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There are many limitations when using traditional laboratory species. Limits on variation, may result in limited outcomes, at both the species and individual level, due to different individuals/species having diverse physiological processes, or differing molecular and genetic mechanisms. By using a variety of model species, we will be able to develop creative solutions to biological problems and identify differences of which we were not previously aware. The laboratory mouse has been a suitable model species for various mammalian studies, however most are bred specifically for laboratory research with limited variability due to selective breeding. Marsupial models offer unique research opportunities compared to eutherian models. We believe that there should be an expansion in marsupial model species, and the introduction of the red-tailed phascogale (Phascogale calura), a dasyurid marsupial, should be one of them. Phascogales are easily managed in captivity, and there are now multiple studies involving their development, reproduction, nutrition, behavior and immune system, which can serve as a baseline for future studies. The addition of the phascogale as a model species will improve future mammalian studies by introducing variability and offer alternate solutions to biological problems, particularly in the areas of genetics, nutrition, immunology, the neuro-endocrine system, and ageing, due to their semelparous reproductive strategy and hence, subsequent predictive physiology. In this review, we provide information based on existing research on red-tailed phascogales to support their inclusion as a model species.

Hearing is essential for communication, to locate prey and to avoid predators. We addressed the paucity of information regarding hearing in Australian native mammals by specifically assessing the hearing range and sensitivity of the red-tailed phascogale (Phascogale calura), the kultarr (Antechinomys laniger) and the spinifex hopping-mouse (Notomys alexis). Auditory brainstem response (ABR) audiograms were used to estimate hearing thresholds within the range of 1–84 kHz, over a dynamic range of 0–80 dB sound pressure level (SPL). Phascogales had a hearing range of 1–40 kHz, kultarrs 1–35 kHz and hopping-mice 1–35 kHz, with a dynamic range of 17–59 dB SPL, 20–80 dB SPL and 30–73 dB SPL, respectively. Hearing for all species was most sensitive at 8 kHz. Age showed no influence on optimal hearing, but younger animals had more diverse optimal hearing frequencies. There was a relationship between males and their optimal hearing frequency, and greater interaural distances of individual males may be related to optimal hearing frequency. Because nocturnal animals use high-range hearing for prey or predator detection, our study suggests this may also be the case for the species examined in this study. Future studies should investigate their vocalizations and behaviour in their natural environments, and by exposing them to different auditory stimuli.

Expressed coding sequences for interleukin-6 (IL-6) and interleukin-6 receptor α (IL-6R) were examined in five marsupial species. Full length expressed coding sequences for IL-6 and IL-6R were identified and characterized in the gray short-tailed opossum (Monodelphis domestica). For IL-6, ∼225 bp fragments of the mRNA sequence were identified in the red-tailed phascogale (Phascogale calura), kultarr (Antechinomys laniger), and stripe-faced dunnart (Sminthopsis macroura), while ∼563 bp fragments of mRNA encoding IL-6R were identified in the red-tailed phascogale, kultarr, stripe-face dunnart and fat-tailed dunnart (Sminthopsis crassicaudata). Relative expression levels of IL-6 and IL-6R were examined in the heart, muscle, lung, liver, spleen and kidney of adult red-tailed phascogales, and IL-6 gene expression was found to be significantly higher in the lung and spleen than the other tissues examined, while the expression of IL-6R was significantly higher in the liver, lung and spleen. These results now serve as a reference point for examining the role and levels of IL-6 and IL-6R in the health and disease of these marsupial species. The pro-tumorigenic nature of IL-6 is of particular interest, and the identification of these IL-6 and IL-6R coding sequences provides a platform for further work to evaluate the potential role of IL-6 in marsupial cancers.

Marsupials are born immunologically premature, relying on cells and molecules in maternal milk for immune protection. Both immunoglobulin and complement proteins have been identified in marsupial milk, but the expression of specific complement proteins remains largely unexplored. We report partial cDNA sequences for two complement-activating proteins, C3, C1r, CFP and MASP2, in liver tissues from red-tailed phascogale (Phascogale calura). Conservation of functionally relevant motifs were identified in the translated cDNA sequences from phascogale C3, CFP and MASP2 and their eutherian homologues. Gene expression of representative molecules from each of the major complement pathways was also investigated in whole body tissues from 1 to 18 day old animals and liver tissues from 31-day to 14-month old animals. Average complement expression in whole bodies and liver tissues of C1r, CFP, MASP2 and C3 increased significantly in juveniles compared to pouch young, presumably due to the maturation of the young's own complement system. Comparing expression in liver tissues only, we found that the average CFP expression were higher in pouch young compared to juveniles, while results were still statistically similar to the average expression of all tissues for C1r, MASP2 and C3. The average complement expression then significantly decreased as the animals aged into adulthood.

ContextFeral cats have benefitted from effective control of foxes in south-western Australia and, consequently, their impact on some threatened mammal species has increased. Control of feral cats in the region can be enhanced by use of the Eradicat® cat bait, but its impact on non-target animal populations requires investigation before widespread use. AimsThe aim of the present study was to determine through field trials whether consumption of Eradicat® baits by resident red-tailed phascogales, following a broadscale baiting operation to control feral cats, was sufficiently frequent to cause significant rates of mortality in wild populations of phascogales. MethodsNine radio-tagged red-tailed phascogales were monitored through an Eradicat® baiting event to determine their survival. Removal and consumption of toxic and non-toxic rhodamine B-labelled baits by a range of species were monitored with camera traps and by subsequent trapping of red-tailed phascogales and other mammals to sample whiskers for evidence of rhodamine uptake. Key resultsAlthough some phascogales showed interest in baits and sometimes moved them from the deposition site, all radio-tagged phascogales survived for at least 1 week after baiting, by which time very few or no baits remained. Examination of whiskers sampled from individuals exposed to rhodamine-labelled baits showed that consumption of non-toxic Eradicat® baits by phascogales was negligible; only one phascogale of 62 sampled showed any rhodamine banding. ConclusionsThe present study provided no evidence that red-tailed phascogales in the study region are at risk from an Eradicat® baiting episode in autumn. ImplicationsThe risk to red-tailed phascogale populations through the use of Eradicat® baiting to control cats in their habitat in the Great Southern region of Western Australia is likely to be low. Further research to elucidate any impact of repeated baiting on populations of this species at several locations is recommended.

Background The red-tailed phascogale is a ‘Near Threatened’ dasyurid marsupial. Males are semelparous and die off shortly after the breeding season in the wild due to a stress-related syndrome, which has many physiological and immunological repercussions. In captivity, males survive for more than 2 years but become infertile after their first breeding season. Meanwhile, females can breed for many years. This suggests that captive males develop similar endocrine changes as their wild counterparts and undergo accelerated aging. However, this remains to be confirmed. The health status and immune function of this species in captivity have also yet to be characterized. Results Through an integrative approach combining post-mortem examinations, blood biochemical and hematological analyses, we investigated the physiological and health status of captive phascogales before, during, and after the breeding season. Adult males showed only mild lesions compatible with an endocrine disorder. Both sexes globally maintained a good body condition throughout their lives, most likely due to a high quality diet. However, biochemistry changes potentially compatible with an early onset of renal or hepatic insufficiency were detected in older individuals. Masses and possible hypocalcemia were observed anecdotally in old females. With this increased knowledge of the physiological status of captive phascogales, interpretation of their immune profile at different age stages was then attempted. During the breeding season, males developed a stress leukogram characterized by a marked lymphopenia, further aggravated by a severe leukopenia after the breeding season. To determine whether these changes were limited to the peripheral blood or had more profound implications, histopathology of the spleen was performed opportunistically. Adult males showed white pulp atrophy, at various degrees. The atrophy was mainly lymphoid and more severe in 1.5-year-old males than in 3.5-year-old females. These results suggest that captive males undergo accelerated immunosenescence. Conclusions Functional studies are now needed to characterize the underlying mechanisms leading to immunosenescence in marsupials. Semelparous dasyurids present great potential for studying the effects of sex and stress on immunity in marsupials. Characterization of these immune-endocrine interactions may help refine veterinary treatment plans, husbandry protocols and conservation programs to maintain the health of captive and wild populations.

Objective Marsupials suffer from an increasing number of stressors in this changing world. Functional studies are thus needed to broaden our understanding of the marsupial immune system. The red-tailed phascogale (Phascogale calura) is a small Australian marsupial previously used in descriptive immunological studies. Here, we aimed to develop functional assays by isolating and stimulating blood and spleen mononuclear cells in vitro. Results While peripheral blood mononuclear cell (PBMC) were relatively easy to isolate, only 105 mononuclear cells (> 90% purity and > 75% viability) could be recovered from the spleen, independently of the sex and age of the animal or the centrifugation time and speed tested. The pores of the mesh sieve used for tissue homogenization might have been too big to yield a single cell suspension. Nevertheless, in spite of the overall low number of cells recovered, PBMC and splenic mononuclear cells were successfully activated in preliminary trials with phytohemaglutinin. This activation state was evidenced by a change in shape and the presence of small cell aggregations in the mitogen-stimulated cultures. A non-radioactive colorimetric assay was also performed to confirm cell proliferation in these wells. This work highlights the importance of developing and reporting detailed methodological protocols in non-traditional research species.

Expressed coding sequences were identified for the T cell receptors TCRα, TCRβ, TCRγ, TCRδ, TCRμ, and co-receptors CD3e, CD4, and CD8α in the red-tailed phascogale (Phascogale calura). Expression of these genes was examined in the developing thymus and spleen of pouch young and juvenile individuals to detect any changes in expressionrelative to developmental stages. Transcripts of CD3e, CD4, TCRδ and TCRμ were first detected in the thorax at 1 day postpartum (dpp), and transcripts of all target genes were detected in the thymus from 3 dpp, and the spleen from 17 dpp. The relative expression of all target genes changed significantly over the course of pouch life and was associated with histological milestones of both the thymus and the spleen. Peak gene expression was observed early in pouch life in the thymus, with a decrease in expression associated with timing of thymic involution, while expression peaked later in the spleen and was associated with the initial differentiation of the red and white pulp and a population of T cells forming the periarterial lymphatic sheath (PALS). Active expression of these target genes within the thymus and spleen indicates that the young marsupials are actively developing immunocompetence during pouch life.

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.

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.

Very few assays that are used to assess the status of mammalian immunity have proved useful for assessment of marsupial health and/or diagnosis of disease. This is largely due to the lack of species cross-reactive reagents that underpin such experiments. To begin to address this deficit, we describe the activation of classical and alternative complement pathways of red-tailed phascogales (RTP; Phascogale calura). Using standard haemolytic assays, the existence of both complement pathways were established in RTP serum based on its ability to lyse unsensitised rabbit erythrocytes (RbE) and sensitised sheep erythrocytes (SE), respectively. The alternative complement pathway assays were conducted using pooled serum of male and female RTPs, and the remaining RTP sera were opportunistically used to test the presence of a functional classical complement system in individual animals, a first in non-eutherian animals. Observations from this study suggest that the activation of these two complement pathways in RTPs are comparable to that seen in other mammals. Since this assay was able to be used on very small samples of blood, it could serve as a useful tool to gather data for comparative immunological studies and to further our knowledge of the mechanisms of immunity available to marsupial young.

We report the capture of individuals of two species of phascogale (Phascogale tapoatafa wambenger and P. calura) at the same locations within the same habitat and during the same survey event, something that has not been reported previously. This would suggest that these species may occur in sympatry where their distributions overlap. Further investigations are required to confirm the extent of sympatry as this could have implications for the conservation and management of both species.

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 (34.7 g) 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 ± 0.076 mL O2 g−1 h−1), evaporative water loss (1.68 ± 0.218 mg H2O g−1 h−1) and wet thermal conductance (3.8 ± 0.26 J g−1 h−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.

Lyn is a tyrosine kinase molecule required for modulation of signalling cascades in cell populations including B lymphocytes of the mammalian immune system. We have characterised the coding domain of the marsupial lyn gene of two macropod marsupials; the Tammar Wallaby (Macropus eugenii) and the Bridled Nailtail Wallaby (Onychogalea fraenata) and show the co-expression of two Lyn isoforms in cells and tissues of these and three other marsupials (Brush-tail Possum, Trichosurus vulpecula; American Grey Short-tailed Opossum, Monodelphis domestica and Red-tailed Phascogale, Phascogale calura). The predicted Lyn proteins (LynA and LynB) were highly conserved across vertebrate species, with amino acid identities of 94% with their human orthologues and conservation of key tyrosine kinase motifs that suggests that marsupial Lyn most likely functions in cell signalling. Comparison of our cDNA data to annotations for Lyn transcripts (available through the Ensembl Genome Browser) for the Tammar Wallaby confirm splice sites for a number of exons in the wallaby transcript that are missing from the current annotation. This is the first report of the expression of kinase signalling molecules that influence immunity in metatherian mammals and provides key information to support ongoing studies of immune regulation in marsupials.

Antimicrobial substances in serum include circulating complement proteins and acute phase proteins (APPs). We identified gene sequences for APPs, haptoglobin (Hp), C-reactive protein (CRP) and serum amyloid A (SAA) in marsupial genomes. Hp and SAA levels were measured in red-tailed phascogale ( Phascogale calura ) sera using commercially available assays. Hp levels were higher in males than females, while SAA levels suggest the phascogales used in this study were healthy. Serum was co-cultured with four bacterial species. Bacterial growth was inhibited after incubation at 37 °C, however effectiveness differed with bacteria and incubation time. The least amount of bacterial growth was noticed after introduction to K. pneumoniae , and most when introduced to P. aeruginosa . Despite marsupials not having mature immune tissues at birth, and unable to mount specific immune responses, this study suggests other immune strategies, such as APPs in serum likely aid marsupials in their defence against pathogens.

BackgroundReference genes serve an important role as an endogenous control/standard for data normalisation in gene expression studies. Although reference genes have recently been suggested for marsupials, independent analysis of reference genes on different immune tissues is yet to be tested. Therefore, an assessment of reference genes is needed for the selection of stable, expressed genes across different marsupial tissues.MethodsThe study was conducted on red-tailed phascogales (Phascogale calura) using five juvenile and five adult males. The stability of five reference genes (glyceraldehyde-3-phosphate dehydrogenase,GAPDH;β-actin,ACTB;18SrRNA,18S; 28SrRNA, 28S;and ribosomal protein L13A,RPL13A) was investigated using SYBR Green and analysed with the geNorm application available in qBasePLUSsoftware.ResultsGene stability for juvenile and adult tissue samples combined show thatGAPDHwas most stable in liver and lung tissue, and18Sin small intestine and spleen. While all reference genes were suitable for small intestine and spleen tissues, all reference genes except28Swere stable for lung and only18Sand28Swere stable for liver tissue. Separating the two age groups, we found that two different reference genes were considered stable in juveniles (ACTBandGAPDH) and adults (18Sand28S), andRPL13Awas not stable for juvenile small intestine tissue. Except for28S, all reference genes were stable in juvenile and adult lungs, and all five reference genes were stable in spleen tissue.DiscussionBased on expression stability,ACTBandGAPDHare suitable for all tissues when studying the expression of marsupials in two age groups, except for adult liver tissues. The expression stability between juvenile and adult liver tissue was most unstable, as the stable reference genes for juveniles and adults were different. Juvenile and adult lung, small intestine and spleen share similar stable reference genes, except for small intestine tissues where all reference genes were stable in adults butRPL13Awas not suitable in juveniles.

Red-tailed phascogales Phascogales calura are near-threatened (Friend, 2008) arboreal Dasyurids. A breeding programme was established at Alice Springs Desert Park in 2001 to aid species recovery. Twenty-five captive-bred phascogales were released into a suitable habitat at the park in 2006. If shown to be successful, the initial release was to be expanded with the release of further captive-bred phascogales into a suitable habitat in the nearby National Park and into South Australia. In this study, a dietary analysis was conducted to determine the preferred diet of the translocated phascogales in the park environment. Scats were collected during July–October, 2006 and January–March, 2007 from nesting sites within the park. Faecal samples were weighed, soaked in hot water and particles were separated through sieves before examination under a microscope. Scat analysis methods identified that red-tailed phascogales were primarily insectivorous with 92.6% of all scats containing arthropods. They are also opportunistic predators within the park, consuming birds (51.6%), small mammals (33.3%) and on occasion reptiles, and plant material (27.4%). Seasonal comparison of data through SIMPER analyses showed there was significant variation (P=0.009) between spring and summer, due to a large portion of birds present in the diet in spring. The red-tailed phascogale is able to exploit a number of prey types and it is therefore likely that they would survive a ‘hard’ translocation into the wild provided the site chosen has adequate food supply.

The red-tailed phascogale (Phascogale calura) is an endangered dasyurid from southwestern Western Australia that has been bred in captivity since 2001. It is an annual breeder that has a restricted breeding period, and males only participate in a single breeding season. We examined the reproductive biology of female red-tailed phascogales, assessing methods for detection of estrus, variation in the timing of breeding in captivity across facilities and years, and reproductive success. Body mass and pouch changes were useful indicators of estrus, whereas assays for fecal estradiol and progesterone did not allow for accurate prediction of ovulation. Females mated with multiple males and matings occurred over a period of at least 5 days, with females storing sperm in the lumen and crypts of the oviduct. Births tended to occur in July at Alice Spring Desert Park, with births at Adelaide Zoo occurring from early June to late August. The predictable births at Alice Springs are similar to those observed with Antechinus, but with flexibility remaining in the reproductive strategy of the species as observed at Adelaide. Of the 146 breeding females at Alice Springs, 127 females produced 846 pouch young, of which 68% were weaned. A female bias was observed in weaned young. Information gained from this study has been incorporated into the captive-breeding program for this species.

The life histories of carnivorous marsupials, or dasyurids, make them useful subjects for studying maternal investment, such as sex ratio and lactational investment. One group of annual breeding dasyurids are male semelparous, strongly sexually dimorphic, produce large litters that weigh two to three times the weight of the mother at weaning and show biases in siring success and sex ratio. Red-tailed phascogales Phascogale calura belong to this group and in captivity they have shown biases in siring success with body weight. The growth rates of young of this species were investigated to determine whether sex-biased maternal investment occurs. No relationship was evident between maternal weight and the sex ratio of young, indicating no sex-ratio adjustment with maternal condition. In contrast, a positive relationship was evident between maternal weight and the weight of offspring at weaning, with weaning weight being correlated with weight at maturity. Dimorphism in weight emerged during suckling, with an average dimorphic ratio of 1.5 achieved by maturity. In contrast, dimorphism in skeletal measures did not emerge until after weaning, with an average dimorphic ratio of 1.14 achieved by maturity. The sex differences in growth during suckling provide support for a male bias in maternal investment.

The cyto- and chemoarchitecture of the cerebral cortex has been examined in three small (mouse-sized) polyprotodont marsupial carnivores from Australia (the stripe-faced dunnart, Sminthopsis macroura; the brown antechinus, Antechinus stuartii; and the red-tailed phascogale, Phascogale calura) in order to compare the cortical topography of these marsupials with that of diprotodontids, didelphids and eutherians. All three species studied had similar cortical cytoarchitecture. The isocortical surface was dominated by primary somatosensory (S1) and visual (V1) areas. Putative secondary sensory areas (S2, V2M, V2L) were also identified. The primary somatosensory cortex demonstrated clumps of granule cells in the presumptive mystacial field, whereas the primary visual area showed a distinctive chemical signature of intense calbindin immunoreactivity in layer IV. On the other hand, the primary auditory area was small and indistinct, but flanked by a temporal association area (TeA). A cytoarchitecturally distinct primary motor cortex (M1) with prominent pyramidal neurons in layer V and poor layer IV was identified medially to S1, and at rostral levels a putative secondary motor area was identified medial to M1. Transitional areas between isocortex and allocortical regions showed many cyto- and chemoarchitectural similarities to those reported for eutherian (and in particular rodent) cortex. Medially, two cingulate regions were found at rostral levels, with dysgranular and granular ‘retrosplenial’ areas identified caudally. Laterally, granular and agranular areas surrounded the rostral rhinal fissure, to be replaced by ectorhinal and perirhinal areas caudally. The findings indicate that the cyto- and chemoarchitectural features which characterize the iso- and allocortex in these small marsupial carnivores are similar to those reported in didelphids and eutherians and our findings suggest the existence of putative dedicated motor areas medial to the S1 field.

44. Red-tailed Phascogale Phascogale calura French: Petit Phascogale / German: Kleine Pinselschwanzbeutelmaus / Spanish: Fascogalo de cola roja Other common names: Red-tailed \Wambenger Taxonomy. Phascogale calura Gould, 1844, Williams River, Military Station, Western Australia, Australia. The type specimen of P. calura was collected by J. Gilbert at the “Military Station on the Williams River,” 150 km south-east of Perth (Western Australia’s capital) in 1843, the early years of European settlement. J. Gould formally named the species a year later. At the time of capture, Gilbert commented “I was indebted to a domestic cat who had captured it in the night. The soldiers informed me that they had often met with it in the storeroom of the Station, but they could give me no other information respecting it, except that specimens with much larger or bushier tails were sometimes seen.” Subsequent surveys extended the species’ distribution to the junction of the Murray and Darling rivers in eastern Australia by the mid-19" century, to central Australia in the late-19"™ century, and to the Canning Stock Route in Western Australia in 1931. A live specimen was also apparently taken around Adelaide at some time before 1888. Nevertheless, for all localities other than south-western Western Australia, these were the first and last records for the species. In 2001, measurements of genetic differ entiation among P. calura, P. tapoatafa, and P. pirata (then recognized as the subspecies Pt. pirata) were estimated using mtDNA (cytochrome-b gene); 16% sequence divergence separated P. caluraand P. tapoatafa, which supported clear morphological distinctions between the two species. P. caluraand P. pirata averaged 14-6% genetic divergence, which is also corroborated by their clear morphological distinction. Monotypic. Distribution. SW Australia, now entirely confined to the Southern wheat belt region in Western Australia. Descriptive notes. Head-body 10-5-12:2 cm (males) and 9.3-10.5 cm (females), tail 13.4-14.5 cm (males) and 11.9-14.4 cm (females); weight 39-68 g (males) and 38-48 ¢ (females). The Red-tailed Phascogale is ashy gray above and cream to white below; there is a blackish patch in front of eye. Ears and upper proximal part oftail are distinctive reddish brown; distal half oftail has a brush of long black hairs. Habitat. A variety of habitats with greater canopy density and greater abundance of hollows than unoccupied sites. Red-tailed Phascogales are found in isolated patches of forest that receive 300-600 mm of rain/year. They prefer habitats that are generally denser and taller climax vegetation within wandoo (Eucalyptus wandoo, Myrtaceae) and rock sheoak (Allocasuarina huegeliana, Casuarinaceae); hollows in wandoo provide nesting sites. One study found that the Red-tailed Phascogale occurs mostly in woodland habitat with old-growth hollow-producing eucalypts, primarily wandoo or york gum (E. loxophleba). Records from the periphery of its current distribution appear to represent a broader variety of habitats, including shrublands, mosaics of woodland, and scrub-heath. Red-tailed Phascogales occupy areas of remnant vegetation of varying sizes from very small to very large, many on privately owned agricultural land. Large connected areas, such as riverine corridors and stands of upland remnant vegetation, appear important to long-term persistence of the Red-tailed Phascogale; however, sites isolated by increasing distance from other occupied sites tended to be unoccupied by the Red-tailed Phascogale. Food and Feeding. Like its congeners, the Red-tailed Phascogale is arboreal. It can leap up to 2 m, covering considerable distances while foraging in the forest canopy. Red-tailed Phascogales often feed on the ground and are opportunists, taking a wide variety of insects and spiders (preferring prey less than 1 cm in length); they will also eat small birds and mammals (particularly the House Mouse, Mus musculus). Prey satisfies water requirements. One study examined feces from Red-tailed Phascogales that had been translocated to the Alice Springs Desert Park; they were primarily insectivorous, with 92:6% of all feces containing arthropods. They also consumed birds (51:6% of feces), small mammals (33-:3%), plant material (27-4%), and occasionally reptiles; birds were a large proportion of the diet in spring. Breeding. Female Red-tailed Phascogales show an increase in weight prior to estrus, and mating occurs during a three-week period in July. Captive copulations haves lasted up to six hours. Individual females may be receptive to males for at least five days, and births may be tightly synchronized or spread over a couple of weeks. Females are able to store viable sperm for at least four days prior to ovulation; gestation is 28-30 days. Females ovulate c.16 eggs, with up to 13 young observed at birth, despite availability of only eight teats. At least two males can sire young within a single litter. Unlike males, which all die synchronously at the conclusion of breeding, female Red-tailed Phascogales are capable of surviving and reproducing in a second or even third season. At birth, young weigh c.15 mg and are c¢.5 mm long. Fur on young begins to appear at c.34 days, and young first detach from teats while in a nest at c¢.45 days. Weaning of young occurs at ¢.90 days when they weigh c.20 g. In the wild, males live for only 11-5 months (similar to male Antechinus, the sister genus). Captive males can survive for up to five years. A recent study reported successful captive breeding in four-year-old female Red-tailed Phascogale; females can survive until at least five years of age in captivity. These findings have implications for captive breeding programs, providing evidence that older females can be successfully bred. Males are reproductively senescent after their first breeding season. Prior to mating, male germ cells needed for production of sperm are depleted, and sperm production ceases. Sperm stored in the epididymis during the mating period thus sires the next generation. Activity patterns. Red-tailed Phascogales are mainly nocturnal, but they have been seen emerging during the day to investigate potential food sources. Movements, Home range and Social organization. Home ranges of male Red-tailed Phascogales increase about tenfold during the mating period. Home ranges of females remain at c.8 ha. Status and Conservation. Classified as Near Threatened on The IUCN Red List. Listed as endangered in Australia. There are probably fewer than 10,000 mature Red-tailed Phascogales in the wild, and the overall population may be decreasing. Rate of decrease is likely less than 10% over ten years, so it is close to qualifying as Vulnerable under criterion C of the IUCN. Populations of Red-tailed Phascogales apparently fluctuate with rainfall. There are no apparent current population declines, but there were large declines historically. Survival of Red-tailed Phascogales in Western Australia may be related to presence of Gastrolobium and Oxylobium, legume-like plants that produce monosodium fluoracetate (‘1080’), a chemical that can be lethal to introduced species. Native species have evolved a tolerance to the fluoroacetate; their bodies can contain enough of it to poison introduced carnivores, such as the Red Fox (Vulpes vulpes), that pose threats to their survival. Too frequent burning of forests also negatively affects survival of the Red-tailed Phascogale by destroying nesting hollows and dense, protective foliage. Suitable habitat for the Red-tailed Phascogale appears widespread, but it is under threat over the longer term. Increasing dryland salinity in lowland areas, loss of dense stands of rock sheoak in upland areas, and continuing loss of corridors of vegetation along roadsides due to road widening contribute to loss of habitat and habitat connectivity. The Red-tailed Phascogale now occupies less than 1% ofits former distribution. Today, it occurs in parts of the Avon Wheatbelt, Jarrah Forest, Mallee, and Esperance Plains bioregions. Red-tailed Phascogales persist only in areas that have been extensively cleared for agriculture and where remaining bush land is highly fragmented. It does not appear to extend into unfragmented habitat in the Jarrah Forest to the west or Mallee region to the east. Predation by domestic and feral cats and red fox also reduce numbers of Red-tailed Phascogale. Taken together, these factors, particularly fragmentation and lack of suitable nesting hollows, suggest that the long-term persistence of Red-tailed Phascogales in areas beyond the wandoo belt is far from assured. One study on a translocated population found that Red-tailed Phascogales are able to exploit various prey types and therefore are likely candidates to survive a “hard” (without acclimation prior to release) translocation into the wild, provided the site chosen had adequate food supply. Bibliography. Bradley (1997), Bradley et al. (2008), Foster & Taggart (2008), Foster et al. (2006), Friend (2008b), Gould (1844, 1863), Kitchener (1981), Short & Hide (2012), Short et al. (2011), Spencer et al. (2001), Stannard, Borthwick et al. (2013), Stannard, Caton & Old (2010)., Published as part of Russell A. Mittermeier & Don E. Wilson, 2015, Dasyuridae, pp. 232-348 in Handbook of the Mammals of the World – Volume 5 Monotremes and Marsupials, Barcelona :Lynx Edicions on pages 324-325, DOI: 10.5281/zenodo.6608102

Reproduction and especially lactation are nutritionally costly for mammals. Maternal access to adequate and optimal nutrients is essential for fecundity, survival of offspring, and offspring growth rates. In eutherian species energy requirements during lactation can be heavily dependent on litter size and the body mass of the female. In marsupials litter size does not appear to affect nutritional requirements during lactation; however, studies of marsupial nutritional requirements during lactation are rare. Marsupials are distinct from eutherians as they give birth to young at a much more underdeveloped state and the majority of their investment into the growth of their offspring occurs postnatally. Nutritional requirements of adult female red-tailed phascogales (Phascogale calura) were measured to determine the differences between those lactating and not lactating. On average females that were lactating had maintenance energy requirements of 1728 ± 195 kJ kg(-0.75) d(-1), double that of non-lactating animals. There was no significant correlation between energy requirements and litter size among lactating female phascogales. Apparent absorption of macronutrients did not differ between lactating and non-lactating individuals. The study has shown that food needs to be increased by at least double during late lactation. Litter size appears to have no influence on maternal nutrient requirements when food is available ad libitum and offspring in smaller litters grow faster than those in larger litters.

Diversity in major histocompatibility complex (MHC) genes can be correlated with the level of immunological fitness of an individual or group of individuals. This study tested published primer sets designed to amplify fragments of the MHC Class II DAB and DBB genes to amplify the equivalent gene fragments in red-tailed phascogales (Phascogale calura). Seventeen genomic DNA samples extracted from phascogale muscle tissue were used to amplify the initial DAB and DBB fragments; however, only DAB PCR proved successful. The fragments were 172 bp in length between the primers and had a high level of identity to other known marsupial MHC Class II DAB gene sequences (89–98%), including those of the koala (Phascolarctos cinereus), Tasmanian devil (Sarcophilus harrisii), common brushtail possum (Trichosurus vulpecula) and several wallaby species. Multiple sequence alignment revealed limited variability of MHC Class II genes between the individuals, but eight individual sequences in total. Genomic DNA was subsequently extracted from three fresh red-tailed phascogale scat samples and DAB fragments successfully amplified. The technique will allow for red-tailed phascogales to be sampled non-invasively in the wild and to determine the level of MHC diversity among individuals in the population.

A population of the red-tailed phascogale (Phascogale calura), a marsupial with a restricted distribution, was studied during a three-year period at a small reserve in the South-Western Wheatbelt of Western Australia. This species shows a life-history pattern which is typical of many Antechinus species and is characterized by a synchronized winter mating period followed by a complete male post-mating mortality. Mating occurs during a three-week period in July. In the field, males live only 11.5 months while females may live up to 36 months. Females are monoestrous and polyovular and have eight teats which are usually all occupied by pouch young. The production of supernumerary young is common. Pregnant females become aggressive toward the males.

Red-tailed phascogales (Phascogale calura) were reintroduced to Wadderin Sanctuary in the eastern wheatbelt of Western Australia in April 2009 with individuals sourced from remnant native vegetation on farmland some 180 km to the west. Their establishment was monitored initially by radio-telemetry and trapping, and subsequently by the checking of nest boxes both within and outside the sanctuary. Translocated phascogales established well and bred successfully in their first season. Phascogales remain extant at Wadderin more than five years after release and appear to be abundant and to occupy all available habitat. They have spread beyond the fenced sanctuary to adjoining woodland and to shrubland and woodland habitat in a remnant 1.4 km away. Comparison with two other reintroductions of this species (one apparently successful, one not) suggests management and habitat factors that may have contributed to the outcomes.

The lymphoid tissues of the red-tailed phascogale (Phascogale calura) were examined using histological and immunohistochemical techniques. The distribution of immune cells in the tissue beds was documented using antibodies to surface markers CD3 and an MHC Class II antigen (equivalent to HLA DRII). Spleen, gut-associated lymphoid tissues (GALT), lung, bronchus-associated lymphoid tissue (BALT) and liver were examined. The spleen had defined areas of red and white pulp, with follicles containing tingible-bodied macrophages. Anti-CD3 and anti-HLA DRII antibodies revealed the presence of T cells in areas of white pulp and around the peri-arterial lymphatic sheaths. GALT and BALT were detected and appeared as scattered areas of lymphocytes in the tissues beds. This is the first study to report on the lymphoid tissues of this endangered species of marsupial and the first report of the capacity of anti-human antibodies to a surface MHC molecule to react with Dasyurid cells.

This paper reports successful breeding by 4-year-old female red-tailed phascogales (Phascogale calura) and that they can survive until at least 5 years of age in captivity, whilst males can survive until at least 2 years of age in captivity. These findings have implications for captive breeding programs, providing evidence that older females can be successfully bred. In the longer term we hope these findings may aid conservation efforts of this endangered dasyurid.

The red-tailed phascogale once extended widely across semiarid and arid Australia, but is now entirely confined to the southern wheatbelt of Western Australia, occupying less than 1% of its former range. Here it occurs in a portion of the Avon Wheatbelt, Jarrah Forest, Mallee, and Esperance Plains biogeographical regions. The species persists only in areas that have been extensively cleared for agriculture and where the remaining bushland is highly fragmented. It does not appear to extend into unfragmented habitat in either the Jarrah Forest to the west or Mallee region to the east. It occurs primarily in woodland habitat with old-growth hollow-producing eucalypts, primarily wandoo (Eucalyptus wandoo) or York Gum (E. loxophleba), but records from the periphery of its current range appear to come from a broader range of habitats, including shrublands and various mosaics of woodland, shrubland, and scrub-heath. Key factors limiting persistence are likely to be fragmentation of habitat that is likely to greatly increase the risks associated with dispersal, a shortage of suitable nesting hollows in many vegetation associations, and predation by feral and domestic cats and by foxes. These factors, particularly fragmentation and lack of suitable nesting hollows, suggest that the species’ long-term persistence in areas beyond the wandoo belt is far from assured.

Context The red-tailed phascogale once occurred widely across semiarid and arid Australia, but is now confined to the southern wheatbelt of Western Australia. Its apparently extensive former range suggests a broad habitat tolerance, yet it is now reported primarily from remnant vegetation within farmland containing wandoo Eucalyptus wandoo and rock sheoak Allocasuarina huegeliana associations. Aims To establish the habitat requirements of phascogales with a view to understanding their current and likely future distribution and status. Methods We established presence or absence of phascogales at a number of sites within their current range, primarily by trapping, and then compared habitat attributes between the two classes of sites to establish those of apparent significance to species persistence. Key results Phascogales are widespread in suitable upland (wandoo–rock sheoak) and lowland habitat (riverine fringing vegetation of swamp sheoak Casuarina obesa, York gum E. loxophleba and wandoo). They occupy areas of remnant vegetation of varying sizes from very small to very large, many on private agricultural land. Large connected areas, such as riverine corridors and clusters of upland remnants appear important to their long-term persistence. Sites isolated by increasing distance from another occupied site tended to be unoccupied. Habitats occupied by phascogales typically had a greater canopy density and greater abundance of hollows than unoccupied sites. The presence of plants of the genus Gastrolobium, often cited as a key factor in the persistence of phascogales, did not appear to influence the presence or absence of phascogales. Conclusions Red-tailed phascogales currently occupy a broader range of habitats than identified in the literature and the role of some key aspects of habitat in protecting them from further decline may have been overstated. The presence of suitable hollows for nesting and shelter and a dense mid-storey canopy, perhaps to protect from predation by owls, are key features of suitable phascogale habitat. Implications Suitable habitat for phascogales appears widespread in the surveyed portion of the remaining range of the species, but is under threat over the longer term. Increasing salinity in lowland areas (which transforms woodland to samphire with a consequent long-term loss of nesting hollows), lack of fire in upland areas to maintain dense stands of rock sheoak and the increasing loss of corridors of vegetation along roadsides due to the widening of roads by local councils are all contributing to loss of habitat and habitat connectivity.

Digestibility was studied in the red-tailed phascogale (Phascogale calura) and the kultarr (Antechinomys laniger), small insectivorous/carnivorous marsupials, to determine their nutrient requirements in captivity. The marsupials were fed a range of insects, rat (Rattus rattus) and small carnivore food (Wombaroo). Digestibility experiments were conducted for a total of 12 days, which incorporated a five-day adjustment phase followed by a seven-day collection period. The apparent digestibility values for the phascogale and kultarr were above 81% for dry matter, energy, protein and lipids on all diets provided. No significant difference was found between phascogales and kultarrs on the same diet with respect to apparent digestibility of dry matter, energy, protein and lipids. The apparent absorption of minerals varied for each diet for the phascogale and kultarr. Maintenance energy requirements were determined to be 954 kJ kg0.75 day–1 for the red-tailed phascogale and 695 kJ kg0.75 day–1 for the kultarr. Presented here are the most comprehensive data on diet digestibility for dasyurids thus far.

Phascogale calura Gould, 1844. Proc. Zool. Soc. Lond., 1844:104. TYPE LOCALITY: Australia, Western Australia, Williams River, Military Station. DISTRIBUTION: Inland SW Western Australia, formerly in Northern Territory, South Australia, NW Victoria, SW New South Wales, but probably extinct in all places except the Western Australia wheat belt. STATUS: IUCN - Indeterminate; limited distribution, vulnerable., Published as part of Colin P. Groves, 1993, Order Dasyuromorphia, pp. 29-37 in Mammal Species of the World (2 nd Edition), Washington and London :Smithsonian Institution Press on page 33, DOI: 10.5281/zenodo.7353066

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.

An investigation was made into the factors which lead to an elevation in plasma free cortisol concentration during the last weeks of life of males in natural populations of the red-tailed phascogale Phascogale calura . The dexamethasone suppression-test was employed to examine the glucocorticoid feedback control of plasma cortisol both before and during the breeding season. In both sexes ACTH alone or in combination with dexamethasone caused an elevation in the plasma concentration of cortisol, corticosterone and free cortisol. Dexamethasone administration in both males and females resulted in significant decreases in the plasma concentration of each of the glucocorticoid groups both before and during the first week of the breeding season (June and early July), however during the last week of breeding (late July) dexamethasone decreased the plasma glucocorticoid concentration of females but not of males. Administration of ACTH caused a significant elevation in the plasma cortisol concentration in all groups. However, the magnitude of this response diminished with time in both sexes. Dexamethasone treatment resulted in a decrease in the plasma testosterone concentration in males before and early in the breeding season however toward the end of breeding this effect was abolished. It is apparent that towards the end of the breeding season and during the last week of life of the males, glucocorticoid feedback control of ACTH is almost abolished. These changes, which occur only in the males late in the breeding season and near the time of their disappearance from the population, are consistent with a condition known as end organ resistance to steroid hormones.

The red-tailed phascogale (Phascogale calura) is an endangered dasyurid species that has recently been brought into captivity in an effort to increase numbers before release back into the wild. As part of investigations into the reproductive biology of the species, information on the growth and development of young was collected throughout lactation from litters raised in three separate colonies. Growth curves for aging young throughout lactation and a timetable of developmental changes were constructed. While two colonies, with fourth- and fifth-generation captive animals, showed no significant difference in growth, animals from a third colony that had been wild caught before breeding displayed a slower rate of growth from 34 days of age. The pattern of development resembled that of other dasyurids, with young left in the nest from 44 days of age, fully furred by 78 days and weaned between 90 and 110 days. Captive phascogales invest heavily in their young, with litters weighing 380 ± 67% of maternal bodyweight at weaning.

An investigation was made of endocrine changes occurring during the life history of Phascogale calura, a small, arboreal, squirrel-like insectivorous marsupial. Following a 3-week mating period in July each year, all males disappear from the population and it is presumed that they die. During the mating period the plasma cortisol concentration in males increased to a greater extent than did the plasma corticosterone. During this period the plasma concentration of CBG decreased in the males but not in the females, which resulted in competition between the two glucocorticoids for binding sites and a 25-fold sex difference in free cortisol concentration. The plasma testosterone concentration in males reached its maximum value about the time of disappearance of the males and the plasma lacked high-affinity binding for androgens. The depression in CBG concentration was androgen dependent since castration of captive males caused a marked increase in plasma CBG concentration which could be reversed with androgen administration. Postmorten examination of moribund males revealed evidence of hemorrhage from gastric ulcers and some evidence of immune suppression and disease. It is considered that a state of stress in males triggered by aggressive interactions following an elevation in plasma testosterone concentration during mating and antagonized by an androgen-dependent decrease in CBG concentration results in suppression of both immune and inflammatory reactions. This is the first detailed description of endocrine changes which accompany a stress-related total male mortality in a dasyurid marsupial species which does not belong to genus Antechinus.

Phascogale calura Gould, 1844. Proc. Zool. Soc. Lond., 1844:104. TYPE LOCALITY: Australia, Western Australia, Williams River. DISTRIBUTION: Inland S. W. Western Australia, Northern Territory, South Australia, N. W. Victoria, S.W. New South Wales. ISIS NUMBER: 5301402002012001001., Published as part of James H. Honacki, Kenneth E. Kinman & James W. Koeppl, 1982, Order Marsupialia, pp. 18-51 in Mammal Species of the World (1 st Edition), Lawrence, Kansas, USA :Alien Press, Inc. & The Association of Systematics Collections on page 30, DOI: 10.5281/zenodo.7353009

The metabolic rates and water fluxes of free-living Phascogale calura were determined with doubly labelled water. The highest rates of water influx occurred in October, when the adult population consisted of lactating females only. The highest metabolic rates occurred in June, and the lowest rates of both water influx and metabolism occurred in March. The value of the data in designing toxic baits for the control of foxes or other exotic pests, while minimising the hazard to phascogales of accidental poisoning, is discussed.

The tolerances to sodium fluoroacetate (1080) were estimated for Dasyurus geoffroii (LD*50, ca. 7.5 mg 1080 kg-1), D. hallucatus (ca. 7.5 mg kg-1), Antechinus flavipes (ca. 11.0 mg kg-1) and Phascogale calura (ca. 17.5 mg kg-1) from Western Australia and comparisons were made with D. viverrinus (ca. 1.5 mg kg-1) and A. flavipes (ca. 3.5 mg kg-1) from south-eastern Australia. The species from Western Australia have had evolutionary exposure to naturally occurring fluoroacetate and were more tolerant to the toxin than dasyurids from south-eastern Australia, Presumably, they have acquired this tolerance through feeding on prey which had fed on plants containing fluoroacetate.

Blood samples were taken from a wild population of red-tailed phascogale Phascogale calura at intervals up until the annual post-mating disappearance of males. While sexual dimorphisms in haematological and blood chemical values were not found, there were detected some age-related changes. Reductions in haematocrit and haemoglobin concentration between mid- and late-July were detected both in females and males but contrary to the finding in another small dasyurid sharing this unusual life history pattern, these decreases in the males could not be described as anaemias. The changes in erythrocyte parameters in the blood of females at about this time conform to the pattern of a macrocytic anaemia which may be nutritionally based. A marked lymphocytopenia and neutrophilia observed at the end of July in males, but not in females, is consistent with other evidence of the development of a stress response.