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A central goal of ecology is to understand how environmental variation affects populations. Long-term studies of marked individuals can quantify the effects of environmental variation on key life-history traits. We monitored the survival and growth of 336 individually marked juvenile eastern grey kangaroos (Macropus giganteus), a large herbivore living in a seasonal but unpredictable environment. During our 12-year study, the population experienced substantial variation in rainfall, forage biomass, and density. We used structural equation modeling to determine how variation in temperature and rainfall affected juvenile survival and growth through its effect on forage biomass and population density. Independently of population density, forage biomass had strong positive effects on survival from 10 to 21 months. At low population density, forage biomass also had a positive effect on skeletal growth to 26 months. Increasing maternal body condition improved rearing success for daughters but not for sons. High population density reduced skeletal growth to 26 months for both sexes. Rainfall had an increasingly positive effect on forage biomass at high temperatures, indicating a seasonal effect on food availability. Our study reveals interacting effects of environmental variation on juvenile survival and growth for a large mammal with a conservative reproductive strategy that experiences substantial stochasticity in food availability. [ABSTRACT FROM AUTHOR]

Baseline haematology, blood chemistry and acute phase protein parameters have not previously been published for free-ranging eastern grey kangaroos (Macropus giganteus). Eight eastern grey kangaroos, including three adult males, three adult females and two subadult males from two different populations, were examined. Assays assessed the antibacterial activity of kangaroo serum against one Gram-positive and three Gram-negative bacteria. The kangaroo serum had a strong antibacterial response to Klebsiella pneumoniae, and moderate responses to Escherichia coli and Staphylococcus aureus. The presence and level of acute phase proteins, haptoglobin and serum amyloid A in kangaroos was investigated. Haptoglobin and serum amyloid A were present in kangaroo serum, but only haptoglobin was elevated in a kangaroo with capture myopathy and necrotic wounds. The findings of this study provide preliminary data on health parameters of free-ranging eastern grey kangaroos. These parameters can be used to assist in assessing health in free-ranging populations. [ABSTRACT FROM AUTHOR]

Camera traps are frequently used in wildlife research and may be a useful tool for monitoring behavioural patterns. The suitability of camera traps to monitor behaviour depends on the size, locomotion, and behaviour of the species being investigated. The suitability of cameras for documenting the behaviour of eastern grey kangaroos was assessed here by comparing activity patterns collected using cameras to published activity patterns for the species. The activity patterns calculated from camera trap data were largely consistent with data from previous studies, although nocturnal activity appeared to be under-represented. Observations of unusual fighting behaviour illustrates the potential for camera traps to enable capture of novel observations. Kangaroo behaviour appeared to be influenced by the presence of cameras; however, no kangaroos retreated from cameras. Data suggested that kangaroos became habituated to cameras after eight months. The findings of this study suggest that camera traps are suitable for assessing the diurnal activity of eastern grey kangaroos and are useful tools for documenting their behaviour. [ABSTRACT FROM AUTHOR]

Macropods are susceptible to capture myopathy. A post mortem examination, and haematological and blood chemistry analysis was conducted on a male eastern grey kangaroo (Macropus giganteus) believed to have capture myopathy. Changes in blood chemistry and necrosis of muscle tissue are the most prevalent sign of myopathy in eastern grey kangaroos. [ABSTRACT FROM AUTHOR]

Animals exhibit a range of dispersal strategies that impact on the organisation of individuals and can be influenced by both the environment and population demography. We examined the fine-scale spatial genetic structure and patterns of relatedness in 139 adult eastern grey kangaroos (Macropus giganteus) to test predictions of male-biased dispersal and female philopatry in comparison with previous studies in different environments in the species' distributions. We found evidence of limited differences between the sexes, with little spatial genetic structure in both males and females. The levels of relatedness among females in close proximity were not indicative of close relatives (e.g. mother-daughter) and there was no evidence of matrilineal structure. Among males, there was little evidence of genetic structure. Although our results are, in general, consistent with those of previous studies, we found study-specific differences in the extent of genetic structure that appear to be related to differences in environmental and demographic conditions across the distribution. This highlights the need for additional research focussing on populations from a range of environmental conditions. [ABSTRACT FROM AUTHOR]

Atmospheric fluorides (gaseous and particulate) are deposited on, and absorbed by, vegetation. Ingested fluoride accumulates in calcified tissues of vertebrates, and if it is excessive, it may lead to dental and skeletal fluorosis. The prevalence, form and severity of the effects vary greatly between species. Foraging strategy can be an important determinant of fluoride exposure in herbivores, because foliar fluoride concentrations vary between plant species, for example, according to vertical and lateral position in the vegetation. We combined microhistological analysis of diet and analysis of foliar fluoride levels to examine interspecific variation in dietary fluoride exposure of macropodid marsupials (swamp wallaby Wallabia bicolor, red-necked wallaby Notamacropus rufogriseus and eastern grey kangaroo Macropus giganteus), in the buffer zone of an aluminium smelter in Victoria, Australia. Dietary niche differentiation between species was evident. The swamp wallaby and the red-necked wallaby were browsers or mixed feeders, depending on the classification system used. The eastern grey kangaroo was a grazer, consuming almost entirely grasses. However, foliar fluoride did not vary significantly between the main plant groups consumed. Our results indicate that interspecific variation in diet at this site is unlikely to explain variation in fluoride exposure. [ABSTRACT FROM AUTHOR]

Males engaging in same-sex competition can assess the strength of an opponent by means of behavioural display in order to avoid escalated interactions. There is no published record of male-male fighting with lethal consequences in eastern grey kangaroos, Macropus giganteus. The combat between two males reported here had a fatal outcome. [ABSTRACT FROM AUTHOR]

The Trivers-Willard hypothesis predicts that, in polygynous and sexually dimorphic mammals, mothers able to provide a large amount of care should produce more sons. Tests of this prediction, however, have generated equivocal results, possibly because multiple factors, including environmental conditions, simultaneously influence progeny sex ratio. We tested the influence of maternal mass, condition, size, previous reproduction and age class on offspring sex ratio in two populations of eastern grey kangaroos ( Macropus giganteus). In one population, heavier and taller mothers produced more sons than did lighter mothers, but maternal condition had no effect on progeny sex ratio. Primiparous females, however, produced an even offspring sex ratio despite being smaller than multiparous females. A strong year effect on progeny sex ratio suggested a likely effect of environmental conditions. In the second population, none of the variables tested influenced progeny sex ratio. Different environmental conditions between the two populations could partly explain these results. Because maternal size and mass likely correlate with reproductive potential, we suggest that our results support the Trivers-Willard hypothesis, but other variables likely also influence progeny sex ratio. [ABSTRACT FROM AUTHOR]

When resources are scarce, female mammals should face a trade-off between lactation and other life-history traits such as growth, survival and subsequent reproduction. Kangaroos are ideal to test predictions about reproductive costs because they may simultaneously lactate and carry a young, and have indeterminate growth and a long breeding season., An earlier study in three of our five study populations prevented female eastern grey kangaroos ( Macropus giganteus) from reproducing during one reproductive season by either inserting contraceptive implants or removing very small pouch young. We explored how individual and environmental variables affect the costs of reproduction over time, combining this experimental reduction of reproductive effort with multi-year monitoring of 270 marked females. Experimental manipulation should control for individual heterogeneity, revealing the costs of reproduction and their likely sources. We also examined the fitness consequences of reproductive effort and offspring sex among unmanipulated individuals to test whether sex allocation strategies affected trade-offs., Costs of reproduction included longer inter-birth intervals and lower probability of producing a young that survived to 7 months in the subsequent reproductive event. Weaning success, however, did not differ significantly between manipulated and control females. By reducing reproductive effort, manipulation appeared to increase individual condition and subsequent reproductive success., Effects of offspring sex upon subsequent reproductive success varied according to year and study population. Mothers of sons were generally more likely to have a young that survived to 7 months, compared to mothers of daughters., The fitness costs of reproduction arise from constraints in both acquisition and allocation of resources. To meet these costs, females delay subsequent parturition and may manipulate offspring sex. Reproductive tactics thus vary according to the amount of resource available to each individual, promoting a wide range in reproductive performance within and among individuals and populations. [ABSTRACT FROM AUTHOR]

The article offers information on a study conducted by researchers Julian Motha, Nino Ficorilli and Carol Anne Hartley from University of Melbourne and Centre for AgriBioscience, to isolate and characterize the novel herpesvirus from a free-ranging eastern grey kangaroo which displayed signs of neurologic and respiratory diseases. It discusses the sequence analysis of the virus that is related to macropodid herpesvirus 2, which is capable of infecting the kangaroos.

Lesions of skeletal and dental fluorosis have been described recently in eastern grey kangaroos ( Macropus giganteus). The present study further examined the epidemiology of skeletal fluorosis in this species. Bone fluoride concentrations were obtained from a range of skeletal sites of animals from a high (Portland Aluminium) and a low (Cape Bridgewater) fluoride environment in Victoria, Australia. Age, but not sex, affected the mean bone fluoride concentration of kangaroos. For a given age, bone fluoride concentrations were significantly higher in kangaroos from Portland than Cape Bridgewater. Concentrations varied between skeletal sites examined, with samples containing cancellous bone having higher fluoride concentrations than those containing only cortical bone. [ABSTRACT FROM AUTHOR]

Marsupials reportedly can implement selective brain cooling despite lacking a carotid rete. We measured brain (hypothalamic) and carotid arterial blood temperatures every 5 min for 5, 17, and 63 days in spring in three free-living western grey kangaroos. Body temperature was highest during the night, and decreased rapidly early in the morning, reaching a nadir at 10:00. The highest body temperatures recorded occurred sporadically in the afternoon, presumably associated with exercise. Hypothalamic temperature consistently exceeded arterial blood temperature, by an average 0.3°C, except during these afternoon events when hypothalamic temperature lagged behind, and was occasionally lower than, the simultaneous arterial blood temperature. The reversal in temperatures resulted from the thermal inertia of the brain; changes in the brain to arterial blood temperature difference were related to the rate of change of arterial blood temperature on both heating and cooling ( P < 0.001 for all three kangaroos). We conclude that these data are not evidence for active selective brain cooling in kangaroos. The effect of thermal inertia on brain temperature is larger than might be expected in the grey kangaroo, a discrepancy that we speculate derives from the unique vascular anatomy of the marsupial brain. [ABSTRACT FROM AUTHOR]

Aim: To determine the culturable biodiversity of anaerobic bacteria isolated from the forestomach contents of an eastern grey kangaroo, Macropus giganteus, using phenotypic characterization and 16S rDNA sequence analysis. Methods and Results: Bacteria from forestomach contents of an eastern grey kangaroo were isolated using anaerobic media containing milled curly Mitchell grass ( Astrebla lappacea). DNA was extracted and the 16S rDNA sequenced for phylogenetic analysis. Forty bacterial isolates were obtained and placed in 17 groups based on phenotypic characteristics and restriction enzyme digestion of 16S rDNA PCR products. DNA sequencing revealed that the 17 groups comprised five known species ( Clostridium butyricum, Streptococcus bovis, Clostridium sporogenes, Clostridium paraputrificum and Enterococcus avium) and 12 groups apparently representing new species, all within the phylum Firmicutes. Conclusions: Foregut contents from Australian macropod marsupials contain a microbial ecosystem with a novel bacterial biodiversity comprising a high percentage of previously unrecognized species. Significance and Impact of the Study: This study adds to knowledge of Australia's unique biodiversity, which may provide a future bioresource of genetic information and bacterial species of benefit to agriculture. [ABSTRACT FROM AUTHOR]