Bandicoot Isoodon Macrourus Research Articles

Camera trapping ekes out some improvement for surveying sparse mammal populations in northern Queensland

Monitoring is a critical component of conservation land management and the choice of methods can influence the final inventory of species recorded. The use of camera trapping has increased in recent years as a cost-effective method to record more species and to identify more cryptic and rare species. In this study we first examined data from detailed field surveys (which did not employ camera trapping) in northern Queensland to examine the abundance and frequency of mammals detected by cage, box and pitfall traps, and spotlighting. We then used data from an additional set of sites that compared these methods with camera trapping. Twenty-five species were recorded in the first data set and 26 species were recorded in the second. Overall, mammals were recorded in exceedingly low numbers, and camera trapping only improved the detection of some species such as larger species that could not be trapped (i.e. dingo Canis familiaris and pig Sus scrofa) or were uncommon (i.e. northern quoll Dasyurus hallucatus and northern brown bandicoot Isoodon macrourus). Our results suggest that survey effort should be substantial and use the most suitable methods to identify management, threat and habitat relationships for potentially precarious wildlife communities.

Investigating the effects of fire management on savanna biodiversity with grid‐based spatially explicit population simulations

Abstract The development of effective fire management for biodiversity conservation is a global challenge. The highly dynamic nature of fire, the difficulty in replicating ‘real‐world’ fire experiments and the need to understand population changes at large spatiotemporal scales make computer simulations particularly useful for identifying optimal fire management regimes for biodiversity conservation. We aimed to develop a flexible modelling approach with which to investigate how the spatiotemporal application of fire (i.e. management scenarios) influences savanna biodiversity. We used existing data from a landscape‐scale fire experiment to develop population simulations for the common brushtail possum Trichosurus vulpecula, grassland melomys Melomys burtoni and northern brown bandicoot Isoodon macrourus across the Kapalga area of Kakadu National Park in northern Australia. We simulated how populations were expected to change between 1995 and 2015 in response to the fire patterns observed at Kapalga over this period, and under a hypothetical management scenario of extensive prescribed burning. Our models predicted a substantial decline in all three species in response to the observed fire regime at Kapalga, suggesting that the fire patterns observed at Kapalga, with the associated mechanisms and interactions with other ecological processes, were not conducive with the persistence of native mammal populations. Our prescribed burning scenario had little effect on the predicted population trajectory of the common brushtail possum and grassland melomys, but markedly improved the population trajectory of the northern brown bandicoot. These inconsistencies highlight the need for a nuanced approach to fire management across northern Australian savannas, that is tailored to local conditions and management objectives. Synthesis and applications. The modelling approach outlined here provides a basis for identifying fire patterns that are beneficial for conserving biodiversity, thereby increasing our capacity to establish clear targets for prescribed fire management. Importantly, this approach is flexible and can be easily adapted to other taxa and fire‐prone ecosystems.

Fire impacts recruitment more than survival of small‐mammals in a tropical savanna

The frequency and spatial patterning of fire for optimal biodiversity conservation is often poorly understood by managers, in part due to a lack of understanding of the mechanisms responsible for altering population dynamics of individual species. We investigated changes in the vital rates (survival and recruitment) of four small mammal species (three marsupials and one rodent) in a tropical savanna under four different experimental fire treatments applied at a landscape scale. Apparent survival declined in all fire treatments for only one of four small mammal species (northern brown bandicootIsoodon macrourus). Recruitment was reduced in three of four species in multiple fire treatments. The suppression of recruitment in the northern brown bandicoot and the brushtail possumTrichosurus vulpeculapopulations was greatest immediately after the initial fire treatment was applied, compared to remaining treatment applications in successive years, possibly due to an elevated fire intensity as a result of higher initial fuel loads. The results suggest that higher intensity fire impacted recruitment more than survival for small mammals at this site. To assist fire managers to conserve small mammal populations in tropical savannas, we recommend fire regimes that optimise habitat resources for recruitment. This may be achieved by a reduction in fire frequency and managing fuel loads to prevent an increase in fire intensity.

Reproductive ecology of the northern brown bandicoot (Isoodon macrourus) in habitat fragments of urban Brisbane

The reproductive ecology of wildlife can have an enormous impact on their ability to survive within heavily modified landscapes, such as urbanised environments. This paper examines the reproductive ecology of northern brown bandicoots (Isoodon macrourus) in small bush fragments within urban Brisbane, where much of the diverse original mammal fauna has become locally extinct. During the 33-month study, 46 independent female bandicoots were captured and 45 litters were examined from 27 mature females. Reproduction was found to be seasonal with most mature females carrying young during late winter, spring and summer; the proportion of breeding females diminished during autumn and there appeared to be a short period of non-breeding each year around late autumn and/or early winter. There was no significant association between breeding and rainfall. Litter size reduction during pouch young development was observed in numerous females, with the mean number of young falling from 3.7 early in lactation to 1.9 late in lactation (40+ days). Survivorship of young during pouch development was estimated to be between 51% and 75%. Annual fecundity of females was estimated at 4.7 litters per year, resulting in an estimated mean of 11–13 weaned young per female. The study highlights the considerable reproductive capacity and flexible annual breeding pattern of northern brown bandicoots. In combination with their generalist habitat and dietary requirements, these reproductive traits are considered important life-history characteristics that have facilitated the species’ survival in bush fragments of Brisbane’s urban landscape.

Reproduction in the northern brown bandicoot (Isoodon macrourus) in the Australian Wet Tropics

We investigated timing of reproduction in a wild population of northern brown bandicoots (Isoodon macrourus) in the Australian Wet Tropics. Almost all births occurred during the late dry season and early wet season, and most adult females (78–96%) were carrying pouch young during those times. Litter sizes ranged from 1 to 6 pouch young (mean = 3.1) and was not influenced by season. Adult males had significantly larger testes in the late dry and early wet seasons, corresponding with the peak in births. Daylength was the only environmental factor that predicted the presence of a litter; when daylength exceeded 12 h, more than 70% of captured females were carrying pouch young, and most (94%) births were estimated to have occurred on days with >12 h of daylight. Various environmental factors have been proposed as a cue for breeding in I. macrourus, with daylength though to be the primary cue initiating breeding in temperate Australia, but temperature and rainfall thought to be more important in the tropics. Our data suggest that in the Australian Wet Tropics, increasing daylength in the late dry season acts as the primary cue for breeding.

Changes in mammal populations in relatively intact landscapes of Kakadu National Park, Northern Territory, Australia

A previous study (Braithwaite & Muller 1997) reported substantial declines in mammal abundance over the period 1986–1993 for a large study area (300 km2) within Kakadu National Park in the tropical savannas of northern Australia. This decline was reported as being a ‘natural’ response to fluctuating groundwater levels, driven by runs of poor wet seasons. We resampled mammals in this area in 1999, following a series of unusually good wet seasons, and examined the prediction that mammal numbers should have recovered. Increases in abundance were evident for four species: the smallest dasyurid (red-cheeked dunnart Sminthopsis virginiae) and the three smallest rodents (delicate mouse Pseudomys delicatulus, western chestnut mouse Pseudomys nanus and grassland melomys Melomys burtoni). In contrast, the abundance of all mammals combined and that for seven individual mammal species (northern quoll Dasyurus hallucatus, fawn antechinus Antechinus bellus, common brushtail possum Trichosurus vulpecula, northern brown bandicoot Isoodon macrourus, dusky rat Rattus colletti, black-footed tree-rat Mesembriomys gouldii and pale field rat Rattus tunneyi) continued to decline. The decline in abundance of these mammal species is consistent with limited observations elsewhere in northern Australia. Although far from conclusive, these observations suggest that the biota of the vast relatively undisturbed tropical savannas can no longer be assumed to be intact nor safe. Further research is needed to test this possible pattern of decline and, if confirmed, to identify and ameliorate the processes contributing to it.

Evolution of mammalian CD1: marsupial CD1 is not orthologous to the eutherian isoforms and is a pseudogene in the opossum Monodelphis domestica

CD1 is a member of the major histocompatibility complex (MHC) class I family of proteins that present lipid antigens to T cells and natural killer (NK) T cells; it is found in both eutherian mammals and birds. In eutherians, duplication of the CD1 gene has resulted in multiple isoforms. A marsupial CD1 homologue was identified in a set of expressed sequence tags from the thymus of the bandicoot Isoodon macrourus. Southern blot and genomic sequence analyses revealed that CD1 is a single copy gene in both I. macrourus and a distantly related marsupial, the opossum Monodelphis domestica, which is currently the only marsupial species for which a whole genome sequence is available. We found that the opossum CD1 is located in a genomic region with a high degree of conserved synteny to the chromosomal regions containing human and mouse CD1. A phylogenetic analysis of mammalian CD1 revealed that marsupial CD1 is not orthologous to the eutherian CD1 isoforms, consistent with the latter having emerged by duplication after the separation of marsupials and eutherians 170-180 million years ago. The I. macrourus CD1 gene is actively transcribed and appears to encode a functional protein. In contrast, transcription of the M. domestica CD1 was not detected in any tissue and the predicted CD1 gene sequence contains a number of deletions that appear to render the locus a pseudogene.

Induction of birth in the bandicoot (Isoodon macrourus) with prostaglandin and oxytocin.

As in eutherians, maturation of the fetal pituitary and adrenal glands together with an increase in prostaglandin and mesotocin or oxytocin production initiates birth in marsupials. In this study, prostaglandin (Lutalyse) or oxytocin (Syntocinon) were administered to pregnant bandicoots at 05:00 h on the calculated day of birth and the resultant effects were filmed for analysis. The administration of prostaglandin caused the bandicoot to adopt the birth position several minutes after injection (n = 2). However, the bandicoot did not give birth for several hours. Birth occurred at a similar time of day to that observed for untreated bandicoots (n = 7), between 08:00 h and 12:00 h. After an injection of oxytocin, the bandicoot assumed the birth position and birth occurred within several minutes. The young were alive while still connected to their allantoic stalks. However, they were unable to attach to the teats and did not survive (n = 4). The induced young were the colour of venous blood and died soon after the umbilicus was separated, indicating that the cardiopulmonary system of these neonates was underdeveloped and inadequate to maintain life. The results from this study demonstrate that prostaglandin is required to prepare the bandicoot for birth, and mesotocin is required for contraction of the uterus and for birth to occur.

Parasites and pathology of the respiratory tracts of native and feral mammals in Australia - a review.

This paper summarizes knowledge of the biodiversity and pathology associated with parasites of the respiratory tract of wild mammals, including feral species, in Australia. Representatives of 21 genera of nematodes distributed in the superfamilies Trichostrongyloidea, Metastrongyloidea, Thelazioidea, Filarioidea, Trichinelloidea and Muspiceoidea are included. Larval stages of the cestode, Echinococcus granulosus, occur in the lungs of macropodids and feral pigs (Sus scrofa). Trematodes occur in the lungs of dugongs (Dugong dugon) and in the cranial sinuses and blowholes of dolphins. Pentastomes occur in the lungs of the sugar glider (Petaurus breviceps) and in the frontal sinuses of dingoes (Canis lupus dingo) and foxes (Vulpes vulpes). Nymphal stages of the latter have been found in the lungs of rabbits (Oryctolagus cuniculus) and nymphs of a pentastome of tree pythons occur in the lungs of the northern brown bandicoot (Isoodon macrourus). Pneumonyssid mites occur in the lungs of the northern brushtail possum (Trichosurus vulpecula arnhemensis) and an undescribed speleognathine mite has been found in the lungs of P. breviceps. Trombiculid, tydeoid, dermanyssid and halarachnid mites are endoparasitic in the nasal sinuses of rodents, antechinuses, possums, gliders, elephant seals and fur seals. Larvae of oestrid bot-flies occur in the trachea of macropodids and in the nasal sinuses of camels (Camelus dromedarius). Host specificity in these parasites represents the full spectrum from species specific to class catholic with the intranasal chigger, Ascoschoengastia rattus, occuring in metatherian and eutherian mammals as well as varanid lizards. Similarly, pathological changes associated with these parasites range from inapparent to verminous bronchitis and bronchiolitis resulting in mortalities or severely impaired respiratory reserve or hypoxia precipitating death.

Changes in mammal populations in relatively intact landscapes of Kakadu National Park, Northern Territory, Australia

AbstractA previous study (Braithwaite & Muller 1997) reported substantial declines in mammal abundance over the period 1986–1993 for a large study area (300 km2) within Kakadu National Park in the tropical savannas of northern Australia. This decline was reported as being a ‘natural’ response to fluctuating groundwater levels, driven by runs of poor wet seasons. We resampled mammals in this area in 1999, following a series of unusually good wet seasons, and examined the prediction that mammal numbers should have recovered. Increases in abundance were evident for four species: the smallest dasyurid (red‐cheeked dunnart Sminthopsis virginiae) and the three smallest rodents (delicate mouse Pseudomys delicatulus, western chestnut mouse Pseudomys nanus and grassland melomys Melomys burtoni). In contrast, the abundance of all mammals combined and that for seven individual mammal species (northern quoll Dasyurus hallucatus, fawn antechinus Antechinus bellus, common brushtail possum Trichosurus vulpecula, northern brown bandicoot Isoodon macrourus, dusky rat Rattus colletti, black‐footed tree‐rat Mesembriomys gouldii and pale field rat Rattus tunneyi) continued to decline. The decline in abundance of these mammal species is consistent with limited observations elsewhere in northern Australia. Although far from conclusive, these observations suggest that the biota of the vast relatively undisturbed tropical savannas can no longer be assumed to be intact nor safe. Further research is needed to test this possible pattern of decline and, if confirmed, to identify and ameliorate the processes contributing to it.

The contribution of fungus to the diets of three mycophagous marsupials in Eucalyptus forests, revealed by stable isotope analysis

1. Many field studies have shown that small herbivorous mammals include fungus (usually hypogeous sporocarps of ectomycorrhizal fungi) in their diets. However, the dietary importance of fungus relative to other foods is generally unclear because of limitations on the power of conventional techniques of diet analysis. Stable isotope analysis in conjunction with faecal analysis was used in an attempt to overcome these limitations. 2. Two foregut‐fermenting marsupials (the Northern Bettong Bettongia tropica and Rufous Bettong Aepyprymnus rufescens) and a hindgut fermenter (the Northern Brown Bandicoot Isoodon macrourus) were studied. The Northern Bettong and Northern Brown Bandicoot are of similar body size (around 1 kg); the Rufous Bettong is significantly larger at 3 kg. Faecal analysis showed that the two bettongs ate a variety of grasses, lilies and fungi; the bandicoot ate these foods and also invertebrates. 3. Ratios of 15N/14N and 13C/12C differed in major food types collected in the field (fungus, grass, lily and invertebrates). Grass was clearly separated from the other food types by its low 13C/12C ratio, while fungus was separated from the other types by its high 15N/14N ratio. Invertebrates and lilies differed slightly in 13C/12C ratios. 4. Isotope ratios in body tissue (sampled in hair) of the three mammals were also discrete, showing that the species differed in the predominant sources of their C and N. Estimates of the proportion of C assimilated in body tissue that was derived from grass were 80% for the Rufous Bettong, 40% for the Northern Bettong and 45% for the Northern Brown Bandicoot. Analysis of 15N/14N ratios suggested that the Northern Bettong derived almost all its N from fungus, the Northern Brown Bandicoot derived practically no N from fungus, and the Rufous Bettong was intermediate. 5. The results confirm that for the Northern Bettong, fungus is a predominant source of N and C assimilated into body tissue. Differences between the use of fungi by the Northern Bettong and the Northern Brown Bandicoot strengthen conclusions from other studies that foregut fermentation confers on small mammals a greater ability to utilize fungus than does hindgut fermentation. It is hypothesized that the limited use of fungus by the Rufous Bettong is due to the patchy distribution of hypogeous sporocarps, which would result in a high energy cost of foraging for this larger‐bodied species with a higher absolute food requirement.

Sex-chromosome elimination in the bandicoot Isoodon macrourus using Y-linked markers

Cytogenetic studies have shown that the Y chromosome is eliminated from many somatic cell types of the bandicoot Isoodon macrourus, an Australian marsupial. Molecular techniques allow examination of a greater range of tissue types than that possible using cytogenetic techniques. The presence or absence of the Y chromosome was established using partial sequences of the Y-linked SRY and UBE1Y genes in I. macrourus, with the X-linked gene G6PD as a control. We show that a very small proportion of cells comprising hematopoietic tissues, and even fewer cells in peripheral blood, retain the Y chromosome. The Y chromosome is retained in most brain, liver, kidney, and lung cells and in cardiac and skeletal muscle. We also show that the bandicoot Y chromosome is retained in some cell types within tissues previously believed to completely eliminate the Y chromosome.

The circadian rhythm of body temperature of four marsupials

The 24-h pattern of body temperature of the brushtail possum Trichosurus vulpecula, the northern brown bandicoot Isoodon macrourus, the South American opossum Didelphis marsupialis and the Virginian opossum Didelphis virginiana was determined with temperature transmitters (Titley Electronics, Ballina, NSW). Although all four species exhibited a circadian rhythm with a peak at midnight and a nadir at noon, the profile of D. virginiana was not as defined as those of the other three species, with one D. virginiana not showing a definitive 24-h rhythm. The mean body temperatures of the possum, bandicoot, and the two opossums were 37.4, 36.2, 35.5 and 35.4°C, respectively. The mean 24-h body temperatures had a range of 35.0 to 39.0°C in eutherian species. This range was 35.4 to 37.4°C in the four marsupial species.

Entrainment of Circadian Wheel-Running Rhythms of the Northern Brown Bandicoot,Isoodon macrourus, by Daily Restricted Feeding Schedules

Northern brown bandicoots (Isoodon macrourus) were subjected to restricted feeding for 3 h in the middle of the light period of a 14: 10 light/dark cycle and immediately following this in constant dark. When feeding was restricted to the middle of the light period of the light/dark cycle, all bandicoots maintained a nocturnal activity rhythm. In addition to the nocturnal rhythm, a few bandicoots showed meal-anticipatory activity during the light period. In bandicoots that did not show meal-anticipatory activity, diurnal activity was sometimes evident either during or shortly after the daily meal time. The observation of meal-anticipatory activity in some bandicoots suggests that this species may have a mechanism separate from the light-entrainable mechanism that allows the daily anticipation of periodically available food sources. In the next stage of the experiment, which was in constant dark, the meal was presented at the same time of day as it had been in the previous stage. In all bandicoots, the prev...

Growth-Rates of the Bandicoot Isoodon-Macrourus and the Brushtail Possum Trichosurus-Vulpecula

Although the bandicoot Isoodon macrourus and the brushtail possum Trichosurus vulpecula give birth to similar-size young, about 200 mg, the pouch young of the bandicoot grow more quickly than those of the possum. The bandicoot is weaned at 59 days when the body weight is between 90 and 250 g. A young possum weighs about 20 g at Day 60 and between 780 and 1031 g when weaned at Day 170-180 post partum. The body weight of both species has been described previously as a continuous curve expressed by a quadratic equation. In this study, instead of assuming the growth curve to be continuous, the growth curve has been expressed as two components. The growth rates of both species were similar from birth until Day 12 post partum; the bandicoot then had a faster growth rate. The results from iterative analysis indicated a change in growth rate at Day 30 (data for Days 31 and 32 were missing) and Day 96 post partum for the bandicoot and possum, respectively. Thus, both marsupials showed a change in growth rate as hair appeared, eyes opened and the young first left the pouch.

Scanning electron microscopy of red blood cells from eleven species of marsupial

Samples of red of blood cells (RBC), washed free of plasma, from eleven marsupial species were examined in a Jeol JSM-6300 F scanning electron microscope. The diameters of the RBC, lying completely flat or exactly on edge, were measured on photographs using a binocular enlarging optical system with a calibrated eye piece. RBC from the following species were studied: bandicoot (Isoodon macrourus), bilby (Macrotis lagotis sagitta), Bennett's wallaby (Macropus rufogriseus), Goodfellow's tree kangaroo (Dendrolagus goodfellowi), koala (Phascolarctos cinereus), parma wallaby (Macropus parma), red kangaroo (Macropus rufus), swamp wallaby (Wallabia bicolor), Tammar wallaby (Macropus eugenii), Tasmanian devil (Sarcophilus harrish) and whiptail wallaby (Macropus parryi). In all species the RBC were biconcave discs. The major morphological difference was in the size of the cells. Taking the human RBC as a reference (with a diameter of 8.0 μm), the RBC of the Tasmanian devil, bilby, bandicoot and Goodfellow's tree kangaroo were ∼7 μm in diameter, whereas those of the other marsupials ranged from 7.8 to 8.6 μm.

Immunocytochemical location of oxytocin and mesotocin within the hypothalamus of two Australian marsupials, the bandicoot Isoodon macrourus and the brushtail possum Trichosurus vulpecula

The presence of oxytocin and mesotocin in the hypothalamus of two Australian marsupials, the bandicoot ( Isoodon macrourus) and the brushtail possum ( Trichosurus vulpecula), was examined by immunocytochemistry. Tissue was fixed in paraformaldehyde in phosphate buffer and immunoreactive cells were detected using highly specific rabbit anti-oxytocin and sheep anti-mesotocin as primary antisera. Immunoreactive oxytocin cells were demonstrated in the paraventricular and supraoptic nuclei of bandicoot and possum hypothalami, with greater density being observed in paraventricular nuclei. Immunoreactive mesotocin cells were also found in both hypothalamic nuclei of the possum but not of the bandicoot. The same cells appeared to stain for both peptides.

The localization of oxytocin and mesotocin in the reproductive tract of the male marsupial bandicoot Isoodon macrourus

The cellular localization of oxytocin and mesotocin within the testis and prostate of the Northern brown bandicoot, Isoodon macrourus, was examined. Tissues were fixed in 4% paraformaldehyde and immunoreactive cells and tissues were detected with antibodies to oxytocin and mesotocin. Immunoreactive oxytocin was present in the Leydig cells and in the spermatids of the adult and the 263-day bandicoots and there was faint staining in the 123-day bandicoot. Mesotocin was not present in the testes of the bandicoot. Immunoreactive oxytocin and mesotocin were present in the ventral portion of the prostate. The oxytocin within the testis may play a role in spermatogenesis and in seminiferous tubule contractility whereas the hormones present in the accessory glands may have a role in sperm transport in the female reproductive tract.

Ultrastructural identification of Merkel cells around the mouth of the newborn marsupial.

The ultrastructure of the epidermal cells surrounding the mouth of three newborn marsupial species, the Northern native cat Dasyurus hallucatus, the brush tail possum Trichosurus vulpecula and the Northern brown bandicoot Isoodon macrourus were examined. The presence of Merkel cells, highly sensitive touch receptors, would suggest that the sense of touch aids the relatively underdeveloped newborn marsupial to move from the urinogenital sinus to the pouch and to locate the teat.

The Estrous-Cycle Length of the Bandicoot Isoodon-Macrourus

The length of the oestrous cycle of the bandicoot Isoodon macrourus was determined. Pouch young were removed from lactating bandicoots at day 30 of lactation and the mothers were subsequently housed in enclosures without males (for oestrous cycle) and with males (for pregnancy). Births were observed 32-48 d after removal of young. The period of removal of young until ovulation was shown to be 6 d, the gestation length was known to be 12.5 d and the length of an oestrous cycle was calculated to be 22.1 � 1.6 d (mean � s.e., N=10), with a range of 14-30 d.