Dasyurus Research Articles

Sleep: Giving it up to get it on

A new study presents evidence of sex-related sleep reduction in males of two marsupial mice species but not in females. The growing experimental data suggest that seasonal sleep reduction, linked to migrations and reproductive periods, is common among animals.

A systematic global review of mammalian carnivore responses to production forests

Abstract Unmodified forests are increasingly rare worldwide, with forestry a major contributor to habitat modification. Extending conservation practices beyond protected areas is important to conserve forest ecosystems. We investigate the response of native mammalian carnivores (both Order Carnivora and Family Dasyuridae) to production forests globally, including harvested native forest and timber plantations. We examine how carnivores recorded in production forests use these forests versus other land uses, particularly native and/or unharvested forest; how habitat use relates to threatened status, body size, diet and harvesting method; carnivore responses to habitat features within production forests; and carnivore denning, breeding and predation behaviour in production forests. We review 294 studies recording 132 carnivore species in production forests. Carnivores generally show higher use of unharvested native forests and lower use of agricultural land than production forests. Threatened species and large carnivores respond more negatively to production forests than non‐threatened species and small carnivores respectively. Hypercarnivores respond more negatively than omnivores to plantations compared to native forest, with no difference in the use of harvested and unharvested native forest between these dietary groups. Notably, a high proportion of carnivore species use clearfelled more than unharvested native forest. In forest with partial harvesting or reduced‐impact logging, most species show no difference in use between harvested and unharvested forest. Carnivores generally respond positively to habitat features such as riparian areas and coarse woody debris. Several carnivores were recorded denning and breeding in production forests. Production forests often influence the prey availability, hunting success and diet of carnivores. We show that many carnivores use production forests, and how they respond to production forestry varies with species traits and conservation status. We recommend that production forests are managed as valuable carnivore habitat, and highlight strategies to enhance the use of these forests by carnivores.

Taxonomic review of the genus Dasycercus (Dasyuromorphia: Dasyuridae) using modern and subfossil material; and the description of three new species

The genus Dasycercus (Dasyuridae: Dasyuromorphia) has a long and ongoing history of taxonomic uncertainty. Currently two species are recognized: Dasycercus cristicauda and Dasycercus blythi, with the previously named Dasycercus hillieri considered a junior synonym of D. cristicauda. This investigation integrates modern, historical and subfossil material from across Australia to provide the most comprehensive review of the genus to date. Cranial and dental morphological characters that enable phylogenetic and morphometric analysis of taxa are established. Linear discriminant analysis (LDA) and principal component analysis (PCA) of craniodental measurements, including from the type specimens of named taxa (D. cristicauda, D. hillieri and D. blythi), are used to assess the validity of each taxon. The results confirm the validity of D. cristicauda and D. blythi as species, but also reconfirm the validity of D. hillieri. As a result, much of the modern ‘D. cristicauda’ material is reassigned to D. hillieri. Three new taxa are proposed: Dasycercus woolleyae sp. nov., Dasycercus archeri sp. nov. and Dasycercus marlowi sp. nov. These six Dasycercus species are distributed across Australia’s arid zone and beyond. Based on prior investigations and the results of this taxonomic review, it is likely that only D. hillieri and D. blythi are extant. The identification of four likely extinct taxa marks the first recorded instance of modern extinction within the family Dasyuridae.Jake Newman-Martin [jake.newman-martin@student.curtin.edu.au], School of Earth and Planetary Sciences, Curtin University Kent St, Bentley, WA, 6102 Australia;Kenny J. Travouillon [Kenny.Travouillon@museum.wa.gov.au], Western Australian Museum, Collections and Research, Locked Bag 49, Welshpool DC, WA, 6986 Australia;Natalie Warburton [N.Warburton@murdoch.edu.au], Harry Butler Institute, Murdoch University, 90 South Street, Murdoch Western Australia 6150 Australia;Milo Barham [Milo.Barham@curtin.edu.au], School of Earth and Planetary Sciences, Curtin University Kent St, Bentley, WA, 6102 Australia;Alison J. Blyth [Alison.Blyth@curtin.edu.au], School of Earth and Planetary Sciences, Curtin University Kent St, Bentley, WA, 6102 Australia.

A comprehensive review of mammalian carnivore translocations

Abstract Carnivore conservation translocations are assumed to provide numerous ecological benefits, including conservation of the translocated carnivores, regulation of prey species and restoration of ecosystems. Reviews of mammalian carnivore conservation translocations and resultant ecosystem effects have focussed on large carnivores. We reviewed global terrestrial carnivore conservation translocations across all taxa, including taxonomic bias, problems influencing their population establishment and their ecosystem effects. We obtained data from 536 conservation translocations of 54 species of terrestrial mammalian carnivore (order Carnivora and family Dasyuridae, 30 g–196 kg), comprising mostly Mustelidae, Canidae, and Felidae species. A third of all projects translocated carnivores into South Africa and a third into fenced reserves. Significant bias occurred relative to threat status, with over‐representation of Mustelidae and Canidae conservation translocations relative to the number of threatened species in each family. Additionally, conservation translocations of small carnivores were generally under‐represented compared to those of large carnivores. Seventeen percent of small carnivore conservation translocations failed, compared with 25% of large carnivore conservation translocations; failure was primarily due to reported anthropogenic mortality. Effects on resident prey species or ecosystems of carnivore conservation translocations were rarely investigated. We found no significant relationship between the carnivore family or size and effects on prey or ecosystems; however, prey impacts were frequently attributed to Felidae, and ecosystem effects were frequently attributed to Canidae and Felidae. Challenges to translocations of mammalian carnivores include threats to resident threatened prey species and difficulties in monitoring the ecological effects of carnivore conservation translocations. Poor postrelease monitoring and a lack of empirical studies remain persistent problems, contributing to the poor understanding of ecosystem effects following carnivore conservation translocations.

Small Alpine Marsupials Regulate Evaporative Water Loss, Suggesting a Thermoregulatory Role Rather than a Water Conservation Role.

AbstractWe show here that evaporative water loss (EWL) is constant over a wide range of ambient relative humidity for two species of small, mesic habitat dasyurid marsupials (Antechinus agilis and Antechinus swainsonii) below thermoneutrality (20°C) and within thermoneutrality (30°C). This independence of EWL from the water vapor pressure deficit between the animal and its environment indicates that EWL is physiologically controlled by both species. The magnitude of this control of EWL was similar to that of two other small marsupials from more arid habitats, which combined with the observation that there were no effects of relative humidity on body temperature or metabolic rate, suggests that control of EWL is a consequence of precise thermoregulation to maintain heat balance rather than a water-conserving strategy at low relative humidities. The antechinus appear to manipulate cutaneous EWL rather than respiratory EWL to control their total EWL by modifying their cutaneous resistance and/or skin temperature. We propose that there is a continuum between enhanced thermoregulatory EWL at high ambient temperature and so-called insensible EWL at and below thermoneutrality.

Community structure of dasyurid marsupials in the arid Pilbara is consistent with a top-down system, their distribution and abundance depend on that of larger members of the guild

The semi-arid Pilbara region of Western Australia has an exceptionally large number of sympatric carnivorous marsupials (dasyurids). The multi-scale patchwork of sandplain grassland, riparian and rock outcrop habitats overlain with fine-scale variation in fire age may provide opportunities for exceptional niche differentiation. The goal of this study was to determine how dasyurids in the Pilbara partition these habitats in space and time. We focused on four species detectable on camera traps: northern quolls (largest), mulgaras, kalutas, and stripe-faced dunnarts (smallest). We found fine-scale partitioning in spatial and temporal patterns among sympatric species, and unusually, fire age specialisation in the smallest species, dunnarts, which were associated with recently burnt areas that had low prey availability. Kalutas were active throughout the 24-h period, with seasonal differences that support the hypothesis of energy preservation. Opposing habitat associations of kalutas and dunnarts are consistent with top-down pressures. We suggest that, in habitats where quolls and mulgaras are absent, kalutas may have experienced mesopredator release.

Diet of the introduced red fox Vulpes vulpes in Australia: analysis of temporal and spatial patterns

Abstract The red fox Vulpes vulpes is one of the world’s most widespread carnivores. A key to its success has been its broad, opportunistic diet. The fox was introduced to Australia about 150 years ago, and within 30 years of its introduction was already recognised as a threat to livestock and native wildlife. We reviewed 85 fox diet studies (totalling 31693 samples) from throughout the species’ geographic range within Australia. Mammals were a major component of fox diet, being present in 70 ± 19% of samples across n = 160 locations. Invertebrates (38 ± 26% n = 130) and plant material (26 ± 25% n = 123) were also both staple foods and often the dominant food category recorded. Birds (13 ± 11% n = 137) and reptiles (10 ± 15% n = 132) were also commonly reported, while frogs were scarcely represented (1.6 ± 3.6% n = 111) in fox diet studies. Biogeographical differences reveal factors that likely determine prey availability. Diet composition varied with ecosystem, level of vegetation clearing and condition, and climate zone. Sample type (i.e. stomach versus scat samples) also significantly influenced reporting of diet composition. Livestock and frogs were underrepresented in records based on analysis of scats, whereas small mammals (native rodents, dasyurid marsupials, and bats) were more likely to be recorded in studies of scats than in studies of stomach contents. Diet varied seasonally, reflecting activity patterns of prey species and food availability. This synthesis also captures temporal shifts in fox diet over 70 years (1951–2020), as foxes have switched to consuming more native species in the wake of successful broadscale biological control of the invasive European rabbit Oryctolagus cuniculus. Diet analyses, such as those summarised in this review, capture the evidence required to motivate for greater control of foxes in Australia. This synthesis also highlights the importance of integrated pest species management to meet biodiversity conservation outcomes.

Predicting mammal responses to pyrodiversity: From microbats to macropods

Fire has shaped Australia's diverse mammal fauna for millennia. However, ongoing changes to fire regimes threaten native mammal populations, and a significant conservation challenge is to understand and promote desirable forms of pyrodiversity (variation in fire regimes). A way forward is to quantify how different aspects of pyrodiversity influence whole mammal assemblages and produce dynamic maps of species distributions to inform conservation. We aimed to determine and map how spatial and temporal variation in fire regimes correlates with a diverse mammal assemblage comprising macropods, microbats, rodents, small marsupials and a monotreme. We built species distribution models for 17 species against fire, climate and environmental covariates in fire-prone woodlands of semi-arid Australia. Spatial measures of fire included the area, diversity and configuration of landscape elements, and temporal measures included time since fire and fire frequency. Native mammals showed a variety of responses to pyrodiversity. Microbats were more likely to occur as time since fire increased, whereas rodents were correlated with recently burned areas. Small dasyurid marsupials were correlated with the area of older post-fire age-classes, while western grey kangaroo occurrence was positively associated with high diversity of post-fire ages. Our new approach, using predictive models to map mammal distributions in relation to spatial and temporal variation in fire regimes, provides outputs that managers can use to improve conservation planning. This enables the positive and negative effects of fire to be better understood and will assist in achieving desirable forms of pyrodiversity that meet the needs of whole mammal assemblages.

Corrigendum to: Conservation of quolls (Dasyurus spp.) in captivity – a review

Quolls are carnivorous marsupials in the family Dasyuridae with characteristic white spots. They are distributed throughout Australia and New Guinea, but uncommonly seen due to their mostly nocturnal solitary nature, and large home ranges. All Australian quolls are listed as ‘near threatened' or ‘endangered' at state, national and international levels, largely due to human-induced threats. Threats include introduced predators, habitat loss through clearing and modifications including changed fire regimes, disease, human persecution, vehicle collisions and accidental or targeted poisoning by humans and cane toads (Rhinella marina). Conservation efforts that have focussed on reducing introduced predators, and minimising the impact of cane toads, have aided some translocations, hence species recovery in some local areas of Australia has occurred. Where species conservation has required captive breeding for translocation, successful captive management has been crucial. We summarise research conducted in captivity on aspects of birth and development, health and disease, and blood and nutrition parameters of quolls, and suggest future directions for research. Further research on captive and wild quoll populations will benefit future translocations, reintroductions and conservation through increased knowledge, improved maintenance and husbandry of captive colonies, and monitoring of wild populations.

Conservation of quolls (Dasyurus spp.) in captivity – a review

Quolls are carnivorous marsupials in the family Dasyuridae with characteristic white spots. They are distributed throughout Australia and New Guinea, but uncommonly seen due to their mostly nocturnal solitary nature, and large home ranges. All Australian quolls are listed as ‘near threatened’ or ‘endangered’ at state, national and international levels, largely due to human-induced threats. Threats include introduced predators, habitat loss through clearing and modifications including changed fire regimes, disease, human persecution, vehicle collisions and accidental or targeted poisoning by humans and cane toads (Rhinella marina). Conservation efforts that have focussed on reducing introduced predators, and minimising the impact of cane toads, have aided some translocations, hence species recovery in some local areas of Australia has occurred. Where species conservation has required captive breeding for translocation, successful captive management has been crucial. We summarise research conducted in captivity on aspects of birth and development, health and disease, and blood and nutrition parameters of quolls, and suggest future directions for research. Further research on captive and wild quoll populations will benefit future translocations, reintroductions and conservation through increased knowledge, improved maintenance and husbandry of captive colonies, and monitoring of wild populations.

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.

Population dynamics of dasyurid marsupials in dryland Australia: Variation across habitat and time

AbstractThe irruptive population dynamics of rodents are a globally renowned wildlife phenomenon; however, the dynamics of other small mammals with which rodents are sympatric are poorly understood. Dryland Australia supports a high diversity of small (<200 g) arthropod‐eating marsupials (Dasyuridae). Here, we test the hypothesis that dasyurid marsupials do not exhibit the same degree of irruptive population dynamics that are shown by rodents. We addressed this question by sampling small mammal assemblages on 20 permanent trapping sites in the Simpson Desert on 20 occasions from 2007 to 2017. Sampling was stratified across three broad habitat types: sandridge, gibber plain and clay plain. We captured 478 dasyurid marsupials of nine species, ranging in mean body mass from 5.75 to 93.50 g, at a capture rate of 1.71 per 100 trap‐nights. Capture rate varied across habitat and over time and the interaction between these two effects was also significant. Capture rate was highest on clay plain (3.35 captures/100 trap‐nights), followed by gibber plain (2.16 captures/100 trap‐nights) and lowest on sand habitat (0.54 captures/100 trap‐nights). Each species had a clear preference for one of the dominant habitat types. Dasyurid assemblages responded to high rainfall pulses in November–December 2008 and January 2015; however, the largest rainfall period in 2010–2011 resulted in very low captures. Likewise, a peak in abundance occurred in April 2008 although it was not preceded by high rainfall. We conclude that, although dasyurid marsupial capture rates varied up to 34 fold during the study period, population changes are not strongly tied to rainfall. Heterothermic physiology in this family, in particular the ability to use daily torpor to save energy, may be central to the decoupling of population dynamics from rainfall‐driven primary productivity.

Diet and behavior of the burrowing owl (Athene cunicularia) in Atiquipa, an ecosystem of Lomas in the south of Peru

Abstract. Luque-Fernández CR. 2019. Diet and behavior of the burrowing owl (Athene cunicularia) in Atiquipa, an ecosystem of Lomas in the south of Peru. Biodiversitas 20: 137-143. The study of trophic and behavioral habits is a fundamental aspect in the knowledge of the natural history of species, especially for those that present a wide range of distribution and that have to adapt to the habitats and available resources that can find to survive. The diet and behavior of Athene cunicularia were studied in a peculiar ecosystem such as the lomas formation, on the arid coast of southern Peru. The analysis of regurgitated pellets from a family group of Athene cunicularia was used and complemented with the monitoring of behavior through the use of trap cameras and direct observations. The results show that the diet during the months of study was based on a high proportion of invertebrate beetles (Tenebrionidae) and scorpions, also finding remains of vertebrates, including rodents, birds and highlighting the presence of a species of marsupial mouse. On the study of behavior, marked and recurrent activities are established during the day for this species, where grooming sessions are frequently reported, as well as interaction with a possible predator of this owl species. These results contribute to the understanding of the trophic relationship and its role in the studied lomas ecosystem, which is added to the importance of this species in the conservation of diversity in desert ecosystems.

Male semelparity and multiple paternity confirmed in an arid‐zone dasyurid

AbstractA fifth of all species in the carnivorous‐insectivorous marsupial family Dasyuridae show obligate male semelparity (die‐off), where males die after their first mating season, but females may breed in more than one season. Life history strategies of many species in the genera Antechinus and Phascogale are well known, but the other dasyurid genus with apparently obligately semelparous males, Dasykaluta, is poorly known, and there have been no demographic studies of this monotypic genus in the wild. Both sexes in Antechinus and Phascogale species are highly polygamous. Comparative and experimental tests of insectivorous marsupials indicate that this polygamy is linked to the evolution of semelparity in more strongly seasonal breeders, through intense sperm competition. We assessed whether the kaluta (Dasykaluta rosamondae), a small dasyurid endemic to the broader Pilbara region of Western Australia, has obligate male semelparity, multiple paternity within litters, and positive testis allometry in the wild. We documented complete die‐off of males over two breeding seasons. Multiple paternity was confirmed in seven of eight litters, where either two or three fathers sired young. The seven young in the remaining litter appeared to be sired by one male. Intraspecific positive testis allometry was found in adult males. We conclude that the life history strategies of wild male and female kalutas are consistent with those of the two other genera of dasyurids with obligate male semelparity (Antechinus and Phascogale), and sperm competition is likely to be important in the mating system of kalutas. Our results show that male obligate semelparity has evolved twice in dasyurids.

Male members of some endemic New Guinean dasyurid marsupials: they help resolve relationships

Penis morphology of 12 species of endemic New Guinean dasyurid marsupials, including the five currently recognized species of Murexia (M. habbema, M. melanurus, M. naso, M. longicaudata, and M. rothschildi); Phascolosorex dorsalis and Ph. doriae; Neophascogale lorentzii; and the four species of Myoictis (My. melas, My. wallacei, My. wavicus, and My. leucura), are described. Differences in form of the tip of the penis can be used to identify some of the species. The levator muscles are small in Murexia, Phascolosorex, and Neophascogale, and large in Myoictis. All species of Myoictis have accessory corpora cavernosa, which form an appendage to the penis. The anatomy of the penis of Myoictis spp. confirms a close relationship with the Australian dasyurid marsupial Parantechinus apicalis, as shown by a recent molecular study. Accessory corpora cavernosa appear to have arisen independently three times within the Dasyurinae.

Prey productivity and predictability drive different axes of life-history variation in carnivorous marsupials.

Variation in life-history strategies has usually been characterized as a single fast-slow continuum of life-history variation, in which mean lifespan increases with age at maturity as reproductive output at each breeding event declines. Analyses of plants and animals suggest that strategies of reproductive timing can vary on an independent axis, with iteroparous species at one extreme and semelparous species at the other. Insectivorous marsupials in the Family Dasyuridae have an unusually wide range of life-history strategies on both purported axes. We test and confirm that reproductive output and degree of iteroparity are independent in females across species. Variation in reproductive output per episode is associated with mean annual rainfall, which predicts food availability. Position on the iteroparity-semelparity axis is not associated with annual rainfall, but species in regions of unpredictable rainfall have longer maximum lifespans, more potential reproductive events per year, and longer breeding seasons. We suggest that these two axes of life-history variation arise because reproductive output is limited by overall food availability, and selection for high offspring survival favours concentrated breeding in seasonal environments. Longer lifespans are favoured when reproductive opportunities are dispersed over longer periods in environments with less predictable food schedules.

Evolution of the Carnassial in Living Mammalian Carnivores (Carnivora, Didelphimorphia, Dasyuromorphia): Diet, Phylogeny, and Allometry

Fil: Tarquini, Sergio Daniel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de La Rioja. - Secretaria de Industria y Mineria. Servicio Geologico Minero Argentino. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Cientificas y Transferencia Tecnologica de La Rioja; Argentina

Niche conservatism and phylogenetic clustering in a tribe of arid-adapted marsupial mice, the Sminthopsini.

The progressive expansion of the Australian arid zone during the last 20Ma appears to have spurred the diversification of several families of plants, vertebrates and invertebrates, yet such taxonomic groups appear to show limited niche radiation. Here, we test whether speciation is associated with niche conservatism (constraints on ecological divergence) or niche divergence in a tribe of marsupial mice (Sminthopsini; 23 taxa) that includes the most speciose genus of living dasyurids, the sminthopsins. To that end, we integrated phylogenetic data with ecological niche modelling, to enable us to reconstruct the evolution of climatic suitability within Sminthopsini. Niche overlap among species was low-moderate (but generally higher than expected given environmental background similarity), and the degree of phylogenetic clustering increased with aridity. Climatic niche reconstruction illustrates that there has been little apparent evolution of climatic tolerance within clades. Accordingly, climatic disparity tends to be accumulated among clades, suggesting considerable niche conservatism. Our results also indicate that evolution of climatic tolerances has been heterogeneous across different dimensions of climate (temperature vs. precipitation) and across phylogenetic clusters (Sminthopsis murina group vs. other groups). Although some results point to the existence of shifts in climatic niches during the speciation of sminthopsins, our study provides evidence for substantial phylogenetic niche conservatism in the group. We conclude that niche diversification had a low impact on the speciation of this tribe of small, but highly mobile marsupials.

Chromosome Evolution in Marsupials.

Marsupials typically possess very large, distinctive chromosomes that make them excellent subjects for cytogenetic analysis, and the high level of conservation makes it relatively easy to track chromosome evolution. There are two speciose marsupial families with contrasting rates of karyotypic evolution that could provide insight into the mechanisms driving genome reshuffling and speciation. The family Dasyuridae displays exceptional karyotype conservation with all karyotyped species possessing a 2n = 14 karyotype similar to that predicted for the ancestral marsupial. In contrast, the family Macropodidae has experienced a higher rate of genomic rearrangement and one genus of macropods, the rock-wallabies (Petrogale), has experienced extensive reshuffling. For at least some recently diverged Petrogale species, there is still gene flow despite hybrid fertility issues, making this species group an exceptional model for studying speciation. This review highlights the unique chromosome features of marsupial chromosomes, particularly for these two contrasting families, and the value that a combined cytogenetics, genomics, and epigenomics approach will have for testing models of genome evolution and speciation.

Seasonal morphometry of the vomeronasal organ in the marsupial mouse, Antechinus subtropicus.

ABSTRACTThe vomeronasal system consists of a peripheral organ and the connected central neuronal networks. The central connections are sexually dimorphic in rodents, and in some species, parameters of the vomeronasal organ (VNO) vary with sex, hormonal exposure, body size and seasonality. The VNO of the dasyurid marsupial mouse, Antechinus subtropicus is presumed to be functional. The unusual life history (male semelparity) is marked by distinct seasonality with differences in hormonal environments both between males and females, and in males at different time points. Body size parameters (e.g., length, weight) display sexual dimorphism and, in males, a pronounced weight gain before breeding is followed by a rapid decline during the single, short reproductive season. VNO morphometry was investigated in male and female A. subtropicus to identify possible life cycle associated activity. The overall length of the VNO is positively correlated with the size of the animal. The amount of sensory epithelium exhibits a negative correlation, decreasing with increasing size of the animal. The effects of sex and breeding condition are not obvious, although they do suggest that sensory vomeronasal epithelium mass declines in the breeding period. The VNO may be more important in A. subtropicus before breeding when it may participate in synchronising reproduction and in the development of the male stress response. J. Morphol. 277:1517–1530, 2016. © 2016 Wiley Periodicals, Inc.