The field energetics and water fluxes of free-living wombats (Marsupialia: Vombatidae)

The Distinctive Biology and Characteristics of the Bare-Nosed Wombat (Vombatus ursinus)

The bare-nosed wombat is an iconic Australian fauna with remarkable biological characteristics and mythology. This solitary, muscular, fossorial, herbivorous marsupial from southeast Australia has continent and continental island subspeciation. Vombatiformes also contains hairy-nosed wombats (Lasiorhinus spp.); koala (Phascolarctos cinereus); and extinct megafauna, Phascolonus gigas (giant wombat), Diprotodon, and Thylacoleo (marsupial lion). Culturally important to Aboriginal people, bare-nosed wombats engineer ecosystems through digging, grazing, and defecation. Olfaction and cubic fecal aggregations appear critical for communication, including identity, courtship, and mating. Though among the largest fossorial herbivores, they have a nutrient-poor diet, a home range up to an order of magnitude smaller than expected, and a metabolism among the lowest extreme for mammals >10 kg. Metabolic depression may confer advantages over resource competitors and fossorial lifestyle protection from predators, fires, and climatic extremes. Bare-nosed wombats are loved and persecuted by European colonists. Recent population increases may reflect softening attitudes toward, and greater protections of, bare-nosed wombats.

Heavy metal wombats? Metal exposure pathways to bare-nosed wombats (Vombatus ursinus) living on remediated tin mine tailings

Rehabilitation of disused mine sites through stabilisation and botanical restoration is ecologically important, but metal transfer pathways to colonising wildlife are often less understood and have never been studied in marsupials. The rehabilitated Royal George tin mine tailings (Tasmania, Australia) and colonisation by bare-nosed wombats (Vombatus ursinus) represented an opportunity to examine potential metal transfer from mine tailings to an herbivorous marsupial. The aim of this study was to examine metal transfer pathways from the mine tailings to wombats, and to determine if wombats are at risk from metal exposure. Concentrations of metals were measured in the tailings substrate, surface water and vegetation, as well as fur samples from a resident wombat, and non-resident (control) wombats. The mineralogy of the tailings is dominated by quartz, muscovite, feldspars, topaz, kaolinite and calcite. Concentrations of several metals were high (exceeding varying health standards) in the tailings (As, Cu, Hg, Pb, Ni, Zn), water (As, Cd, Cu, Zn) and vegetation (As, Cd, Cu, Pb, Mn, Zn). Relative to non-resident wombats, elevated levels of As, Cd, Cu, Pb and Sn were measured in the fur of a resident wombat. Based on modelling of the exposure pathways, consumption of plant material is the most likely metal transfer pathway for As, Cu and Pb, although the risks from ingestion of tailings to this fossorial marsupial should not be discounted. This study is the first to investigate metal exposure pathways to marsupials using rehabilitated mine tailings. Further research is needed to accurately quantify ecological risks and toxicity for wombats and other marsupials native to mining landscapes.

Contrasting population manipulations reveal resource competition between two large marsupials: bare-nosed wombats and eastern grey kangaroos

Resource competition is an important interaction that can structure ecological communities, but is difficult to demonstrate in nature, and rarely demonstrated for large mammals including marsupials. We analysed 10 years of population survey data to investigate resource competition between bare-nosed wombats (Vombatus ursinus) and eastern grey kangaroos (Macropus giganteus) at two sites to assess whether resource competition is occurring. At one site, wombat abundance was reduced by increased mortality from mange disease, whereas at the other site, kangaroo abundance was reduced primarily by culling. We used the modified Lotka-Volterra competition (LVC) models to describe the mechanism of resource competition and fitted those models to the empirical data by maximum likelihood estimation. We found strong negative relationships between the abundance of wombats and kangaroos at each site, and resource competition was also mechanistically supported by the modified LVC models. The estimated competition coefficients indicate that bare-nosed wombats are a slightly superior competitor of eastern grey kangaroos than vice versa, and that intraspecific competition is almost twice as strong as interspecific competition. In addition, this study facilitated the calculation of the transmission rate associated with mange disease at one site (0.011), and the removal rate owing to culling, the introduction of a predator species, and drought at the other site (0.0006). Collectively, this research represents a rare empirical demonstration of resource competition between large mammals and contributes new insight into the ecology of two of Australia's largest grazing marsupials.

Intestines of non-uniform stiffness mold the corners of wombat feces

The bare-nosed wombat (Vombatus ursinus) is a fossorial, herbivorous, Australian marsupial, renowned for its cubic feces. However, the ability of the wombat's soft intestine to sculpt flat faces and sharp corners in feces is poorly understood. In this combined experimental and numerical study, we show one mechanism for the formation of corners in a highly damped environment. Wombat dissections show that cubes are formed within the last 17 percent of the intestine. Using histology and tensile testing, we discover that the cross-section of the intestine exhibits regions with a two-fold increase in thickness and a four-fold increase in stiffness, which we hypothesize facilitates the formation of corners by contractions of the intestine. Using a mathematical model, we simulate a series of azimuthal contractions of a damped elastic ring composed of alternating stiff and soft regions. Increased stiffness ratio and higher Reynolds number yield shapes that are more square. The corners arise from faster contraction in the stiff regions and relatively slower movement in the center of the soft regions. These results may have applications in manufacturing, clinical pathology, and digestive health.

Fluralaner as a novel treatment for sarcoptic mange in the bare-nosed wombat (Vombatus ursinus): safety, pharmacokinetics, efficacy and practicable use

Background

Sarcoptic mange causes significant animal welfare and occasional conservation concerns for bare-nosed wombats (Vombatus ursinus) throughout their range. To date, in situ chemotherapeutic interventions have involved macrocytic lactones, but their short duration of action and need for frequent re-administration has limited treatment success. Fluralaner (Bravecto®; MSD Animal Health), a novel isoxazoline class ectoparasiticide, has several advantageous properties that may overcome such limitations.

Methods

Fluralaner was administered topically at 25 mg/kg (n = 5) and 85 mg/kg (n = 2) to healthy captive bare-nosed wombats. Safety was assessed over 12 weeks by clinical observation and monitoring of haematological and biochemical parameters. Fluralaner plasma pharmacokinetics were quantified using ultra-performance liquid chromatography and tandem mass spectrometry. Efficacy was evaluated through clinical assessment of response to treatment, including mange and body condition scoring, for 15 weeks after topical administration of 25 mg/kg fluralaner to sarcoptic mange-affected wild bare-nosed wombats (n = 3). Duration of action was determined through analysis of pharmacokinetic parameters and visual inspection of study subjects for ticks during the monitoring period. Methods for diluting fluralaner to enable ‘pour-on’ application were compared, and an economic and treatment effort analysis of fluralaner relative to moxidectin was undertaken.

Results

No deleterious health impacts were detected following fluralaner administration. Fluralaner was absorbed and remained quantifiable in plasma throughout the monitoring period. For the 25 mg/kg and 85 mg/kg treatment groups, the respective means for maximum recorded plasma concentrations (C_max) were 6.2 and 16.4 ng/ml; for maximum recorded times to C_max, 3.0 and 37.5 days; and for plasma elimination half-lives, 40.1 and 166.5 days. Clinical resolution of sarcoptic mange was observed in all study animals within 3–4 weeks of treatment, and all wombats remained tick-free for 15 weeks. A suitable product for diluting fluralaner into a ‘pour-on’ was found. Treatment costs were competitive, and predicted treatment effort was substantially lower relative to moxidectin.

Conclusions

Fluralaner appears to be a safe and efficacious treatment for sarcoptic mange in the bare-nosed wombat, with a single dose lasting over 1–3 months. It has economic and treatment-effort-related advantages over moxidectin, the most commonly used alternative. We recommend a dose of 25 mg/kg fluralaner and, based on the conservative assumption that at least 50% of a dose makes dermal contact, Bravecto Spot-On for Large Dogs as the most appropriate formulation for adult bare-nosed wombats.

Graphical abstract

A review of wombat diet and nutrition

In this review we investigated the diet and nutrition of wombats and highlight areas for future research. The low energy requirements of wombats, conservative foraging behaviours and burrowing lifestyle allow them to subsist on low-quality food. Furthermore, their digestive anatomy and physiology is well adapted for digesting the resources available in their habitats. All species feed predominantly on native grasses; however, the nutritional requirements of juvenile and aged wombats are largely unknown. Changes to food availability and grass species in wombat habitats may alter their diet and nutritional intake. Also, despite evidence suggesting that wombats can satisfy their water requirements via the food they eat, the minimum threshold of water content at which wombats will cease feeding is unknown. Other areas for future research include investigating factors that affect digesta retention times (such as age or lactation), and the development of a method to determine age, because unlike most other mammals, wombat teeth grow continuously, hence teeth cannot be used as a reliable predictor of age in wombats.

Incidence of sarcoptic mange in bare-nosed wombats (Vombatus ursinus)

Sarcoptic mange is a threat to bare-nosed wombats (Vombatus ursinus) in Australia and a major factor contributing to the decline in populations of this species. It is caused by a mite, Sarcoptes scabiei, and if untreated can lead to severe irritation, blindness, starvation and eventual death. Modes of transmission likely occur through direct contact between wombats and indirectly from wombat burrows. Our study aimed to estimate and compare the numbers of bare-nosed wombats at three study sites, and to determine how rainfall, temperature and humidity influenced the incidence of sarcoptic mange in the populations. The abundances of macropods and rabbits were also compared with wombat abundance and sarcoptic mange prevalence at the three study sites. Across the study sites, 1655 bare-nosed wombats were observed. Sarcoptic mange prevalence was between 7.0% and 40.7%, depending on site, season and year. Sarcoptic mange prevalence correlated with yearly rainfall, with a higher incidence of sarcoptic mange occurring in higher-rainfall years. Higher numbers of macropods in the study areas also correlated with higher incidences of sarcoptic mange in the wombat populations.

Observations on the mortality of young southern hairy-nosed wombats (Lasiorhinus latifrons) in the Murraylands of South Australia

There are very few reports on mortality of young southern hairy-nosed wombats. We describe the appearance of six young wombats that died when rainfall was well below average in 2017–19. Some of the wombats appeared malnourished, and most died around the age of weaning, which we conclude is a vulnerable time for them. A crude and lower estimate of the mortality of wombats born in 2016 was 31%.

Ecology and conservation of the critically endangered northern hairy-nosed wombat (Lasiorhinus krefftii): past, present and future

The northern hairy-nosed wombat (Lasiorhinus krefftii) is an iconic marsupial endemic to Australia, recognised globally for its status as the largest, herbivorous burrowing mammal. Owing to historical challenges, including anthropogenic conflict and environmental threats, the species was pushed to near extinction and was officially classified as Critically Endangered in 1996. Establishing an effective conservation plan is complicated by ongoing and novel threats as well as by aspects of the species’ ecology that remain unstudied due to its neophobic and nocturnal behaviour. To identify areas where additional research is needed, we conducted a comprehensive search of the literature published on the northern hairy-nosed wombat from 1980 to 2019 to identify where knowledge gaps exist and to suggest where future efforts may be focussed. We found that the breeding ecology, in particular, of the northern hairy-nosed wombat is largely unstudied but could be vital in conservation efforts. Further, there is a need to establish additional populations, and several threats – including disease, invasive species, and climate change – may require ongoing management action to ensure the species’ longevity.

A quick drink: the response of southern hairy-nosed wombats (Lasiorhinus latifrons) to rainfall

This paper describes opportunistic observations of the response of wombats to rainfall. Within a few minutes after heavy showers of rain wombats congregated to drink at an area of exposed calcrete (limestone) where water had accumulated. The wombats interacted socially much more than is typical for wombats. This event demonstrates a level of understanding of their environment and of the availability of a transient resource that has not been documented previously.

The cascading pathogenic consequences of Sarcoptes scabiei infection that manifest in host disease

Sarcoptic mange, caused by the parasitic mite Sarcoptes scabiei, causes a substantive burden of disease to humans, domestic animals and wildlife, globally. There are many effects of S. scabiei infection, culminating in the disease which hosts suffer. However, major knowledge gaps remain on the pathogenic impacts of this infection. Here, we focus on the bare-nosed wombat host (Vombatus ursinus) to investigate the effects of mange on: (i) host heat loss and thermoregulation, (ii) field metabolic rates, (iii) foraging and resting behaviour across full circadian cycles, and (iv) fatty acid composition in host adipose, bone marrow, brain and muscle tissues. Our findings indicate that mange-infected V. ursinus lose more heat to the environment from alopecia-affected body regions than healthy individuals. Additionally, mange-infected individuals have higher metabolic rates in the wild. However, these metabolic demands are difficult to meet, because infected individuals spend less time foraging and more time inactive relative to their healthy counterparts, despite being outside of the burrow for longer. Lastly, mange infection results in altered fatty acid composition in adipose tissue, with increased amounts of omega-6 acids, and decreased amounts of omega-3 acids, a consequence of chronic cutaneous inflammation and inhibition of anti-inflammatory responses. These findings highlight the interactions of mange-induced physiological and behavioural changes, and have implications for the treatment and rehabilitation of infected individuals.

An adaptive management case study for managing macropods on Maria Island National Park, Tasmania, Australia: adding devils to the detail

Adaptive management is driven by structured decision making and evidence from monitoring in a ‘learning’ framework that guides management actions. In a conservation context, this iterative approach includes evaluation of the impacts on natural processes. On Maria Island National Park, Tasmania, Australia, introduced Forester kangaroo, Bennetts wallaby and Tasmanian pademelon have been intensively managed by an annual cull since 1994. Management actions were triggered by high parasite loads, intense grazing pressure and high juvenile mortality during drought periods. Criticism of the annual cull from animal welfare groups initiated the development of an adaptive management approach for decision making that replaces the historic ‘trial and error’ process. Following a comprehensive review of the existing macropod management program in 2011, an integrated monitoring strategy was established to provide evidence for informed decision making. Assessments of animal health and estimates of population trends are the key indicators for management actions to occur. Maintaining viable macropod populations and protecting natural values form the basis of management objectives. Management actions in each year, for each species, represent ‘treatments’ as spatial replication is not possible at such a small scale. An adaptive management approach for macropod management on Maria Island has resulted in only one species being culled in 2014 and 2015 for the first time in almost 20 years. However the recent introduction of a major predator, the Tasmanian devil, has increased uncertainty for long-term macropod management on Maria Island with no cull occurring in 2016 and 2017.

Adaptations of large marsupials to survival in winter snow cover: locomotion and foraging

The small extent of seasonally snow-covered Australian mountains means that there has not been a great selective pressure on the mammalian fauna for adaptations to this environment. Only one large marsupial, the common wombat (Vombatus ursinus (Shaw, 1800)), is widespread above the winter snowline. In the past 20 years, with snow depth and duration declining, the swamp wallaby (Wallabia bicolor (Desmarest, 1804)) has become more common above the winter snowline. The red-necked wallaby (Macropus rufogriseus (Desmarest, 1817)) is common in alpine Tasmania where seasonal snow cover is neither as deep nor as long-lasting as on the mainland, but has only been recorded regularly above the winter snowline in the mainland Snowy Mountains since 2011. This study examines morphological aspects of locomotion of these three herbivorous marsupials in snow. The wombat is the best adapted to snow, with quadrupedal gait and an expanded home range allowing it to locate and feed on the same plant groups as it does at lower elevation. Wallabies are poorly adapted to locomotion in snow, but the browsing swamp wallaby is able to maintain its dietary habit by feeding on exposed shrubs in deep snow, whereas the red-necked wallaby, which depends more on grazing, appears constrained to areas where snow is shallow.

Sarcoptes scabiei: The Mange Mite with Mighty Effects on the Common Wombat (Vombatus ursinus)

Parasitism has both direct and indirect effects on hosts. Indirect effects (such as behavioural changes) may be common, although are often poorly described. This study examined sarcoptic mange (caused by the mite Sarcoptes scabiei) in the common wombat (Vombatus ursinus), a species that shows severe symptoms of infection and often causes mortality. Wombats showed alterations to above ground behaviours associated with mange. Infected wombats were shown to be active outside of the burrow for longer than healthy individuals. Additionally, they spent more time scratching and drinking, and less time walking as a proportion of time spent above ground when compared with healthy individuals. They did not spend a higher proportion of time feeding, but did have a slower feeding rate and were in poorer body condition. Thermal images showed that wombats with mange lost considerably more heat to the environment due to a diminished insulation layer. Infection status did not have an effect on burrow emergence time, although this was strongly dependent on maximum daily temperature. This study, through the most detailed behavioural observations of wombats to date, contributes to a broader understanding of how mange affects wombat health and abundance, and also to our understanding of the evolution of host responses to this parasite. Despite being globally dispersed and impacting over 100 species with diverse intrinsic host traits, the effects of mange on hosts are relatively poorly understood, and it is possible that similar effects of this disease are conserved in other host species. The indirect effects that we observed may extend to other pathogen types.

The effect of group size on vigilance in a semi-solitary, fossorial marsupial (Lasiorhinus latifrons)

Prey species that congregate gain protection against predatory attacks and this advantage is often reflected by a reduction in vigilance behaviour by individuals in larger groups. Comparatively few studies have investigated vigilance in solitary animals, but those that have, found that vigilance increases as group size increases because of the threat posed by conspecifics and/or competition for resources. The southern hairy-nosed wombat (Lasiorhinus latifrons) is a large fossorial, nocturnal marsupial that is neither strictly solitary nor gregarious, sharing warren systems with multiple conspecifics. We investigated the effects of conspecific presence on vigilance behaviour in this semi-solitary species. We observed wild-born, adult L. latifrons wombats in three group sizes (Large (1♂, 3♀), Medium (1♂, 2♀) and Small (1♂, 1♀)) in a captive, naturalistic environment that allowed above-ground and den behaviour monitoring. Vigilance behaviours were performed less frequently by wombats in large groups (e.g. scanning, counts/day, Large: 55, Medium: 69, Small: 115, P=0.002) and more frequently as the distance from their nearest conspecific increased (r64=0.30, P= 0.016). Vigilance within burrows was also affected by social influences, with solitary wombats significantly more vigilant than those denning with a conspecific (e.g. scanning: conspecific absent: 0.13/5min, present: 0.03/5min, P<0.0001). It is concluded that the presence of conspecifics reduces vigilance in L. latifrons wombats, even within burrows, and this may partially explain the occurrence of warren sharing in the wild.

Does artificial light influence the activity of vertebrates beneath rural buildings?

Interactions between humans and wildlife have increased dramatically over the past century as human populations increase and occupy areas formerly dominated by native animals. In Australia, increases in land clearing and farming close to riparian areas has brought humans into contact with the common wombat (Vombatus ursinus), a relatively large-bodied, semifossorial marsupial. The common wombat is regarded as a pest in some agricultural areas due to its habit of burrowing beneath buildings, destroying fences and destabilising stream banks. We examined the effectiveness of artificial lighting to deter wombats from using the subfloor cavity under an historic cottage at ‘Bundanon’ in southern New South Wales, Australia. The response of wombats to artificial light (10 weeks on followed by 10 weeks off) was assessed using heat- and motion-sensing cameras continuously over a period of 58 weeks. While the main focus was on light effects on wombats, the study also allowed us to record non-nuisance animals using the subfloor cavity. Of the total of 1086 animal detections over the 58-week period (2.67 detections day–1), 965 (89%) were of mammals, 106 birds and 15 reptiles. Wombats (622; 57%) and kangaroos (228; 22%) made up 79% of all detections. Nocturnal activity of wombats remained unchanged in response to lighting (on: 266; off: 268), but there were significantly more diurnal detections when the lights were on (58) than off (30). For kangaroos, there were more nocturnal detections when lights were off, but more diurnal detections when lights were on. More antechinus were detected at night (night: 107; day: 8), and with the lights off (99 cf. 8), and insectivorous birds were detected almost entirely during the day, mostly with the lights on (66 cf. 39). Our study showed that, overall, the lighting regime we used was ineffective at reducing wombat activity under the building.

Cost of living dictates what whales, dolphins and porpoises eat: the importance of prey quality on predator foraging strategies

Understanding the mechanisms that drive prey selection is a major challenge in foraging ecology. Most studies of foraging strategies have focused on behavioural costs, and have generally failed to recognize that differences in the quality of prey may be as important to predators as the costs of acquisition. Here, we tested whether there is a relationship between the quality of diets (kJ·g⁻¹) consumed by cetaceans in the North Atlantic and their metabolic costs of living as estimated by indicators of muscle performance (mitochondrial density, n = 60, and lipid content, n = 37). We found that the cost of living of 11 cetacean species is tightly coupled with the quality of prey they consume. This relationship between diet quality and cost of living appears to be independent of phylogeny and body size, and runs counter to predictions that stem from the well-known scaling relationships between mass and metabolic rates. Our finding suggests that the quality of prey rather than the sheer quantity of food is a major determinant of foraging strategies employed by predators to meet their specific energy requirements. This predator-specific dependence on food quality appears to reflect the evolution of ecological strategies at a species level, and has implications for risk assessment associated with the consequences of changing the quality and quantities of prey available to top predators in marine ecosystems.

The effect of environmental variables on the activity patterns of the southern hairy-nosed wombat (Lasiorhinus latifrons) in captivity: onset, duration and cessation of activity

The influence of scotoperiod, ambient temperature and humidity on the activity of captive wombats was examined to differentiate environmental influence from that pertaining to food availability. The activity of 12 wombats (Lasiorhinus latifrons) housed at Rockhampton Zoo was remotely monitored by digital video-surveillance for one year, with environmental variables simultaneously recorded via dataloggers. Mean proportion of total daily time spent active was 18.2 ± 1.8%. Mean daily time spent active varied seasonally according to changes in temperature and humidity. Mean daily activity was greater during winter (301 ± 17 min) and spring (295 ± 16 min), than summer (234 ± 16 min) and autumn (238 ± 15 min) with differences due to a decrease in the number and length of activity bouts in summer and autumn; presumably these results reflect a need to maintain heat balance associated with exposure to elevated temperatures. Activity was positively correlated with temperature during winter (r = 0.60) and spring (r = 0.52) but negatively correlated during summer (r = –0.58) and autumn (r = –0.49), suggesting the existence of a thermoneutral zone where activity is maximised. We conclude that activity in captive wombats is influenced by environmental variables.

Activity patterns of the southern hairy-nosed wombat (Lasiorhinus latifrons) (Marsupialia:Vombatidae) in the South Australian Murraylands

The southern hairy-nosed wombat (Lasiorhinus latifrons) is a large, semifossorial, herbivorous marsupial, adapted to a harsh and unpredictable environment in semi-arid Australia. Limited information is available on the biology and general behaviour of the species. The present study examines monthly variability in ‘nocturnal’ activity patterns. Data-loggers were used to investigate the effect of climate on 57 months of activity patterns of 18 wombats between 1999 and 2004. The average period of activity across the study was 6.27 ± 0.24 h in duration across the study. Multiple excursions above ground were more common in September and significantly correlated with both available water and median temperature. Periods of activity were strongly correlated with temperature across the entire study.

Changes in fine-scale movement and foraging patterns of common wombats along a snow-depth gradient

Context. Feeding strategies of large herbivores in snow-covered environments can be influenced by snow depth and snow quality. Common wombats, Vombatus ursinus, are large marsupial herbivores that occur in subalpine areas of Australia where they must dig through the snow to reach low vegetation. Deeper snow at higher elevations is considered to limit foraging and constrain their range, although there have been no quantitative studies investigating the influence of snow on their foraging behaviour. Aims. The present study examined how snow influenced the foraging behaviour of common wombats along a snow-depth gradient. Methods. During the 2008 winter season, snow tracks of 17 wombats were located within the subalpine zone, in a study area ranging from 1520 to 1850 m asl, and followed to record attributes of the snow cover and environment in relation to wombat activity. Key results. Wombats selected sites to feed where the snow was shallower, and deeper snow at feeding sites caused changes in foraging behaviour. Foraging occurred along fairly direct routes between burrows; however, as snow depth increased, wombats deviated more from their path to seek out suitable foraging sites. Most foraging occurred in shallow snow in open areas or where the snow had melted around the bases of trees, shrubs or boulders. About half (52%) of the feeding sites necessitated the wombats digging through the snow to reach low vegetation, predominantly the grasses of Poa spp. Digging craters for feeding occurred in snow depths up to 100 cm, although depths less than 35 cm were preferred. Some shrub species, such as dusty daisy bush, Olearia phlogopappa, that protruded from the snow, were also eaten where the snow was deeper. Dietary analysis confirmed that monocots made up the majority of the diet (93.3%), although some individuals consumed up to 26% dicots. Conclusions. The present study demonstrated that wombats can adjust to a snow-covered environment by altering both their foraging patterns and diet as snow depth increases. However, they will be limited where snow depths are consistently greater than 100 cm. Implications. Under future climate-change scenarios of declining snow cover, wombats may be able to forage and inhabit higher altitudes than where they currently occur, and this has implications for the grazing-sensitive alpine ecosystem. Predicting shifts in the range of other herbivores to higher altitudes will require knowledge of their species-specific foraging thresholds in snow, such as presented in this study.

Torpor and energetic consequences in free-ranging grey mouse lemurs (Microcebus murinus): a comparison of dry and wet forests

Many endotherms save energy during food and water shortage or unpredictable environment using controlled reductions in body temperature and metabolism called torpor. In this study, we measured energy metabolism and water turnover in free-ranging grey mouse lemurs Microcebus murinus (approximately 60 g) using doubly labelled water during the austral winter in the rain forest of southeastern Madagascar. We then compared patterns of thermal biology between grey mouse lemurs from the rain forest and a population from the dry forest. M. murinus from the rain forest, without a distinct dry season, entered daily torpor independent of ambient temperature (T (a)). There were no differences in torpor occurrence, duration and depth between M. murinus from the rain and dry forest. Mouse lemurs using daily torpor reduced their energy expenditure by 11% in the rain forest and by 10.5% in the dry forest, respectively. There was no significant difference in the mean water flux rates of mouse lemurs remaining normothermic between populations of both sites. In contrast, mean water flux rate of individuals from the dry forest that used torpor was significantly lower than those from the rain forest. This study represents the first account of energy expenditure, water flux and skin temperature (T (sk)) in free-ranging M. murinus from the rain forest. Our comparative findings suggest that water turnover and therefore water requirement during the austral winter months plays a more restricting role on grey mouse lemurs from the dry forest than on those from the rain forest.

Vigilance in a solitary marsupial, the common wombat (Vombatus ursinus)

We studied vigilance activity in a wild population of the common wombat (Vombatus ursinus), a large, solitary, burrow-using, marsupial prey species in which individuals tolerate the presence of conspecifics within their home range. For the first time, we report postures and rates of vigilance in common wombats; our results show a limited repertoire of vigilant postures and low overall rates of vigilance. Because few studies of birds and mammals that have reported the effect of distance to conspecifics on the vigilance of focal animals have considered solitary prey species, we tested this effect in wombats. Our results show that a model including distance to cover and distance to the nearest conspecific, but not time of day, best explained the variation in the proportion of time that focal individuals spent in vigilance. Individual vigilance decreased when distance to cover increased. Vigilance of wombats increased when there was a conspecific within a radius of 70 m of the focal individual. In addition, we tested whether pairs of nearby wombats scanned independently of one another, coordinated their activity in non-overlapping bouts of vigilance or synchronised their bouts of vigilance. Wombats in close proximity exhibited independent bouts of individual vigilant and foraging activity. Thus, in this solitary species, our results support the assumption that individuals scan independently of each other.

Sarcoptic mange in southern hairy-nosed wombats (Lasiorhinus latifrons): distribution and prevalence in the Murraylands of South Australia

This study examined the history, prevalence and distribution of sarcoptic mange in southern hairy-nosed wombats (Lasiorhinus latifrons) in the Murraylands, South Australia. Results from a survey suggested that there had been a long history of sporadic mange outbreaks, with 43% of 85 respondents indicating that they had seen diseased animals. There was a concentration of positive sightings (59%) in the vicinity of one town, Swan Reach. A total of 67 wombats was also caught on three pastoral properties; 0% (n = 21), 4% (n = 21) and 76% (n = 23) were found to have mange at each respective site. Diseased wombats presented with erythema, parakeratosis and alopecia and had lower median condition, subcutaneous fat and higher bone prominence scores than healthy animals. Severely diseased adult wombats had an average bodyweight that was 9.86 kg lower than those without mange. Infected animals suffered higher mortality, with a rate of ~37% in eight months on one property. It is suggested that mange may have a significant effect on southern hairy-nosed wombats and outbreaks could result in the decline and/or possible extinction of small, isolated populations. Population management initiatives, including suspending culling quotas in infected populations, should thus be considered.

Home range, burrow-use and activity patterns in common wombats (Vombatus ursinus)

Wombats are large, marsupial herbivores able to exploit low-productivity habitats largely because of their low energy requirements. In addition to using deep, thermally favourable burrows, wombats might use a strategy of conservative above-ground ranging behaviour to achieve their low energy expenditure. This study examined home range, burrow use and diurnal activity patterns of common wombats (Vombatus ursinus) in eucalypt forest, woodland and pasture using trapping and radio-tracking. Wombats ranged through all three vegetation types with forest and pasture clearly being important habitats. Home ranges (95% harmonic mean) were typically almost circular, and averaged 17.7 ha with core areas (50% harmonic mean) averaging 2.9 ha. Home-range size is small compared with that expected for most mammals of comparable body mass. Ranging behaviour for wombats was similar between sexes and ranges extensively overlapped between and within sexes, indicating that ranges are not actively defended. Wombats did not markedly change the size or location of home ranges, ranging behaviour or feeding areas between summer and winter. The density of active burrows (0.25 ha–1) far exceeded the estimated density of wombats (0.13 ha–1). Wombats typically spent 1–4 days sleeping in the same burrow and then moved to another. On average, each active burrow was used by 2.2 different individuals. The activity pattern of wombats is characterised by a strong diel cycle, with most activity occurring nocturnally. Activity peaks at the beginning and end of each night are consistent with a ‘travel out, graze, travel back’ movement pattern. Despite widely distributed food resources, small home ranges and obligate burrow use constrain wombats to meeting their year-round food and water requirements from a small area near their burrows.

Field evaluation of supplementary feed and water for the northern hairy-nosed wombat, Lasiorhinus krefftii

The northern hairy-nosed wombat, Lasiorhinus krefftii, is listed as critically endangered in Australia and is restricted to a single population of ~90 animals in central Queensland. The area receives low rainfall and is regularly subjected to periods of drought and therefore is at risk from wildfire. There is a clear link between good wet seasons and higher levels of reproductive activity. A long-term management goal of the L. krefftii recovery program has been to determine preferred feed of wombats and to gain acceptance of supplementary feed and water by L. krefftii in order to mitigate the effects of drought and wildfire and potentially increase fecundity and survivorship rates in the population. Prior to this study, there had been several unsuccessful attempts to induce L. krefftii to take supplementary feed and water, but the current study, which was of a longer duration, has shown that L. krefftii will readily take supplementary feed and water. In addition, L. krefftii prefers certain feed types (Complete-O (primarily steam-flaked barley with molasses and lucerne and oaten chaff), and Town and Country pellet mix (primarily wheat, barley and sorghum, with canola and soybean meal)) and will visit sources of feed and water on a nightly basis. Visits by L. krefftii to supplementary feed and water sites were related to the occurrence of rainfall, with visits declining after rain.

Diet and feeding selectivity of common wombats

The seasonal diets and feeding selectivity of common wombats (Vombatus ursinus) in mountainous eucalypt forest, eucalypt woodland and pasture were determined using faecal analysis. Grass species contributed the largest proportion (95%) of epidermal fragment area in faecal pellets, with at least 20 species being eaten. The most abundant grasses in pellets in all seasons were the tough, wiry snow grasses (Poa sieberiana and P. labillardieri), with Microlaena stipoides comprising a substantial proportion of the diet in summer and autumn. Grass leaf was the most abundant plant part in pellets (81%), with grass stem and grass sheath comprising 11%. The seasonal proportion of grass seedhead in pellets varied from just traces during autumn and winter to a substantial component of the diet during summer (21% of epidermal fragments in pellets). Forbs comprised less than 1% of pellet material, and tree or shrub species were not detected in the diet. Feeding selectivity (and hence dietary niche breadth) varied seasonally; wombats become less selective in their feeding as plant diversity and abundance decreased. Positive selection was shown for monocots and negative selection for forbs. Grass species were eaten in broadly similar proportions to their abundances in the field, but with moderate to strong selection or rejection of a few species.

Winter home range and foraging of common wombats (Vombatus ursinus) in patchily burnt subalpine areas of the Snowy Mountains, Australia

In 2003, wombats survived bushfires at subalpine altitudes in the Snowy Mountains of Australia to be faced only weeks later by a further reduction in food availability owing to the winter cover of snow. Where burrows occurred in burnt areas, winter home ranges (95% kernel) were significantly larger (52.6 ± 33.4 ha) than in unburnt areas (16.3 ± 14.5 ha). Wombats were able to survive the winter by foraging further from burrows; the lack of burrows for protection from predators was not an issue owing to a lack of feral dogs at subalpine altitudes. However, distant foraging was restricted by the low availability of burrows in deep snow, particularly at alpine altitudes. Wombats apparently fed mainly on monocots. All studied wombats survived the winter and there was no evidence of significant loss of condition in wombats sighted during the study.