South-eastern Mainland Australia Research Articles

Standing on the shoulders of giants: molecular data confirm Kükenthal’s systematic placement of the Australian endemic Carex archeri (Cyperaceae)

Archer’s sedge (Carex archeri Boott) is a small, rare (or possibly overlooked by collectors due to the diminutive size) species restricted to alpine and subalpine habitats in south-eastern mainland Australia and Tasmania. The systematic placement has been obscure with the species having been historically associated with sections in four of the six recognised Carex subgenera. We investigated the placement of C. archeri by addition to the available Carex molecular phylogenetic framework. Our results support C. archeri belonging to sect. Junciformes (in subg. Psyllophorae), making this the only representative of the subgenus in Australia. This placement was first proposed by Kükenthal (1909) who regarded C. archeri as a synonym of the New Zealand endemic C. acicularis Boott but our phylogenetic analyses support C. archeri as a separate taxon. Our approach highlights the utility of molecular barcoding for elucidating systematic relationships of poorly known taxa. Biogeographic reconstruction suggests Late Miocene dispersal from South America to the south-western Pacific but does not clarify whether New Zealand or Australia was colonised first. We evaluate the conservation status of Carex archeri using IUCN criteria as Endangered at the global level. At the state level, we propose Critically Endangered status in New South Wales, Endangered in Victoria and Data Deficient in Tasmania.

Lead exposure of mainland Australia's top avian predator

Lead (Pb) toxicity, through ingestion of lead ammunition in carcasses, is a threat to scavenging birds worldwide, but has received little attention in Australia. We analyzed lead exposure in the wedge-tailed eagle (Aquila audax), the largest raptor species found in mainland Australia and a facultative scavenger. Eagle carcasses were collected opportunistically throughout south-eastern mainland Australia between 1996 and 2022. Lead concentrations were measured in bone samples from 62 animals via portable X-ray fluorescence (XRF). Lead was detected (concentration >1 ppm) in 84% (n = 52) of the bone samples. The mean lead concentration of birds in which lead was detected was 9.10 ppm (±SE 1.66). Bone lead concentrations were elevated (10–20 ppm) in 12.9% of samples, and severe (>20 ppm) in 4.8% of samples. These proportions are moderately higher than equivalent data for the same species from the island of Tasmania, and are comparable to data from threatened eagle species from other continents. Lead exposure at these levels is likely to have negative impacts on wedge-tailed eagles at the level of the individual and perhaps at a population level. Our results suggest that studies of lead exposure in other Australian avian scavenger species are warranted.

Ring-width and blue-light chronologies of Podocarpus lawrencei from southeastern mainland Australia reveal a regional climate signal

Abstract. High-resolution palaeoclimate proxies are fundamental to our understanding of the diverse climatic history of the Australian mainland, particularly given the deficiency in instrumental datasets spanning more than a century. Annually resolved, tree-ring-based proxies play a unique role in addressing limitations in our knowledge of interannual to multi-decadal temperature and hydroclimatic variability prior to the instrumental period. Here we present cross-dated ring-width (RW) and minimum blue-intensity (BI) chronologies spanning 70 years (1929–1998) for Podocarpus lawrencei Hook.f., the Australian mainland's only alpine conifer, based on nine full-disc cross-sections from Mount Loch in the Victorian Alps. Correlations with climate variables from observation stations and gridded data across the 1929–1998 period reveal a significant positive relationship between RW and mean monthly maximum temperatures in winter throughout central Victoria (r=0.62, p<0.001) and a significant negative correlation to winter precipitation (r=-0.51, p<0.001). We also found significant negative correlations between RW and monthly snow depth at Spencer Creek in New South Wales (r=-0.60, p<0.001). Of the assessed BI parameters, delta blue intensity (ΔBI; the difference between early- and late-wood BI) displayed the greatest sensitivity to climate, with robust spatial correlations with mean October to December maximum and minimum monthly temperatures (r=-0.43, p<0.001; r=-0.51, p<0.001) and July precipitation (r=0.44, p<0.001), across large areas of northern Victoria. These promising findings highlight the utility of this species for future work. With the very limited availability of suitable long-lived and cross-datable species on the Australian mainland, these results have significant implications for advancing high-resolution palaeoclimate science in southeastern Australia and for improving our understanding of past climate in the region.

Species distribution models for conservation: Identifying translocation sites for eastern quolls under climate change

Conservation and natural resource management are frequently hampered by poor understanding of how species distributions have changed over time. Species Distribution Models (SDMs) correlate known occurrences with environmental variables to predict a species’ potential range. These models can then be projected to unsurveyed areas or time periods to overcome gaps in data on species’ distribution. The eastern quoll Dasyurus viverrinus is restricted to Tasmania but until recently occurred over a large area of south-eastern mainland Australia. We used SDMs to reconstruct the distribution of climates suitable for D. viverrinus during the mid-Holocene and present day and identified areas likely to remain suitable in the future which could be prioritised for conservation. Climatically suitable habitat has mostly remained stable since the mid-Holocene, with some expansion. The historic contraction of the species’ distribution was evidently due to threatening processes other than climate change, which are still operating. Under current conditions, large areas of south-eastern Australia still provide suitable habitat for eastern quolls and will continue to do so under predicted climate change scenarios for 2055. Suitable areas include offshore islands, in particular islands within the Nooramunga Marine and Coastal Park in Victoria, and islands that make up the Furneaux Group in the Bass Strait. Translocations to these islands would establish populations in climatically suitable areas separate from threatening processes.

Portable X-ray fluorescence for bone lead measurements of Australian eagles

Lead (Pb) toxicity from ammunition has been shown to be a threat to scavenging birds across the globe. Toxic levels of lead have recently been found in Australia's largest bird of prey, the wedge-tailed eagle (Aquila audax), through inductively coupled plasma mass spectrometry (ICP-MS) analysis of liver and bone samples. However, ICP-MS is consumptive (causing damage to archived specimens), time-consuming, and expensive. For these reasons, portable X-ray fluorescence (XRF) devices have been optimized to measure bone lead in North American avian species, humans, and other environmental samples. In this study, we assessed portable XRF for bone lead measurement in Australian raptors in two parts. First, we validated the method using tissues from wedge-tailed eagles from Tasmania (A. a. fleayi), analysing bone samples taken from sites on the femur immediately adjacent to sites for which we had ICP-MS data (n = 89). Second, we measured lead via portable XRF in the skulls of wedge-tailed eagles from south-eastern mainland Australia (A. a. audax) collected during a criminal prosecution (n = 92). Portable XRF bone lead measurement demonstrated an excellent correlation with ICP-MS results using root-transformed regression (R2 = 0.88). Calculated equivalent ICP-MS values revealed that greater than 50% of the eagles from mainland Australia had elevated lead levels (>10 mg/kg) and 13% had severe lead exposure (>20 mg/kg). Our results support previous studies of North American avian species and suggest that portable XRF could be a useful and inexpensive option for measurement of bone lead in Australian scavenger species.

Elucidating Patterns in the Occurrence of Threatened Ground-Dwelling Marsupials Using Camera-Traps.

Simple SummaryBeing able to effectively monitor the continued plight of highly vulnerable animals against management efforts over time is critical for their conservation. In south-eastern New South Wales, Australia, we used a camera trapping array to collect baseline information about patterns of occurrence of three threatened native ground-dwelling marsupials of conservation interest: the long-nosed bandicoot (Perameles nasuta), long-nosed potoroo (Potorous tridactylus) and southern brown bandicoot (Isoodon obesulus). Over a four-year period, detections of the two bandicoots were more erratic and less predictable than that of the potoroo, resulting in higher uncertainty about occupancy estimates and adequacy of sampling effort. The detection probability of each bandicoot species and that of the potoroo differed variously with structural complexity of vegetation. Detection probability of the southern brown bandicoot was highest where ground cover was most dense and shrub cover most open. The reverse pattern was found for the long-nosed bandicoot. Finally, the detection probability of the long-nosed potoroo was highest where ground and shrub cover was densest. Future camera trapping monitoring efforts need to take better account of these nuances and be flexible to including additional sampling for at least the two bandicoots. In short, when it comes to monitoring approach, one size doesn’t fit all.Establishing trends in endangered fauna against management efforts is a key but often challenging enterprise. Camera-traps offer a new and literal window into monitoring many different mammalian species. Getting it right demands seeking baseline information about how often target species interact with these devices, prior to setting a long-term monitoring strategy. We used a camera-trap array to collect detection data on three species of threatened ground-dwelling marsupials in south-eastern mainland Australia. Over a four-year period, occupancy estimates for two species of bandicoot (southern brown bandicoot Isoodon obesulus and long-nosed bandicoot Perameles nasuta) and a single species of rat-kangaroo (long-nosed potoroo Potorous tridatylus) were generated. These estimates were variously robust depending on visitation history, but nevertheless indicated persistence of these rare and otherwise under threat species. Detection probability for each species differed between study areas, type of management and with complexity of ground and shrub vegetation cover. The relationship between detection and vegetation structure dictated that survey effort was only robust where conditions were optimal for a given species. Outside of that further survey effort would be required to have confidence in survey outcome. In the future this would demand a different sampling strategy, be that through lengthening survey time or adding additional camera units at sites.

Phylogeography of southern brown and golden bandicoots: implications for the taxonomy and distribution of endangered subspecies and species

Southern brown (Isoodon obesulus) and golden (Isoodon auratus) bandicoots are iconic Australian marsupials that have experienced dramatic declines since European settlement. Conservation management programs seek to protect the remaining populations; however, these programs are impeded by major taxonomic uncertainties. We investigated the history of population connectivity to inform subspecies and species boundaries through a broad-scale phylogeographic and population genetic analysis of Isoodon taxa. Our analyses reveal a major east–west phylogeographic split within I. obesulus/I. auratus, supported by both mtDNA and nuclear gene analyses, which is not coincident with the current species or subspecies taxonomy. In the eastern lineage, all Tasmanian samples formed a distinct monophyletic haplotype group to the exclusion of all mainland samples, indicative of long-term isolation of this population from mainland Australia and providing support for retention of the subspecific status of the Tasmanian population (I. o. affinis). Analyses further suggest that I. o. obesulus is limited to south-eastern mainland Australia, representing a significant reduction in known range. However, the analyses provide no clear consensus on the taxonomic status of bandicoot populations within the western lineage, with further analyses required, ideally incorporating data from historical museum specimens to fill distributional gaps.

Molecular data contradicts historical records and cautions translocation of the Lord Howe Island masked owl

Masked owls, reputedly all of the Tasmanian race (Tyto novaehollandiae castanops) were introduced onto Lord Howe Island (LHI) in the 1920s in an attempt to control the black rat (Rattus rattus). This attempt, however, has been unsuccessful and a co-eradication of the rats and masked owls has been planned to reduce the threat to endemic species and breeding seabirds on the island. As the Tasmanian masked owl is considered endangered, translocation of LHI masked owls to Tasmania has been suggested. Before translocation is considered the ancestry of the LHI masked owl needs to be confirmed, as LHI masked owls are typically smaller and paler than individuals occurring in Tasmania. Here we sequenced three sections of mitochondrial gene regions: cytochrome b, ATP6 and ND3 to assess the provenance of the LHI masked owl and screened a suite of microsatellite loci isolated from the barn owl (Tyto alba) to assess contemporary divergence. Phylogenetic analysis revealed two clades, one exhibited by individuals from LHI and south-eastern mainland Australia and the second by those from Tasmania. Cross species amplification of microsatellite loci was successful, with 18 loci polymorphic. Genotypic data revealed significant sub-structuring between LHI, south-eastern mainland Australia and Tasmania. Data presented here indicate that the south-eastern mainland masked owl was introduced to LHI and subsequently reproduced. The genetic integrity of the LHI masked owl population is therefore questionable and as such LHI individuals may not be suitable for translocation to Tasmania.

White-striped freetail bat in Tasmania – resident, vagrant or climate change migrant?

The white-striped freetail bat (Austronomus australis) is distributed throughout mainland Australia, but historically has not been known from the island of Tasmania, off south-eastern mainland Australia. Between 2009 and 2012, echolocation calls identified as those of A. australis were recorded in Tasmania during bat call surveys. There are three hypotheses that could explain the discovery of this species in Tasmania: that A. australis is a previously undetected resident; it is a vagrant; or it is undergoing a southwards range expansion or shift. Based on the limited evidence available, including this species’ long-range flight capabilities (including over open water out to sea), I suggest that this species is a periodic vagrant to Tasmania and that monitoring is necessary to identify whether this species is undergoing a southwards range extension into Tasmania.

Growth responses to thinning and pruning in Eucalyptus globulus, Eucalyptus nitens, and Eucalyptus grandis plantations in southeastern Australia

Growth responses to pruning or thinning are well documented but their interactions are not, even though they are sometimes performed simultaneously. Growth responses to thinning and pruning were examined in nine plantation silvicultural experiments at five sites in southeastern mainland Australia. The species studied were Eucalyptus globulus Labill., Eucalyptus nitens (Deane and Maiden) Maiden, and Eucalyptus grandis Hill ex Maiden. Thinning from about 1100–1300 trees·ha–1 to about 300 or 500 trees·ha–1 at either age 3–4 years or 7–10 years increased the volume of sawlog crop trees in all species. Multiple lift pruning to 6.5 m height on the sawlog crop trees that retained at least 70% of the live crown length at any lift significantly reduced tree growth at only one of the six site–species combinations where both thinning and pruning were studied. And here, thinning interacted with pruning such that the pruning effects were not significant in unthinned stands because only shaded and inefficient foliage was removed. This study shows that thinning and pruning can interact to influence sawlog crop tree growth and this interaction is influenced by site.

Two new rare species in the Thelymitra venosa complex (Orchidaceae) from south-eastern mainland Australia

Two rare species, Thelymitra alpicola Jeanes and Thelymitra incurva Jeanes, are described as new and illustrated. Their relationship with Thelymitra cyanea (Lindl.) Benth., Thelymitra erosa D.L.Jones and M.A.Clem. and Thelymitra venosa R.Br. is discussed and information on distribution, habitat, pollination biology, flowering time and conservation status is given for all five species. A key is also provided to distinguish the five species. The confusion arising from the incorrect application of names in the complex is discussed, including reference to the related New Zealand species Thelymitra pulchella Hook.f.

Trends in the activity levels of forest-dwelling vertebrate fauna against a background of intensive baiting for foxes

The relative activity of ground-dwelling vertebrates was monitored using tracks in sand plots for 10 consecutive years across three nearby study areas in south-eastern mainland Australia. Two areas were subject to intensive 1080 poison baiting for foxes, while one unbaited area acted as a control. At the two 1080 baited sites there was a demonstrable decline in the reporting rate of fox tracks, while that of feral cats also declined concomitantly. In contrast, the reporting rate of wild dog tracks did not change. At the unbaited site the reporting rate of wild dog tracks increased slightly, while that of foxes remained stable and that of feral cats declined slightly. Prevailing ecological theory would suggest that in systems where larger predators are reduced in activity or abundance, smaller predators should increase. This was not the case in our work. Instead, while the larger sized fox has decreased at baited sites, the smaller sized cat has declined at a regional scale, in all likelihood against a backdrop of long-term drought and diminished prey resources. Among the native omnivorous mammals that ordinarily fall prey to foxes, bandicoots, brushtail possums and lyrebirds increased in activity against a background of diminishing fox activity, although these effects were not uniform at both baited sites. In contrast, at the study area where foxes were not baited, the activity of bandicoots, brushtail possums and lyrebirds either did not change or diminished. Trends in the activity levels of these animals, particularly bandicoots, may have been moderated in part by prevailing rainfall conditions. Otherwise, habitat complexity may also help regulate activity patterns. Land managers concerned with preserving and enhancing biodiversity need to not only focus on the baiting of introduced predators but also be mindful of habitat condition and the effects of climate.

Socio-seasonal changes in scent-marking habits in the carnivorous marsupial Dasyurus maculatus at communal latrines

Scat DNA analyses and monthly monitoring were used to elucidate patterns of latrine use in a free-ranging population of a rare Australian marsupial carnivore, the spotted-tailed quoll (Dasyurus maculatus) Kerr. In all, 132 latrines were identified at large complex outcrops and on bedrock in drainage lines, creeks and rivers at a single woodland site in south-eastern mainland Australia. Annual cyclic variation in scat deposition was found over the two years that latrines were monitored. Peaks in scat deposition on latrines coincided with seasonal social behaviours and differed between sites on outcrops and sites along drainage lines. A marked increase in scat deposition on latrines in drainage lines was recorded during the mating season and at outcrop latrines when females were nursing young. Genetic analyses of scats collected over one breeding season revealed that multiple individuals of both sexes defaecated at latrines. The communal use of latrines during the mating season along with the seasonal patterns of scat deposition demonstrates that latrines are important scent-marking sites that facilitate social communication among individuals of this solitary-living species. The collective evidence indicates that latrines play a major role in aiding reproduction and interindividual spacing.

Prevalence of threatened native species in canid scats from coastal and near-coastal landscapes in south-eastern Australia

Predator scat analysis was used to infer the potential impact of wild dogs (Canis lupus dingo, C. l. familiaris and hybrids of the two) on threatened native terrestrial mammals in coastal and near-coastal southern New South Wales, Australia. Prey items recorded in wild dog scats were compared with those occurring in scats of the red fox collected at the same study sites. Six threatened mammal species were recorded in either wild dog or fox scats: eastern pygmy possum, grey-headed flying fox, long-nosed potoroo, southern brown bandicoot, white-footed dunnart and yellow-bellied glider. The prevalence of these threatened species in fox scats was significantly higher than in wild dog scats. Otherwise, wild dogs mostly consumed larger prey items such as swamp wallabies and wombats whereas foxes more heavily preyed on small mammals such as antechinus and rats. Our results suggest that foxes are the major threat to threatened mammal species in the study region. Land management agencies in south-eastern mainland Australia should therefore focus on controlling foxes for biodiversity gain.

Satellite tracking of wild dogs in south-eastern mainland Australian forests: Implications for management of a problematic top-order carnivore

Satellite tracking was used to follow the movements of a problematic top-order carnivore, the wild dog (Canis lupus dingo, C. lupus familiaris and their hybrids), in contiguous forested landscapes in south-eastern mainland Australia. Home range sizes of wild dogs were much larger than previously determined using conventional telemetry methods, averaging 10,000ha with a maximum size of 59,000ha over approximate 3-month periods. Wild dogs at sites with high abundance of kangaroos, wallabies and rabbits had smaller areas of occupancy than did dogs at sites with low availability of these preys. Despite mostly large home ranges, tracked animals were loyal to publicly-owned tenure and there were few instances where individuals moved large distances on to adjacent private tenure. Instead, movement behaviours of most tracked animals were characterised by repeated short distance forays, often at acute angles from previous locations. Consequently, home ranges were stable and otherwise well defined. Analysis of DNA from our study animals indicated that most individuals were of ‘dingo’ ancestry, but otherwise considered hybrids because of the presence of domestic dog genes. Only two of 24 animals could be considered as ‘pure’ dingo. Contemporary wild dog management demarcates lands where control is or is not undertaken, with the latter notionally acting to ‘conserve’ dingoes. Due to the large scale of movement of animals, existing control efforts likely impact over a greater area than previously suspected. Furthermore, our genetic findings suggest that conservation of dingoes in south-eastern mainland Australia is difficult to achieve. A modified approach to wild dog management is needed, taking account of the extent of range of individual animals and the existing genetic characteristics of populations.

Managing a Critically Endangered Species Under Conditions of Extreme Uncertainty: Orange-Bellied Parrots on Southeastern Mainland Australia – Chris Tzaros

Managing a Critically Endangered Species Under Conditions of Extreme Uncertainty: Orange-Bellied Parrots on Southeastern Mainland Australia – Chris Tzaros

Do fungi have a role as soil stabilizers and remediators after forest fire?

The functional roles of fungi in recovery of forest ecosystems after fire remain poorly documented. We observed macrofungi soon after fire at two widely separated sites, one in the Pacific Northwest United States and the other in southeastern mainland Australia. The range of species on-site was compared against macrofungi reported after the volcanic eruption at Mount St. Helens, also in the Pacific Northwest. Each of the three sites shared species, particularly representatives of the genus Anthracobia. Soon after disturbance, we noted extensive mycelial mats and masses of fruit-bodies of this genus, particularly at heavily impacted microsites. The mycelial mats appeared to play an important functional role on-site, possibly aggregating soil particles in otherwise highly erodable landscapes. We hypothesise that fungi such as Anthracobia are pivotal species in early system recovery after disturbance, helping minimize the movement of soil in the absence of plant roots. As plant root systems recover, the importance of these fungi in soil stabilization may diminish. Other functional roles of early postfire fungi might include nutrient acquisition, leading to the reestablishment of vegetation. These potential roles need to be experimentally tested and relevant findings incorporated into programs aimed at restoring forest ecosystems after disturbance.

Factors Influencing the Occurrence of Small Ground-Dwelling Mammals in Southeastern Mainland Australia

We investigated the occurrence of small, ground-dwelling mammals (marsupial mice and rodents) across 128 forested study sites representing a stratified sample of the climatic, geological, and topographic features of far southeastern mainland Australia. We then developed statistical models for the occurrence of the agile antechinus (Antechinus agilis), dusky antechinus (A. swainsonii), and bush rat (Rattus fuscipes) based on various environmental attributes measured for each site. At a landscape scale, the climatic factor mean minimum temperature of the coldest month was an important explanatory variable for the bush rat, with the likelihood of its occurrence increasing with increasing temperature during that period. Sites with greater precipitation during the driest quarter of the year were more likely to support bush rats and the agile antechinus. At an on-site scale, protected slopes and gullies were more likely to support bush rats, and the occurrence of bush rats and the dusky antechinus increased at sites with a higher number of large fallen trees. In multiple-use forests, increasing the number of large fallen trees after timber harvesting may increase habitat quality for both the dusky antechinus and the bush rat, and retaining habitat on protected slopes and gullies also may be important for the latter species.

Winter habitat use by the endangered, migratory Swift Parrot (Lathamus discolor) in New South Wales

Migratory birds are dependent on a combination of suitable wintering, migration and breeding habitats. Identification and protection of these habitats is essential for the conservation of the birds. The endangered Swift Parrot (Psittacidae: Lathamus discolor) migrates north from Tasmania to south-eastern mainland Australia in search of suitable winter food resources. This 5-year study examines the use of known winter foraging habitats by Swift Parrots on a statewide scale not previously attempted. Swift Parrots used a diversity of winter foraging habitats in regions of the coast and western slopes of New South Wales each year, including several habitats that occur in endangered ecological communities. The abundance of Swift Parrots in New South Wales fluctuated significantly between years and regions, with coastal areas providing important drought-refuge habitats for a large proportion of the population. Over half of all foraging sites were used repeatedly, highlighting their likely importance for conservation. Landscapes containing winter foraging habitat included scattered trees, remnant vegetation and continuous forests, and Swift Parrots foraged extensively on lerp and nectar from a diversity of tree species within these. The occurrence of Swift Parrots at foraging sites was primarily associated with the abundance of lerp, nectar and non-aggressive competitors.

Monoecious Nitella species (Characeae, Charophyta) from south-eastern mainland Australia, including Nitella paludigena sp. nov.

Identification of Australian species of Nitella is problematic. Several species of monoecious Nitella have been described from south-eastern mainland Australia, but identification of these based on current treatments has been difficult. In response to the discovery of a new monoecious Nitella from the swamps of the Fleurieu Peninsula in South Australia, the monoecious species of Nitella from south-eastern mainland Australia were examined and compared. N. paludigena M.T.Casanova & K.G.Karol is distinguished from other monoecious species on the basis of its overall vegetative morphology and oospore morphology. N. paludigena is found in peaty tea-tree (Leptospermum sp) swamps on the Fleurieu Peninsula in South Australia, and in the south-west of Victoria. A description of the morphology and ecology of the five monoecious Nitella species from south-eastern mainland Australia is given, along with a key.