Eastern Grey Kangaroos Macropus Giganteus Research Articles

One year on: rapid assessment of fauna and red fox diet after the 2019–20 mega-fires in the Blue Mountains, New South Wales

ABSTRACT Australia’s 2019–20 mega-fires burnt 79% of the Greater Blue Mountains World Heritage Area, prompting an urgent need for rapid on-ground post-fire assessments of flora and fauna to aid in post-fire recovery. This project aimed to determine spatial patterns in populations and assemblages of vertebrates, vertebrate temporal activity, and the diet of the invasive Red Fox Vulpes vulpes, across burnt and unburnt sites. Using remote camera traps we surveyed 12 unburnt and 10 burnt sites approximately 12 months after the fires. We detected 41 species (11 mammals, 28 birds and 2 reptiles), with different species composition, but similar vertebrate species richness across both unburnt and burnt sites. The relative abundance of the Eastern Grey Kangaroo Macropus giganteus, Common Wombat Vombatus ursinus and Australian Magpie Gymnorhina tibicen was higher in burnt sites, while small mammals (< 500 g) had higher relative abundance at unburnt sites. There was no difference in the relative abundance of the Superb Lyrebird Menura novaehollandiae across burnt and unburnt sites, and although 11 species of bird were only detected at unburnt sites, the numbers were too low for reliable estimates of differences. Red Fox scat analysis (n=23) revealed that invertebrates and plant material were the dominant prey items in both burnt and unburnt sites, but medium-sized mammals increased in Red Fox diets in burnt sites, and reptiles were consumed disproportionately more by Red Foxes in burnt compared to unburnt sites. Although the short-term nature of this study and low scat sample size limited detailed insights, our rapid survey was an effective tool to gain preliminary data on species responses to the 2019–20 megafires in the Blue Mountains and contribute to a baseline for understanding species recovery.

Virtual fencing as a wildlife-vehicle collision mitigation measure: technical function, wildlife response and considerations for installation in an urban environment

ABSTRACT Virtual wildlife fencing presents as a cost-effective measure for roadkill mitigation, which aids in reducing fragmentation of wildlife populations by facilitating safer movement of wildlife across the landscape. In this study, we conducted an audit of a virtual fence installation in south-east Queensland, Australia. We assessed its reliability in flows of traffic and the effect that installation parameters and site conditions had on its effective operation in an urban setting. We made observations on the behavioural response of Eastern Grey Kangaroos Macropus giganteus to the acoustic signals produced by the fence. We found that the fencing activated consistently in response to headlights at dusk and dawn, and when traffic flows were dense, despite considerable variations in the range of installation parameters. However, we identified that the response of the virtual fence to headlights was affected by road curvature and we identified inconsistencies in the timing and pattern of activation in response to traffic. Behavioural observations showed a significant increase in kangaroo vigilance in response to the acoustic signal of the fence when resting or grazing, and kangaroos detected the acoustic signal up to 50 m away. While virtual fencing operates effectively and is a low-cost roadkill mitigation option that can be applied to the urban environment, more research is needed to better understand the effect of its acoustic and visual signals on wildlife behaviour and efficacy in busy urban environments.

Reference intervals for parameters of health of eastern grey kangaroos Macropus giganteus and management implications across their geographic range

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.

Behavioural Plasticity by Eastern Grey Kangaroos inResponse to Human Behaviour.

Simple SummaryMany species of wildlife live in landscapes they share with people. Some exploit resources and protection provided by close proximity to people, while others learn to avoid people all together. In this study, we sought to test whether individuals from a population of eastern grey kangaroos altered grouping and spacing behaviour in response to human presence, depending upon whether the intent and actions of those people were benign or harmful. Under harmful conditions, kangaroos failed to form larger groups when far from cover, however, this typical antipredator grouping behaviour persisted when human disturbances were benign. These differences in grouping and spacing behaviour suggest that kangaroos can exhibit bidirectional behavioural plasticity at fine scales, a trait that may confer adaptive advantages when sharing landscapes with humans.Sharing landscapes with humans is an increasingly fraught challenge for wildlife across the globe. While some species benefit from humans by exploiting novel opportunities (e.g., provision of resources or removal of competitors or predators), many wildlife experience harmful effects, either directly through persecution or indirectly through loss of habitat. Consequently, some species have been shown to be attracted to human presence while others avoid us. For any given population of a single species, though, the question of whether they can recognise and change their response to human presence depending on the type of human actions (i.e., either positive or negative) has received little attention to date. In this study, we chose to examine the behavioural plasticity within a single population of eastern grey kangaroos (Macropus giganteus) to both positive and negative human activity. Within a relatively small and contiguous landscape, we identified areas where kangaroos experience a combination of either low and high frequencies of benign and harmful human disturbances. From six sampling sessions over five months, we found that density and group sizes were higher where humans acted benignly towards them, and that these groups had higher representations of sub-adults and juveniles than where humans had harmful intentions. Importantly, we found that the vital antipredator strategy of increasing group size with distance from cover was not detectable at sites with low and high levels of harm. Our findings suggest that these kangaroos are recognising and adjusting their behavioural response to humans at fine spatial scales, a plasticity trait that may be key to the survival of these species in human dominated landscapes.

Town roo, country roo: a comparison of behaviour in eastern grey kangaroos Macropus giganteus in developed and natural landscapes

ABSTRACT Many species have adapted their behaviour to survive in anthropogenically developed environments (hereafter referred to as developed). Eastern grey kangaroos Macropus giganteus are common ...

A suspected case of myopathy in a free-ranging eastern grey kangaroo (Macropus giganteus)

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.

Long-term consequences of mother-offspring associations in eastern grey kangaroos

Abstract: Close behavioural association between mothers and offspring should enhance survival and growth of the young. Eastern grey kangaroos Macropus giganteus are gregarious and live in fission-fusion societies where adult females do not form strong bonds with other females but associate closely with their juvenile offspring. We aimed to determine whether the strength of these mother-offspring associations correlated with offspring size, survival and reproduction. We observed 129 marked offspring, aged 10 to 21 months, and their mothers in a high-density population at Wilsons Promontory National Park, Australia. We used half-weight indices to quantify mother-offspring associations and determined the proportion of time offspring spent with their mother, but isolated from other kangaroos, while foraging. We found strong cohort effects on size, mass, body condition, survival and reproduction. Mother-offspring sociability indices were not correlated with offspring body condition as 2-year-olds or reproduction as 3-year-olds. Juveniles that spent proportionally more time with their mothers at 18–21 months, however, were 6% larger and 19% heavier as 2-year-olds than those that did not associate closely with their mothers. In addition, juveniles that were often found alone with their mothers were more likely to survive than those that were more often found in larger groups. Stronger mother-offspring associations before weaning likely reflected nutritional maternal care in sons but non-nutritional care in daughters and had a beneficial effect on juvenile growth and survival. Significance statement: The possible fitness consequences of mother-offspring behavioural associations can affect reproductive decisions by mothers. These fitness consequences affect population dynamics and are relevant to conservation when mothers may be harvested or killed by vehicles, as is the case for many large herbivores. We show that variability in these associations in kangaroos affects correlates of offspring fitness. Juveniles that spent proportionally more time with their mothers between 18 and 21 months of age were larger and heavier as 2-year-olds. In addition, juveniles that spent proportionally more time with their mothers but isolated from other kangaroos experienced improved survival. This study is among very few to examine the relationship between mother-offspring sociability and reproductive success in a non-primate mammal. Improved juvenile growth in sons appears to result from nutritional maternal care through prolonged nursing. Isolation of the mother with her young-at-foot occurs in all large macropod marsupials, and adaptive benefits of this behaviour should therefore occur in other species of macropods.

A simple framework for a complex problem? Predicting wildlife-vehicle collisions.

SummaryCollisions of vehicles with wildlife kill and injure animals and are also a risk to vehicle occupants, but preventing these collisions is challenging. Surveys to identify problem areas are expensive and logistically difficult. Computer modeling has identified correlates of collisions, yet these can be difficult for managers to interpret in a way that will help them reduce collision risk. We introduce a novel method to predict collision risk by modeling hazard (presence and movement of vehicles) and exposure (animal presence) across geographic space. To estimate the hazard, we predict relative traffic volume and speed along road segments across southeastern Australia using regression models based on human demographic variables. We model exposure by predicting suitable habitat for our case study species (Eastern Grey Kangaroo Macropus giganteus) based on existing fauna survey records and geographic and climatic variables. Records of reported kangaroo–vehicle collisions are used to investigate how these factors collectively contribute to collision risk. The species occurrence (exposure) model generated plausible predictions across the study area, reducing the null deviance by 30.4%. The vehicle (hazard) models explained 54.7% variance in the traffic volume data and 58.7% in the traffic speed data. Using these as predictors of collision risk explained 23.7% of the deviance in incidence of collisions. Discrimination ability of the model was good when predicting to an independent dataset. The research demonstrates that collision risks can be modeled across geographic space with a conceptual analytical framework using existing sources of data, reducing the need for expensive or time‐consuming field data collection. The framework is novel because it disentangles natural and anthropogenic effects on the likelihood of wildlife–vehicle collisions by representing hazard and exposure with separate, tunable submodels.

Habitat preference of the striped legless lizard: Implications of grazing by native herbivores and livestock for conservation of grassland biota

AbstractAcross the globe, many species of reptile are threatened with extinction, with changes in grazing pressure as a significant factor in their decline. Few studies have investigated the role of native herbivores, yet studying natural grazers may provide insight into natural grazing regimes, not apparent in studies of domestic livestock. In this study, we investigate the habitat requirements of a threatened Australian grassland reptile, the striped legless lizard, Delma impar, in grasslands grazed by a native herbivore, the eastern grey kangaroo Macropus giganteus. Delma impar appears sensitive to habitat change resulting from altered grazing intensity, but a lack of information hinders implementation of appropriate grazing regimes. To address this gap, we investigated habitat preferences of D. impar at multiple spatial scales across a grazing gradient. We found that the occurrence of D. impar was not affected by the size of grassland remnants, but was negatively related to the density of native grazers. This result was likely a consequence of the negative effect of high grazing intensity on grass structural complexity, as the probability of encountering a D. impar was positively related to grass structural complexity at the fine scale (1 m2). We recommend that conservation efforts should avoid high intensity grazing (equivalent to > 1.3 kangaroos/ha), yet ensure enough grazing disturbance is maintained to promote the formation of complex grass structures. We also recommend that small floristically degraded and fragmented grassland habitat should be included in conservation efforts. These recommendations will likely benefit a number of faunal species in grasslands grazed by domestic and native grazers. Importantly, our data highlight the need for managing grazing regimes, even in environments dominated by native herbivores.

Interspecific variation in the diets of herbivores in an industrial environment: implications for exposure to fluoride emissions.

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.

Comparative efficacy of levonorgestrel and deslorelin contraceptive implants in free-ranging eastern grey kangaroos (Macropus giganteus)

Context Fertility control of females with levonorgestrel or deslorelin implants shows promise for managing populations of overabundant eastern grey kangaroos (Macropus giganteus). Although these implants have been tested separately in captive and free-ranging kangaroos, there has been no direct comparison under equivalent field conditions. Aims We investigated the long-term efficacy of levonorgestrel and deslorelin implants, together with the cost of treatment, ease of administration, and the welfare of the animals, in a side-by-side trial under realistic management conditions. Methods We captured 65 adult female kangaroos over 11 days at a golf course in Anglesea, Victoria, Australia. We assigned each female to one of the following three experimental groups: levonorgestrel (210 mg, n = 18), deslorelin (9.4 mg, n = 24) or procedural control (n = 23). We monitored reproductive success for 8 years, by observing young in the pouch in winter and spring. Key results Natural fertility was high; in most years, less than 20% of control females failed to reproduce. For deslorelin-treated females, the odds of failing to reproduce were four times higher than for the control group; for levonorgestrel-treated females, these odds were 74 times higher. Deslorelin was ineffective after 3 years, whereas levonorgestrel was effective for at least 5 years. Conclusions Levonorgestrel was markedly superior in efficacy, as shown by a stronger contraceptive effect persisting for longer. In other respects, the two implants were comparable, being similar in cost and ease of delivery, and equally safe. Implications Only levonorgestrel implants fulfill their promise for non-lethal, long-term control of kangaroo populations. Deslorelin implants cannot be recommended for this purpose.

The complete mitochondrial genome of the eastern grey kangaroo (Macropus giganteus)

We present the complete mitochondrial genome (accession number: LK995454) of an iconic Australian species, the eastern grey kangaroo (Macropus giganteus). The mitogenomic organization is consistent with other marsupials, encoding 13 protein-coding genes, 22 tRNA genes, 2 ribosomal RNA genes, an origin of light strand replication and a control region or D-loop. No repetitive sequences were detected in the control region. The M. giganteus mitogenome exemplifies a combination of tRNA gene order and structural peculiarities that appear to be unique to marsupials. We present a maximum likelihood phylogeny based on complete mitochondrial protein and RNA coding sequences that confirms the phylogenetic position of the grey kangaroo among macropodids.

Hopping Down the Main Street: Eastern Grey Kangaroos at Home in an Urban Matrix.

Simple SummaryEastern 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.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.

Estimations of Species Richness in The Complex Communities of Nematode Parasites Found in The Stomachs of Kangaroos and Wallabies (Family Macropodidae)

Kangaroos and wallabies harbour a diverse array of strongyloid nematodes in their sacculated forestomachs. Determining the number of nematode species present in complex communities such as these can be technically difficult due to the large size of the host organ, the large numbers of nematodes and the large number of closely related nematode species. This problem was investigated using species accumulation methods in 16 eastern grey kangaroos (Macropus giganteus), 15 red-necked wallabies (Macropus rufogriseus) and 6 swamp wallabies (Wallabia bicolor). Nematodes from a subsample of known size were identified individually to species and the number of nematodes which needed to be examined before all of the species in the subsample were found was determined. In M. giganteus (mean worm burden 20,500), between 27 and 92 (mean 57) nematodes had to be examined before all (13) species were recovered. In M. rufogriseus (mean worm burden 60,600), an examination of between 16 and 178 (mean 57) nematodes recovered all (8) species while in W. bicolor (mean worm burden 16,300), 16–196 (mean 67) nematodes needed to be examined to recover all (15) species present. It was concluded that examination of samples of 200 nematodes from each animal would have been sufficient to identify all parasite species present.

Facultative geophagy at natural licks in an Australian marsupial

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.

Individual traits influence vigilance in wild female eastern grey kangaroos

Vigilance is an essential component of antipredator behaviour and is also used to monitor conspecifics, but is traded off against feeding in herbivores. This trade-off can be influenced by variation in many environmental, social and individual traits. Our aim was to test the relationship between individual-level traits, including boldness, body condition and reproductive state, and vigilance, while controlling for environmental and social variables. Using multiple 5-min video samples of 30 foraging, individually recognisable, female eastern grey kangaroos (Macropus giganteus) at Sundown National Park in Queensland, we investigated individual-level variation in the duration, intensity and target of vigilance behaviour during foraging. On separate occasions, we used flight-initiation distance tests to measure boldness in our kangaroos. Females with longer flight-initiation distances (shyer females) spent more time vigilant, providing preliminary support for studies of animal personality that have suggested that boldness may covary with vigilance. Body condition did not affect the total time spent vigilant, but females in poorer body condition spent more of their vigilance time in low-intensity vigilance. Vigilance patterns were not related to reproductive state, but varied among months and differed between mornings and afternoons, and females spent more time in high-intensity vigilance when further from cover. Even after accounting for all our variables we found that 7% of the variation in total time vigilant and 14% of the variation in vigilance intensity was explained by individual identity. This highlights the importance of individual-level variation in vigilance behaviour.

Individual variation in vigilance in female eastern grey kangaroos

For herbivores, vigilance usually involves a trade-off with foraging, and a further trade-off between antipredator and social vigilance. Thus individual variation in vigilance may result in significant fitness consequences. We used mixed-effects models to document individual variation in vigilance in wild adult female eastern grey kangaroos (Macropus giganteus) in Queensland, Australia. We tested the effects of group size, presence of adult males and wind on vigilance patterns and variation by analysing 399 five-minute samples on 31 individually identified females who were foraging on the periphery of groups. We determined the proportion of time that individuals spent vigilant, and the proportions of vigilance time spent in social versus antipredator vigilance and in low- versus high-intensity vigilance postures. The proportion of time females spent vigilant decreased with increasing group size but was not affected by wind speed or male presence, while the amount of their vigilance time spent in social vigilance was affected by interactions among the variables. After controlling for these effects, 13 females’ vigilance patterns were significantly different from the population mean. Individual variation was also found in vigilance postures used and the effect of male presence. Understanding individual variation in vigilance is important for understanding individuals’ antipredator and social strategies.

Bone fluoride concentrations of eastern grey kangaroos (Macropus giganteus) resident near an aluminium smelter in south-eastern Australia

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.

Haemorheology of the eastern grey kangaroo and the Tasmanian devil

The blood of two Australian marsupials, the eastern grey kangaroo (Macropus giganteus) and the Tasmanian devil (Sarcophilus harrisii), has been reported to have greater oxygen-carrying capacity (i.e. haemoglobin content) when compared with that of placental mammals. We investigated whether alterations of blood rheological properties are associated with the increased oxygen-carrying capacity of these marsupials. Eastern grey kangaroos (n = 6) and Tasmanian devils (n = 4) were anaesthetised for blood sampling; human blood (n = 6) was also sampled for comparison. Laboratory measurements included blood and plasma viscosity, red blood cell (RBC) deformability, RBC aggregation and the intrinsic tendency of RBC to aggregate, RBC surface charge and haematological parameters. Scanning electron micrographs of RBC from each species provided morphological information. High-shear blood viscosity at native haematocrit was highest for the Tasmanian devil. When haematocrit was adjusted to 0.4 L L–1, lower-shear blood viscosity was highest for the eastern grey kangaroo. RBC deformability was greatly reduced for the Tasmanian devil. Eastern grey kangaroo blood had the highest RBC aggregation, whereas Tasmanian devil RBC did not aggregate. The surface charge of RBC for marsupials was ~15% lower than that of humans. The dependence of oxygen-delivery effectiveness on haemoglobin concentration (i.e. oxygen content) and blood viscosity was quantitated by calculating the haematocrit to blood viscosity ratio and was 15–25% lower for marsupials compared with humans. Our results suggest that environmental pressures since the marsupial–monotreme divergence have influenced the development of vastly different strategies to maintain a match between oxygen demand and delivery.

Bennett’s wallaby ( Macropus rufogriseus) marrow quality vs quantity: evaluating human decision-making and seasonal occupation in late Pleistocene Tasmania

A pilot study on the fatty acid composition of the bone marrow, brain tissue and muscle (flesh) of the medium-sized marsupial the Bennett’s wallaby ( Macropus rufogriseus), aimed to explore the mechanisms behind the dominance of this human prey species in late Pleistocene southwest Tasmania. In particular it was designed to investigate why humans frequently selected and transported the wallaby hindquarters, breaking open their longbones and metatarsals to expose the marrow cavity, when these animals could easily have been transported whole. Initial results indicated that the percentage of unsaturated fatty acids particularly palmitoleic acid (C 16:1) and oleic acid (C 18:1) in the bone marrow increased distally away from the body core temperature or the heart, towards the hands and feet. There is a corresponding decrease in the percentage of the saturated fatty acids, particularly palmitic acid (C 16:0) and stearic acid (C 18:0). This is similar to the pattern identified in placental artiodactyls (even-toed ungulates) and rodents. The preliminary study was then expanded to a year-long seasonal experiment involving wallabies from different Tasmanian environmental and climatic zones to see if this can better help explain the apparent seasonal occupation of caves indicated from recent Bennett’s wallaby teeth annuli (Skeletochronological studies). It was found that the Bennett’s wallaby remained a relatively stable and dependable resource throughout the year, with environmental, altitudinal and seasonal variability having only a minor effect on the fatty acid composition or nutritional quality of their bone marrow, muscle and brain tissue. Interestingly, the animals had increased desirable unsaturated fatty acids in their marrow, muscle and brain during the winter and spring with decreased amounts during the summer and autumn. This lends support to an earlier Kidney Fat Index (KFI) analysis for the Bennett’s wallaby which recorded significant seasonal differences within and between regions, indicating an environmental effect on overall body condition. Fatty acid analysis of the Common wombat Vombatus ursinus, the Tasmanian pademelon Thylogale billardierii, and the Forester or Eastern Grey kangaroo Macropus giganteus were also included to ascertain why these animals remained constant, although minor, prey species throughout the late Pleistocene. While the results from these animals were similar to the Bennett’s wallaby, there were some unexpected and surprising patterns that require further investigation. All of these fatty acid analyses have important implications for understanding human decision-making and occupation of southwest Tasmania during the Last Glacial Maximum, for modern dietary and palaeodietary benefits, and for understanding the physiology of these unique Australian marsupials.