Diurnal sheltering preferences and associated conservation management for the endangered sandhill dunnart, Sminthopsis psammophila

Dasyurids are small mammals that can conserve energy and water by using shelters that insulate against extreme conditions, prevent predation, and facilitate torpor. To quantify the diurnal sheltering requirements of a poorly known, endangered dasyurid, the sandhill dunnart, Sminthopsis psammophila, we radiotracked 40 individuals in the Western Australian Great Victoria Desert between 2015 and 2019. We assessed the effect of habitat class (broad habitat features), plot-level (the area surrounding each shelter), and shelter characteristics (e.g., daily temperature ranges), on shelter selection and sheltering habitat preferences. Two hundred and eleven diurnal shelters (mean of 5 ± 3 shelters per individual) were located on 363 shelter days (the number of days each shelter was used), within mature vegetation (mean seral age of 32 ± 12 years postfire). Burrows were used on 77% of shelter days and were typically concealed under mature spinifex, Triodia spp., with stable temperature ranges and northern aspects facing the sun. While many burrows were reused (n = 40 across 175 shelter days), spinifex hummock shelters typically were used for one shelter day and were not insulative against extreme temperatures. However, shallow scrapes within Lepidobolus deserti hummock shelters had thermal advantages and log shelters retained heat and were selected on cooler days. Sminthopsis psammophila requires long-unburned sheltering habitat with mature vegetation. Summer fires in the Great Victoria Desert can be extensive and destroy large areas of land, rendering them a key threat to the species. We conclude that the survey and conservation of S. psammophila requires attention to long-unburned, dense lower stratum swale, sand plain, and dune slope habitats, and the tendency of S. psammophila to burrow allows the species to survive within the extreme conditions of its desert environment.

Reproductive biology of captive female southern hairy-nosed wombats (Lasiorhinus latifrons). Part 2: oestrous behaviour

The poor captive breeding success of southern hairy-nosed wombats (SHNWs; Lasiorhinus latifrons) has been attributed to the difficulty in accurately characterising oestrous behaviour and their relationship to circulating reproductive hormones. Over two wombat breeding seasons, the use of infrared cameras for 24-h remote behavioural monitoring and the analysis of urine samples collected from seven captive females, were investigated to determine the relationship between behaviour and changes in urinary progesterone metabolites (P4M). Urinary P4M was divided into two concentrations: (1) ≤ baseline P4M values and (2)>baseline P4M values and evaluated against urine volume (mL) and the duration (s) and frequency of 23 behaviours recorded for 8 days surrounding D0 of the luteal phase (D0: a sustained increase in P4M for three or more consecutive days). When P4M was ≤ baseline, the duration of urination and volume both decreased, whereas the duration and frequency of both pacing and rump bites by the female towards the male increased. These results suggest that there were detectable behavioural changes that can be mapped to the changes in the SHNW oestrous cycle, which may be used as behavioural indicators to identify the reproductive status of females.

Reproductive biology of captive southern hairy-nosed wombats (Lasiorhinus latifrons). Part 1: oestrous cycle characterisation

Southern hairy-nosed wombats (SHNWs: Lasiorhinus latifrons) do not breed well in captivity. To better understand their reproduction, daily urine samples were collected from nine captive females and analysed for volume (mL), specific gravity and a qualitative index of the number of epithelial cells, then stored at -20°C until samples could be analysed for progesterone metabolites (P4M). The mean oestrous cycle length was 35.1±2.4 days; however, individual cycle length ranged from 23 to 47 days. The mean luteal phase length was 20.8±1.3 days (range: 12 to 33 days). Urinary P4M was divided into four oestrous cycle stages: (1) early follicular phase, (2) late follicular phase, (3) early luteal phase, (4) late luteal phase, and analysed against urinary characteristics. During the late follicular phase, urine volume decreased (P=0.002) while urine specific gravity (P=0.001) and concentration of epithelial cells (P=0.004) both increased. The level of variability in oestrous cycle length suggests that some captive females may exhibit abnormal cycles; however, the changes in the urinary characteristics associated with the different stages of the oestrous cycle appear to offer a possible non-invasive means of monitoring the reproductive status of captive SHNWs.

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.