generally limited to riparian buffers in agricultural landscapes, these results are important as a first step toward managing and restoring the riparian zone. Restoration strategies, for ex le, may need to consider retaining patches of shrubs, even if they are weeds, whereas native shrubs are established in interspersed patches along larger rivers, in order to maintain suitable wombat habitat.
Animal personality drives individual dietary specialisation across multiple dimensions in a mammalian herbivore
Publisher: Wiley
Date: 15-08-2021
Abstract: Animal personality influences how in iduals perceive and react to different stimuli, such as food quality and predation risk, thereby shaping foraging behaviour. As a consequence, animal personality is predicted to influence the diet and dietary specialisation of in iduals within a population, but animal personality and dietary specialisation have yet to be linked. Here, we tested whether in idual diet and dietary specialisation are a function of animal personality, using an arboreal herbivore, the common brushtail possum, as a model species. We hypothesised that proactive in iduals have more erse foraging opportunities than reactive in iduals. We therefore predicted that proactive animals (more exploratory, bold and more active) would be less specialised, with a broader and higher quality diet than their reactive counterparts. We quantified the personality traits and dietary niche using proportional similarity index and specialisation categories of possums ( n = 30) in a population flanking native eucalypt woodland and residential gardens in suburban Sydney, Australia. We found that personality traits were related to the breadth and quality of the realised diets of in idual possums. As predicted, proactive in iduals had a broad, high‐quality diet with less in idual dietary specialisation than reactive in iduals. Highly exploratory in iduals had a more erse diet than less exploratory in iduals, and bold in iduals were more likely than shy in iduals to consume plants on the ground. Our study demonstrates an important link between animal personality and in idual dietary specialisation. The finding that the personality of in iduals is associated with different diet choices within the same landscape is fundamentally significant. First, personality as a driver of niche partitioning likely reduces within‐species competition and hence could contribute to adaptive capacity. Second, the strength of ecological processes arising from interactions (e.g. predator–prey and plant–herbivore interactions) could differ among in iduals according to their personality traits. Our findings are also relevant for effectively managing both threatened native and invasive species. Management strategies will be improved by incorporating knowledge of in idual traits and their ecological consequences, plus the ecological context of food‐ and fear‐scapes. A free Plain Language Summary can be found within the Supporting Information of this article.
Leveraging Motivations, Personality, and Sensory Cues for Vertebrate Pest Management
Publisher: Elsevier BV
Date: 11-2020
Behavioural responses to indirect and direct predator cues by a mammalian herbivore, the common brushtail possum
Publisher: Springer Science and Business Media LLC
Date: 07-09-2012
Identifying factors related to the severity of mammalian browsing damage in eucalypt plantations
Publisher: Elsevier BV
Date: 09-2003
Roles of the volatile terpene, 1,8-cineole, in plant-herbivore interactions: A foraging odor cue as well as a toxin?
Publisher: Springer Science and Business Media LLC
Date: 12-10-2014
DOI: 10.1007/S00442-013-2801-X
Abstract: Olfaction is an important sense for many animals, yet its role in foraging by herbivores is poorly known. Many plants contain volatile compounds, such as terpenes, that are not only volatile but can be toxic if ingested. Volatile terpenes can be used by herbivores to assess leaf quality, but there is little evidence for whether they are also used as a searching cue. We applied the giving-up density (GUD) framework to examine fine-scale foraging by two free-ranging mammalian herbivores, the brush-tail possum (Trichosurus vulpecula) and the sw wallaby (Wallabia bicolor), using patches with food and an inedible matrix that varied in content of a volatile terpene, 1,8-cineole. We tested the effect of (1) increasing dietary cineole concentration, and (2) masking the food odor by adding cineole to the inedible matrix, thus overriding the smell released by the diet. In both species GUD was affected by dietary cineole a high cineole concentration raised GUD, consistent with its role as a toxin. There was a significant effect of masking on GUD for wallabies but not for possums, suggesting that odor was an important foraging cue at the feeding patch only for the former. Differences in ecological niche and diet may explain this pattern. We suggest that herbivores, such as the sw wallaby, opportunistically eavesdrop on plant volatiles, i.e., take advantage of the signal proffered for a different function. The cost of this eavesdropping for plants, however, is presumably counteracted by other ecological benefits of these volatiles, including a reduction in leaf consumption as a function of toxicity.
Quantifying the response of free-ranging mammalian herbivores to the interplay between plant defense and nutrient concentrations
Publisher: Springer Science and Business Media LLC
Date: 09-03-2016
DOI: 10.1007/S00442-014-2980-0
Abstract: While trying to achieve their nutritional requirements, foraging herbivores face the costs of plant defenses, such as toxins. Teasing apart the costs and benefits of various chemical constituents in plants is difficult because their chemical defenses and nutrient concentrations often co-vary. We used an approach derived from predator-prey studies to quantitatively compare the foraging response of a free-ranging mammalian herbivore, the sw wallaby (Wallabia bicolor), through three feeding trials with artificial diets that differed in their concentrations of (1) the terpene 1,8-cineole, (2) primary constituents (including nitrogen and fiber), and (3) both the terpene and the primary constituents. Applying the giving-up density (GUD) framework, we demonstrated that the foraging cost of food patches increases with higher dietary cineole concentration and decreases with higher dietary nutrient concentration. The effect of combined differences in nutrients and cineole concentrations on GUD was interactive, and high nutrient food required more cineole to achieve the same patch value as low nutrient food. Our results indicate that sw wallabies equate low nutrient, poorly defended food with high nutrient, highly defended food, providing two contrasting diets with similar cost-benefit outcomes. This behavior suggests that equal concentrations of chemical defenses provide nutrient-poor plants with relatively greater protection as nutrient-rich plants. Nutrient-rich plants may therefore face the exacerbated problem of being preferred by herbivores and therefore need to produce more defense compounds to achieve the same level of defense as nutrient-poor plants. Our findings help explain the difference in anti-herbivore strategy of nutrient-poor and rich plants, i.e., tolerance versus defense.
Integrating the costs of plant toxins and predation risk in foraging decisions of a mammalian herbivore
Publisher: Springer Science and Business Media LLC
Date: 21-07-2010
DOI: 10.1007/S00442-010-1717-Y
Abstract: Foraging herbivores must satisfy their nutrient requirements in a world of toxic plants while also avoiding predators. Plant toxins and perceived predation risk at food patches should both reduce patch residency time, but the relative strengths of these factors on feeding decisions has rarely been quantified. Using an arboreal generalist herbivore, the common brushtail possum Trichosurus vulpecula, we tested the effects on food intake of the plant toxin, cineole, and regurgitated pellets from one of its predators, the powerful owl Ninox strenua at the small spatial scale of the food patch. We used the giving-up density (GUD) framework, with animals harvesting food items (sultanas) in an inedible matrix (small pebbles). We ran two consecutive field experiments in a eucalypt woodland in eastern Australia, 1 month apart in the same location. In experiment 1, there was a significant interaction between cineole [at 17% of dry matter (DM)] and owl pellets. The GUD was lowest in the absence of both cineole and owl pellet, intermediate in the presence of owl pellet and highest with cineole ± owl pellet. The effect of owl pellet diminished over time. In experiment 2, only cineole (at 10% DM) increased the GUD significantly. The difference in effect of owl pellet was probably due to both habituation and freshness of the cue. Our study demonstrates the importance of synthesising predator-prey and plant-herbivore ecology to better understand the complex set of constraints influencing foraging herbivores. The greater effect of toxin than fear on possums is likely to be due to its high, but ecologically relevant concentration. This highlights the need to explore the relative and net impacts of a range of concentrations of plant toxins and predation risks.
Evaluating effects of nursery and post-planting nutrient regimes on leaf chemistry and browsing of eucalypt seedlings in plantations
Publisher: Elsevier BV
Date: 10-2004
Predation risk and competitive interactions affect foraging of an endangered refuge-dependent herbivore
Publisher: Wiley
Date: 25-02-2011
A systematic review of factors affecting wildlife survival during rehabilitation and release
Publisher: Public Library of Science (PLoS)
Date: 17-03-2022
DOI: 10.1371/JOURNAL.PONE.0265514
Abstract: Millions of native animals around the world are rescued and rehabilitated each year by wildlife rehabilitators. Triage and rehabilitation protocols need to be robust and evidence-based, with outcomes consistently recorded, to promote animal welfare and better understand predictors of wildlife survival. We conducted a global systematic review and meta-analysis of 112 articles that reported survival rates of native mammals and birds during rehabilitation and after release to determine intrinsic and extrinsic factors associated with their survival. We assessed survival during rehabilitation and in the short- and long-term post-release, with the hypothesis that survival will vary as a function of species body size, diel activity pattern, trophic level and study location (region of the world). We aimed to determine the direction of effect of these factors on survival to assist in decision-making during triage and rehabilitation. Results showed that mammals and birds were equally likely to survive all stages of rehabilitation, and survival rates varied between locations. Birds in North America had the poorest survival rates post-release, particularly long-term, as did diurnal and carnivorous birds in the short-term post-release. Anthropogenic factors such as motor vehicle collisions and domestic or feral animal attack contributed to morbidity and post-release mortality in 45% (168 of 369) of instances. The reasons for rescue and associated severity of diagnosis were commonly reported to affect the likelihood of survival to release, but factors affecting survival were often species-specific, including bodyweight, age, and characteristics of the release location. Therefore, evidence-based, species-specific, and context-specific protocols need to be developed to ensure wildlife survival is maximised during rehabilitation and post-release. Such protocols are critical for enabling rapid, efficient rescue programs for wildlife following natural disasters and extreme weather events which are escalating globally, in part due to climate change.
Factors influencing the success of hand-reared juvenile brushtail possums (
Publisher: CSIRO Publishing
Date: 26-07-2022
DOI: 10.1071/WR22056
Abstract: Context Wildlife is ubiquitous in urban environments, resulting in frequent interactions with humans and human infrastructure. The result of these interactions is often negative, in the form of road injury, orphaning of dependent young or eviction from natural home ranges. Wildlife rehabilitation programmes are devised to counter these negative interactions. However, the success of current management strategies is rarely assessed. Aims We aimed to determine whether short-term survival of juvenile hand-reared common brushtail possums (Trichosurus vulpecula) released in the wild was a function of (1) intrinsic factors such as sex, in idual personality and level of human habituation, and (2) extrinsic factors such as release practice (soft vs hard-release) or location (urban vs rural). We also evaluated the relationship between habituation to humans and time spent in care by possums, if presence of conspecifics during the rehabilitation process influenced the development of in idual personality, and if this differed in hand-raised animals compared with wild in iduals. Methods We radio-tracked and monitored 20 hand-reared juvenile possums (10 females and 10 males) for up to 40 days after release in the wild. Key results Eight possums (40%) survived until the end of the study, nine possums (45%) were killed by foxes or had to be returned into care and three possums (15%) had unknown fates (i.e. lost VHF signal). We found that more exploratory in iduals and those less human-habituated were more likely to be successful in the wild in both rural and urban areas, whether or not they were hard or soft released. Conclusions Our results suggest that personality is a key criterion to consider when evaluating the success of rehabilitation programmes. Behavioural traits of hand-reared brushtail possums differed significantly from those of wild in iduals, showing that captive conditions can affect the development of personality. Hand-reared possums that spent more time in care were also more likely to display highly human-habituated behaviours. Implications By demonstrating which factors influence success of hand-reared wildlife after release in the wild, our results help in evaluating current rearing and release practices, and improve the evidence base for developing best practice wildlife rehabilitation guidelines.
Risk of predation and disease transmission at artificial water stations
Publisher: CSIRO Publishing
Date: 10-02-2022
DOI: 10.1071/WR21044
Abstract: Abstract Context Providing wildlife with supplementary water is a conservation technique that offers an immediate positive impact to animals. However, the potential negative impacts should be assessed. Aims We aimed to assess the potential negative effects of water stations on visiting wildlife due to the risk of predation and disease transmission. Methods We assessed potential benefits and costs of water supplementation in rural Australia by investigating the behavioural response of animals, at koala (Phascolarctos cinereus) water stations, to weather and to previous visitor species. To determine the risk of disease transmission, water and swab s les were taken from the water stations. Faecal contamination was quantified, and real-time PCR was used to identify various pathogens, including Chlamydia. Key results We found that koalas, brushtail possums (Trichosurus vulpecula) and foxes (Vulpes vulpes) responded to hot, dry weather with longer visits to water stations, indicating a benefit of water supplementation to native wildlife, but also to invasive species. Native animals did not alter their behaviour when their visits were preceded by another species, even when this was a potential predator. The presence of pathogens (i.e. Chlamydia and C. perfringens) at the stations did not depend on the number of species that visited but was higher in summer (December to February), representing a potential risk of disease transmission. Conclusions Water stations are an effective conservation tool because they can benefit threatened species during hot, dry weather, but there are risks associated with using supplemental water. Implications Although potential risks are low, they should still be considered. Efforts should be taken to exclude invasive species and water stations should be cleaned regularly while appropriate personal protective equipment is worn.
It is safe to go out on a limb: within-tree leaf age and location do not alter predation risk for insect herbivores
Publisher: Wiley
Date: 13-11-2016
DOI: 10.1111/AEN.12183
Head capsule stacking by caterpillars: Morphology complements behaviour to provide a novel defence
Publisher: PeerJ
Date: 29-02-2016
DOI: 10.7717/PEERJ.1714
Abstract: Herbivores employ a variety of chemical, behavioural and morphological defences to reduce mortality from natural enemies. In some caterpillars the head capsules of successive instars are retained and stacked on top of each other and it has been suggested that this could serve as a defence against natural enemies. We tested this hypothesis by comparing the survival of groups of the gumleaf skeletoniser Uraba lugens Walker caterpillars, allocated to one of three treatments: “−HC,” where stacked head capsules were removed from all in iduals, “+HC,” where the caterpillars retained their stacked head capsules, and “mixed,” where only half of the caterpillars in a group had their stacked head capsules removed. We found no difference in predation rate between the three treatments, but within the mixed treatment, caterpillars with head capsules were more than twice as likely to survive. During predator choice trials, conducted to observe how head capsule stacking acts as a defence, the predatory pentatomid bug attacked the −HC caterpillar in four out of six trials. The two attacks on +HC caterpillars took over 10 times longer because the bug would poke its rostrum through the head capsule stack, while the caterpillar used its head capsule stack to deflect the bug’s rostrum. Our results support the hypothesis that the retention of moulted head capsules by U. lugens provides some protection against their natural enemies and suggest that this is because stacked head capsules can function as a false target for natural enemies as well as a weapon to fend off attackers. This represents the first demonstration of a defensive function.
A multistressor, multitrait approach to assessing the effects of wind and dust on Eucalyptus tereticornis
Publisher: Wiley
Date: 08-2016
DOI: 10.3732/AJB.1600112
Abstract: Plants are routinely subjected to multiple environmental stressors, and the ability to respond to these stressors determines species survival and ecological breadth. Despite stressors such as wind and dust significantly influencing plant development, morphology, and chemistry, the combined influence of these factors is yet to be investigated. We used a manipulative glasshouse approach to compare the morphological, physiological, and biomechanical responses of Eucalyptus tereticornis to the independent and combined effects of wind and dust. Wind decreased both E. tereticornis height and stem flexural stiffness. Additionally, wind had no effect on leaf physiology, nor did dust have any significant effect on any of the traits measured. Our results suggest that wind and dust in combination may have an additive effect on several plant traits and provide new insight into the effects and importance of studying wind, dust, and different stress combinations.
Fire and grazing influence food resources of an endangered rock-wallaby
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/WR11208
Abstract: Context Fire and grazing have complex and interacting impacts on food resources available to endangered herbivores and can potentially be manipulated as part of conservation strategies. Aims We examined the interacting impacts of fire and grazing on the food resources available to a colony of endangered brush-tailed rock-wallabies (Petrogale penicillata) to test fire as a potential management tool. Methods We conducted two manipulative experiments using a repeated-measures split-block design. We measured the effects of grazing and strategic burning on total vegetation biomass and on particular plants selected by rock-wallabies. In the first experiment we measured the impact of rock-wallaby grazing alone. In the second experiment we measured grazing impacts by both rock-wallabies and potentially competitive sympatric macropods. Grazing was manipulated with three treatments: grazed (open), ungrazed (fenced) and procedural control (half fence). Key results In both experiments, burning resulted in greater above-ground biomass of plants selected by rock-wallabies. The response of different plant functional groups to fire was staggered, with forb biomass peaking early and browse biomass increasing above unburnt levels a year after burning. Conclusions Despite the limited grazing pressure exerted by the small colony of rock-wallabies in Experiment 1 we detected a negative grazing effect on forbs growing after fire in burnt plots. In Experiment 2, grazing pressure was much more marked due to the high densities of sympatric macropods. In this case, while burning resulted in greater biomass of plants selected by rock-wallabies, grazing (predominantly by sympatric macropods) negated this effect. Implications Small patchwork burning can be a useful tool to improve food resources for brush-tailed rock-wallabies, with effects sustained over more than two years. However, when rock-wallabies are sympatric with possible competitor species, the grazing impacts of sympatric macropods may cancel out any benefits to rock-wallabies.
Leaf odour cues enable non‐random foraging by mammalian herbivores
Publisher: Wiley
Date: 09-10-2017
Abstract: Searching for food is the first critical stage of foraging, and search efficiency is enhanced when foragers use cues from foods they seek. Yet we know little about food cues used by one major group of mammals, the herbivores, a highly interactive component of most ecosystems. How herbivores forage and what disrupts this process, both have significant ecological and evolutionary consequences beyond the animals themselves. Our aim was to investigate how free-ranging mammalian herbivores exploit leaf odour cues to find food plants amongst a natural and complex vegetation community. Our study system comprised the native "deer equivalent" of eastern Australian forests, the sw wallaby Wallabia bicolor, and seedlings of Eucalyptus, the foundation tree genus in these ecosystems. We quantified how foraging wallabies responded to odour cues from plants manipulated in several ways: varying the quantity of visually concealed leaves, comparing damaged vs. undamaged leaves, and whole plants vs. those with suppressed cues. The rate of discovery of leaves by wallabies increased with odour cue magnitude, yet animals were extremely sensitive to even a tiny odour source of just a few leaves. Whole seedlings were discovered faster if their leaves were damaged. Wallabies found whole seedlings and those with suppressed visual cues equally rapidly, day and night. Seedlings with very little odour were discovered mainly by day, as nocturnal foraging success was severely disrupted. This study shows how leaf odour attracts mammalian herbivores to food plants, enabling non-random search for even tiny odour sources. As damaged leaves enhanced discovery, we suggest that the benefit of attracting natural enemies to invertebrate herbivores feeding on plants (potential "cry for help") may be offset by a cost-increased browsing by mammalian herbivores. This cost should be incorporated into multi-trophic plant-animal studies. Finally, the breakdown in capacity to find plants at night suggests substantial but unrecognized foraging costs to herbivores when abiotic factors, such as cold temperatures or pollution, reduce or degrade plant odour cues. We predict that an increasingly polluted world will alter the foraging success of mammalian herbivores, with significant ecological ramifications given that browsing can shape ecosystems.
Sideroxylonal in Eucalyptus foliage influences foraging behaviour of an arboreal folivore
Publisher: Springer Science and Business Media LLC
Date: 05-10-2006
DOI: 10.1007/S00442-005-0268-0
Abstract: Plant secondary metabolites (PSMs) offer plants chemical defences against herbivores, and are known to influence intake and diet choice in both insect and mammalian herbivores. However, there is limited knowledge regarding how PSMs influence herbivore foraging decisions. Herbivore foraging decisions, in turn, directly impact on which in idual plants, and plant species, are selected for consumption. We took advantage of the natural variation in sideroxylonal concentrations in the foliage of Eucalyptus melliodora (Cunn. ex Schauer) to investigate feeding patterns of a marsupial folivore, the common ringtail possum, Pseudocheirus peregrinus (Boddaert 1785). Foliage, collected from six trees, contained between 0.32 and 12.97 mg g-DM(-1) sideroxylonal. With increasing sideroxylonal concentrations, possums decreased their total intake, rate of intake and intake per feeding bout, and increased their cumulative time spent feeding. Possums did not alter their total feeding time, number of feeding bouts or time per feeding bout in response to increasing sideroxylonal concentrations. Results demonstrate important behavioural changes in foraging patterns in response to sideroxylonal. These behavioural changes have important implications, in relation to altered foraging efficiency and potential predation risk, for herbivores foraging in the field. As a result, the spatial distribution of dietary PSMs across a landscape may directly influence herbivore fitness, and ultimately habitat selection of mammalian herbivores.
Linking animal personality to problem-solving performance in urban common brushtail possums
Publisher: Elsevier BV
Date: 04-2020
The dilemma of foraging herbivores: dealing with food and fear
Publisher: Springer Science and Business Media LLC
Date: 10-2014
DOI: 10.1007/S00442-014-3076-6
Abstract: For foraging herbivores, both food quality and predation risk vary across the landscape. Animals should avoid low-quality food patches in favour of high-quality ones, and seek safe patches while avoiding risky ones. Herbivores often face the foraging dilemma, however, of choosing between high-quality food in risky places or low-quality food in safe places. Here, we explore how and why the interaction between food quality and predation risk affects foraging decisions of mammalian herbivores, focusing on browsers confronting plant toxins in a landscape of fear. We draw together themes of plant-herbivore and predator-prey interactions, and the roles of animal ecophysiology, behaviour and personality. The response of herbivores to the dual costs of food and fear depends on the interplay of physiology and behaviour. We discuss detoxification physiology in dealing with plant toxins, and stress physiology associated with perceived predation risk. We argue that behaviour is the interface enabling herbivores to stay or quit food patches in response to their physiological tolerance to these risks. We hypothesise that generalist and specialist herbivores perceive the relative costs of plant defence and predation risk differently and intra-specifically, in iduals with different personalities and physiologies should do so too, creating in idualised landscapes of food and fear. We explore the ecological significance and emergent impacts of these in idual-based foraging outcomes on populations and communities, and offer predictions that can be clearly tested. In doing so, we provide an integrated platform advancing herbivore foraging theory with food quality and predation risk at its core.
Validation of an Enzyme Immunoassay to Measure Faecal Glucocorticoid Metabolites in Common Brushtail Possums (Trichosurus vulpecula) to Evaluate Responses to Rehabilitation
Publisher: MDPI AG
Date: 24-06-2022
DOI: 10.3390/ANI12131627
Abstract: Volunteer wildlife rehabilitators rescue and rehabilitate thousands of native animals every year in Australia. However, there is little known about how exposure to novel stimuli during rehabilitation could affect the physiology of wildlife. We investigated this question in a species that commonly enters rehabilitation, the common brushtail possum (Trichosurus vulpecula). We evaluated five enzyme immunoassays (EIA) to determine the most suitable for measuring faecal glucocorticoid metabolites (FGM) as a proxy for evaluating the response of brushtail possums to potential stressors during rehabilitation. An adrenocorticotrophin hormone (ACTH) challenge was conducted on wild-caught possums to determine the best-performing EIA based on the successful detection of FGM peaks in at least two of three possums. While a number of assays met these criteria, the 11-oxoaetiocholanolone (abbreviation: 72a) EIA was selected as it had the largest litude of change in response to the ACTH challenge. This assay was then used to measure FGM concentrations in 20 possums during rehabilitation. There was high variation in baseline FGM concentrations and response to captivity between possums. Significant changes in FGM levels were detected in most possums during captivity, but were not reliably associated with potentially stressful events that were identified by rehabilitators. The probability of an FGM peak occurring within five days of a potentially stressful event was about 50%, regardless of the type of event. Our study has demonstrated that injured and orphaned possums show changes in FGMs during captivity and rehabilitation and has identified events that can induce a physiological response in some in iduals. We recommend that research now focus on the relationship between these responses during rehabilitation and pre- and post-release survival.
Olfactory and visual plant cues as drivers of selective herbivory
Publisher: Wiley
Date: 25-07-2016
DOI: 10.1111/OIK.03422
Diet and diet selection of two species in the macropodid browser-grazer continuum: do they eat what they 'should'?
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/ZO01043
Abstract: On the basis of their dentition, species of Macropus are predicted to be grazers and species of Thylogale are predicted to be browsers. We tested these predictions by comparing diet and diet selection of the red-necked wallaby (Macropus rufogriseus rufogriseus) and red-bellied pademelon (Thylogale billardierii), by analysing forestomach contents of animals that had fed in the same region of a young pine plantation. Grasses, followed by broad-leafed forbs, were the most abundant plant groups in the field (together comprising 71% of the plant biomass), and were also the main dietary components of both macropodid species (91%). No differences were detected in diet of the two species when summarised in terms of diet ersity, evenness or overlap. When diet selection was compared, however, distinct differences were found between the two species. Red-necked wallabies selected for grasses (74% of the diet compared with 55% in the field) whereas red-bellied pademelons selected for broad-leafed forbs (38% of the diet compared with 16% in the field). Feeding patterns were therefore consistent with dietary predictions, provided diet selection was considered rather than simply diet. Diet selection is more appropriate for testing dietary predictions, because it reflects animals' attempts to consume food items that they prefer, that is, that they are functionally suited to consuming, even when such items are not as abundant as less preferred food.
Modelling nutritional interactions: from individuals to communities.
Publisher: Elsevier BV
Date: 2010
DOI: 10.1016/J.TREE.2009.06.012
Abstract: Nutrient acquisition is a major context for ecological interactions among species but ecologists and nutritionists have developed theory in isolation from each other. Developments in agent-based modelling, state-space modelling of nutrition and multi-scale modelling of landscape ecology provide the components for a new synthesis in nutritional ecology linking the nutritional biology of in idual organisms to population- and community-level processes across multiple scales within an evolutionary context. We review the core elements for such a synthesis and set out the principles for a generic modelling framework that could be used to test specific ecological hypotheses.
The foraging tightrope between predation risk and plant toxins: A matter of concentration
Publisher: Wiley
Date: 14-11-2012
Do high recapture rates indicate representative sampling? The relationship between recapture probability, risk-taking, and personality
Publisher: CSIRO Publishing
Date: 2023
DOI: 10.1071/WR22046
Petrol exhaust pollution impairs honey bee learning and memory
Publisher: Wiley
Date: 23-10-2019
DOI: 10.1111/OIK.05405
How does ontogeny in a Eucalyptus species affect patterns of herbivory by Brushtail Possums?
Publisher: Wiley
Date: 18-09-2006
A practical guide to avoid giving up on giving-up densities
Publisher: Springer Science and Business Media LLC
Date: 08-2013
Follow your nose: leaf odour as an important foraging cue for mammalian herbivores
Publisher: Springer Science and Business Media LLC
Date: 02-07-2016
DOI: 10.1007/S00442-016-3678-2
Abstract: Studies of odour-driven foraging by mammals focus on attractant cues emitted by flowers, fruits, and fungi. Yet, the leaves of many plant species worldwide produce odour, which could act as a cue for foraging mammalian herbivores. Leaf odour may thus improve foraging efficiency for such herbivores in many ecosystems by reducing search time, particularly but not only, for plants that are visually obscured. We tested the use of leaf odour by a free-ranging mammalian browser, the sw wallaby (Wallabia bicolor) to find and browse palatable tree seedlings (Eucalyptus pilularis). Wallabies visited patches non-randomly with respect to the presence of seedlings. In the absence of visual plant cues, they used leaf odour (cut seedlings in vials) to find patches earlier, and visited and investigated them more often than control patches (empty vials), supporting the hypothesis that wallabies used seedling odour to enhance search efficiency. In contrast, the grey kangaroo (Macropus giganteus), a grazer, showed no response to seedling odour. When the availability of seedling visual and olfactory cues was manipulated, wallabies browsed seedlings equally quickly in all treatments: upright (normal cues), pinned to the ground (reduced visual cues), and upright plus pinned seedlings (double olfactory cues). Odour cues play a critical role in food-finding by sw wallabies, and these animals are finely tuned to detecting these cues with their threshold for detection reached by odours from only a single plant. The global significance of leaf odour in foraging by mammalian herbivores consuming conifers, eucalypts, and other odour-rich species requires greater attention.
Particulate matter deposition on roadside plants and the importance of leaf trait combinations
Publisher: Elsevier BV
Date: 12-2016
Dealing with your past: Experience of failed predation suppresses caterpillar feeding behaviour
Publisher: Elsevier BV
Date: 04-2014
Herbivore search behaviour drives associational plant refuge
Publisher: Elsevier BV
Date: 08-2015
Effects of within‐patch characteristics on the vulnerability of a plant to herbivory
Publisher: Wiley
Date: 04-10-2006
Patch quality and habitat fragmentation shape the foraging patterns of a specialist folivore
Publisher: Oxford University Press (OUP)
Date: 17-07-2022
Abstract: Research on use of foraging patches has focused on why herbivores visit or quit patches, yet little is known about visits to patches over time. Food quality, as reflected by higher nutritional quality and lower plant defenses, and physical patch characteristics, which offer protection from predators and weather, affect patch use and hence should influence their revisitation. Due to the potentially high costs of moving between patches, fragmented habitats are predicted to complicate foraging decisions of many animals. We aimed to determine how food quality, shelter availability and habitat fragmentation influence tree reuse by a specialist folivore, the koala, in a fragmented agricultural landscape. We GPS-tracked 23 koalas in northern New South Wales, Australia and collated number of revisits, average residence time, and average time-to-return to each tree. We measured tree characteristics including food quality (foliar nitrogen and toxic formylated phloroglucinol compounds, FPCs concentrations), tree size, and tree connectedness. We also modeled the costs of locomotion between trees. Koalas re-visited isolated trees with high leaf nitrogen disproportionately often. They spent longer time in trees with high leaf nitrogen, and in large trees used for shelter. They took longer to return to trees with low leaf nitrogen. Tree connectivity reduced travel costs between patches, being either in idual or groups of trees. FPC levels had no detectable effect on patch revisitation. We conclude that food quality and shelter drive koala tree re-visits. Scattered, isolated trees with nutrient-rich leaves are valuable resource patches for koalas despite movement costs to reach them.
Non-lethal strategies to reduce browse damage in eucalypt plantations
Publisher: Elsevier BV
Date: 12-2009
A Possible Link between the Environment and Cryptococcus gattii Nasal Colonisation in Koalas (Phascolarctos cinereus) in the Liverpool Plains, New South Wales
Publisher: MDPI AG
Date: 11-04-2022
Abstract: Cryptococcosis caused by yeasts of the Cryptococcus gattii species complex is an increasingly important mycological disease in humans and other mammals. In Australia, cases of C. gattii-related cryptococcosis are more prevalent in the koala (Phascolarctos cinereus) compared to humans and other animals, likely due to the close association that both C. gattii and koalas have with Eucalyptus species. This provides a cogent opportunity to investigate the epidemiology of spontaneous C. gattii infections in a free-living mammalian host, thereby offering insights into similar infections in humans. This study aimed to establish a link between nasal colonisation by C. gattii in free-ranging koalas and the tree hollows of Eucalyptus species, the key environmental source of the pathogen. We (i) detected and genotyped C. gattii from nine out of 169 free-ranging koalas and representative tree hollows within their home range in the Liverpool Plains, New South Wales, and (ii) examined potential environmental predictors of nasal colonisation in koalas and the presence of C. gattii in tree hollows. Phylogenetic analyses based on multi-locus sequence typing (MLST) revealed that the koalas were most likely colonised by the most abundant C. gattii genotypes found in the Eucalyptus species, or closely related genotypes. Importantly, the likelihood of the presence of C. gattii in tree hollows was correlated with increasing hollow size.
Foxes in trees: a threat for Australian arboreal fauna?
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/AM16049
Abstract: We document the first evidence of tree climbing by red foxes (Vulpes vulpes) in Australia. Camera traps recorded foxes in trees on the Liverpool Plains, New South Wales. This finding prompts a reassessment of the impact that this invasive predator has on Australian fauna: from purely terrestrial to also potentially arboreal.
Mixing nutrients mitigates the intake constraints of a plant toxin in a generalist herbivore
Publisher: Oxford University Press (OUP)
Date: 06-04-2012
Wind affects morphology, function, and chemistry of eucalypt tree seedlings
Publisher: University of Chicago Press
Date: 2010
DOI: 10.1086/647917
Urbanisation and wing asymmetry in the western honey bee (Apis mellifera, Linnaeus 1758) at multiple scales
Publisher: PeerJ
Date: 03-12-2018
DOI: 10.7717/PEERJ.5940
Abstract: Changes in the mean and variance of phenotypic traits like wing and head morphology are frequently used as indicators of environmental stress experienced during development and may serve as a convenient index of urbanization exposure. To test this claim, we collected adult western honey bee ( Apis mellifera Linnaeus 1758, Hymenoptera, Apidae) workers from colonies located across an urbanization gradient, and quantified associations between the symmetries of both wing size and wing shape, and several landscape traits associated with urbanization. Landscape traits were assessed at two spatial scales (three km and 500 m) and included vegetation and anthropogenic land cover, total road length, road proximity and, population and dwelling density. We then used geometric morphometric techniques to determine two wing asymmetry scores—centroid size, a measure of wing size asymmetry and Procrustes distance, a measure of wing shape asymmetry. We found colony dependent differences in both wing size and shape asymmetry. Additionally, we found a negative association between wing shape asymmetry and road proximity at the three km buffer, and associations between wing shape asymmetry and road proximity, anthropogenic land cover and vegetation cover at the 500 m buffer. Whilst we were unable to account for additional variables that may influence asymmetry including temperature, pesticide presence, and parasitism our results demonstrate the potential usefulness of wing shape asymmetry for assessing the impact of certain landscape traits associated with urbanization. Furthermore, they highlight important spatial scale considerations that warrant investigation in future phenotypic studies assessing urbanization impact.
Inheritance of resistance to mammalian herbivores and of plant defensive chemistry in a Eucalyptus species
Publisher: Springer Science and Business Media LLC
Date: 03-2005
DOI: 10.1007/S10886-005-2030-9
Abstract: Hybridization in plants provides an opportunity to investigate the patterns of inheritance of hybrid resistance to herbivores, and of the plant mechanisms conferring this resistance such as plant secondary metabolites. We investigated how inter-race differences in resistance of Eucalyptus globulus to a generalist mammalian herbivore, Trichosurus vulpecula, are inherited in their F1 hybrids. We assessed browsing damage of three-year-old trees in a common environment field trial on four hybrid types of known progeny. The progency were artificial intra-race crosses and reciprocal inter-race F1 hybrids of two geographically distinct populations (races) of E. globulus north-eastern Tasmania and south-eastern Tasmania. Populations of trees from north-eastern Tasmania are relatively susceptible to browsing by T. vulpecula, while populations from south-eastern Tasmania are more resistant. We assessed the preferences of these trees in a series of paired feeding trials with captive animals to test the field trial results and also investigated the patterns of inheritance of plant secondary metabolites. Our results demonstrated that the phenotypic expression of resistance of the inter-race F1 hybrids supported the additive pattern of inheritance, as these hybrids were intermediate in resistance compared to the pure parental hybrids. The expression of plant secondary metabolites in the F1 hybrids varied among groups of in idual compounds. The most common pattern supported was dominance towards one of the parental types. Together, condensed tannins and essential oils appeared to explain the observed patterns of resistance among the four hybrid types. While both chemical groups were inherited in a dominant manner in the inter-race F1 hybrids, the direction of dominance was opposite. Their combined concentration, however, was inherited in an additive manner, consistent with the phenotypic differences in browsing.
Do we ditch digestive physiology in explaining the classic relationship between herbivore body size diet and diet quality?
Publisher: Wiley
Date: 18-09-2014
Distance from cover affects artificial food-patch depletion by macropod herbivores
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/WR05063
Abstract: Artificial food patches were used to examine whether red bellied-pademelons (Thylogale billiardierii) and Bennett’s wallabies (Macropus rufogriseus rufogriseus) altered their foraging behaviour in an open habitat (a young plantation) in response to distance from cover, used as a surrogate for predation risk. Analyses using the full dataset showed no significant relationship between the amount of food eaten at a station and any of the cover variables. In contrast, regression analyses of the upper bounds dataset indicated that both increased distance from windrow (2.5-m-high stacks of burnt wood) and from nearest cover (windrow or forest at plantation edge) significantly reduced the amount of food consumed at a station. This indicates that distance from cover acts as a constraint on the amount of food eaten. When the feeding-station data were overlayed onto a map of scat densities across the study site, the amount of food eaten was positively related to the density of scats of both red-bellied pademelons and Bennett’s wallabies. Our results demonstrate that these macropods trade-off increased foraging benefits in order to forage closer to protective cover. Furthermore, they represent the first time that artificial food patches, with progressively decreasing reward per search effort, have been used to assess foraging behaviour in macropods. This opens up a wide range of research opportunities aimed at examining macropod foraging, with both ecological and practical applications.
Grow up, be persistent, and stay focused: keys for solving foraging problems by free-ranging possums
Publisher: Oxford University Press (OUP)
Date: 28-06-2023
Abstract: In iduals within a species often vary in both their problem-solving approach and ability, affecting their capacity to access novel food resources. Testing problem-solving in free-ranging in iduals is crucial for understanding the fundamental ecological implications of problem-solving capacity. To examine the factors affecting problem-solving in free-ranging animals, we presented three food-extraction tasks of increasing difficulty to urban common brushtail possums (Trichosurus vulpecula). We quantified two measures of problem-solving performance: trial outcome (success/failure) and time to solve and tested the influence of a range of potential drivers, including in idual traits (personality, body weight, sex, and age), mechanistic behaviors that quantify problem-solving approach (work time, functional behavior time, behavioral ersity, and flexibility), and prior experience with the puzzles. We found that mechanistic behaviors were key drivers of performance. In iduals displaying greater persistence (higher work and functional behavior time) were more likely to solve a food-extraction task on their first attempt. In iduals also solved problems faster if they were more persistent and had lower behavioral flexibility. Personality indirectly affected time to solve one of the three problems by influencing time allocated to functional behaviors. Finally, adults solved the most difficult problem faster than juveniles. Overall, our study provides rare insight into the drivers underlying the problem-solving performance of wild animals. Such insight could be used to improve management strategies and conservation efforts, such as food or bait deployment, tailored to suit the innovative foraging abilities of target in iduals in new and changing environments.
Multiple scales of diet selection by brush-tailed rock-wallabies (Petrogale penicillata)
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/AM10041
Abstract: Detailed data on diet and diet selection helps to predict how species will respond to changes in their environment. We measured the diet of brush-tailed rock-wallabies (Petrogale penicillata) using microscopic examination of plant cuticle fragments in faeces over two years from three populations across New South Wales: Warrumbungles in the central west, Curracabundi in the New England Tablelands, and Kangaroo Valley south of Sydney. Diet was analysed at the level of plant functional groups for all three populations, then in more detail at the plant species level in the Warrumbungles. Diet selection was measured by comparing diets with vegetation biomass. Across all three populations, rock-wallaby diet comprised 10–40% grass, 30–50% browse, 12–45% forbs and minor quantities of orchid/lilies and sedges. Rock-wallabies selected food resources on multiple scales by combining a generalist feeding strategy at the broad spatial scale (across populations) with a more specialist strategy for particular plant species at the fine spatial scale (within one population).
Behavioral responses of a generalist mammalian folivore to the physiological constraints of a chemically defended diet
Publisher: Springer Science and Business Media LLC
Date: 04-05-2006
DOI: 10.1007/S10886-006-9076-1
Abstract: Mammalian herbivores, particularly browsers and folivores, encounter and consume a range of plant chemical defenses [plant secondary metabolites (PSMs)] on a regular basis. The physiological regulation of PSM ingestion and the resulting behavioral responses of mammalian herbivores directly affect their feeding decisions and the subsequent foraging strategies that they adopt. Generalist mammalian herbivores are hypothesized to consume a generalized diet because of physiological limitations of their detoxification systems. The consumption of a generalized diet is proposed to enable toxin (PSM) dilution through the use of multiple detoxification pathways. We tested the predictions of the detoxification-limitation hypothesis by offering two chemically different plant species, Eucalyptus regnans and E. globulus, to a generalist mammalian folivore, the common brushtail possum (Trichosurus vulpecula), as single- and mixed-species diets. By feeding more efficiently, brushtail possums benefited more, through increased intake, on the mixed-species diet than on either of the single-species diets. We argue that frequently switching between chemically erse foliage reduces the physiological constraints imposed by a PSM-rich diet and enables more efficient feeding. The behavioral responses of brushtail possums were consistent with the proposed physiological constraints of a chemically defended diet, offering support for predictions of the detoxification-limitation hypothesis. We suggest that feeding behavior of herbivores may be a useful indicator of the physiological constraints imposed by a chemically defended diet.
Differential distribution of leaf chemistry in eucalypt seedlings due to variation in whole-plant nutrient availability
Publisher: Elsevier BV
Date: 2005
DOI: 10.1016/J.PHYTOCHEM.2004.11.004
Abstract: We investigated the effects of whole-plant nutrient-availability on the degree of distribution of some plant primary and secondary (nitrogen, fibre, flavonols, gallotannins and cineole) chemicals across young, mature and old leaves of seedlings of Eucalyptus nitens. Four treatments that ranged from low to high nutrient-application rates resulted in mean whole-plant foliar concentrations of 0.63%, 0.85%, 1.11% and 1.82% nitrogen dry matter (N%DM) for treatments A, B, C and D, respectively. Within-plant distribution (across the leaf age profile of young, mature and old leaves within a eucalypt seedling) of N%DM ranged from zero in treatment A to a wide range of distribution in treatment D (low N%DM concentrations in old leaves to high N%DM concentrations in young leaves). Similarly, the distribution of fibre ranged from zero in treatment A to a wide range of distribution in treatment D, but with high concentrations in old leaves and low concentrations in young leaves. In contrast, flavonols (weakly) and gallotannins had a wide range of distribution in treatment A (low concentrations in old leaves to high concentrations in young leaves) but were little or not distributed in the other treatments. Again in contrast, cineole was strongly distributed between old and young leaves (low concentrations in old leaves to high concentrations in young leaves) across all treatments while concentrations in mature leaves reflected one or other leaf age depending on treatment. Protein precipitable phenols in treatments A, B and C were high in young, and low in old leaves whereas in treatment D they were low and similar between leaves of different ages.
Space use by animals on the urban fringe: interactive effects of sex and personality
Publisher: Oxford University Press (OUP)
Date: 26-11-2020
Abstract: Personality traits shape in idual perceptions of risks and rewards, and so, should affect how animals value and use their environment. Evidence is emerging that personality affects foraging, space use, and exploitation of novel environments such as urban habitat. But the influence of personality is also hypothesized to be sex-dependent when primary motivation for space use differs between sexes, as often occurs in polygynous species. We tested the influence of personality traits, interacting with sex, on space use by the polygynous common brushtail possum, Trichosurus vulpecula, in an urban-woodland boundary in Sydney, Australia. We quantified personality traits, including exploration, using behavioral assays in an artificial arena. We also GPS-tracked free-ranging in iduals, and measured range size, core area: home range, and proportional urban range. We found that personality traits affected space use either as a main effect or, as predicted, an interaction with sex. More exploratory animals, regardless of sex, had higher core area: home range ratios and proportionally larger ranges within urban habitat. However, less exploratory females yet more exploratory males had larger ranges. Our findings provide new insight into movement ecology by demonstrating, for the first time, the sex-dependent influence of personality. The demonstrated influence of personality on urban use by possums also suggests a personality filter for wildlife, as populations transition into urban areas. Finally, as in iduals at the interface between urban and natural habitat are also a conduit between the two, a corollary of our findings is that there may be personality-mediated spread of disease across this boundary.
The ethics of intervening in animal behaviour for conservation
Publisher: Elsevier BV
Date: 09-2023
Personality affects the foraging response of a mammalian herbivore to the dual costs of food and fear
Publisher: Springer Science and Business Media LLC
Date: 08-10-2014
DOI: 10.1007/S00442-014-3110-8
Abstract: Predators attack and plants defend, so herbivores face the dilemma of how to eat enough without being eaten. But do differences in the personality of herbivores affect the foraging choices of in iduals? We explored the ecological impact of personality in a generalist herbivore, the brushtail possum (Trichosurus vulpecula). After quantifying personality traits in wild in iduals brought temporarily into captivity, we tested how these traits altered foraging by in iduals when free-ranging in their natural habitat. To measure their responses to the dual costs of predation risk and plant toxin, we varied the toxin concentration of food in safe foraging patches against paired, non-toxic risky patches, and used a novel synthesis of a manipulative Giving-Up-Density (GUD) experiment and video behavioural analysis. At the population level, the cost of safe patches pivoted around that of risky patches depending on food toxin concentration. At the in idual level, boldness affected foraging at risky high-quality food patches (as behavioural differences between bold and shy), and at safe patches only when food toxin concentration was low (as differences in foraging outcome). Our results ecologically validate the personality trait of boldness, in brushtail possums. They also reveal, for the first time, a nuanced link between personality and the way in which in iduals balance the costs of food and fear. Importantly, they suggest that high plant defence effectively attenuates differences in foraging behaviour arising from variation in personality, but poorly defended plants in safe areas should be differentially subject to herbivory depending on the personality of the herbivore.
How do soil nutrients affect within-plant patterns of herbivory in seedlings of Eucalyptus nitens?
Publisher: Springer Science and Business Media LLC
Date: 10-10-2006
DOI: 10.1007/S00442-006-0525-X
Abstract: This study assessed how the palatability of leaves of different age classes (young, intermediate and older) of Eucalyptus nitens seedlings varied with plant nutrient status, based on captive feeding trials with two mammalian herbivores, red-bellied pademelons (Thylogale billardierii), and common brushtail possums (Trichosurus vulpecula). Seedlings were grown under three nutrient treatments (low, medium and high), and we determined how palatability was related to chemical and physical characteristics of the leaves. Pademelons ate more older leaves than young and intermediate leaves for all treatments. This pattern was best explained by sideroxylonals (formylated phloroglucinol compounds known to deter herbivory by other marsupials), and/or essential oil compounds that were present in lower concentrations in older leaves. In the low-nutrient treatment, possums also ate more of the older leaves. However, in the medium- and high-nutrient treatments, possums ate more intermediate leaves than older leaves and showed a behavioural preference for young leaves (consuming younger leaves first) over intermediate and older leaves, in spite of high levels of sideroxylonals and essential oils. The young leaves did, however, have the highest nitrogen concentration of all the leaf age classes. Thus, either sideroxylonals and essential oils provided little or no deterrent to possums, or the deterrent was outweighed by other factors such as high nitrogen. This study indicates that mammalian herbivores show different levels of relative use and damage to leaf age classes at varying levels of plant nutrient status and, therefore, their impact on plant fitness may vary with environment.
Repellent and stocking guards reduce mammal browsing in eucalypt plantations
Publisher: Springer Science and Business Media LLC
Date: 17-02-2011
Characteristics of tree seedlings and neighbouring vegetation have an additive influence on browsing by generalist herbivores
Publisher: Elsevier BV
Date: 06-2006
Visit, consume and quit: Patch quality affects the three stages of foraging
Publisher: Wiley
Date: 06-08-2018
Abstract: Foraging is a three-stage process during which animals visit patches, consume food and quit. Foraging theory exploring relative patch quality has mostly focused on patch use and quitting decisions, ignoring the first crucial step for any forager: finding food. Yet, the decision to visit a patch is just as important as the decision to quit, as quitting theories can only be used if animals visit patches in the first place. Therefore, to better understand the foraging process and predict its outcomes, it is necessary to explore its three stages together. We used the common brushtail possum (Trichosurus vulpecula) as a model to investigate foraging decisions in response to food varying in quality. In particular, we tested whether patch nutritional quality affected the following: (1) patch visits (2) behaviours at the patch during a foraging visit and (3) patch quitting decisions (quantified using giving up density-GUD). Free-ranging possums were presented with diets varying in nitrogen content and concomitantly volatile organic compound (VOC) composition at feeding stations in the wild. We found that possums were able to distinguish between different quality foods from afar, despite the location of the diets changed daily. Possums used VOC (i.e. odour cues) emitted by the diets to find and select patches from a distance. High-quality diets with higher protein and lower fibre were visited more often and for longer. Possums spent more time foraging on diets high in nutritional content, resulting in lower GUDs. Our study provides important quantitative evidence that foraging efficiency plays out during all the three stages of the foraging process (i.e. visit, consume and quit), and demonstrates the significance of considering all these stages together in future studies and foraging models. Sensory cues such as food odours play a critical role in helping foragers, including mammalian herbivores, find high-quality food. This allows foragers to make quick, accurate and important decisions about food patches well before patch quitting decisions come into play.
Habitat complexity does not affect arthropod community composition in roadside greenspaces
Publisher: Elsevier BV
Date: 03-2018
Diet switching in a generalist mammalian folivore: fundamental to maximising intake
Publisher: Springer Science and Business Media LLC
Date: 02-12-2006
DOI: 10.1007/S00442-005-0305-Z
Abstract: Generalist mammalian herbivores exploit a erse diet. A generalised feeding strategy utilises a mixed diet to obtain a range of nutrients and to reduce the detoxication load of similar groups of plant secondary metabolites (PSMs). There is limited research investigating how mammalian herbivores achieve this dietary mixing in their daily foraging activities. We investigated the patterns of, and behaviours associated with, dietary mixing in a generalist mammalian folivore, the common brushtail possum (Trichosurus vulpecula). Possums were offered foliage of two eucalypt species (Eucalyptus globulus and E. regnans) as either (a) Full choice: both species offered for 8 h (b) Restricted choice: both species offered for 2x2 h blocks (c) G-R no choice: E. globulus offered for the first 4 h, E. regnans offered for next 4 h and (d) R-G no choice: E. regnans offered for first 4 h, E. globulus offered for next 4 h. We hypothesised that possums would maximise intake on the Full choice diet, where time availability was greatest in combination with a choice of foliage. We also hypothesised that diet switching, defined as the frequency of changing between food types while feeding, would play a fundamental role in maximising intake. Possums achieved maximum intake on the Full choice diet and minimum intake on the No choice diets. Although intake was similar between the Restricted choice and No choice diets, possums achieved this intake in half the amount of time when able to switch regularly between foliage on the Restricted choice diet. We conclude that a generalist herbivore's ability to effectively switch diets when foraging is fundamental to maximising intake. Hence, the degree of plant heterogeneity in an environment, and the spatial scale at which it occurs, may affect an herbivore's foraging decisions and, ultimately, influence its foraging efficiency.
Plant volatiles are a salient cue for foraging mammals: elephants target preferred plants despite background plant odour
Publisher: Elsevier BV
Date: 09-2019
Early ontogenetic trajectories vary among defence chemicals in seedlings of a fast-growing eucalypt
Publisher: Wiley
Date: 29-03-2010
Comparison of three methods of estimating the population size of an arboreal mammal in a fragmented rural landscape
Publisher: CSIRO Publishing
Date: 2021
DOI: 10.1071/WR19148
Abstract: Abstract Context Precise and accurate estimates of animal numbers are often essential for population and epidemiological models, as well as for guidance for population management and conservation. This is particularly true for threatened species in landscapes facing multiple threats. Estimates can be derived by different methods, but the question remains as to whether these estimates are comparable. Aims We compared three methods to estimate population numbers, namely, distance s ling, mark–recapture analysis, and home-range overlap analysis, for a population of the iconic threatened species, the koala (Phascolarctos cinereus). This population occupies a heavily fragmented forest and woodland habitat on the Liverpool Plains, north-western New South Wales, Australia, on a mosaic of agricultural and mining lands. Key resultsAll three methods produced similar estimates, with overlapping confidence intervals. Distance s ling required less expertise and time and had less impact on animals, but also had less precision however, future estimates using the method could be improved by increasing both the number and expertise of the observers. ConclusionsWhen less intrusive methods are preferred, or fewer specialised practitioners are available, we recommend distance s ling to obtain reliable estimates of koala numbers. Although its precision is lower with a low number of sightings, it does produce estimates of numbers similar to those from the other methods. However, combining multiple methods can be useful when other material (genetic, health and demographic) is also needed, or when decisions based on estimates are for high-profile threatened species requiring greater confidence. We recommend that all estimates of population numbers, and their precision or variation, be recorded and reported so that future studies can use them as prior information, increasing the precision of future surveys through Bayesian analyses.
Acute exposure to urban air pollution impairs olfactory learning and memory in honeybees
Publisher: Springer Science and Business Media LLC
Date: 11-09-2019
DOI: 10.1007/S10646-019-02081-7
Abstract: While the ecological effects of pesticides have been well studied in honeybees, it is unclear to what extent other anthropogenic contaminants such as air pollution may also negatively affect bee cognition and behaviour. To answer this question, we assessed the impacts of acute exposure to four ecologically relevant concentrations of a common urban air pollutant-diesel generated air pollution on honeybee odour learning and memory using a conditioned proboscis extension response assay. The proportion of bees that successfully learnt odours following direct air pollution exposure was significantly lower in bees exposed to low, medium and high air pollutant concentrations, than in bees exposed to current ambient levels. Furthermore, short- and long-term odour memory was significantly impaired in bees exposed to low medium and high air pollutant concentrations than in bees exposed to current ambient levels. These results demonstrate a clear and direct cognitive cost of air pollution. Given learning and memory play significant roles in foraging, we suggest air pollution will have increasing negative impacts on the ecosystem services bees provide and may add to the current threats such as pesticides, mites and disease affecting colony fitness.
A new conceptual and quantitative approach to exploring and defining potential open-access olfactory information.
Publisher: Wiley
Date: 13-09-2022
DOI: 10.1111/NPH.18432
Abstract: All organisms emit odour, providing 'open-access' olfactory information for any receiver with the right sensory apparatus. Characterizing open-access information emitted by groups of organisms, such as plant species, provides the means to answer significant questions about ecological interactions and their evolution. We present a new conceptual framework defining information reliability and a practical method to characterize and recover information from amongst olfactory noise. We quantified odour emissions from two tree species, one focal group and one outgroup, to demonstrate our approach using two new R statistical functions. We explore the consequences of relaxing or tightening criteria defining information and, from thousands of odour combinations, we identify and quantify those few likely to be informative. Our method uses core general principles characterizing information while incorporating knowledge of how receivers detect and discriminate odours. We can now map information in consistency-precision reliability space, explore the concept of information, and test information-noise boundaries, and between cues and signals.
Needing a drink: Rainfall and temperature drive the use of free water by a threatened arboreal folivore
Publisher: Public Library of Science (PLoS)
Date: 29-05-2019
Effective field-based methods to quantify personality in brushtail possums (Trichosurus vulpecula)
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/WR15216
Abstract: Context There is growing recognition of the importance of animal personality in wildlife ecology and management. In iduals that differ consistently in their behaviours from others of the same population are considered to exhibit different personalities. Personality can be easily quantified with repeat tests on animals held in captivity. However, captive-based tests may not always be possible for logistical reasons and tests conducted in captivity can alter naturally occurring behaviours. Development of methods to assess personality in the field over short-term capture is an important alternative to long-term captive tests. Aims To develop and refine field-based tests that can be used to easily define personality traits of wild common brushtail possum (Trichosurus vulpecula), eliminating the need to bring in iduals into captivity for an extended period of time. Methods We developed a series of short-term capture protocols to quantify personality traits of the common brushtail possum in the field, using handling-bag tests, modified open-field tests, trap-behaviour tests and release tests. Key results Personality traits of brushtail possums could be measured in several different ways, but refining methods was crucial to reveal traits efficiently. Behaviours related to several personality traits (boldness, docility and activity/exploration) could be measured rapidly in the field with our methods, and were repeatable over time. Conclusions Rapid, reliable and easy-to-perform quantification of personality of brushtail possums in the field is possible. This may sometimes be the only available option, and has advantages over long captive trials in terms of animal welfare and cost. Implications The present study provides a baseline for future research on the personality of common brushtail possums and its application to management and control strategies for the species.
Effects of nutrient variability on the genetic-based resistance of Eucalyptus globulus to a mammalian herbivore and on plant defensive chemistry
Publisher: Springer Science and Business Media LLC
Date: 04-12-2005
DOI: 10.1007/S00442-004-1769-Y
Abstract: Plant resistance to herbivores can be influenced not only by the independent effects of plant genotype and environmental variation, but by interactions between the two. The main aim of this study was to assess the effects of environmental variability (nutrient treatment) on the known genetic-based expression of resistance and defensive chemistry of Eucalyptus globulus to browsing by the generalist mammalian herbivore Trichosurus vulpecula. In a captive feeding trial, we measured intake of seedlings from one relatively resistant (Blue Gum Hill) and one relatively susceptible (St Helens) population of E. globulus grown under two nutrient treatments (no fertiliser, plus fertiliser). There was a significant genotypexfertiliser interaction effect on intake of E. globulus foliage by T. vulpecula, and the predicted genetic-based resistance of the two populations was expressed only for the non-fertilised treatment. Expression of resistance largely reflected the combined and inverse effects of nitrogen and condensed tannin concentrations. The expression of plant secondary metabolite concentration differed between compounds, but in all cases the effects of plant genotype and fertiliser treatment were independent. The formylated phloroglucinol compounds differed significantly between genotypes but not between fertiliser treatments. In contrast, the effect of plant genotype on the expression of condensed tannins was weak but they were significantly reduced by fertiliser. Essential oils were influenced by both plant genotype and fertiliser treatment and were significantly higher in the fertilised seedlings than in the non-fertilised seedlings. This study highlights interactive effects of plant genotype and environment in influencing the phenotypic expression of resistance in a eucalypt species to a mammalian browser. It also demonstrates that this interactive effect is the net result of independent effects of genotype and environment on plant chemistry and finally, that different groups of compounds within a plant can respond very differently to variation in environmental conditions.
Spatial scale and opportunities for choice influence browsing and associational refuges of focal plants
Publisher: Wiley
Date: 13-10-2009
DOI: 10.1111/J.1365-2656.2009.01589.X
Abstract: 1. Foraging decisions by herbivores depend on variation in food types, the scale(s) at which this variation occurs and the opportunity and capacity for herbivores to respond to such variation. These decisions affect not only the herbivores themselves, but also the vulnerability of in idual plants to being eaten. Associational plant refuges, in which neighbouring plants alter focal plant vulnerability, are an emergent property of foraging decisions. 2. Using the red-bellied pademelon (Thylogale billardierii) as a model generalist mammalian herbivore, we investigated the spatial scale(s) at which animals made foraging decisions and the resultant effect on focal plant vulnerability. In a replicated design, we varied vegetation at the in idual plant scale, generating intraspecific differences in Eucalyptus nitens seedlings by altering their nutrient status (high, low). We varied vegetation at the patch scale, in which seedlings were planted, using high- (grass) and low- (herbicided) quality patches. Animals were allowed to choose where they fed and what they ate. Animal behaviour was recorded and intake of seedlings measured. 3. We found that animals made foraging decisions first at the patch scale then at the scale of in idual plants both patch and focal seedling characteristics influenced browsing. Pademelons spent most of their time in high-quality patches, and seedlings were consequently more vulnerable there than in low-quality patches. Pademelons also ate more foliage from high- than from low-nutrient status seedlings. This behaviour concentrated resources, increasing foraging efficiency and making focal plants more vulnerable to browsing. 4. The opportunity and capacity to choose at both plant and patch scales resulted in a pattern of focal plant vulnerability consistent with the repellent-plant hypothesis. This contrasts with our previous study, in which animals were only provided with choice at the plant level and plant vulnerability followed the attractant-decoy hypothesis. These combined results demonstrate that the influence of neighbouring vegetation on consumption of a focal plant depends on the spatial scale of selection and on opportunities (and capacity) for herbivores to choose.
Associational refuge in practice: Can existing vegetation facilitate woodland restoration?
Publisher: Wiley
Date: 18-11-2015
DOI: 10.1111/OIK.01782
The Olfactory Landscape Concept: A Key Source of Past, Present, and Future Information Driving Animal Movement and Decision-making
Publisher: Oxford University Press (OUP)
Date: 06-07-2022
Abstract: Odor is everywhere, emitted across the landscape from predators, prey, decaying carcasses, conspecifics, vegetation, surface water, and smoke. Many animals exploit odor to find food, avoid threats, and attract or judge potential mates. Here, we focus on odor in terrestrial ecosystems to introduce the concept of an olfactory landscape: real-time dynamic olfactory contours reflecting the patchy distribution of resources and risks, providing a key source of information used by many animals in their movement and decision-making. Incorporating the olfactory landscape into current frameworks of movement ecology and animal behavior will provide a mechanistic link to help answer significant questions about where, why, and when many animals move, and how they do so efficiently in both space and time. By understanding how animals use the olfactory landscape to make crucial decisions affecting their fitness, we can then manipulate the landscape to modify ecological interactions and, ultimately, ecosystem consequences of these interactions.
Genetic variation in resistance of Eucalyptus globulus to marsupial browsers
Publisher: Springer Science and Business Media LLC
Date: 2002
Abstract: The evolution of plant defensive traits in response to selection pressures imposed by herbivores is central to co-evolutionary theory. To demonstrate the role of herbivores as selective agents on plant resistance there must be variability in plant resistance to herbivores within a plant population. This variability must be under genetic control, and the variability in plant resistant traits and consequently herbivore damage to plants must reflect variability in plant fitness. We used a common eucalypt species, Eucalyptus globulus, and two major mammalian herbivores, the common brushtail possum (Trichosurus vulpecula) and the red-bellied pademelon (Thylogale billardierii), as a system to investigate intraspecific variation in plant resistance to mammalian herbivores and to investigate if this variation has a genetic basis. We measured mammalian browsing damage on 2,302 in idual trees of E. globulus, from 563 families derived from range-wide native stand seed collections of known pedigree and grown in a common environment field trial. Using a selection of trees from the field trial we then conducted a feeding trial with captive herbivores to assess if the genetic variation in plant resistance in the field was reflected in feeding preferences of captive animals, as measured by relative intake. Results from the field trial showed significant genetic variation in plant resistance amongst races, localities and amongst different families. These results were consolidated in the captive trial with similar trends in genetic variation among E. globulus localities. Dry matter intake of foliage by Trichosurus vulpecula was consistently greater than that by Thylogale billardierii however, the intraspecific preferences of the two herbivores were significantly correlated.
Behavioural drivers of survey bias: interactive effects of personality, the perceived risk and device properties
Publisher: Springer Science and Business Media LLC
Date: 09-2021
Global patterns of leaf mechanical properties
Publisher: Wiley
Date: 25-01-2011
DOI: 10.1111/J.1461-0248.2010.01582.X
Abstract: Leaf mechanical properties strongly influence leaf lifespan, plant-herbivore interactions, litter decomposition and nutrient cycling, but global patterns in their interspecific variation and underlying mechanisms remain poorly understood. We synthesize data across the three major measurement methods, permitting the first global analyses of leaf mechanics and associated traits, for 2819 species from 90 sites worldwide. Key measures of leaf mechanical resistance varied c. 500-800-fold among species. Contrary to a long-standing hypothesis, tropical leaves were not mechanically more resistant than temperate leaves. Leaf mechanical resistance was modestly related to rainfall and local light environment. By partitioning leaf mechanical resistance into three different components we discovered that toughness per density contributed a surprisingly large fraction to variation in mechanical resistance, larger than the fractions contributed by lamina thickness and tissue density. Higher toughness per density was associated with long leaf lifespan especially in forest understory. Seldom appreciated in the past, toughness per density is a key factor in leaf mechanical resistance, which itself influences plant-animal interactions and ecosystem functions across the globe.
Field screening for genetic-based susceptibility to mammalian browsing
Publisher: Elsevier BV
Date: 10-2011
The power of odour cues in shaping fine-scale search patterns of foraging mammalian herbivores
Publisher: The Royal Society
Date: 07-2020
Abstract: Foraging by mammalian herbivores has profound impacts on natural and modified landscapes, yet we know little about how they find food, limiting our ability to predict and manage their influence. Mathematical models show that foragers exploiting odour cues outperform a random walk strategy. However, discovering how free-ranging foragers exploit odours in real, complex landscapes has proven elusive because of technological constraints. We took a novel approach, using a sophisticated purpose-built thermal camera system to record fine-scale foraging by a generalist mammalian herbivore, the sw wallaby ( Wallabia bicolor ). We tested the hypothesis that odour cues shape forager movement and behaviour in vegetation patches. To do this, we compared wallaby foraging in two odour landscapes: Control (natural vegetation with food and non-food plants interspersed) and +Apple (the same natural vegetation plus a single, highly palatable food source with novel odour (apple)). The +Apple treatment led to strongly directed foraging by wallabies: earlier visits to vegetation patches, straighter movement paths, more hopping and fewer stops than in the Control treatment. Our results provide clear empirical evidence that odour cues are harnessed for efficient, directed search even at this fine scale. We conclude that random walk models miss a key feature shaping foraging within patches.
Influences of seedling size, container type and mammal browsing on the establishment of Eucalyptus globulus in plantation forestry
Publisher: Springer Science and Business Media LLC
Date: 28-06-2010
Inheritance of resistance to mammalian herbivores and of plant defensive chemistry in an Eucalyptus species
Publisher: Springer Science and Business Media LLC
Date: 02-2005
DOI: 10.1007/S10886-005-1346-9
Abstract: Hybridization in plants provides an opportunity to investigate the patterns of inheritance of hybrid resistance to herbivores, and of the plant mechanisms conferring this resistance such as plant secondary metabolites. We investigated how inter-race differences in resistance of Eucalyptus globulus to a generalist mammalian herbivore, Trichosurus vulpecula, are inherited in their Fl hybrids. We assessed browsing damage of 3-year-old trees in a common environment field trial on four hybrid types of known progeny. The progeny were artificial intra-race crosses and reciprocal inter-race F1 hybrids of two geographically distinct populations (races) of E. globulus north-eastern Tasmania and south-eastern Tasmania. Populations of trees from north-eastern Tasmania are relatively susceptible to browsing by T. vulpecula, while populations from south-eastern Tasmania are more resistant. We assessed the preferences of these trees in a series of paired feeding trials with captive animals to test the field trial results and also investigated the patterns of inheritance of plant secondary metabolites. Our results demonstrated that the phenotypic expression of resistance of the inter-race Fl hybrids supported the additive pattern of inheritance, as these hybrids were intermediate in resistance compared to the pure parental hybrids. The expression of plant secondary metabolites in the Fl hybrids varied among major groups of in idual compounds. The most common pattern supported was dominance towards one of the parental types. Together, condensed tannins and essential oils appeared to explain the observed patterns of resistance among the four hybrid types. While both chemical groups were inherited in a dominant manner in the inter-race Fl hybrids, the direction of dominance was opposite. Their combined concentration, however, was inherited in an additive manner, consistent with the phenotypic differences in browsing.
Native predators can learn new prey cues to overcome naivete and hunt novel alien prey
Publisher: Elsevier BV
Date: 08-2023
Habitat fragmentation affects movement and space use of a specialist folivore, the koala
Publisher: Wiley
Date: 16-05-2020
DOI: 10.1111/ACV.12596
Elevated volatile concentrations in high-nutrient plants: Do insect herbivores pay a high price for good food?
Publisher: Wiley
Date: 29-05-2014
DOI: 10.1111/EEN.12124
Titrating the cost of plant toxins against predators: Determining the tipping point for foraging herbivores
Publisher: Wiley
Date: 02-03-2011
DOI: 10.1111/J.1365-2656.2011.01822.X
Abstract: 1. Foraging herbivores must deal with plant characteristics that inhibit feeding and they must avoid being eaten. Principally, toxins limit food intake, while predation risk alters how long animals are prepared to harvest resources. Each of these factors strongly affects how herbivores use food patches, and both constraints can pose immediate proximate costs and long-term consequences to fitness. 2. Using a generalist mammalian herbivore, the common brushtail possum (Trichosurus vulpecula), our aim was to quantitatively compare the influence of plant toxin and predation risk on foraging decisions. 3. We performed a titration experiment by offering animals a choice between non-toxic food at a risky patch paired with food with one of five toxin concentrations at a safe patch. This allowed us to identify the tipping point, where the cost of toxin in the safe food patch was equivalent to the perceived predation risk in the alternative patch. 4. At low toxin concentration, animals ate more from the safe than the risky patch. As toxin concentration increased at the safe patch, intake shifted until animals ate mainly from the risky patch. This shift was associated with behavioural changes: animals spent more time and fed longer at the risky patch, while vigilance increased at both risky and safe patches. 5. Our results demonstrate that the variation in toxin concentration, which occurs intraspecifically among plants, can critically influence the relative cost of predation risk on foraging. We show that herbivores quantify, compare and balance these two different but proximate costs, altering their foraging patterns in the process. This has potential ecological and evolutionary implications for the production of plant defence compounds in relation to spatial variation in predation risk to herbivores.
Interactions between fire and introduced deer herbivory on coastal heath vegetation
Publisher: Wiley
Date: 25-02-2016
DOI: 10.1111/AEC.12349
Negotiating multiple cues of predation risk in a landscape of fear: what scares free‐ranging brushtail possums?
Publisher: Wiley
Date: 21-05-2014
DOI: 10.1111/JZO.12146
To eat, or not to eat: a phantom decoy affects information-gathering behavior by a free-ranging mammalian herbivore
Publisher: Oxford University Press (OUP)
Date: 27-07-2023
Abstract: When foraging, making appropriate food choices is crucial to an animal’s fitness. Classic foraging ecology theories assume animals choose food of greatest benefit based on their absolute value across multiple dimensions. Consequently, poorer options are considered irrelevant alternatives that should not influence decision-making among better options. But heuristic studies demonstrate that irrelevant alternatives (termed decoys) can influence the decisions of some animals, indicating they use a relative rather than absolute evaluation system. Our aim was to test whether a decoy influenced the decision-making process—that is, information-gathering and food choice—of a free-ranging mammalian herbivore. We tested sw wallabies, Wallabia bicolor, comparing their behavior toward, and choice of, two available food options over time in the absence or presence of the decoy. We used a phantom decoy—unavailable option—and ran two trials in different locations and seasons. Binary preferences (decoy absent) for the two available food options differed between trials. Irrespective of this difference, across both trials the presence of the decoy resulted in animals more likely to overtly investigate available food options. But, the decoy only shifted food choice, weakly, in one trial. Our results indicate that the decoy influenced the information-gathering behavior during decision-making, providing the first evidence that decoys can affect decision-making process of free-ranging mammalian herbivores in an ecologically realistic context. It is premature to say these findings confirm the use of relative evaluation systems. Whether the foraging outcome is more strongly affected by other decoys, food dimensions, or ecological contexts, is yet to be determined.
Influences of Plant Toxins and Their Spatial Distribution on Foraging by the Common Brushtail Possum, a Generalist Mammalian Herbivore
Publisher: Springer Science and Business Media LLC
Date: 23-11-2012
DOI: 10.1007/S10886-012-0218-3
Abstract: Generalist herbivores forage on a variety of plant species, allowing them to gain nutrients while limiting ingestion of harmful toxins. As the capacity to mix diets appears important for maximizing intake, the spatial scale in heterogeneity of food resources should influence the foraging behavior of herbivores. Our aim was to identify how the feeding strategy of a generalist mammalian herbivore, the common brushtail possum, responds to foods within a spatially defined environment. We evaluated foraging responses against increasing spatial separation between pairs of artificial diets that differed in flavor and toxin profile, to determine how distance and diet affect intake and behavior. Foraging responses were influenced by the type of diet or the degree of spatial separation between foods but not by their interaction. Diet influenced intake, time spent feeding, and feeding rate, but had no effect on nightly foraging interval, number of feeding bouts, or bout length. The number of switches between paired food resources and foraging efficiency (intake per unit distance, which accounts for the energetic costs of travelling), were influenced only by distance. Titrating foraging against a range of distances demonstrated how quickly foraging efficiency can decline in response to the spatial separation of food resources, highlighting the importance of spatial heterogeneity of plants within the home range of an herbivore.
Testing transgenerational transfer of personality in managed wildlife populations: a house mouse control experiment
Publisher: Wiley
Date: 05-12-2020
DOI: 10.1002/EAP.2247
Abstract: Pest species control operations are most effective if every in idual in a population is targeted. Yet, in idual personality drives variation in animal responses to devices such as traps and baits. Failing to account for differences in behavior during control operations may drive a selective removal, resulting in residual animals with biased expressions of personality. If these biased traits are passed onto offspring, control operations would become increasingly problematic. To test if biased trait expressions in founding populations are passed on to offspring, we quantified personality traits in wild‐caught house mice ( Mus musculus ) and created founder populations selected for biased (high, low) or intermediate expressions of activity. We released the behaviorally biased populations into outdoor yards to breed to the F 1 generation and, 10 weeks later, removed the mice and quantified the personality traits of the offspring. Despite the strong personality bias in founder populations, we observed no transgenerational transfer of personality and detected no personality bias in the F 1 generation. Our results provide reassuring evidence that a single intensive control operation that selects for survivors with a personality bias is unlikely to lead to a recovering population inherently more difficult to eradicate, at least for house mice.
Do bare-nosed wombat (Vombatus ursinus) mounds influence terrestrial macroinvertebrate assemblages in agricultural riparian zones?
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/ZO09060
Abstract: Riparian ecosystems contain a complex mosaic of habitat structure types that can support distinct macroinvertebrate communities. Bare-nosed wombats (Vombatus ursinus) are often an integral component of agricultural riparian systems in south-eastern Australia. In these systems, wombats construct large burrow systems and mounds in the stream banks. Wombat mound structures vary markedly from the surrounding landscape and they may influence macroinvertebrate assemblages. We examined this ecosystem-engineering role of wombats as well as the ecological variability within our agricultural riparian study sites on the possible influence on macroinvertebrate assemblages. There were no detectable effects of wombat mounds on the richness or abundance of macroinvertebrates on the soil surface. At the site level, however, macroinvertebrate assemblages were most influenced by litter depth, upper canopy cover, cattle hoof prints and slope. The ecological variables within the study sites strongly affected macroinvertebrate assemblages. These findings reflect an influence of anthropogenic impact on communities of ground-dwelling invertebrates that have been found in other studies. It is possible that a finer resolution of taxa may highlight a unique pattern of macroinvertebrate use of wombat mounds.
Exposure to wind alters insect herbivore behaviour in larvae of Uraba lugens (Lepidoptera: Nolidae)
Publisher: Wiley
Date: 28-10-2016
DOI: 10.1111/AEN.12175
Determining predator identity from attack marks left in model caterpillars: guidelines for best practice
Publisher: Wiley
Date: 30-06-2014
DOI: 10.1111/EEA.12207
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