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Q fever, caused by Coxiella burnetii, is an important zoonotic and public health concern worldwide. Kangaroos are thought to be a likely wildlife reservoir for C. burnetii in Australia and the kangaroo tick (Amblyomma triguttatum) has often been considered a vector. In this descriptive study of ticks collected from a population of eastern grey kangaroos (Macropus giganteus) with a high serological (84 %) and molecular (65 %) prevalence of C. burnetii in northern New South Wales, a total of 72 A. triguttatum ticks were tested by PCRs targeting the IS1111, htpAB, and com1 genes of the Coxiella genome. Despite the remarkably high prevalence of coxiellosis in the host population, none of the ticks were positive for Coxiella. This finding suggests that the kangaroo tick may not play a significant role in the transmission dynamics of C. burnetii in this particular host population.

Large herbivores typically have consistently high prime‐aged adult survival and lower, more variable, juvenile, and senescent survival. Many kangaroo populations undergo greater fluctuations in density compared with other large herbivores, but age‐ and sex‐specific survival of kangaroos and their response to environmental variation remain poorly estimated. We used long‐term capture–mark–recapture data on 920 individuals to investigate the survival component of eastern grey kangaroo (Macropus giganteus) population dynamics. Forage availability and population density were monitored quarterly and included as predictors of survival in Bayesian Cormack–Jolly–Seber models. Annual survival probabilities were estimated for five age classes: 0 years (juveniles), 1–2 years (subadults), 3–6 years (prime‐aged adults), 7–9 years (presenescent adults), and ≥10 years (senescent adults). Survival of juveniles varied widely during our 12‐year study, ranging from 0.07 to 0.90 for females and 0.05–0.92 for males. Subadult survival was 0.80–0.93 for females and 0.75–0.85 for males, while that of prime‐aged adults was ≥0.94 for females and ≥0.83 for males, despite large fluctuations in forage and density. The survival of presenescent adults spanned 0.86–0.93 for females and 0.60–0.86 for males. Senescent survival was variable, at 0.49–0.90 for females and 0.49–0.80 for males. Male survival was significantly lower than female survival in prime‐aged and presenescent adults, but not in other age classes. Although most of the models supported by Watanabe–Akaike Information Criterion selection included at least one environmental covariate, none of these covariates individually had a discernible effect on survival. Temporal variability in overall survival appeared mostly due to changes in the survival of juvenile and senescent kangaroos. Kangaroo survival patterns are similar to those of ungulates, suggesting a strong role of sex–age structure on population dynamics. [ABSTRACT FROM AUTHOR]

Q fever, caused by Coxiella burnetii , is an important zoonotic and public health concern worldwide. Kangaroos are thought to be a likely wildlife reservoir for C. burnetii in Australia and the kangaroo tick (Amblyomma triguttatum) has often been considered a vector. In this descriptive study of ticks collected from a population of eastern grey kangaroos (Macropus giganteus) with a high serological (84 %) and molecular (65 %) prevalence of C. burnetii in northern New South Wales, a total of 72 A. triguttatum ticks were tested by PCRs targeting the IS 1111, htpAB , and com1 genes of the Coxiella genome. Despite the remarkably high prevalence of coxiellosis in the host population, none of the ticks were positive for Coxiella. This finding suggests that the kangaroo tick may not play a significant role in the transmission dynamics of C. burnetii in this particular host population. [ABSTRACT FROM AUTHOR]

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]

An adult female Eastern Grey kangaroo (Macropus giganteus) was examined for lameness due to a mass located at the right tibiotarsal joint. Radiographs revealed a metal arrowhead‐shaped foreign body within the mass alongside a pathologic fracture. Grossly, at necropsy, there was a multilobulated and haemorrhagic mass with intralesional metal fragments, associated osteolysis of the tibiotarsus and pulmonary metastatic nodules. Histologically the neoplasm was composed of plump elongated and fusiform cells that often formed concentrically around small vessels. The pulmonary nodules were composed of similar neoplastic cells, necrosis and haemorrhage. Neoplastic cells were positive immunohistochemically for vimentin and smooth muscle actin. The histological features, immunohistochemical profiles and behaviour of this tumour support a diagnosis of a primary angioleiomyosarcoma with lung metastasis associated with a metal foreign body. [ABSTRACT FROM AUTHOR]

To treat dental disorders and estimate age, it is important that veterinarians understand teeth eruption sequence for the animal in question. Few dental images of the eastern grey kangaroo have been published. In the present study, radiographic imagings of 29 kangaroos, ranging in age from 12 months to 10 years 9 months, was used to surveil the replacement of premolars and the eruption of molars. These images revealed eruption patterns in five stages, while the second and third deciduous premolars were shed non-systematically. Furthermore, the third premolars and fourth molars erupted in the mandible earlier than in the maxilla, which may contribute to the frequency of mandibular dental disorders. [ABSTRACT FROM AUTHOR]

When resources are limited, organisms face allocation conflicts. Indeterminate growth creates a persistent conflict with reproduction, as growth may enhance future reproduction, but diverts resources from current reproduction. Little is known about allocation trade-offs in mammals with indeterminate growth. We studied growth and reproduction in adult female eastern grey kangaroos ( Macropus giganteus), an iteroparous mammal with indeterminate growth. Allocation trajectories varied with age and size: for 4-year-old females, fecundity increased from 30 to 82% from shortest to average-sized individuals. Older females had high fecundity regardless of size. The smallest females grew 30% more annually than average-sized females, but females that reached average size at an older age had lower growth rates. Environmental conditions affected allocation to size and reproduction. Rainy springs increased fecundity from 61 to 84% for females that had previously reproduced, but rainy winters reduced leg growth. Females in better relative condition grew 40% more than average, whereas most young of females below average relative condition failed to survive to 10 months of age. These results highlight an age-specific trade-off between growth and reproduction. Tall young females benefit from a smaller trade-off between somatic growth and early fecundity than shorter females of the same age, but older females appear to favor reproduction over growth regardless of size. Our study highlights how individual heterogeneity determines trade-offs between life-history components. We speculate that cohort effects affect age-specific reproductive success in this long-lived mammal. [ABSTRACT FROM AUTHOR]

Seasonal variation in food resources and predation risk imposes major constraints on herbivores, which must adjust their behaviour to maximize their energy intake and survival. In seasonally driven landscapes, it is not yet clear what the primary drivers are that shape seasonal variation in vigilance and feeding rates. These rates have been shown to vary in relation to various environmental, social and individual factors, but many of these factors also vary through the year, due to variation in food supply. We studied wild female eastern grey kangaroos, Macropus giganteus , under low predation risk over a year to investigate whether vigilance and feeding rates varied seasonally and whether this variation was mainly driven by food quantity or quality, group size or individuals' reproductive states. Both vigilance and feeding rates varied seasonally, as did food quantity and quality and group size. Vigilance, including antipredator (head orientation away from the group) and exclusive (i.e. vigilance without chewing) vigilance, decreased and feeding rate increased with increasing group size. However, because group size increased with food quality and quantity, food resources emerged as the primary driver of variation in behavioural strategies. These results suggest that the observed effects of group size on the trade-off between food acquisition and safety are in fact corollaries of the seasonal variation in food supply in our study system, in which the risk of predation on adults is low, and hence are by-products of the foraging choices made by kangaroos in response to the dynamics of the quantity and quality of food. [ABSTRACT FROM AUTHOR]

Sociability, how individuals interact with conspecifics, is considered to be a key axis of animal personality. Consistent differences between individuals in measures of sociability have been demonstrated in some taxa, yet individuals also exhibit plasticity in their sociability across differing ecological conditions, particularly in gregarious species that do not occur in stable cohesive groups. Although repeatability and plasticity of measures of sociability are both important for understanding animal personality they have rarely been studied concurrently. Between and even within species, multiple behaviours have been considered to represent sociability, but there is still little understanding of the degree to which different measures of sociability reflect distinct traits. In this study, our first aim was to determine the repeatability of four different measures, representing two broad aspects of individual females' sociability, in a wild population of eastern grey kangaroos, Macropus giganteus . Our second aim was to investigate how shorter-term environmental conditions and individuals' states related to plasticity in these measures. Using data collected each month over a 5-year period on over 100 adult females, we analysed factors contributing to variation in individuals' grouping patterns (to reflect general gregariousness) and in the number of different conspecifics with which individuals associated (their ‘choosiness’ of social partners). Rainfall, body condition and reproductive state were all related to females' mean group sizes, and females with older dependent young foraged further from their neighbours. Females were more selective about group members when there was more food, and when they were in poor or excellent body condition. Although social preferences exist among females in this population, and females' measures of sociability are repeatable and differ between individuals over the long term, these current findings suggest that the influences of individuals' states and environmental conditions contribute to variation in females' patterns of sociability over shorter periods. [ABSTRACT FROM AUTHOR]

Social relationships established early in life can have effects on social structure and influence individual fitness. Eastern grey kangaroos, Macropus giganteus , nurse their young for at least 18 months, allowing for a strong bond to develop between mothers and young. Because most female kangaroos are philopatric, the mother-offspring relationship established during lactation could persist into adulthood, resulting in clusters of female kin. Strong social bonds, however, are based on affiliative behaviours and frequent interactions. In particular, one might not expect strong bonds among related individuals unless there are advantages to interacting with relatives compared to associating with unrelated conspecifics. We examined development of the mother-offspring relationship in eastern grey kangaroos from permanent emergence from the pouch to the time of weaning. We studied a high-density population at Wilsons Promontory National Park, Victoria, Australia. There were few differences in the behaviour of sons and daughters towards mothers. However, daughters foraged slightly closer than sons to their mothers and daughters were weaned approximately 2 months later than sons if the mother did not have a surviving large pouch young. Mothers associated more closely with their daughters than their sons when offspring were aged 10–29 months but neither sex associated closely with their mothers beyond 33 months of age. Mothers never intervened to defend their young from aggressive individuals and it was the offspring that maintained spatial proximity to their mothers. Kangaroo mothers had few interactions with their juvenile offspring other than nursing. Females may be philopatric and settle near close kin as adults but kangaroos appear to have few of those early affiliative interactions necessary for social bonds to develop. [ABSTRACT FROM AUTHOR]

Infection with the introduced trematode Fasciola hepatica was associated with anemia, mild to moderate azotemia, hypoalbuminemia, and elevated liver enzymes and creatine kinase values in two free-ranging eastern grey kangaroos ( Macropus giganteus). Both kangaroos were euthanized because of the severity of clinical signs associated with infection. Histopathologic changes included severe cholangiohepatitis, biliary hyperplasia, and fibrosis. Hepatic, splenic, and intestinal amyloidosis was present in one kangaroo and hepatic abscessation in the other; neither histologic change has been reported in macropodids with fascioliasis previously. [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]

Understanding the relationship between kinship and female social preferences in mammalian societies is frequently complicated by philopatric behaviour and variation in pairwise home range overlap. While the influence of space use on association patterns is increasingly being considered in studies using network analysis, methods are needed for generating null models that control for pairwise home range overlap. We investigated female associations in a wild population of eastern grey kangaroos, Macropus giganteus, a species with higher fission–fusion dynamics, to test the influences of home range overlap and kinship on pairwise association strengths. Genetic analysis revealed that females were highly philopatric and we found that association strengths were significantly correlated with home range overlap. To test for social preferences, we compared observed associations with random associations based on individuals' space use, simulated using Digiroo2. HWIG, a version of the half-weight association index that controls for among-individual variation in gregariousness was used for all analyses. Preferred associates had significantly higher pairwise relatedness than expected. Although some females had strong social relationships with some of their close kin, in general, space use had a much stronger correlation with association strengths than both pairwise relatedness and maternal lineage. This suggests that familiarity may play a key role in driving association patterns in female kangaroos. We recommend controlling for individuals' space use when undertaking studies on social preferences and social structure in general. [ABSTRACT FROM AUTHOR]

For many herbivorous mammal species across the world, geophagy, the consumption of soil, is an important method for obtaining minerals, especially sodium. However, this behavior has not been recorded in marsupials. The eastern grey kangaroo (Macropus giganteus), an intensively studied macropod species, is known to use physiological and micromorphological adaptations to conserve sodium. We present results of another adaptation, the use of natural licks, by this species and 3 other macropod species at Sundown National Park, Australia. Natural licks had significantly higher levels of sodium, magnesium, and sulfur than surrounding soils. We examined patterns of lick use by kangaroos to test 3 possible proximate causes of geophagy: whether lick use was affected by dietary mineral content, life-history stage, and thermoregulation. The number of kangaroos visiting the licks increased with temperature and mean cloud cover, varied among months, and was marginally significantly influenced by dietary mineral content. Visit durations to one lick increased with temperature and were influenced by month and life-history stage; females with high lactation demand and large males spent the most time at the lick. The proportion of time spent in geophagy when at a focal lick varied with month and reproductive state. Therefore geophagy is not restricted to eutherian mammals, and kangaroos, like many eutherian species, appear to adjust this behavior in response to their mineral demand. Geophagy in kangaroos is facultative, rather than obligative, and has not been detected in other intensively studied populations. In areas of Australia with low levels of sodium, high temperatures, and suitable lick sites, geophagy may play a key role in marsupial ecology. [ABSTRACT FROM AUTHOR]

Communities, clusters of individuals who interact socially primarily with each other, are fundamental elements of social structure in many species. Community membership can be influenced by spatial factors and by social preferences resulting from genetic or phenotypic assortment or shared behavioural strategies. Very little is known about community social structure in herbivorous mammals with higher fission–fusion dynamics, which are societies in which group membership frequently changes. Using network analysis on data from 171 wild female eastern grey kangaroos, Macropus giganteus, a species exhibiting these foraging and social attributes, we quantified the presence of significant, strong community structure. Lagged association rates confirmed the temporal stability of this intermediate-level social tier. Communities' home ranges overlapped considerably, but their core home ranges were more dispersed, suggesting some influence of spatial factors on community membership. However, community-level social assortment was maintained in areas in which core home ranges overlapped, even though communities used these areas simultaneously, implying that social preferences also influence the presence of communities in female kangaroos. Within-community pairwise relatedness levels based on microsatellite markers were somewhat higher than those across the population, probably because of philopatry, but mitochondrial DNA revealed that communities did not reflect matrilines. This study contributes to the growing literature attempting to understand the factors driving fission–fusion social dynamics by showing that extensive home range overlap among communities can occur in the absence of behaviours usually associated with the maintenance of social preferences. [ABSTRACT FROM AUTHOR]

In mammals, lactation is the most energetically demanding component of female reproduction. Theory predicts an increase in food intake by lactating females, but very few studies have used contraceptives to experimentally test the influence of reproduction on foraging behaviour of wild mammals. From 2009 to 2011, we observed 182 individually marked female eastern grey kangaroos, Macropus giganteus, in two populations, including 29 that received an experimental contraceptive treatment. We sought to determine whether lactating females increase their foraging rate compared to contracepted and naturally nonlactating females. The proportion of time spent foraging during 10min focal samples did not vary according to reproductive status in one population. In the other, lactating females spent 4% less time feeding than nonlactating females. Day and midday activity and bite and chewing rates were higher in lactating than in nonlactating females. Bite rate increased with the size of the pouch young and was higher for mothers of sons than for mothers of daughters. Bite rate was also affected by reproductive effort in the previous year, being higher for females that had weaned a young. Foraging behaviour was independent of body mass and group size, but bite rate appeared to decrease with female age. In one population, we found strong effects of date and year on foraging behaviour. Our study is a rare experimental manipulation of reproduction in free-ranging large mammals. We found that foraging behaviours were affected by both previous and current reproductive effort and varied with individual characteristics and environmental conditions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: Toxoplasma gondii infection is frequently asymptomatic; however, it can be severe or even fatal to some hosts. In this study, diagnosis of disseminated toxoplasmosis in one red kangaroo (Macropus rufus) and one great grey kangaroo (Macropus giganteus) from the La Plata Zoo, Argentina and the isolation and molecular characterization of T. gondii are reported. Both male kangaroos showed depression and sudden death. Toxoplasma gondii infection was diagnosed by fresh examination, histophatology, immunohistochemistry, PCR and bioassay in mice. During fresh examination many protozoan cysts were observed in diaphragm, heart and hind limb muscles of M. rufus. Cysts were also observed in samples from M. giganteus, although in lower number. Cysts from both kangaroos stained strongly with T. gondii anti-serum by immunohistochemistry. The M. rufus showed more considerable histopathological lesions like non-suppurative meningoencephalitis, myositis and myocarditis. All mice inoculated with tissues from both kangaroos developed IFAT titers to T. gondii (titer ≥800) and brain cysts at necropsy. Both T. gondii isolates were maintained by mice passages and the M. rufus isolate was also maintained in cell culture. Toxoplasma gondii DNA from tissue samples was analyzed by PCR-RFLP analysis using the markers 5′SAG2, 3′SAG2, BTUB, GRA6, SAG3, c22-8, L358, PK1, c29-2 and Apico. Genotyping revealed that the T. gondii isolate from M. rufus was clonal type III and the isolate from M. giganteus was clonal type II. This is the first report of disseminated toxoplasmosis in M. rufus and M. giganteus in Argentina caused by genotypes of T. gondii considered non-virulent in a mouse model. [Copyright &y& Elsevier]

Large mammalian herbivores must balance foraging efficiency with multiple constraints, including the risk of gastrointestinal parasitism. The costs imposed by gastrointestinal parasites are likely to exert selective pressure on hosts to develop aversion behaviors. Fecal aversion, or the avoidance of foraging patches contaminated by feces, is one mechanism by which herbivores can reduce their exposure to gastrointestinal parasites transmitted through the fecal contamination of foraging grounds. As feces also fertilize the surrounding pasture, herbivores may face a choice between the benefits of increased nutrient intake and an increased risk of parasitism. We investigated fecal aversion in free-ranging eastern grey kangaroos (Macropus giganteus), including the potential conflict between fecal aversion and increased nutrient intake, through a combination of field observations and a field experiment. Kangaroos exhibited fecal aversion by moving through contaminated patches as they were encountered. The experiment revealed that both sward height and fecal contamination affected the kangaroos’ choice of foraging patches: kangaroos preferred taller grass but would not accept a higher risk of parasitism for increased nutrient intake. [ABSTRACT FROM PUBLISHER]

The mean vigilance of animals in a group often decreases as their group size increases, yet nothing is known about whether there is individual variability in this relationship in species that change group sizes frequently, such as those that exhibit fission–fusion social systems. We investigated variability in the relationship between group size and vigilance in the eastern grey kangaroo ( Macropus giganteus) by testing whether all individuals showed decreased vigilance with increased group size, as has been commonly assumed. We carried out both behavioural observations of entire groups of kangaroos and focal observations of individually recognised wild female kangaroos. As in other studies, we found a collective group-size effect on vigilance; however, individuals varied in their vigilance patterns. The majority (57%) of the identified individual kangaroos did not show significant group-size effects for any of the recorded measures of vigilance. The females that did not show a negative group-size effect were, on average, more vigilant than those females that did show a group-size effect, but this difference was not significant. We propose that some females exhibit higher levels of social vigilance than others, and that this social vigilance increases with group size, cancelling out any group-size effect on anti-predator vigilance for those females. Our results therefore suggest that only some prey individuals may gain anti-predator benefits by reducing their time spent scanning when in larger groups. The large amount of variation that we found in the vigilance behaviour of individual kangaroos highlights the importance of collecting and analysing vigilance data at the individual level, which requires individual recognition. [ABSTRACT FROM AUTHOR]

Little is known about the determinants of females'' social interactions in species with fission–fusion social organization, in which individuals associate with different individuals at different times. Even less is known about social organization in marsupials. We investigated the association patterns of wild female eastern grey kangaroos in southeast Queensland. Female kangaroos had a nonrandom social structure and we present a new methodology for analysing social structure that accounts for the amount of spatial overlap shared by pairs of female kangaroos. This simulation model showed that patterns of association among our female kangaroos were not simply those predicted by their patterns of spatial overlap. Females that associated frequently with certain associates were able to graze for longer because they were less vigilant, and thus were able to benefit from having frequent associates. Female kangaroo social structure was affected by the loss of key members of the society during a period of unusually high predation. Information-theoretical modelling showed that the factors affecting grazing behaviour changed after partial population turnover, with the strength of association between nearest neighbours having a positive effect on grazing behaviour before population turnover and group size having a positive effect on grazing behaviour after population turnover. We propose that social organization within this marsupial is more structured than previously thought. [Copyright &y& Elsevier]

Abstract: A novel herpesvirus was detected in a captive mob of eastern grey kangaroos (Macropus giganteus) during diagnostic workup for individuals with ulcerative cloacitis. Virus was initially detected in tissues using a consensus herpesvirus PCR. No viral inclusions or particles had been evident in routine histologic or transmission electron microscopic sections of cloacal lesions. Virus was isolated from samples and transmission electron microscopy of the resulting isolates confirmed that the virus was morphologically consistent with a herpesvirus. Nucleotide sequencing of the PCR product from tissue samples and from the isolates revealed that the virus was in the subfamily Gammaherpesvirinae and was distinct from other known herpesviruses. The correlation between the lesions and the novel virus remains unknown. Two herpesviruses, both in the subfamily Alphaherpesvirinae, have previously been described in macropods and are known to cause systemic clinical disease. This is the first reported gammaherpesvirus within the order Marsupialia, and may provide valuable information regarding the evolution and phylogeny of this virus family. Based on current herpesvirus nomenclature convention, the authors propose the novel herpesvirus be named Macropodid herpesvirus 3 (MaHV-3). [Copyright &y& Elsevier]

1. Viggers & Hearn (2005) examined the encroachment of native herbivores on to farmland. They presented kangaroo home range estimates and pasture biomass data for three sites in south-eastern Australia, then made broad management recommendations regarding the preservation of remnant habitat. 2. While Viggers & Hearn identified potentially important patterns, we believe that their data were neither sufficient nor appropriate to reveal the processes that underlie these patterns. 3. Specifically, their study was unreplicated at the land-use level, used inappropriate density estimates for their study populations, failed to measure resources adequately, used flawed methods of home range analysis, and demonstrated limited understanding of key concepts and of their study species and thus could not draw valid conclusions. 4. Synthesis and applications. In view of these fundamental problems, we recommend that decisions on the management of kangaroos and remnant vegetation not be based on the work reported by Viggers & Hearn. [ABSTRACT FROM AUTHOR]

Vigilance activity is usually considered an adaptive advantage of group living conferring protection against predators. An individual of a prey species is assumed to benefit from an increase in the number of group members by reducing its own investment in vigilance. However, the proximate mechanism generating the decrease in vigilance with increasing group size is unclear. Most models of this relation assume that either individuals coordinate their scans in nonoverlapping bouts of vigilance or animals scan independently of one another. We studied the relation between vigilance and group size in the eastern grey kangaroo, Macropus giganteus, analysing vigilance at two structural levels, individual vigilance and collective vigilance of the group. We tested both assumptions, coordination and independence of scanning. The time that an individual spent vigilant decreased with group size. However, the time during which at least one individual in the group scanned the environment (collective vigilance) increased up to a group size of seven individuals but decreased thereafter. Analyses revealed that individuals neither coordinated their scanning in an asynchronous way nor scanned independently of one another. On the contrary, both the onset and the end of individuals'' scanning bouts were synchronized between group members, producing waves of collective vigilance. Bouts of vigilance and nonvigilance activity tended to be synchronized. Our results appear to support a hypothesis of allelomimetic vigilance. [Copyright &y& Elsevier]

Ideal free distribution (IFD) theory predicts that animals in competitive situations should distribute themselves among available habitat patches according to the density of conspecifics and its regulatory effect on resources. To investigate the applicability of IFD models to free-ranging herbivores, we quantified the dispersion and foraging behaviour of eastern grey kangaroos Macropus giganteus among habitat patches of differing suitability, within and outside a reservoir catchment in southern Victoria, Australia. Kangaroo densities within the catchment had a regulatory effect on resource density, while surrounding farmland maintained a higher standing crop despite higher densities of competitors. This difference was slight in autumn, however, when the system was apparently close to equilibrium. Gross bite rates of individuals foraging in farmland were lower than for individuals foraging within the catchment, and vigilance behaviour occurred more frequently in farmland habitat than any other, decreasing time devoted to feeding. Interference competition occurred in only 1.9% of focal samples, although competitive differences based on phenotype were observed. Although resource gains by individual kangaroos are likely to be influenced by other factors, including resource dynamics, predation risk and phenotypic differences, IFD theory provides a valuable analytical framework for this herbivore foraging system. [ABSTRACT FROM AUTHOR]

Models of kangaroo populations have primarily focused on the prediction of population growth and distribution in relation to environmental variation at broad geographic scales. Current understanding of small-scale patterns in distribution, habitat breadth, and niche occupation is less complete. A powerful model of dispersion is ideal free distribution (IFD) theory. In plant-herbivore grazing systems, the most appropriate IFD models are those that allow for the incorporation of a standing crop of resources. Using eastern grey kangaroos (Macropus giganteus). we test the predictions of a previously described standing-crop IFD model where the number of consumers on a patch is proportional to the resource input rate, the standing crop of resources on all patches at equilibrium are equal (in the absence of interference), and the resource mortality rate is directly equivalent to the resource input rate, and is independent of the resource density (in the absence of interference). We make these comparisons at both the habitat and patch scale. At the habitat scale, we observed significant departures from these predictions that are consistent with the commonly reported occurrence of undermatching, whereas at the patch scale. little concordance with the predictions was observed. These results suggest that eastern grey kangaroos select for resources at the habitat scale but not at the level of the patch. [ABSTRACT FROM AUTHOR]

1. The management of kangaroo populations is a major land management and conservation issue in many parts of Australia. 2. Viggers & Hearn (2005 ) reported the results of a substantial radio-tracking study of the eastern grey kangaroo ( Macropus giganteus Shaw) in south-eastern Australia. Martin et al. (2007 ) critique the study design, home range analysis, biomass assessment and other aspects of the work by Viggers & Hearn (2005 ). 3. We reject the criticisms made by Martin et al. (2007 ) and believe that the study design employed by Viggers & Hearn (2005 ) was sound. The work also was preceded by extensive day and night-time field assessments to enable contrasts between low and high density M. giganteus populations. We also contend that the home range analysis was not flawed: the methods employed by Viggers & Hearn (2005 ) were in fact the same ones recommended by Martin et al. (2007 ). We believe that other criticisms made by Martin et al. (2007 ) also cannot be sustained. 4. Synthesis and applications. Viggers & Hearn (2005 ) found that patches of remnant native vegetation were used as day and night-time refuges by M. giganteus. This creates a disincentive for farmers to conserve remnant native vegetation. The criticisms by Martin et al. (2007 ) have no bearing on this conclusion; hence the kangaroo conundrum stands. [ABSTRACT FROM AUTHOR]