Environmental factors influencing the distribution of the Kangaroo Island dunnart (Sminthopsis fuliginosus aitkeni)

Determining the factors that drive the distributions of threatened species is often critical for informing effective conservation management actions. Species distribution models can be used to distinguish common habitat features shared by limited historical records and identify other areas where a species might persist. In this study, we built a species distribution model for the Endangered and cryptic Kangaroo Island dunnart (Sminthopsis fuliginosus aitkeni). We fitted generalised linear models using incidental records and presence-absence data from surveys between 1969 and 2018. In the models we included the variables rainfall, percentage native vegetation in the surrounding 2 km2, and post-fire vegetation age. The modelling suggested that rainfall and to a lesser extent post-fire vegetation age are good predictors of dunnart occurrence, with dunnart occurrence greatest in areas of high rainfall (>600 mm) and vegetation age classes <30 years post fire. Potentially suitable habitat for the KI dunnart was predicted to be on the central-western side of Kangaroo Island. These results suggest that careful fire management could benefit the dunnart, and that decreased rainfall (as projected by Australian climate models), will be a threat in the long term. Extensive recent fires on western Kangaroo Island suggest that climate-related threats are already being realised.

Small marsupial, big dispersal? Broad- and fine-scale genetic structure of an endangered marsupial from the Australian arid zone

The irregular nature of rainfall in the Australian arid and semiarid zones results in a heterogeneous distribution of resources in both time and space. The mammal species that reside in these regions are uniquely adapted to these climatic conditions, often occurring in naturally low densities and increasing significantly in numbers following major rainfall events. We investigated how these adaptations may influence genetic diversity and gene flow across the landscape in an endangered semiarid/arid-zone marsupial, the sandhill dunnart (Sminthopsis psammophila), from three known populations in southern Australia. Analyses of mitochondrial control region (CR) sequences and microsatellite loci revealed that S. psammophila had maintained similar levels of genetic diversity to other sympatric Sminthopsis species despite its endangered status. There was no evidence for significant phylogeographic structure within the species, but each population was genetically differentiated, based on the frequency of microsatellite alleles and CR haplotypes, suggesting that they should be considered as distinct Management Units for conservation. At a fine spatial scale, no significant genetic structure or sex-biased dispersal was detected within a study site of 240km2. These findings suggest that both sexes are highly mobile, which allows individuals to locate localised resource patches when they become available. We detected evidence of a genetic bottleneck within the population, possibly caused by a recent drought. Our study highlights the importance of maintaining connectivity across the landscape for semiarid- and arid-zone species to enable them to track resource pulses and maintain genetic diversity.

Breeding in wild populations of a small dasyurid marsupial, Planigale ingrami, in north-western Queensland using a novel method for collection of specimens

The reproductive biology of the long-tailed planigale (Planigale ingrami) is less well known than that of its congeners P. gilesi and P. tenuirostris. Aspects of the anatomy of reproductive structures and the pattern of reproduction of P. ingrami were established by examination of specimens extracted from the stomachs of feral cats shot in north-western Queensland. This species has an extended breeding season that commences in August and probably ends in December, and both males and females may live to breed in more than one season, providing support for the similarity of the reproductive strategies of these three species of Planigale. Females of P. ingrami have twelve nipples in the pouch, the form of which may differ from that of other planigales. Pouch morphology may prove useful in the identification of species of Planigale providing observations are made on the appearance of the pouch throughout the breeding cycle.

Resource pulses and mammalian dynamics: conceptual models for hummock grasslands and other Australian desert habitats

Resources are produced in pulses in many terrestrial environments, and have important effects on the population dynamics and assemblage structure of animals that consume them. Resource-pulsing is particularly dramatic in Australian desert environments owing to marked spatial and temporal variability in rainfall, and thus primary productivity. Here, we first review how Australia's desert mammals respond to fluctuations in resource production, and evaluate the merits of three currently accepted models (the ecological refuge, predator refuge and fire-mosaic models) as explanations of the observed dynamics. We then integrate elements of these models into a novel state-and-transition model and apply it to well-studied small mammal assemblages that inhabit the vast hummock grassland, or spinifex, landscapes of the continental inland. The model has four states that are defined by differences in species composition and abundance, and eight transitions or processes that prompt shifts from one state to another. Using this model as a template, we construct three further models to explain mammalian dynamics in cracking soil habitats of the Lake Eyre Basin, gibber plains of the Channel Country, and the chenopod shrublands of arid southern Australia. As non-equilibrium concepts that recognise the strongly intermittent nature of resource pulsing in arid Australia, state-and-transition models provide useful descriptors of both spatial and temporal patterns in mammal assemblages. The models should help managers to identify when and where to implement interventions to conserve native mammals, such as control burns, reduced grazing or predator management. The models also should improve understanding of the potential effects of future climate change on mammal assemblages in arid environments in general. We conclude by proposing several tests that could be used to refine the models and guide further research.