Dasyurus Hallucatus Research Articles

Small terrestrial mammals on Doongan Station, in the Northern Kimberley bioregion, Western Australia

There are significant gaps in knowledge of the small terrestrial mammals (<2 kg) in the Northern Kimberley bioregion (NOK). There have been no known extinctions of small mammals in the NOK, despite broad-scale declines being observed across much of northern Australia. The few studies in the NOK have focussed largely on three major national parks and NOK islands and thus may not be fully representative of the region. Mammal surveys were undertaken on Doongan Station, a pastoral property adjacent to these national parks to determine the presence/absence of small mammals. Five species were found to be common (Pseudomys nanus, P. delicatulus, Rattus tunneyi, Zyzomys argurus and Sminthopsis virginiae), two species were detected less frequently (Leggadina lakedownensis and Isoodon macrourus), and four species were scarcely detected (Melomys burtoni, Hydromys chrysogaster, Planigale maculata and Dasyurus hallucatus). Two species were detected only opportunistically outside of the survey effort (Petropseudes dahli and Petaurus breviceps). The trap success was consistently low, with levels in most years being below those regarded as critically low elsewhere in northern Australia.

Do individual differences in behavior influence wild rodents more than predation risk?

Prey can enhance their survival by eliciting an appropriate response to predators. Theoretically, prey should distinguish odors of predators and nonpredators. The manifestation of defensive antipredator behaviors has been extensively researched in domestic species (i.e., the relationship between laboratory-bred rats and domestic cats). However, little is known about the expression of these behaviors in wild rodents. Studies have so far focused on quantitative assessments of cost–benefit trade-offs or giving-up densities. We examined the expression of fine-scale defensive behaviors in Arnhem rock rats (Zyzomys maini) in response to fecal cues from 2 predators (the northern quoll [Dasyurus hallucatus] and the dingo [Canis dingo]), a nonpredator (the short-eared rock-wallaby [Petrogale brachyotis]), and a control (water). We adapted a predator-odor avoidance apparatus that has been widely used for domestic rodent studies to film the behavior of wild rock rats in a captive environment. Rock rats did not alter their behavior in the presence of odors of nonpredators, predators, or controls. In the current study, individual rock rats behaved in a consistent manner across time, and we identified 3 individually consistent behaviors which may suggest the existence of personality traits in this species. We suggest that these individual differences may influence wild rock rat behavior more than predation risk. These differences should therefore be taken into consideration when investigating behavioral responses to predators in wild populations.

Comment on a research note reporting new populations of the northern quoll in Western Australia

The recent report by Turpin and Bamford (2015) notes a range extension for northern quolls in the Pilbara Bioregion of Western Australia. Mitochondrial DNA sequences derived from five scats show that the new individuals nest within a clade containing all other Pilbara animals. Northern quolls from the Pilbara Bioregion are genetically distinct from congeners from the Kimberley Bioregion. We note that there is no evidence for maternal gene flow between these two regions.

Phylogenetic relationships withinDasyurus(Dasyuromorphia: Dasyuridae): quoll systematics based on molecular evidence and male characteristics

Phylogenetic relationships among the 6 species of quolls (Dasyurus) are resolved using DNA sequences from 4 mitochondrial and 5 nuclear loci (approximately 15 kb) sampled from 1 to 29 individuals per species. Our estimate of quoll phylogeny concurs with previous DNA-based estimates in placing Dasyurus hallucatus as sister to the remaining species, and D. maculatus as sister to a clade containing D. viverrinus, D. albopunctatus, D. geoffroii + D. spartacus. We also provide the first formal description of penis anatomy in the northern quoll (D. hallucatus), documenting it as the only species of Dasyurus lacking an appendage to the penis. This appendage thus appears to constitute a morphological synapomorphy for the clade of 5 species that excludes D. hallucatus. The sequence from our single specimen of bronze quoll (D. spartacus) nested within a clade of 3 western quoll (D. geoffroii) sequences, suggesting that the species boundary between these groups (if it exists) is not yet reflected in reciprocal monop...

Running faster causes disaster: trade-offs between speed, manoeuvrability and motor control when running around corners in northern quolls (Dasyurus hallucatus).

Movement speed is fundamental to all animal behaviour, yet no general framework exists for understanding why animals move at the speeds they do. Even during fitness-defining behaviours like running away from predators, an animal should select a speed that balances the benefits of high speed against the increased probability of mistakes. In this study, we explored this idea by quantifying trade-offs between speed, manoeuvrability and motor control in wild northern quolls (Dasyurus hallucatus) - a medium-sized carnivorous marsupial native to northern Australia. First, we quantified how running speed affected the probability of crashes when rounding corners of 45, 90 and 135 deg. We found that the faster an individual approached a turn, the higher the probability that they would crash, and these risks were greater when negotiating tighter turns. To avoid crashes, quolls modulated their running speed when they moved through turns of varying angles. Average speed for quolls when sprinting along a straight path was around 4.5 m s(-1) but this decreased linearly to speeds of around 1.5 m s(-1) when running through 135 deg turns. Finally, we explored how an individual's morphology affects their manoeuvrability. We found that individuals with larger relative foot sizes were more manoeuvrable than individuals with smaller relative foot sizes. Thus, movement speed, even during extreme situations like escaping predation, should be based on a compromise between high speed, manoeuvrability and motor control. We advocate that optimal - rather than maximal - performance capabilities underlie fitness-defining behaviours such as escaping predators and capturing prey.

Quolls slow down to avoid a crash

Northern quolls, small carnivorous marsupials native to northern Australia, have been wiped out in many parts of their original range. Predation by cats, foxes and dogs is partly to blame. That's why it's important to understand which factors determine quolls' ability to escape predators, says Robbie Wilson, a performance biologist at the University of Queensland, Australia. And that may involve some counterintuitive ideas. Quolls might be expected to run as fast as they can when trying to escape capture. ‘But this ignores the fact that there are huge costs for running at your fastest speeds', says Wilson. ‘It's likely that an animal running at top speed will not be able to turn or manoeuver as quickly.’ To explore these trade-offs, Wilson teamed up with Melissa Wynn, Christofer Clemente and Ami Fadhillah Amir Abdul Nasir. ‘We wanted to see how running speed constrains an animal's ability to make rapid turns, which are likely to be very important for escaping predators, and what morphological attributes determine how well an animal can turn’, Wilson explains (p. 433).When studying an endangered species, the first challenge is finding enough animals. Luckily, Groote Eylandt, an island off Australia's northeastern coast, remains a quoll stronghold. Using baited traps to capture 66 quolls, the team then put the marsupials through their paces in a specially designed racetrack consisting of two moveable channels joined with one of three removable angle structures (45, 90 and 135 deg) that allowed the team to challenge the animals' manoeuvrability. Then they chased quolls along the track with a polystyrene block and filmed their actions from above using a high-speed digital camera to explore how running speed affected the animals' chances of crashing when running around a corner.As the team expected, quolls crashed more frequently when they approached a corner at high speed and when running around tighter corners. Then, knowing that higher running speeds increased the likelihood of the animal slipping, the team reasoned that quolls should choose to run more slowly when approaching a sharp corner, but do they slow down when negotiating tight turns in practice? It turns out that they do. When the team analysed footage of the running animals, they found that average turning speed decreased as the magnitude of the turn angle increased, and when negotiating 135 deg turns, quolls decreased their running speeds to around a third of their straight-line speeds. Finally, the team wondered how an animal's build may affect its agility. ‘We expected that larger animals would find it harder to get around tighter corners’, says Wilson, because they have to overcome greater angular momentum. But to their surprise, the team found this was not the case. Instead, they found that foot length was the strongest predictor of manoeuvrability. ‘It appears that it's the foot size of the animals that constrains their ability to negotiate a corner successfully’, Wilson explains. ‘The larger the foot size, the greater their grip.’The team concludes that an animal's running speed constrains its ability to make quick, rapid turns. ‘This means that an animal should modify its speed when running away from a predator, optimising its combination of speed and manoeuvrability to maximise its chances of success’, says Wilson. In other words, the quolls that are most likely to survive attacks by introduced predators are those that master the optimal compromise between speed and agility.

Stemming the tide: progress towards resolving the causes of decline and implementing management responses for the disappearing mammal fauna of northern Australia

Recent studies at some sites in northern Australia have reported severe and rapid decline of some native mammal species, notwithstanding an environmental context (small human population size, limited habitat loss, substantial reservation extent) that should provide relative conservation security. All of the more speciose taxonomic groups of mammals in northern Australia have some species for which the conservation status has been assessed as threatened, with 53% of dasyurid, 46% of macropod and potoroid, 33% of bandicoot and bilby, 33% of possum, 31% of rodent, and 24% of bat species being assessed as extinct, threatened or Near Threatened. This paper reviews disparate recent and ongoing studies that provide information on population trends across a broader geographic scope than the previously reported sites, and provides some information on the conservation status and trends for mammal groups (bats, larger macropods) not well sampled in previous monitoring studies. It describes some diverse approaches of studies seeking to document conservation status and trends, and of the factors that may be contributing to observed patterns of decline. The studies reported provide some compelling evidence that predation by feral cats is implicated in the observed decline, with those impacts likely to be exacerbated by prevailing fire regimes (frequent, extensive and intense fire), by reduction in ground vegetation cover due to livestock and, in some areas, by ‘control’ of dingoes. However the impacts of dingoes may be complex, and are not yet well resolved in this area. The relative impacts of these individual factors vary spatially (with most severe impacts in lower rainfall and less topographically rugged areas) and between different mammal species, with some species responding idiosyncratically: the most notable example is the rapid decline of the northern quoll Dasyurus hallucatus due to poisoning by the introduced cane toad Rhinella marina , which continues to spread extensively across northern Australia. The impact of disease, if any, remains unresolved. Recovery of the native mammal fauna may be impossible in some areas. However, there are now examples of rapid recovery following threat management. Priority conservation actions include: enhanced biosecurity for important islands, establishment of a network of substantial predator exclosures, intensive fire management (aimed at increasing the extent of longer-unburnt habitat and in delivering fine scale patch burning), reduction in feral stock in conservation reserves, and acquisition for conservation purposes of some pastoral lands in areas that are significant for mammal conservation.

More famine than feast: pattern and variation in a potentially degenerating mammal fauna on Cape York Peninsula

Context Global mammal populations continue to be threatened by environmental change, and recent decadal monitoring in northern Australia suggests a collapse in mammal abundance in key locations. Cape York Peninsula has globally significant natural values but there is very little published about the status and distribution of mammals in this region. Aims Following an extensive field survey we investigated two key questions: (i) what is the composition, spatial variation and change from previous regional surveys in the mid to late 1900s in the native terrestrial and arboreal mammal fauna recorded; and (ii) which landscape and site factors best predict mammal richness and abundance. Methods We sampled 202 one-hectare sites across seven locations from 2009 to 2012 in woodlands, closed forestand dune scrub and tussock grasslands. We collected landscape and site-based environmental data for each location, representing fire, weather and vegetation factors. We used generalised linear mixed models to examine the relationship between mammals and these factors. Key results Mammals were generally scarce across the sites and were more abundant and species rich in wet coastal grasslands or closed forests then tropical savanna woodlands. Fire frequency data and the surrounding vegetation complexity were consistent landscape-scale predictors of mammals; ground cover and woody complexity were significant at the site scale. Conclusions Notwithstanding interpretational constraints related to the limited evidence base of historic sampling, the mammal fauna recorded in this study for Cape York Peninsula was similar in composition to the mammal fauna described from 1948–1980 and surveys in 1985, with some species seemingly declining (e.g. Melomys burtoni, Dasyurus hallucatus, Sminthopsis virginiae) and others stable (e.g. Rattus sordidus) or more common (e.g. Rattus tunneyi); however, across all sites abundance was low, and many sites had few or no mammals. Implications In the absence of consistent long-term systematic monitoring it is difficult to determine if this survey and historical surveys represent pre-European patterns for mammals. The absence or low abundance of mammals in most sites suggest that cotemporary patterns may not represent an intact mammal fauna. Due to the equivocal nature of these findings a critical next step is to establish robust monitoring and experimental work to reveal the response of mammals to management interventions.

Best bait for your buck: bait preference for camera trapping north Australian mammals

Critical evaluations of bait attractiveness for camera trapping wildlife are scant even though use of the most attractive bait should improve detection of cryptic, threatened species. We aimed to determine the most attractive bait for camera trapping the northern hopping-mouse (Notomys aquilo) and sympatric mammals. We also tested the effectiveness of overhead camera trap orientation in identifying individual northern quolls (Dasyurus hallucatus) as this could be used to define a camera trap event for analysis purposes. Using white-flash camera traps, the attractiveness of four baits (peanut butter with oats, corn, sesame oil and sunflower kernels) and a control were compared for N. aquilo, D. hallucatus, the northern brown bandicoot (Isoodon macrourus) and the agile wallaby (Notamacropus agilis). Spot patterns of D. hallucatus were compared to determine the visitation rate of individuals. Peanut butter– and sesame oil–based baits were significantly more attractive to D. hallucatus, while I. macrourus strongly preferred the peanut butter bait. Bait type did not affect the mean number of events for N. aquilo or N. agilis. The consistently identifiable images of individual D. hallucatus were used to determine the optimal event delineator of 15 min. The improved techniques for camera trapping D. hallucatus should be valuable for future capture–recapture studies of this species. Camera trapping is a viable replacement for the ineffective method of indexing the abundance of N. aquilo using indirect signs.

North Kimberley Mammals – on the fringe of the high-rainfall zone

Six areas were surveyed for terrestrial fauna during remote hiking expeditions in the Kimberley during 2009, 2010, 2013 and 2014. A total of 19 mammal species were recorded, comprising one introduced and 18 native taxa. Significant populations of the northern quoll, monjon, golden-backed tree-rat and scaly-tailed possum were recorded, including from areas where the species were previously unknown. Fractured, rocky terrain in association with rainforest appears to provide important habitat for these species. The use of motion-sensitive cameras, particularly in areas where foraging signs are evident (tracks, diggings, feeding middens, scats) is shown to be a successful and complementary survey technique in detecting critical-weight-range species in the north Kimberley. Such taxa appear to persist in the far north Kimberley in the absence of several threatening processes attributable to large-scale mammal decline across northern Australia.

A new population of the northern quoll (Dasyurus hallucatus) on the edge of the Little Sandy Desert, Western Australia

A fauna survey was conducted within the Throssell and Broadhurst Ranges in the Little Sandy Desert Bioregion of Western Australia during August and September 2012. The endangered northern quoll (Dasyurus hallucatus) was recorded from two distinct locations of similar habitat: deep dissected rocky gorges containing caves and permanent waterholes. One individual was photographed by a motion-sensitive camera and several scats were collected, with mitochondrial DNA analysis confirming the identification. These records represent a significant range extension (~200 km) and due to habitat restrictions are likely to represent the very eastern extreme of the species’ range.

Variation of prey responses to cues from a mesopredator and an apex predator

AbstractDetection and avoidance of predator cues can be costly, so it is important for prey to balance the benefits of gaining food against the costs of avoiding predators. Balancing these factors becomes more complicated when prey are threatened by more than one type of predator. Hence, the ability to recognize species‐specific predator odours and prioritize behaviours according to the level of risk is essential for survival. We investigated how rock rats, Zyzomys spp. modify their foraging behaviour and giving‐up density (GUD) in the presence of an apex predator, the dingo Canis dingo, a mesopredator, the northern quoll Dasyurus hallucatus, a herbivore, the rock wallaby Petrogale brachyotis as a pungency control and water as a procedural control. Both dingoes and quolls consume rock rats, but because quolls can enter small crevices inhabited by rock rats, they pose a greater threat to rock rats than dingoes. Rock rats demonstrated a stronger avoidance to quoll odour than dingo odour, and no avoidance of the pungency control (rock wallaby) and the procedural control (water). GUD values declined significantly over the duration of the study, but did not differ between odour treatments. Our results support the hypothesis that prey vary behaviour according to perceived predator threat, and show stronger responses to potentially more dangerous predators.

New host records for ticks (Ixodidae) from the northern quoll (Dasyurus hallucatus) in north Queensland

Ticks (Ixodidae) were collected from northern quolls (Dasyurus hallucatus) from three sites on the Atherton Tableland, north Queensland. Four species of ticks (Haemaphysalis humerosa, Ixodes fecialis, I. holocyclus and I. tasmani) were collected from quolls. Prevalence of infestation of ticks varied from 44 to 92% across the three sites. The collection of the three species of Ixodes represents new host records for D. hallucatus, thus adding valuable new details to the ecology of the parasite fauna of an endangered marsupial.

Queensland northern quolls are not immune to cane toad toxin

Context The release of the highly toxic South American cane toad (Bufo marinus) to the toad-free Australian continent in 1935, and their subsequent rapid spread over large areas of tropical Australia, has resulted in a massive decline of predators such as yellow-spotted goannas (Varanus panoptes) and northern quolls (Dasyurus hallucatus). In spite of dramatic declines of northern quoll populations in the Northern Territory, a few populations still persist in areas of Queensland where northern quolls have co-existed with toads for several decades. Aims To determine whether the remaining quoll populations in Queensland have evolved resistance to cane toad toxins. Methods The extracellular H1–H2 domain of the α1 subunit of the sodium–potassium-ATPase gene was sequenced in four Queensland as well as four Northern Territory quolls. The transcribed sodium–potassium-ATPase enzyme from this gene is specifically targeted by toad toxins. Key results In all of the eight quolls, the sequences representing the 36 bp of the H1–H2 domain of the α1 subunit of the sodium–potassium-ATPase gene were identical. Conclusions Our results showed that Queensland quolls have not evolved an increased resistance to the toad toxins. We therefore suggest that the persistence of northern quolls in a few toad infested areas of Queensland could to be due to a combination of optimal habitat quality, and concomitant large quoll numbers, as well as an aversion to feeding on these highly toxic amphibians. Implications We suggest that a sample of northern quolls from the Queensland populations should be captured and their response, as well as that of their offspring and grand-offspring, to cane toads should be investigated to guide management of this declining species.

Individual identification of northern quolls (Dasyurus hallucatus) using remote cameras

We have developed a technique to identify individual northern quolls (Dasyurus hallucatus) from their spot patterns using photographs taken by remote infrared cameras. We suggest a method for bait placement and camera set-up to optimise the identification of individual quolls. We compared two methods, which differed in the placement of the bait and number of photographs per trigger, to determine which produced the best images for the purposes of identification. When the bait was positioned so that quolls needed to reach to access it, and a greater number of images were taken per trigger, a higher percentage of individuals were successfully identified. Variation in bait placement did not significantly affect the amount of time the quolls spent around the cameras. The study concludes that individual northern quolls are identifiable from their spot patterns using remote cameras, and adjustments to bait placement and the number of photographs per trigger significantly improves the quality of the information that the cameras provide.

Threatened mammals become more predatory after small-scale prescribed fires in a high-rainfall rocky savanna

Understanding mechanisms underlying fire regime effects on savanna fauna is difficult because of a wide range of possible trophic interactions and feedbacks. Yet, understanding mechanisms underlying fauna dynamics is crucial for conservation management of threatened species. Small savanna mammals in northern Australia are currently undergoing widespread declines and regional extinctions partly attributable to fire regimes. This study investigates mammal trophic and ecosystem responses to fire in order to identify possible mechanisms underlying these declines. Mammal trophic responses to fire were investigated by surveying mammal abundance, mammal diet, vegetation structure and non-mammal fauna dynamics in savannas six times at eight sites over a period of 3 years. Known site-specific fire history was used to test for trophic responses to post-fire interval and fire frequency. Mammal and non-mammal fauna showed only minor responses of post-fire interval and no effect of fire frequency. Lack of fauna responses differed from large post-fire vegetation responses. Dietary analysis showed that two mammal species, Dasyurus hallucatus and Isoodon auratus, increased their intake of large prey groups in recently burnt, compared to longer unburnt vegetation. This suggests a fire-related change in trophic interactions among predators and their prey, after removal of ground-layer veg- etation. No evidence was found for other changes in food resource uptake by mammals after fire. These data provide support for a fire-related top-down ecosystem response among savanna mammals, rather than a bottom-up resource limitation response. Future studies need to investigate fire responses among other predators, including introduced cats and dingoes, to determine their roles in fire-related mammal declines in savannas of northern Australia.

Ensuring applied ecology has impact

Ensuring applied ecology has impact E. J. Milner-Gulland*, Jos Barlow, Marc W. Cadotte, Philip E. Hulme, Gillian Kerby and Mark J. Whittingham Department of Life Sciences, Imperial College London, Silwood Park, Buckhurst Road, Ascot, SL5 7PY, UK; Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK; Department of Biological Sciences, University of Toronto, Scarborough, ON, Canada; Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada; Bio-Protection Research Centre, PO Box 84, Lincoln University, Canterbury, New Zealand; British Ecological Society, Charles Darwin House, 12 Roger Street, London WC1N 2JU, UK; and School of Biology, Ridley Building, Newcastle University, Newcastle-Upon-Tyne, NE1 7RU, UK

The mammal fauna of the Sir Edward Pellew island group, Northern Territory, Australia: refuge and death-trap

Context Australian islands have provided a major conservation refuge for many native mammals; however, conversely, island populations may also be highly susceptible to the introduction of novel threats. Nearby islands subject to different arrays of threats or different timing of arrival of those threats may provide a natural experiment, offering particular insight into the relative impacts of different threats to Australian mammals more generally. Aims The present study sought to document the native mammal fauna occurring on the main islands of the Sir Edward Pellew group, Northern Territory, and the changes in that fauna over a ~50-year period, and to seek to identify those factors that have contributed to such change. Methods In different combinations, the five main islands (and three smaller islands) were subject to standard wildlife survey methods in 1966–67, 1988, 2003, 2004–05, and 2009–10. Sampling procedures were not identical in all periods; however, a measure of abundance (trap success rate) could be calculated for all sampling. This conventional survey approach was complemented by documentation of ethno-biological knowledge. Key results For many species, these islands held populations of biogeographic or conservation significance. However, there has been a major loss or decline of mammal species from most islands. Extirpation is difficult to prove; however, we consider it most likely that the important regional populations of brush-tailed rabbit-rat (Conilurus penicillatus), northern quoll (Dasyurus hallucatus), northern brush-tailed phascogale (Phascogale pirata), common brushtail possum (Trichosurus vulpecula) and canefield rat (Rattus sordidus) have been lost from these islands, and that northern brown bandicoot (Isoodon macrourus), western chestnut mouse (Pseudomys nanus), pale field-rat (Rattus tunneyi) and long-haired rat (Rattus villosissimus) have been lost from most of the islands on which they formerly occurred. Some species–island combinations are known only from the ethno-biological record, and the loss of these populations probably mostly occurred in the period 30–50 years ago. Many other declines and losses occurred in the period between the second (1988) and third (2003) survey. The loss of the northern quoll from Vanderlin Island occurred in 2008. No single factor unambiguously accounts for the declines, although the introduction of cats (Felis catus) provides the best fit to the pattern of decline. A notable exception is the extirpation of northern quoll on Vanderlin Island, which is closely linked to the colonisation of that island by cane toads (Rhinella marina). Conclusions The Sir Edward Pellew group of islands have lost much of their formerly high conservation significance for native mammals over the past 50 years, mostly because of introductions of cats, and to a lesser extent, natural colonisation of the islands by cane toads. Implications The present study has provided some insight into the relative impacts of a range of factors that have been considered as possibly implicated in the decline of native mammals on the northern Australian mainland, with most support being offered here for a primary role for predation by feral cats. The study has also demonstrated the need for better quarantining of islands with significant conservation values. The comprehensive natural colonisation of these islands by cane toads offers a further lesson, of most importance to managers of islands in north-western Australia currently just beyond the range of toads.

Conditioned taste aversion enhances the survival of an endangered predator imperilled by a toxic invader

Summary 1. Even when we cannot eradicate an invasive species, we may be able to reduce its ecological impact. In Australia, a critically endangered predator, the northern quoll Dasyurus hallucatus is threatened by the invasion of the highly toxic cane toad Bufo marinus. Following toad invasion, quoll populations have become extinct across Northern Australia. Toads are continuing to spread, and will soon invade the Kimberley, one of the quoll’s last strongholds. To prevent future local extinctions, we need a new approach for mitigating the impact of cane toads on this iconic predator. 2. We investigated whether conditioned taste aversion (CTA) could be used to modify quoll predatory behaviour and mitigate toad impacts. We successfully induced an aversion to live toads in juvenile northern quolls by feeding them a dead toad containing a nausea-inducing chemical (thiabendazole). 3. To investigate whether CTA enhanced quoll survival, we fitted radiocollars to 31 toad-smart and

Comparative physiology of Australian quolls (Dasyurus; Marsupialia)

Quolls (Dasyurus) are medium-sized carnivorous dasyurid marsupials. Tiger (3,840 g) and eastern quolls (780 g) are mesic zone species, northern quolls (516 g) are tropical zone, and chuditch (1,385 g) were once widespread through the Australian arid zone. We found that standard physiological variables of these quolls are consistent with allometric expectations for marsupials. Nevertheless, inter-specific patterns amongst the quolls are consistent with their different environments. The lower T (b) of northern quolls (34 degrees C) may provide scope for adaptive hyperthermia in the tropics, and they use torpor for energy/water conservation, whereas the larger mesic species (eastern and tiger quolls) do not appear to. Thermolability varied from little in eastern (0.035 degrees C degrees C(-1)) and tiger quolls (0.051 degrees C degrees C(-1)) to substantial in northern quolls (0.100 degrees C degrees C(-1)) and chuditch (0.146 degrees C degrees C(-1)), reflecting body mass and environment. Basal metabolic rate was higher for eastern quolls (0.662 +/- 0.033 ml O(2) g(-1) h(-1)), presumably reflecting their naturally cool environment. Respiratory ventilation closely matched metabolic demand, except at high ambient temperatures where quolls hyperventilated to facilitate evaporative heat loss; tiger and eastern quolls also salivated. A higher evaporative water loss for eastern quolls (1.43 +/- 0.212 mg H(2)O g(-1) h(-1)) presumably reflects their more mesic distribution. The point of relative water economy was low for tiger (-1.3 degrees C), eastern (-12.5 degrees C) and northern (+3.3) quolls, and highest for the chuditch (+22.6 degrees C). We suggest that these differences in water economy reflect lower expired air temperatures and hence lower respiratory evaporative water loss for the arid-zone chuditch relative to tropical and mesic quolls.