Two systematic regional fauna surveys conducted in the central-north of the state, and an ancillary review of existing published data, identified many new localities and provided an opportunity to describe aspects of this species' ecology and habitat. As well as in typical Triodia grasslands, Pseudomys desertor was recorded in a wide range of sub-tropical savanna woodland, shrubland and grassland vegetation types, many within a zone with rainfall of 500–750 mm. In these higher-rainfall areas, average bodyweight was significantly larger than previously reported for arid-zone specimens. Generalised linear modelling was used to examine which environmental factors best explained the species' abundance, and ground cover was a consistent predictor across the two study areas. Despite occurring in sites mechanically cleared of trees, P. desertor was more abundant in those pastures with a high cover of native hummock grasses. Though superficially indicating a degree of tolerance of disturbance, the evidence suggests that P. desertor is a fire- and grazing-decreaser. Overall, P. desertor was most abundant in areas with the least historical grazing pressure and disturbance.
Context Global mammal populations continue to be threatened by environmental change, and recent decadal monitoring in northern Australia suggests a collapse in mammal abundance in key locations. Cape York Peninsula has globally significant natural values but there is very little published about the status and distribution of mammals in this region. Aims Following an extensive field survey we investigated two key questions: (i) what is the composition, spatial variation and change from previous regional surveys in the mid to late 1900s in the native terrestrial and arboreal mammal fauna recorded; and (ii) which landscape and site factors best predict mammal richness and abundance. Methods We sampled 202 one-hectare sites across seven locations from 2009 to 2012 in woodlands, closed forestand dune scrub and tussock grasslands. We collected landscape and site-based environmental data for each location, representing fire, weather and vegetation factors. We used generalised linear mixed models to examine the relationship between mammals and these factors. Key results Mammals were generally scarce across the sites and were more abundant and species rich in wet coastal grasslands or closed forests then tropical savanna woodlands. Fire frequency data and the surrounding vegetation complexity were consistent landscape-scale predictors of mammals; ground cover and woody complexity were significant at the site scale. Conclusions Notwithstanding interpretational constraints related to the limited evidence base of historic sampling, the mammal fauna recorded in this study for Cape York Peninsula was similar in composition to the mammal fauna described from 1948–1980 and surveys in 1985, with some species seemingly declining (e.g. Melomys burtoni, Dasyurus hallucatus, Sminthopsis virginiae) and others stable (e.g. Rattus sordidus) or more common (e.g. Rattus tunneyi); however, across all sites abundance was low, and many sites had few or no mammals. Implications In the absence of consistent long-term systematic monitoring it is difficult to determine if this survey and historical surveys represent pre-European patterns for mammals. The absence or low abundance of mammals in most sites suggest that cotemporary patterns may not represent an intact mammal fauna. Due to the equivocal nature of these findings a critical next step is to establish robust monitoring and experimental work to reveal the response of mammals to management interventions.
Context Habitat degradation and fragmentation of vegetation can transform and deplete local wildlife populations, and is a key threatening process globally. In northern Australian tropical savannas, clearing is relatively rare across the biome, although it is slowly intensifying as a result of increasing agricultural development. However, the terrestrial vertebrates in these largely intact landscapes are undergoing current population declines because of a variety of land-management changes, one of which is increasing land clearing; therefore, there is a need to understand the relative effect of small-scale land clearing the fauna.
Aims The present study examined the variation in abundance of birds, mammals and reptiles in intact, thinned and cleared Eucalyptus woodlands in a tropical savanna bioregion.
Methods The vertebrate fauna were sampled in 88 sites over two general geographic locations within the Desert Uplands in 2005 and 2006. Standardised 1-ha surveys were employed in a single vegetation type and across three treatments. As two discrete locations were examined, linear mixed models were used in the analysis.
Key results The fauna composition varied significantly across the intact, thinned and cleared sites. Bird species richness reduced from intact to thinned and cleared sites, and reptile richness and abundance declined in cleared sites, but was largely unaffected by thinning. Seventeen bird species recorded significant variation in abundance across the three vegetation structural types, with 12 most abundant in the intact sites. Mammals on the whole were recorded in very low abundances and in few sites. For reptiles, two were most abundant in thinned sites and three in intact sites.
Conclusions In the present study, we have demonstrated that small-scale clearing and vegetation manipulation via thinning, even within largely intact tropical savanna woodland, can cause localised depletion of some species, although most notably where the vegetation disruption was most severe (i.e. clearing). Birds are most affected, and many species that declined in abundance are the same as those that suffered severe population reductions as a result of broad-scale clearing in south-eastern Australia.
Implications The proposed increase in the intensity of agricultural land use in northern Australia will result in incremental landscape change as a result of clearing. Understanding how the gradual reduction of vegetation cover and habitat will change the faun assemblage is important for pre-emptive conservation planning. This is vital to avoid the mistakes of extensive landscape change in southern Australia that has left a legacy of a permanently depleted fauna.
Context Night parrots (Pezoporus occidentalis) are one of Australia's most endangered birds, and there is evidence suggesting feral cats (Felis catus) are a major cause of decline. However, because night parrots currently have a restricted distribution, little is known of the ecology of feral cats around their remaining populations. This limits the development of effective management strategies. Aims The aims of this study were to understand feral cat movement and habitat selection around night parrots, and to then estimate the effectiveness of possible management actions. Methods Research was conducted around the only confirmed night parrot population in eastern Australia. In 2019 and 2020, we obtained GPS data from nine feral cats, and used step selection functions to assess preferred habitats. Management options were then simulated based on cat movement data, including altering trap numbers and layout, and changing routes for night spotlight shooting (using existing roads, random walking or creating new roads in preferred habitats). Key results Feral cats preferred alluvial and riparian habitats and avoided rocky woodlands and roads. Simulated control efforts were more successful if traps are placed at 'pinch points' where drainage lines converged, and if new roads were created near to creek lines and alluvial habitats. Conclusions Feral cats move around the last known population of night parrots in eastern Australia, travelling through and using many shared habitats. Targeting creek lines and alluvial areas in cat control operations would improve effectiveness and potentially reduce predation impacts on night parrots. Implications Conservation of endangered birds like night parrots can be enhanced through understanding the ecology of threats such as feral cats to develop locally tailored control operations.
Context There is growing evidence that vertebrates inhabiting the extensive savannas of northern Australia are undergoing a widespread decline as a result of the effects of anthropogenic land management such as the grazing of domestic stock. Despite the ubiquity of pastoral grazing in the Australian savannas, few studies have examined the changes in terrestrial vertebrate fauna following destocking.
Aims The present study monitored the response of birds, mammals and reptiles to destocking of a newly acquired conservation reserve in north-eastern Australia.
Methods The vertebrate fauna was sampled over a 5-year period. Standardised 1-ha survey was conducted twice a year in 2006, 2007 and 2010, at 40 sites representing six habitat types.
Key results The fauna assemblage, the abundance and richness of major taxa, and the abundance of a suite of individual species were found to vary significantly with time since destocking. Although some of the observed trends were consistent with previously reported responses of vertebrates to grazing, in general species richness and abundance did not increase linearly over time since destocking, with an overall decline in the first year, and an increase in the subsequent survey. Mammals remained at very low abundance and displayed a trend contrary to that for birds and reptiles, and variation was often confounded by habitat type.
Conclusions In general, where there has been a long history of pastoral land management, destocking alone may not induce short-term increases in the vertebrate fauna thought to be affected by grazing in Australian savannas.
Implications Monitoring the outcomes of conservation management activity is a critical component of understanding the success, failures and adaptation needed to maximise the costs and benefits of conservation investment. The recovery of the vertebrate fauna thought to be of conservation concern in relatively intensively used, long-grazed landscapes may be lengthy and contingent on other factors, such as periods of favourable weather, or understanding the interactive effects of herbivore removal, fire pattern and feral predators. In such landscapes, it is possible that recovery of some elements of the vertebrate fauna may not occur without deliberate interventions, such as reintroductions or intense predator control.
