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Context Determining population size or density is often fundamental for wildlife conservation. For nocturnal species, indices are commonly used in place of abundance estimates, with spotlighting indices (e.g. sighting rate per km) being prevalent. Distance sampling is a collection of techniques that provide estimates of wildlife abundance from line-transect data, by correcting raw counts for imperfect detection. These methods have rarely been used to assess the abundance of nocturnal arboreal mammals. Aims To develop and evaluate a method for estimating the abundance and density of nocturnal arboreal mammals using double-observer distance sampling, and to apply the approach to a survey of the southern greater glider (Petauroides volans) in the Strathbogie Ranges, Victoria, Australia. Methods Two observers, 15–20 min apart, surveyed 25 randomly located 500 m transects, and recorded greater gliders using spotlights and binoculars. Densities and abundances were derived from the line-transect data by using mark–recapture distance sampling (MRDS) models and were compared with conventional distance sampling analysis (CDS). Key results Using the double-observer approach, we estimated an overall density of 0.96 gliders ha−1 (95% CI 0.60–1.50), giving a population estimate of 24 575 greater gliders across the Strathbogie Ranges (25 865 ha, 95% CI 15 620–38 661). The corresponding estimates for the study area derived using CDS applied to either both observers’ observations or to the first observer’s observations only, were 87% and 53% respectively, of the MRDS estimate. The analysis confirmed that the probability of detection of gliders along the transect line was less than one, justifying the use of the double-observer method to obtain accurate estimates of abundance. Conclusions The low detectability of greater gliders means that uncorrected spotlight counts will underestimate abundance, as will CDS. The double-observer method corrects for the negative bias associated with raw counts, enabling more accurate estimation of abundance for survey, monitoring and management purposes. Implications We recommend that double-observer distance sampling is adopted as a standard technique for estimating the abundance of greater gliders. The double-observer method potentially has wider relevance for assessing population size of other arboreal mammals, providing the assumptions of the approach can be met.

Extreme weather can have significant impacts on plant species demography; however, most studies have focused on responses to a single or small number of extreme events. Long-term patterns in climate extremes, and how they have shaped contemporary distributions, have rarely been considered or tested. BIOCLIM variables that are commonly used in correlative species distribution modelling studies cannot be used to quantify climate extremes, as they are generated using long-term averages and therefore do not describe year-to-year, temporal variability. We evaluated the response of 37 plant species to base climate (long-term means, equivalent to BIOCLIM variables), variability (standard deviations) and extremes of varying return intervals (defined using quantiles) based on historical observations. These variables were generated using fine-grain (approx. 250 m), time-series temperature and precipitation data for the hottest, coldest and driest months over 39 years. Extremes provided significant additive improvements in model performance compared to base climate alone and were more consistent than variability across all species. Models that included extremes frequently showed notably different mapped predictions relative to those using base climate alone, despite often small differences in statistical performance as measured as a summary across sites. These differences in spatial patterns were most pronounced at the predicted range margins, and reflect the influence of coastal proximity, continentality, topography and orographic barriers on climate extremes. Species occupying hotter and drier locations that are exposed to severe maximum temperature extremes were associated with better predictive performance when modelled using extremes. Understanding how plant species have historically responded to climate extremes may provide valuable insights into our understanding of contemporary distributions and help to make more accurate predictions under a changing climate.

Reference intervals (RIs) describe baseline parameters of healthy animals, providing a powerful tool for wildlife managers to monitor health, identify disease and assess animal welfare. This paper reports haematological, glucose and serum protein RIs for one of Australia's most iconic and managed mammals, the eastern grey kangaroo Macropus giganteus. Blood samples (n = 514) were collected from 11 populations of eastern grey kangaroos, across much of their geographic range. A species-level RI was initially established based on samples collected from four sites (n = 245) and was further partitioned based on significant differences associated with sexual maturity and season. Unique population means were established from a further seven sites to investigate the importance of biotic (sex and sexual maturity) and abiotic (season, site, rainfall, temperature and laboratory) factors on kangaroo health parameters. Random forest analysis of health parameters revealed that abiotic factors (site, rainfall, temperature and season) were largely responsible for differences in haematological, glucose and serum protein values. Sex was found to have no influence, while sexual maturity and laboratory of analysis had moderate effects. Based on these findings, interpretation of individual and population haematological and serum protein values requires careful consideration of the timing of sample collection, environmental conditions and sexual maturity. When assessing kangaroo health, the relevant sexual maturity RI must be considered initially. For populations with similarities to those described (for example high density or captive populations) users should also consider site specific mean haematological and serum protein values. The RIs reported are valuable when establishing the health status of kangaroo populations. Furthermore, understanding the influence of biotic and abiotic factors will improve the utility of these RIs to assess health, disease status and improve welfare in eastern grey kangaroos.

Increasing impacts of climatic change and anthropogenic disturbances on natural ecosystems are leading to population declines or extinctions of many species worldwide. In Australia, recent climatic change has caused population declines in some native fauna. The projected increase in mean annual temperature by up to 4°C by the end of the 21st century is expected to exacerbate these trends. The greater glider (Petauroides volans), Australia’s largest gliding marsupial, is widely distributed along the eastern coast, but has recently experienced drastic declines in population numbers. Its association with hollow‐bearing trees, used for nesting, has made it an important species for the conservation of old‐growth forest ecosystems. Fires and timber harvesting have been identified as threats to the species. Greater gliders have disappeared however from areas that have experienced neither raising questions about the role of other factors in their decline. A unique physiology and strict Eucalyptus diet make them vulnerable to high temperatures and low water availability. As such, climatic conditions may drive habitat selection and recent climatic trends may be contributing to observed population declines. Using presence:absence data from across its distribution in Victoria, coupled with high spatial and temporal resolution climatic data and machine‐learning modeling, we tested the influence of climatic, topographic, edaphic, biotic, and disturbance variables on greater glider occupancy and habitat suitability. We found that climatic variables, particularly those related to aridity and extreme weather conditions, such as number of nights warmer than 20°C, were highly significant predictors of greater glider occurrence. Climatic conditions associated with habitat suitability have changed over time, with increasing aridity across much of its southeastern distribution. These changes in climate are closely aligned with observed population declines across this region. At higher elevation, some areas where the greater glider is observed at high densities, conditions have become wetter, which is improving habitat quality. These areas are of growing significance to greater glider conservation as they will become increasingly important as climatic refugia in the coming decades. Protecting these areas of habitat will be critical for facilitating the conservation of greater gliders as the broader landscape becomes less hospitable under future climatic change.

1. The transmission of pathogens between wildlife and livestock is a globally recognised threat to the livestock industry, as well as to human and wildlife health. Wild cervids are susceptible to many diseases affecting livestock. This presents a challenge for wildlife and domestic animal disease management because the frequent use of agricultural areas by wild cervids may hamper the effectiveness of disease control strategies. 2. Six deer species have established wild populations in Australia and are expanding in range and abundance. A comprehensive literature review of diseases impacting deer and livestock was undertaken, resulting in consideration of 38 pathogens. A qualitative risk assessment was then carried out to assess the overall risk posed by the pathogens to the livestock industry. 3. Five diseases (bovine tuberculosis, foot and mouth disease, malignant catarrhal fever, surra, and screw‐worm fly infestation) ranked highly in our risk assessment. Of these five diseases, only one (malignant catarrhal fever) is currently present in Australia, but all five are notifiable diseases at a national level. Data on these diseases in deer are limited, especially for one of the most abundant species, the sambar deer Rusa unicolor, highlighting a further potential risk attributable to a lack of understanding of disease epidemiology. 4. This paper provides a detailed review of the pathogens affecting both cervids and livestock in Australia, and applies a qualitative framework for assessing the risk posed by deer to the livestock industry. The qualitative framework used here could easily be adapted to assess disease risk in other contexts, making this work relevant to scientists and wildlife managers, as well as to livestock industry workers, worldwide.

Grooming is an important behaviour for the control of ectoparasites in mammals but it is also energetically costly. Therefore, the time an animal allocates to grooming may be used to evaluate the potential cost of an ectoparasite to its host. Most mammals are host to more than one ectoparasite species, which may impose different costs. We experimentally evaluated the relative cost of three ectoparasite species by observing the grooming response of their host, Gould's wattled bat (Chalinolobus gouldii), to the manipulation of parasite load. The parasite that spent its entire lifecycle on the host, the mite Spinturnix novaehollandiae, triggered the greatest increase in grooming. A grooming response was not as evident for the other parasites (a smaller mite, Trichonyssus womersleyi, and a bat fly, Basilia troughtoni), possibly because part of their lifecycle occurred in the roost, which the host may avoid by discriminative roost selection. Grooming behaviour, although not significantly altered by parasites other than S. novaehollandiae, was performed by most bats, which maintained a baseline grooming rate even when relatively parasite free. This study suggests heterogeneity in the costs imparted on a host by members of its ectoparasite community and the potential importance of considering parasite life-history when evaluating the influence of parasites on the host.

Mammalian herbivores are typically infected by parasitic nematodes, which are acquired through direct, faecal–oral transmission. These parasites can cause significant production losses in domestic livestock, but much less is known about impacts on wild mammalian hosts. We review three elements of parasitism from the host's perspective: fitness costs of infection, risks of infection during foraging and benefits of nutritious pasture. The majority of wildlife studies have been observational, but experimental manipulation is increasing. Treatment with anthelmintics to manipulate parasite load has revealed varied impacts of parasites on fitness variables across host species, but has not produced consistent evidence for parasite-induced anorexia or impaired body condition. Some experimental studies of infection risk have manipulated faecal contamination and detected faecal avoidance by hosts. Only two field studies have explored the trade-off between infection risk and nutritional benefit generated by avoidance of contaminated patches. Overall, field studies of costs, risks and benefits of the host–parasite relationship are limited and few have examined more than one of these elements. Parasitism has much in common with predation, and future insights into anti-parasite responses by wild hosts could be gained from the conceptual and technical developments in research on anti-predator behaviour. This article is part of the Theo Murphy meeting issue ‘Evolution of pathogen and parasite avoidance behaviours’.

Large mammalian herbivores are commonly infected with gastrointestinal helminths. Heavily parasitised hosts are likely to have increased nutritional requirements and would be predicted to increase their food intake to compensate for costs of being parasitised, but experimental tests of the impacts of these parasites on the foraging efficiency of hosts are lacking, particularly in free-ranging wildlife. We conducted a field experiment on a population of free-ranging eastern grey kangaroos (Macropus giganteus) to test this prediction, removing nematodes from one group of adult females using an anthelmintic treatment. We then carried out observations before and following treatment to assess the influence of parasites on foraging behaviour. Contrary to our predictions, the manipulation of parasite burdens did not result in changes in any of the key foraging variables we measured. Our results suggest that despite carrying large burdens of gastrointestinal parasites, the foraging strategy of female kangaroos is likely be driven by factors unrelated to parasitism, and that kangaroos in high nutritional environments may be able acquire sufficient nutrients to offset the costs of parasitism. We conclude that the drivers of forage intake likely differ between domesticated and free-ranging herbivores, and that free-ranging hosts are likely more resilient to parasitism.

Reproduction can lead to a trade-off with growth, particularly when individuals reproduce before completing body growth. Kangaroos have indeterminate growth and may always face this trade-off. We combined an experimental manipulation of reproductive effort and multi-year monitoring of a large sample size of marked individuals in two populations of eastern grey kangaroos to test the predictions (1) that reproduction decreases skeletal growth and mass gain and (2) that mass loss leads to reproductive failure. We also tested if sex-allocation strategies influenced these trade-offs. Experimental reproductive suppression revealed negative effects of reproduction on mass gain and leg growth from 1 year to the next. Unmanipulated females, however, showed a positive correlation between number of days lactating and leg growth over periods of 2 years and longer, suggesting that over the long term, reproductive costs were masked by individual heterogeneity in resource acquisition. Mass gain was necessary for reproductive success the subsequent year. Although mothers of daughters generally lost more mass than females nursing sons, mothers in poor condition experienced greater mass gain and arm growth if they had daughters than if they had sons. The strong links between individual mass changes and reproduction suggest that reproductive tactics are strongly resource-dependent.

Simple Summary Eastern Grey Kangaroos (Macropus giganteus) occur throughout the seaside town of Anglesea in southern Victoria, Australia. We have tagged about half of these kangaroos in a longitudinal study of population dynamics and behavior. A golf course forms the nucleus of this population. Females live on and around the golf course, but males roam across the town in autumn and winter, living in bush reserves, empty blocks and back yards. Most females breed every year, but over half of their young disappear. Vehicles are the major cause of adult deaths, killing a much higher proportion of males than females. Abstract Most urban mammals are small. However, one of the largest marsupials, the Eastern Grey Kangaroo Macropus giganteus, occurs in some urban areas. In 2007, we embarked on a longitudinal study of this species in the seaside town of Anglesea in southern Victoria, Australia. We have captured and tagged 360 individuals to date, fitting each adult with a collar displaying its name. We have monitored survival, reproduction and movements by resighting, recapture and radio-tracking, augmented by citizen science reports of collared individuals. Kangaroos occurred throughout the town, but the golf course formed the nucleus of this urban population. The course supported a high density of kangaroos (2–5/ha), and approximately half of them were tagged. Total counts of kangaroos on the golf course were highest in summer, at the peak of the mating season, and lowest in winter, when many males but not females left the course. Almost all tagged adult females were sedentary, using only part of the golf course and adjacent native vegetation and residential blocks. In contrast, during the non-mating season (autumn and winter), many tagged adult males ranged widely across the town in a mix of native vegetation remnants, recreation reserves, vacant blocks, commercial properties and residential gardens. Annual fecundity of tagged females was generally high (≥70%), but survival of tagged juveniles was low (54%). We could not determine the cause of death of most juveniles. Vehicles were the major (47%) cause of mortality of tagged adults. Road-kills were concentrated (74%) in autumn and winter, and were heavily male biased: half of all tagged males died on roads compared with only 20% of tagged females. We predict that this novel and potent mortality factor will have profound, long-term impacts on the demography and behavior of the urban kangaroo population at Anglesea.

Effective anthelmintics are valuable tools for biologists conducting manipulative field experiments to examine effects of parasites on wildlife. However, before such experiments are carried out the efficacy of these drugs must be determined. We conducted three field experiments (May 2010-September 2011) on free-ranging eastern grey kangaroos (Macropus giganteus) at a golf course in Victoria, Australia, treating animals with the anthelmintic drugs moxidectin (subcutaneous, 1 mg/kg, 2 mg/kg), ivermectin (subcutaneous, 200 μg/kg), and albendazole (oral, 3.8 mg/kg). After treatment we monitored strongylid fecal egg counts (FECs) over time and assessed anthelmintic efficacy using fecal egg count reduction tests (FECRTs). We also performed a larval development assay (LDA) to evaluate directly the efficacy in the nematode population. Unexpectedly, moxidectin and ivermectin had low efficacy with maximum FEC reductions of 82% and 28%, respectively. However, treatment with albendazole reduced FECs by 100% in all kangaroos and egg counts remained low for up to 3 mo. The results from the LDA supported the FECRTs, with low macrocyclic lactone efficacy and high albendazole efficacy. Macrocyclic lactones, at recommended dose rates, were much less effective against strongylid nematodes in kangaroos than has been reported for domestic herbivores. This may be partly due to pharmacokinetics in the host and partly due to low susceptibility in some of the nematodes infecting eastern grey kangaroos.

Lactation is the most energetically expensive component of reproduction in mammals. Theory predicts that reproducing females will adjust their behaviour to compensate for increased nutritional demands. However, experimental tests are required, since comparisons of the behaviour of naturally reproducing and non-reproducing females cannot distinguish between true costs of reproduction, individual differences or seasonal variation. We experimentally manipulated reproduction in free-ranging, eastern grey kangaroos ( Macropus giganteus ), using a fertility control agent. Our novel field experiment revealed that females altered their behaviour in direct response to the energetic demands of reproduction: reproducing females increased bite rates, and thus food intake, when the energetic demands of lactation were highest. Reproducing females did not reduce the time spent on vigilance for predators, but increased their forage intake on faecal-contaminated pasture, thereby increasing the risk of infection by gastrointestinal parasites—a largely unrecognized potential cost of reproduction.

Parasite infection is increasingly recognised as a factor shaping the population dynamics, life history and behaviour of hosts. However, before the impacts of parasites on wildlife hosts can be investigated, seasonal patterns in host exposure to parasitic agents must be determined. We examined infection patterns at three sites in Victoria, and combined field experiments and observations to construct a generalised life cycle of the helminth community in eastern grey kangaroos (Macropus giganteus). Kangaroo populations in Victoria had very similar helminth communities, with 20–25 species detected at each site. Despite examining relatively few hosts in this study, at least 87% of all gastrointestinal helminths were recovered according to bootstrap estimates. The prepatent period of infection in eastern grey kangaroo nematodes was at least 3 months, and faecal egg output showed a distinct seasonal pattern, with a peak in egg counts from October through to January each year. Data from one site indicated that faecal egg counts were influenced predominantly by the abundance of a single nematode species (Pharyngostrongylus kappa), despite adults accounting for only 7% of the total nematode burden. This highlights the problems associated with using faecal egg counts to estimate nematode burdens in this host. Contamination of pasture plots showed that nematode eggs take ~14 days to larvate once deposited, and that autumn rains likely triggered emergence from faecal pellets. The abundance of infective larvae in the environment therefore appears to be closely tied to environmental conditions, with a peak in infection of hosts in the winter months.

Graphical abstract, Highlights • We examine differences between parasitised and non-parasitised juvenile kangaroos. • Kangaroo helminths affect host albumin levels. • Kangaroo helminths have surprisingly few effects on host growth and body condition. • Haematological parameters are more sensitive to parasitism than growth parameters. • Juvenile kangaroos can possibly compensate for the costs of parasites., Large mammalian herbivores are commonly infected with gastrointestinal helminths. In many host species, these helminths cause clinical disease and may trigger conspicuous mortality events. However, they may also have subclinical impacts, reducing fitness as well as causing complex changes to host growth patterns and body condition. Theoretically, juveniles should experience significantly greater costs from parasites, being immunologically naive and undergoing a significant growth phase. The aims of our study were to quantify the subclinical effects of helminths in juvenile eastern grey kangaroos (Macropus giganteus), which commonly harbour large burdens of gastrointestinal nematodes and are susceptible to associated mass mortality during cold, wet conditions. We conducted a field experiment on a population of free-ranging kangaroos, removing nematodes from one group of juveniles using an anthelmintic treatment. We then compared growth parameters (body condition and growth rates) and haematological parameters of this group with an age-matched, parasitised (untreated) control group. Treated juvenile kangaroos had significantly higher levels of plasma protein (albumin) but, contrary to our predictions, showed negligible changes in all the other parameters measured. Our results suggest that juvenile kangaroos are largely unaffected by their gastrointestinal helminth burdens, and may be able to compensate for the costs of parasites.