Dasyurid Species Research Articles

Density of a cryptic Australian small mammal: The threatened Julia Creek dunnart (Sminthopsis douglasi).

Globally, hundreds of mammal species face the threat of extinction in the coming decades, and in many cases, their ecology remains poorly understood. Fundamental ecological knowledge is crucial for effective conservation management of these species, but it is particularly lacking for small, cryptic mammals. The Julia Creek dunnart (Sminthopsis douglasi), a threatened, cryptic carnivorous marsupial that occurs in scattered populations in the central west of Queensland, Australia, was once so poorly studied that it was believed extinct. Sporadic research since its rediscovery in the early 1990s has revealed that S. douglasi is distributed across land at risk from many threats. Fundamental knowledge of S. douglasi population density is urgently required to inform conservation management at key sites, yet the species has historically proven hard to detect. Indeed, the status of the largest known population of S. douglasi, in Bladensburg National Park, is unknown. Here, we conducted a population study on S. douglasi at two sites within Bladensburg National Park via live mark-recapture surveys during 2022 and 2023. From likelihood-based spatially explicit capture-recapture (SECR) modelling we provide the first estimates of density and population size for S. douglasi. Live trapping resulted in captures of 49 individual S. douglasi (with 83 captures total, including recaptures). We estimated S. douglasi to occur at a density of 0.38 individuals ha-1 (0.25-0.58) at one site and 0.16 individuals ha-1 (0.09-0.27) at another site, with an estimated mean population size in suitable habitat at Bladensburg National Park of 1211 individuals (776-1646). Our S. douglasi density estimates were similar to that reported for other threatened small mammals in Australia. We also found evidence of extreme S. douglasi population fluctuations over time at Bladensburg National Park, which is of concern for its future conservation. Our study has provided the first estimate of density for S. douglasi, a threatened dasyurid species from the Mitchell Grass Downs of central western Queensland, Australia. Our research provides crucial population data to assist the management of this poorly studied species. We demonstrate a method that can be applied to species with low detection probability to ultimately help address the mammal extinction crisis faced by Australia and the rest of the world.

Initiation and early development of the postcanine deciduous dentition in the dasyurid marsupial Dasyurus viverrinus

There has been disagreement for more than 100 years concerning the presence or absence of deciduous and successional third premolars in the dentition of the Australian dasyurid marsupial Dasyurus viverrinus as well as in other species of the genus Dasyurus. Most authors during the 19th and 20th centuries have considered the missing premolar in Dasyurus to be the third premolar family in both jaws, in part because of the reduction in size of the third deciduous premolar in many other genera of dasyurids. While other authors, found “the deciduous premolar to be constantly present in the young mammary foetus as a small and precociously calcified vestigial tooth”. However, the fate of this deciduous tooth, and its possible successor in later developmental stages, was never described; and the vestigial dp3 and its possible successor were assumed to undergo absorption during foetal life. With access to later developmental stages of Dasyurus viverrinus, via the extensive collections of Professor J.P. Hill, we present new evidence for the later development of dP3 and P3 in both jaws, the probable eruption of the successional P3 in both jaws and evidence that dP2 is the missing tooth in both jaws of this dasyurid species.

Class Conflict: Diffuse Competition between Mammalian and Reptilian Predators

(1) Diffuse competition affects per capita rates of population increase among species that exploit similar resources, and thus can be an important structuring force in ecological communities. Diffuse competition has traditionally been studied within taxonomically similar groups, although distantly related intraguild species are likely also to compete to some degree. (2) We assessed diffuse competition between mammalian and reptilian predators at sites in central Australia over 24 years. Specifically, we investigated the effect of dasyurid marsupial abundance on the diet breadth of three groups of lizards (nocturnal dietary generalists, diurnal dietary generalists and dietary specialists). (3) Nocturnal generalist lizards had progressively narrower diets as dasyurid abundance increased. The diet breadth of diurnal generalist lizards was unaffected by overall dasyurid abundance, but was restricted by that of the largest dasyurid species (Dasycercus blythi). Ant- and termite-specialist lizards were unaffected by dasyurid abundance. (4) Diffuse competition, mediated by interference, between dasyurids and nocturnal generalist lizards appears to have strong effects on these lizards, and is the first such between-class interaction to be described. Diffuse interactions may be widespread in natural communities, and merit further investigation among other disparate taxon groups that occur in the same ecological guilds.

The geography of speciation in dasyurid marsupials

AbstractAimTo determine the effects of competition and divergence time on morphological dissimilarity and geographical range overlap between dasyurid species at both regional and local scales. Our hypothesis is that speciation in this group has been largely allopatric at regional scale, but involved morphological divergence at local scale through sympatric character displacement.LocationAustralia, New Guinea and surrounding islands.TaxonDasyurid (Dasyuridae) marsupials, 67 species.MethodsGeographical range overlap was quantified using polygons representing the outer limits of species distributions. Local‐scale range overlap was quantified as the degree of co‐occurrence of two taxa across a set of ecological survey plots representing 83 sampled communities. Phylogenies were generated using a novel DNA dataset, with divergence times estimated via total‐evidence dating incorporating fossils. Morphological divergence was determined using body mass and lower molar row length as proxy traits for reconstructing niche exploitation.ResultsSister species pairs were found to be sympatric in 52% (11/21) of cases. Range overlap tended to increase with node age, which supports the hypothesis that mammalian speciation is routinely allopatric. We detected no evidence of character displacement with increasing range overlap between sister species pairs. However, a negative relationship was observed between morphological divergence in body mass and range overlap across all sampled taxa, suggesting that selection in sympatry is convergent, while divergent selection occurs in allopatry. Local‐scale co‐occurrences revealed no trace of species aversion, indicating that competition has not impacted on the spatial distribution of dasyurids.Main conclusionsDespite moderate levels of sympatry through time, our results evince low rates of spatial co‐occurrence between dasyurid species. Although this may be indicative competitive exclusion, the lack of character displacement suggests that biotic interactions have likely not acted as a dominant driver of phenotypic evolution in this radiation. We alternatively posit that abiotic factors including aridity and geographical connectivity have more feasibly propagated character convergence, and led to both niche conservatism and speciation in this ubiquitous australidelphian clade.

Does aridity affect spatial ecology? Scaling of home range size in small carnivorous marsupials.

The aim of our study was to determine how body mass affects home range size in carnivorous marsupials (dasyurids) and whether those species living in desert environments require relatively larger areas than their mesic counterparts. The movement patterns of two sympatric species of desert dasyurids (body mass 16 and 105g) were investigated via radio-telemetry in southwestern Queensland and compared with published records for other Australian dasyurids. Both species monitored occupied stable home ranges. For all dasyurids, home range size scaled with body mass with a coefficient of > 1.2, almost twice that for metabolic rate. Generally, males occupied larger home ranges than females, even after accounting for the size dimorphism common in dasyurids. Of the three environmental variables tested, primary productivity and habitat, a categorical variable based on the 500mm rainfall isopleth, further improved model performance demonstrating that arid species generally occupy larger home ranges. Similar patterns were still present in the dataset after correcting for phylogeny. Consequently, the trend towards relatively larger home ranges with decreasing habitat productivity can be attributed to environmental factors and was not a result of taxonomic affiliation. We therefore conclude that alternative avenues to reduce energy requirements on an individual and population level (i.e. torpor, basking and population density) do not fully compensate for the low resource availability of deserts demanding an increase in home range size.

Nutritional status and functional digestive histology of the carnivorous Tasmanian devil (Sarcophilus harrisii)

Tasmanian devils (Sarcophilus harrisii) are the largest carnivorous marsupial in Australia. Currently many animals are being held in captivity as a management procedure to combat Devil Facial Tumor Disease. Only one published study thus far has investigated nutrition in Tasmanian devils, determining their maintenance energy requirements and digestibility on a rodent diet. More information is needed on Tasmanian devil nutritional and gastrointestinal function to aid in their management. Our study aimed to investigate the current nutritional status of Tasmanian devils in a captive population and functional morphology and histology of their gastrointestinal tract. Animals were maintained on a diet of kangaroo, rabbit, quail and chicken wings and digestibility of these items by the devils was high (>85% for dry matter, protein and lipid). Kangaroo and rabbit were high protein diet items while the quail and chicken wings provided high lipid to the diet, and carbohydrates were minimal (≤3% energy). Maintenance energy requirements were determined to be 620kJkg−0.75d−1 with no significant difference between males and females. Opportunistic samples for gastrointestinal morphology were obtained from captive specimens. Tasmanian devils have a simple digestive tract similar to other dasyurid species. Both the morphology and histology of the gastrointestinal tract show specialization for a high protein carnivorous diet.

Why is the marsupial kaluta, Dasykaluta rosamondae, diurnally active in winter: Foraging advantages or predator avoidance in arid northern Australia?

The majority of animals have a specific activity rhythm over the 24 h daily cycle such that they can be categorised as either diurnal or nocturnal. This stability creates interest in understanding species that can invert their activity rhythm. The kaluta, Dasykaluta rosamondae, a small dasyurid marsupial endemic to northern arid Australia, is one such species. In contrast to most other dasyurid species and in fact most small mammals, the kaluta is almost exclusively diurnal in winter. To assess the potential benefits of diurnal activity we examined the diet and assessed potential predators and competitors. We identified 33 food categories including four classes of invertebrates, three classes of vertebrates and plant material. Diet was dominated by Coleoptera (beetles, 26.7% volume) and Formicidae (ants, 25.0% volume). We found no evidence that the prey base of kalutas differed as a consequence of diurnal activity. Likewise, diurnal foraging was probably not driven by competition. A likely explanation of diurnal activity in winter in this species is that it both allows temporal separation in activity from a significant predator, the brush-tailed mulgara, Dasycercus blythi, and reduces thermoregulatory foraging costs.

Bust economics: foragers choose high quality habitats in lean times.

In environments where food resources are spatially variable and temporarily impoverished, consumers that encounter habitat patches with different food density should focus their foraging initially where food density is highest before they move to patches where food density is lower. Increasing missed opportunity costs should drive individuals progressively to patches with lower food density as resources in the initially high food density patches deplete. To test these expectations, we assessed the foraging decisions of two species of dasyurid marsupials (dunnarts: Sminthopsis hirtipes and S. youngsoni) during a deep drought, or bust period, in the Simpson Desert of central Australia. Dunnarts were allowed access to three patches containing different food densities using an interview chamber experiment. Both species exhibited clear preference for the high density over the lower food density patches as measured in total harvested resources. Similarly, when measuring the proportion of resources harvested within the patches, we observed a marginal preference for patches with initially high densities. Models analyzing behavioral choices at the population level found no differences in behavior between the two species, but models analyzing choices at the individual level uncovered some variation. We conclude that dunnarts can distinguish between habitat patches with different densities of food and preferentially exploit the most valuable. As our observations were made during bust conditions, experiments should be repeated during boom times to assess the foraging economics of dunnarts when environmental resources are high.

Histological Development of the Immune Tissues of a Marsupial, the Red-Tailed Phascogale (Phascogale calura).

Red-tailed phascogale (Phascogale calura) pouch young at birth were relatively underdeveloped in comparison with their eutherian counterparts, and the lymphoid tissues of the immune system were found to be histologically immature. The phascogale thymus rapidly developed in the first few days of pouch life and was quickly populated with lymphocytes. By the end of pouch life, involution of the thymus was underway. The bone marrow started to develop in the early stage of pouch life, although adipocytes and megakaryocytes were not observed until slightly later. The liver was hematopoietic from birth and reached histological maturity toward the end of pouch life. The lymph nodes were difficult to detect macroscopically because of their small size, but were easily identified microscopically later in pouch life, particularly in the mesentery, and these lymph nodes exhibited germinal centers by the end of pouch life. The early spleen was predominately mesenchymal, but exhibited some erythropoiesis. Follicles with well-developed germinal centers were not observed until the latest stage of pouch life. Although intraepithelial lymphocytes were detected in the intestines early in pouch life, the discrete lymphoid aggregates and Peyer's patches characteristic of the gut-associated lymphoid tissue (GALT) were not detected until later in pouch life. This is the first report of histological development in phascogale pouch young, as well as the first report of the thymus, bone marrow, and lymph nodes in this dasyurid species at any age.

To bask or not to bask: Behavioural thermoregulation in two species of dasyurid, Phascogale calura and Antechinomys laniger

Torpor is an important physiological process used to reduce body temperature and thus energy needs in mammals and birds. Rewarming from torpor can be costly. In some small mammals basking is used to reduce the cost of rewarming from torpor. The use and duration of basking was measured in two native Australian marsupials, the red-tailed phascogale (Phascogale calura) and kultarr (Antechinomys laniger), using a heat rock. Animals were observed via video cameras to determine whether they used basking behaviours and whether this behaviour was affected by food availability. Both species became accustomed to the heat rock as time progressed. Absence of food increased basking duration and frequency in some individuals but not all animals. Generally kultarrs basked for longer periods than phascogales, and kultarrs would bask at all hours of the day while phascogales showed a strict nocturnal regime (1900–0700h). The results demonstrate that basking may be an important behavioural adaptation of the kultarr; while the phascogale requires further research.

Exploiting boom times. Southern Boobook OwlNinox novaeseelandiaediet during a rodent irruption in central Australia

Populations of Australian desert rodents are known to undergo booms in response to resource pulses following periods of high rainfall. Australia's arid-adapted Tyto owls have been recorded responding functionally and numerically to these small mammal booms, though it is not known whether Southern Boobook Ninox novaeseelandiae is able to respond similarly. We aimed to determine whether Southern Boobooks could find and exploit a localised rodent irruption in the western Simpson Desert, in a location with few roost trees and no tree hollows. Boobook owls immigrated to the site from an estimated distance of ≥ 32 km and appeared to be resident over a period of ≥ 4 months, coinciding with a localised irruption of Plains mice Pseudomys australis. Dietary analysis confirmed that the owls specialised on small mammals, with rodent and dasyurid species accounting for c. 98% of prey items and > 99% of prey biomass. There was no evidence of reproductive activity among the owls and they vacated the area as the small mammal irruption subsided. Although a dietary generalist across its range, our results indicate the Southern Boobook is capable of specialising on small mammals during population irruptions.

Metabolic, hygric and ventilatory physiology of the red-tailed phascogale (Phascogale calura; Marsupialia, Dasyuridae): Adaptations to aridity or arboreality?

The red-tailed phascogale is a small arboreal dasyurid marsupial that inhabits semi-arid to arid regions of Western Australia's wheat belt. Its body mass (34.7g) is only ∼15% of that predicted based on its phylogenetic position among other dasyuromorphs; we interpret this as an adaptation to its scansorial and semi-arid/arid lifestyle. The standard physiology of this species at a thermoneutral ambient temperature of 30°C conforms to that of other dasyurid marsupials; body temperature (34.7±0.37°C), basal metabolic rate (0.83±0.076mLO2g−1h−1), evaporative water loss (1.68±0.218mgH2Og−1h−1) and wet thermal conductance (3.8±0.26Jg−1h−1°C−1) all fall within the 95% predication limits for the respective allometric relationships for other dasyurid species. Thermolability confers an energy savings at low Ta and water savings at high Ta. Torpor, observed at low Ta, was found to be more beneficial for energy savings than for water economy. The red-tailed phascogale therefore has a physiology suitable for the challenges of arid environments without any obvious requirement for adaptations to its scansorial lifestyle, other than its considerably lower-than-expected body mass.

Evolution in a transmissible cancer: a study of the chromosomal changes in devil facial tumor (DFT) as it spreads through the wild Tasmanian devil population

Tasmanian devils (Sarcophilus harrisii) are the largest extant marsupial carnivores. This species, now confined to Tasmania, is endangered from the emergence of a transmissible cancer, devil facial tumor disease (DFTD). In the present study, we use cytogenetic and molecular techniques to examine the stability of devil facial tumor (DFT) cell lines across time and space. This article describes disease progression from February 2004 to June 2011. We demonstrate evolutionary changes in the disease, which affects devils in different sites across Tasmania and over a period of several years, producing several chromosomal variants (strains) that are capable of transmission between devils. We describe the evolution of DFTs in the field and speculate on the possible impacts on the disease, including (1) development of less aggressive forms of the disease; (2)development of more aggressive forms of the disease; (3) development of forms capable of affecting closely related species of dasyurids (e.g., quolls); (4) extinction of the disease as it acquires additional deleterious mutations that affect either cell viability or transmissibility; and (5) co-evolution of the disease and the host. We also speculate about the future of the Tasmanian devil in the wild. We note that although DFTs are regarded as unstable by comparison with another much older transmissible cancer, canine transmissible venereal tumor (CTVT), the potential for development of less aggressive forms of DFTs or for development of resistance in devils is limited by devils' small numbers, low genetic diversity, and restricted geographical distribution.

Short-term movement patterns and diet of small dasyurid marsupials in semiarid Australia

Since little information is available on the spatial ecology of small arid-zone marsupials, we used radio-tracking to investigate the small-scale activity patterns of three dasyurid species in semiarid Australia. Sminthopsis crassicaudata, Planigale gilesi and S. macroura were equipped with miniature radio-transmitters to monitor choice of resting sites and daily movements. Resting sites were located within an area of 1.27 ± 0.36 ha, 0.12 ± 0.02 ha and 3.60 ± 0.95 ha, respectively and individuals returned to previously used resting sites regularly. We also analysed scat samples of S. crassicaudata and P. gilesi, and identified Araneae, Hymenoptera and Orthoptera as the major prey taxa for both species. Our study presents the first radio-tracking-based information on movements for these species in semiarid habitat, which indicates that, over a period of several weeks, resting sites are situated within small and defined areas.

The diet of some New Guinean dasyurid marsupials

We investigated the diets of five forest-dwelling species of dasyurid marsupials endemic to New Guinea by using faecal and gut content analysis and compared the contents with the results of pitfall trapping for terrestrial invertebrates carried out coincidently. In one study area, in montane forest 2060–2340 m above sea level, three dasyurid species were trapped. In another area, in forest 1000–1470 m above sea level, two other species were captured. All five species ate a diverse range of invertebrates but beetles (Coleoptera) and spiders (Araneae) formed the bulk of their diet, followed by grasshoppers and crickets (Orthoptera). Earthworms (Annelida) were eaten by all species and some vertebrate remains were found in samples from four species. We found some significant differences between diets of the sympatric species. Some of the invertebrates commonly collected in pitfall traps, such as isopods (Isopoda) and amphipods (Amphipoda), were rarely detected in the diets of any of the species and millipedes (Diplopoda) and centipedes (Chilopoda) were never detected. Our results are broadly in agreement with what is known about the diets of the small Australian species of dasyurid marsupials.

Generation of sex ratio biases in the red-tailed phascogale (Phascogale calura)

Male semelparous dasyurid species are annual breeders that use a promiscuous mating system. These species have shown biases in litter sex ratios and, with females producing more young than they have available teats, this provides an opportunity for the manipulation of the sex ratio at birth. The sex ratio of embryos and pouch young, and the degree of embryonic overproduction, in red-tailed phascogales (Phascogale calura) was investigated to gain an understanding of the mechanism by which sex biases may be generated. The sex ratio of embryos did not differ from parity, but a male bias was observed in young attaching to teats. Females produced an average of 15.1 +/- 1.9 corpora lutea and 10.5 +/- 3.5 viable embryos, with no difference in fecundity observed with female age or weight. Because females only have eight teats, the overproduction of young, and male-biased attachment, was sufficient to explain the observed male bias in pouch young. No relationship was observed between maternal weight and sex ratio, but heavier females did tend to produce more ova. Meta-analysis of studies providing information on litter sex ratios in male semelparous dasyurid species did not show any consistent trend.

Dispersal and the influence of rainfall on a population of the carnivorous marsupial swamp antechinus (Antechinus minimus maritimus)

Although there is evidence that recent climatic changes have had significant impacts on a wide range of species in the Northern Hemisphere, the influence of climate change, particularly drought, on Australian native small mammal species is poorly understood. In this study we investigated dispersal patterns and the influence of rainfall on the swamp antechinus (Antechinus minimus maritimus). Peak abundance occurred after the highest total annual rainfall for two decades, in 2001. A year later the population had declined to 10% of the peak. Birth dates appeared to occur three weeks earlier following a year of high rainfall. The dispersal of nine litters of pouch young (n = 62) was assessed following two breeding seasons. Young males remained on the natal site until December–January and dispersed before the breeding season. New males entered the population between January and June. More than 50% of females were residents and remained on the site to breed; the remaining females were trapped only once. After the male die-off the movements of pregnant females increased and they appeared to expand their home ranges. A. minimus exhibits philopatry of females and dispersal of males, as observed in other Antechinus species but dispersal occurs 2–3 months after weaning. This contrasts with juveniles of other Antechinus species that disperse abruptly after weaning. This study provides evidence that precipitation does have a major effect on the abundance of dasyurid species, making them vulnerable to drought and local or regional extinctions, particularly in areas of fragmented habitat and drying climates.

Phylogenetic Relationships of the Dasyurid Marsupial Genus Murexia

Five species of dasyurid marsupials endemic to New Guinea and herein referred to as Murexia longicaudata, M. rothschildi, M. habbema, M. naso, and M. melanurus have a varied taxonomic history. Until 1984, the latter 3 species had been assigned to the otherwise strictly Australian genus Antechinus, but comparisons of phallic morphology showed that this arrangement was untenable. Immunological and DNA hybridization studies of dasyurids suggested that New Guinean “antechinuses” were part of a clade that included M. longicaudata and M. rothschildi, a finding that was confirmed by early DNA sequence comparisons. Comprehensive analyses of cytochrome b, 12S rRNA, and protamine P1 sequences from all recognized dasyurid species led to the recommendation that these 5 species be included in a single genus (Murexia) that, along with Phascogale and Antechinus, constitutes the dasyurid tribe Phascogalini. Recently, however, a morphocladistic study concluded that these species are neither closely related to one another nor to any other dasyurid clade, placing them instead as successive basal branches within the family and assigning each to a distinct genus. Here we report results from an expanded DNA sequence data set that includes 2 additional mitochondrial loci (16S rRNA and control region) and 2 nuclear loci (beta-fibrinogen intron 7 and interphotoreceptor retinoid-binding protein exon 1) from phascogalin species and selected dasyurid and myrmecobiid outgroups. Phylogenetic analyses of these sequences show strong support for the monophyly of Murexia and its placement within Phascogalini, and provide the 1st resolved phylogeny of Murexia and Antechinus species. Reassessment of the morphological data suggests that the apparently primitive cranidental anatomy of Murexia may be an artifact of character polarizations or indicative of extreme homoplasy.

Description of capillariid nematodes (Trichinelloidea: Capillariidae) parasitic in Australian marsupials and rodents

Capillariid nematodes (Trichinelloidea: Capillariidae) parasitic in Australian dasyurid, peramelid and potoroid marsupials and murid rodents are described. Diagnosis of the genus Eucoleus and a key to species are given. Two species are redescribed: E. gastricus (Baylis) and E. rickardi (Beveridge and Barker), comb. nov. Nine species are described as new: E. breviductus sp. nov., E. buckenbourensis sp. nov., E. fluvidus sp. nov., E. longiductus sp. nov., E. parvulus sp. nov., E. perplexus sp. nov., E. plumosus sp. nov., E. posterus sp. nov. and E. pseudoplumosus sp. nov. Three additional species are recognized but not named. Species of Eucoleus occur in a diverse range of epithelial tissue habitats in Australian hosts throughout eastern Australia; one species is known from peramelids in Western Australia. Members of the genus have not been found in any other families of Australian marsupials. Three species are parasites of dasyurids, eight species are parasites of peramelids, two species occur in both dasyurid and peramelid hosts and two species are parasites of murid rodents. Morphologically, species of Eucoleus appear to be reasonably host specific at the family level. Molecular evidence indicates that sibling species of Eucoleus occur in distinct but closely related host species. Baruscapillaria conspecta sp. nov. is described from murid rodents and the potoroid marsupial rufous rat kangaroo, Aepyprymnus rufescens, primarily in north Queensland. Capillaria ornamentata sp. nov. is described from the distal nasal sinus behind the orbit of the eye of species of dasyurids of the genus Antechinus in southeastern Australia. Aonchotheca praeputialis (Obendorf, 1979) comb. nov. is redescribed and appears to occur exclusively in the native Rattus fuscipes. New host and geographic records, and tissue localities of the trichurid nematode, Anatrichosoma haycocki (Trichinelloidea: Trichuridae, Trichosomoidinae) are given.

Distribution, abundance, and individual strategies: a multi‐scale analysis of dasyurid marsupials in arid central Australia

We investigated the effects of different environmental factors on the distribution and abundance of 6 species of dasyurid marsupials using a multiple‐scale analysis. Data collected in the spinifex dunefields of the Simpson Desert, Australia, were analysed at 3 spatial scales spanning more than 5 orders of magnitude: “metasite” (covering an area of 1000–2000 km2), site (2–12 km2) and grid (0.01 km2). Temporal variability was also investigated, using data collected in March, April, and May in 4 consecutive years from 1997 to 2000. Both abiotic and biotic factors influenced the capture rates of different species at different times and spatial scales. At the coarsest spatial scale, Dasycercus cristicauda (mulgara) was consistently limited in its distribution by the intensity of rainfall, probably as an indirect result of increased grazing pressure from pastoral activity and a higher density of feral predators in high rainfall areas. However, at the finest spatial scale, this partly carnivorous species was scarce in areas of dense spinifex, perhaps because such habitats yield lowest returns during foraging, and was more common in areas where small invertebrate prey were abundant. Factors affecting the distribution of the most abundant dasyurid species in the study area, Sminthopsis youngsoni (lesser hairy‐footed dunnart), could not be identified at any scale; we conclude that this reflects the opportunistic foraging strategies and flexible habitat requirements of this insectivorous species. Both Ningaui ridei (wongai ningaui) and Sminthopsis hirtipes (hairy‐footed dunnart) were less abundant throughout the study region. For N. ridei, a spinifex specialist, predictors of occurrence could be identified only at the finest scale of analysis; at the grid level, a close positive association was detected in 2 of the 4 study years between capture rate and spinifex cover. For S. hirtipes, all 3 levels of spatial analysis revealed a negative association between capture rate and both rainfall and spinifex density. For the rarely‐caught S. crassicaudata (fat‐tailed dunnart) and Planigale tenuirostris (narrow‐nosed planigale), no clear results were obtained at any spatial scale, and we interpret this to indicate that the study region represents sub‐optimal habitat for these species.Given that different factors affected the distribution and abundance of dasyurids at different spatial scales over time, we conclude that a multiple‐scale approach to population and community analysis is vital to accurately identify which environmental processes shape population and community dynamics. Understanding the interplay between regional and local processes will be crucial for management of existing species populations and for prediction of their distributions and abundances in future.