Context. The disease toxoplasmosis, caused by infection with the intra-cellular protozoan parasite Toxoplasma gondii, is a potential threat to the conservation of some endothermic vertebrates. Toxoplasmosis has been reported to cause disease and acute death in many marsupials, including endangered bandicoots. Methods are required to quantify the environmental contamination with T. gondii and, hence, assess the relative threat it poses to resident species. A multi-modal approach to assess an environment for the presence of pathogens increases the likelihood of a more accurate estimate of the level of contamination and inferred risk of infection to target species.

Aim. This project aimed to use a multi-modal approach to estimate the environmental contamination with T. gondii across two separate landscapes with differing cat populations in the northern hinterland of Western Port, Victoria, Australia.

Methods. The following four parameters were used: the presence of IgG antibodies to T. gondii in free-ranging southern brown bandicoots (Isoodon obesulus) using the modified agglutination test (MAT); the presence of T. gondii DNA in the tissues of free-ranging rabbits (Oryctolagus cuniculus) and mice (Mus musculus) by real-time quantitative polymerase chain reaction (qPCR); and the presence of T. gondii oocysts in the soil using filtration methods and real-time qPCR.

Key results. Toxoplasma gondii was not identified in any of the soil samples (n = 594), southern brown bandicoots (n = 24) or mice (n = 267). Only one rabbit tested positive for T. gondii (n = 118).

Conclusions. The tests across soils and three different mammalian species all delivered similar results, leading to the conclusion that the landscapes measured had low T. gondii contamination at the time of assessment.

Implications. This Australian study is the first to show that the use of pathogen detection in target and two sentinel species, combined with soil analysis, may be a useful approach to assess the environmental risk of T. gondii infection in endangered and vulnerable species. Further research is recommended across sites with a gradient of T. gondii contamination and into the use of other sentinel species. Further refining of techniques for direct soil analysis in Australian conditions is recommended.

Context. Aerial distance sampling surveys are a widely used approach for estimating the abundance of wildlife populations, including kangaroos and other macropods. When analysing such data, design-based estimates of abundance extrapolate density from the sampled region to the broader area. In contrast, model-based approaches that use relationships between population density and habitat variables can deliver greater precision and ecological insight into population estimates.

Aims. This study aimed to evaluate recent spatio-temporal trends in the abundance of grey kangaroos (Macropus giganteus and M. fuliginosus) in Victoria, Australia using both design-based and model-based distance sampling.

Methods. Aerial surveys were conducted in seven management zones spread across the non-forested parts of Victoria on four occasions between 2017 and 2022. Distance sampling data were analysed to obtain design-based and model-based estimates of population size and relative precision across the entire study area, and for each management zone for each of the four surveys.

Key results. Model-based and design-based estimates of abundance proved to be broadly comparable, but with mostly higher precision for the model-based estimates at both statewide and management zone scales. The model-based approach revealed relationships between transect-level abundance and land-use type, normalised difference vegetation index (NDVI), annual rainfall and the amount of ecotonal habitat in the vicinity of the transects. Between 2017 and 2022 (a period coinciding with a prolonged La Niña event), the total abundance of grey kangaroos increased by approximately 87% (based on the model-based inferences) despite an ongoing harvesting program.

Conclusions. In addition to improved precision, model based estimation revealed relationships between habitat variables and transect-level abundance, allowing prediction of abundance at small scales.

Implications. The improved precision of model-based estimates of abundance will provide greater confidence in kangaroo management decisions such as setting of statewide harvest quotas. Model-based estimates at smaller spatial scales will similarly support localised management decisions.

Context. Urban areas are rapidly expanding, increasing anthropogenic pressure on global biodiversity. There are many threats associated with urbanisation, such as habitat loss and the spread of invasive species. Thus, to effectively manage urban greenspaces for native species, we need to understand species assemblages, and the factors that influence their diversity.

Aims. We assessed how assemblages of terrestrial vertebrate species differ across urbanisation levels in northern Sydney, Australia, and whether habitat characteristics influenced them. We also investigated the role of invasive species in these areas by comparing daily activity patterns between invasive and native species.

Methods. Nine forest (dry sclerophyll) patches, surrounded by three urbanisation levels (high-urban, mid-urban and low-urban), each with five motion-sensor cameras, were used to survey terrestrial fauna in northern Sydney from May to July 2023. Five vegetation variables and eight spatial variables were also recorded at each patch.

Key results. There were differences in terrestrial vertebrate assemblages across the three urbanisation levels, with more invasive species, including red foxes (Vulpes vulpes) and black rats (Rattus rattus), in high-urban areas. We also found native species assemblages (particularly superb lyrebirds, Menura novaehollandiae; long-nosed bandicoots, Perameles nasuta; and bush rats, Rattus fuscipes) to differ with tall and low shrub cover, whereas invasive species did not differ. Furthermore, mean activity peaks did not differ between red foxes and a critical weight range (CWR) mammal was recorded in high-urban sites. Last, we observed a significant negative relationship between invasive species richness and native species diversity.

Conclusions. Urbanisation has a strong effect on the assemblages, activity and interactions of native and invasive terrestrial vertebrate species in Sydney. Whereas remnant patches may support native species, the prevalence of invasive fauna in areas that are more highly urbanised may compound other factors affecting biodiversity.

Implications. This study has provided a baseline understanding of urban terrestrial vertebrate assemblages in northern Sydney, and has shown that mid-urban areas may be good candidates for reintroduction sites. Our findings can be used to guide management actions to support the conservation or re-establishment of native species in the region or other urban areas.

Context. Invasive mammalian predators have caused population declines and extinctions of wildlife worldwide. Many of these species exhibit some form of prey naïveté, which heightens their vulnerability to novel predators. In Australia, introduced feral cats (Felis catus) and red foxes (Vulpes vulpes) have had a particularly negative effect on native fauna, with the impacts of cats on mammals and birds well documented. Although feral cats are known to regularly prey on Australian reptiles, little is known about the behavioural responses of reptiles to cats, including whether native reptiles can recognise cats as a predation risk, and if so, which cues they use.

Aims. We investigated behavioural responses of two Australian lizard species, the shrubland morethia skink (Morethia obscura) and eastern striped skink (Ctenotus robustus), to the visual cues of feral cats in semiarid, south-eastern Australia.

Methods. We used arena trials to test lizards for predator recognition by using visual cues of an alien mammal predator (taxidermied cat, Felis catus), a native mammal predator (taxidermied western quoll, Dasyurus geoffroyi) and a mammal non-predator (taxidermied European rabbit, Oryctolagus cuniculus), as well as a procedural control (bucket) and a negative control (nothing).

Key results. We found little evidence of behavioural change when lizards were exposed to the taxidermied cat. Morethia obscura basked less when exposed to all treatments and C. robustus increased vigilance when in the presence of the taxidermied cat, but overall responses were similar among treatments.

Conclusions. Our findings suggest that stationary visual cues of cats do not trigger behavioural responses in these two lizard species.

Implications. Future research should assess behavioural responses to combinations of cat cues (e.g. movement, scent). Developing a deeper understanding of predator recognition systems and prey naïveté in reptile communities will be crucial for conservation of Australian reptiles that are negatively affected by feral cats.

Context. Ecosystem assessment using acoustic monitoring technologies can be an efficient method for determining species community composition and breeding activity, but many factors affect the quality of acoustics-data and subsequent level of confidence in derived inferences.

Aims. We aimed to assess variability in detection probabilities of five frog species using autonomous recording units (ARUs) deployed across a single 1 km² wetland, comprising a lagoon and surrounding area, and subsequently determine the required number of ARUs with 95% confidence in derived presence–absence data.

Methods. Ten ARUs were deployed in two rings around the lagoon’s centroid close to the water’s edge. Occupancy models were used to derive detection probabilities of species calling in the lagoon from data describing the temporal pattern of calling at each site, which were derived using call recognition software.

Key results. Only two of the five target species were detected by all 10 ARUs. All target species’ non-zero ARU detection probabilities varied by a factor of 14, and the coefficients of variation in individual ARU detection probability for each species varied by a factor of seven. Simulations revealed seven or eight ARUs are required to achieve 95% confidence in confirming presence of either of the two species with the highest observed detection probabilities, given they are present and calling. Even with ten deployed ARUs, the probability of successful detection of the other three species known to be calling on any day was less than 40%.

Conclusions. Effective detection was not achieved for all targeted species by several ARUs during a period when hydrology and season suited recruitment activity. Despite all ARUs being deployed at locations favourable for detecting targeted species, stochastic factors drove spatial variability in detection resulting in markedly different data for each ARU and each species.

Implications. Data describing species presence derived from automated recording units may not be representative due to spatiotemporal variability in detection that varies by species. To improve ARU deployment strategies, a priori knowledge of typical detection probabilities and species spatial variability can be used to determine the required number of call recorders for a set level of confidence.

Context. Indigenous Australians who lived in the desert used fire for many purposes. The interruption of these practices following colonisation, and the spread of invasive predators, coincided with massive faunal loss. Many extant species are still threatened by invasive predators and changed fire regimes. The study indicates that reinvigoration of traditional fire practice could help conserve declining species. The work presented here arises from a collaboration of scientists and Pintupi people (Traditional Custodians of the Kiwirrkurra Indigenous Protected Area, IPA). Some Pintupi co-authors grew up with a traditional nomadic lifestyle, and they include members of the Pintupi Nine, the last Pintupi people to walk out of that nomadic life, joining the Kiwirrkurra community in 1984.

Aim. To understand how traditional burning practices affect two threatened and culturally significant species: ninu (greater bilby, Macrotis lagotis) and tjalapa (great desert skink, Liopholis kintorei), on the Kiwirrkurra IPA.

Methods. We used satellite imagery to examine fire regimes in a 40-year time series (1980–2020) that includes transitions of people leaving, or returning, to different parts of the IPA. We collated information about traditional fire practices shared by Kiwirrkurra co-authors. Finally, we examined how ninu and tjalapa are affected by people presence and the fire regime.

Results. People influenced the fire regime by burning while hunting, by increasing the number of fires, decreasing their size, shifting the fire season (towards cooler months), and increasing the extent of long-unburnt vegetation. This regime reduced the fire extent after prolonged, widespread rainfall. Hunters have been active in the Kiwirrkurra community over the past 35 years, and fire patterns resemble those in the 1950s before the desert was depopulated. Under this fire regime, both bilbies and great desert skinks have persisted over 20 years of monitoring, with no large fires occurring since 2002. By contrast, they have disappeared from surrounding unmanaged parts of the landscape.

Conclusions. We suggest traditional burning helps ninu and tjalapa by increasing food resources in the fresh firescars and reducing vulnerability to predators by maintaining more mature habitat.

Implications. We support the use of traditional foot-based hunting fires in accessible hunting areas. Where prescribed burning is used for conservation, we recommend burns that are the width of typical hunting fires (~100−200 m wide). After significant rainfall events, burning should occur as grasses cure so that fuel continuity can be broken up, and extensive fires prevented.

Context. Management of broadly distributed invasive species requires knowledge of population densities across multiple ecosystems. The feral cat (Felis catus) has a continental distribution in Australia and has caused many declines and extinctions; however, density estimates from several ecosystems are few or lacking. Camera trapping data coupled with spatially explicit capture–recapture analysis is a suitable approach for estimating cat densities. However, if a large portion of individuals cannot be identified, density estimation may be difficult and estimates may be too low.

Aims. We aimed to estimate the feral cat density and population size within the subtropical Gondwanan Rainforest of eastern Australia, an area with world heritage status and high biodiversity values, and in which cat density was not known.

Methods. We used feral cat data from a grid of 60 camera traps deployed over 305 days in Border Ranges National Park, totalling 18,300 camera trapping nights. We employed a ‘random thinning’ spatially explicit capture–recapture model that considered detections of both known and unknown feral cat identities. Our modelling included a primary detection history of identified individuals and a secondary detection history that included pelage type, which allowed us to account for individuals with homogeneous pelage types.

Key results. Feral cat density was estimated at 0.858 cats km⁻² (95% HPDI 0.432, 1.385), which is much higher than the average feral cat density across the Australian continent of 0.27 cats km⁻² (95% CI: 0.18–0.45). The probability of identifying unique individuals was low for black and tabby cats compared with other pelage types. Population sizes during the four survey periods were estimated to be similar, with posterior medians ranging from 197 to 202 individuals and 95% highest posterior density intervals ranging from 95 to 329 individuals within a ~234 km² area.

Conclusions. Our study provides the first robust feral cat density estimate from a subtropical rainforest ecosystem.

Implications. Our results add to a growing body of literature that suggests feral cat densities are high in productive mesic reserves of eastern Australia. Management of feral cats in Gondwanan World Heritage Areas should be prioritised to limit impacts on narrow-range endemic species that are likely prey to feral cats.

Context. Rainforests typically evolved without the influence of fire or with only low-intensity fires, making them vulnerable to contemporary increases in fire frequency and intensity. Rainforest-associated species are predicted to be less adaptable than generalist species, but little is known about how fire in rainforest margins affects their habitat use and behaviour.

Aims. We investigated how mammal community composition, diversity, probability of habitat use and probability of movement were affected by wildfires that occurred in rainforest margins in South East Queensland, Australia, in 2019–20.

Methods. We deployed camera traps at 23 sites spanning the following three fire-habitat categories: unburnt rainforest (UR), burnt rainforest (BR) and surrounding burnt sclerophyll forest (BS), and used passive detection to analyse habitat use and behaviour.

Key results. Fire-habitat category had little influence on community composition. Species diversity was highest in unburnt rainforest compared with burnt rainforest and surrounding burnt sclerophyll forest. The probability of habitat use was highest in unburnt rainforest for both the long-nosed bandicoot (Perameles nasuta, estimated mean probability (95% CI): UR = 57.1% (22.98, 85.6), BR = 0%, BS = 0%) and the fawn-footed melomys (Melomys cervinipes: UR = 100%, BR = 87.5% (46.3, 98.3), BS = 50% (20.0, 80.0)). Probability of movement for the bush rat (Rattus fuscipes) increased with increasing elevation in burnt sclerophyll and was unaffected by elevation in unburnt and burnt rainforest.

Conclusions. Rainforest margins that experienced wildfire had reduced species diversity, most likely owing to a reduction in habitat use by rainforest-associated species. Movement patterns of mammal species were complex and not consistently related to recent fire history.

Implications. Rainforest margins and associated species are likely to be negatively affected by increasing wildfire intensity and frequency. In addition to urgent climate-change mitigation, land management that prevents wildfire incursion is likely to benefit rainforest communities in future.