Suchergebnisse

In most areas of Australia, mammals constitute the staple diets of cats, foxes and dingoes. In central Australia the abundance of mammals is often too low to meet the dietary requirements of these carnivores and yet populations of cats, foxes and dingoes persist. To investigate alternative feeding strategies of cats, foxes and dingoes in arid environments, their diets were monitored in relation to prey availability in two areas of the Tanami Desert where rabbits do not occur. Dietary information was obtained by analysing predator scats collected between 1995 and 1997. Prey availability was monitored by track counts, pitfall trapping, Elliott trapping, and bird counts along walked transects. In contrast to dietary studies elsewhere in Australia, it was found that reptiles were an important component of the diets of predators in the Tanami Desert, and should be classified as seasonal staples. Birds increased in importance in the diets of cats and foxes during the winter, when reptiles were less active. There was considerable overlap between the diets of all three predators, although dingoes ate more large prey items (e.g.�macropods) than the other two predators. Results highlight the opportunistic feeding habits of cats, foxes and dingoes and show that, although mammalian prey are less important in central Australia than has been found elsewhere, species that are vulnerable to extinction, such as the bilby (Macrotis lagotis), mulgara (Dasycercus cristicauda) and marsupial mole (Notoryctes typhlops), are also consumed by these predators.

Australian deserts are characterised by highly patterned plant productivity
and an extremely unpredictable climate. The Tanami Desert in central Australia
is dominated by vast sandplains interspersed with more productive habitats
such as palaeodrainage lines. During 1996 and 1997 fauna surveys were
conducted in two areas of the Tanami Desert to investigate the relative
importance of palaeodrainage habitat for fauna under different seasonal
conditions. The two areas were at latitudes separated by approximately 400 km,
and during the study period the northern study area (Tennant) received
considerably more rainfall than the southern study area (Kintore). The species
richness and abundance of a range of taxonomic groups were compared between
the two study areas and between palaeodrainage habitat and adjacent sandplain
habitat. The only significant difference between habitats was that small
reptiles were more abundant in sandplain than palaeodrainage habitat. Overall,
bilbies, bustards and macropods were significantly more abundant at Tennant
than Kintore, but significantly more small mammals were captured at Kintore.
In both habitats and areas, capture rates, track counts and species richness
of reptiles varied significantly with season. The biomass of invertebrates
captured also showed significant temporal fluctuations. Burrowing frogs were
active only after rain, and birds showed significant fluctuations in abundance
and species richness associated with rainfall. The abundance of small mammals
did not vary significantly during this study. Overall, local seasonal
conditions were generally more important determinants of the abundance of
fauna in the spinifex grasslands of central Australia than was habitat type.

Feral cats (Felis catus) occur throughout central Australia. In this study, we analysed the stomach contents of 390 feral cats collected between 1990 and 1994 from the southern half of the Northern Territory. Cats fed on a wide variety of invertebrates, reptiles, birds and mammals, including animals up to their own body mass in size. Mammals were the most important prey but reptiles were regularly eaten in summer and birds were important in winter. Invertebrates were present in the diet in all seasons. Carrion appeared in stomach samples during dry winters only and this has implications for future control of feral cats.

We evaluated three monitoring techniques to determine the spatial pattern and relative abundance of the bilby (Macrotis lagotis) in the Tanami Desert, Northern Territory. All the methods examined relied on the identification of animal sign (foot imprints or diggings) to indicate the presence of a species. With fixed transects, a 10-km prepared tracking surface was monitored regularly using an all-terrain vehicle. With random plots, an unprepared tracking surface within a 200 × 300 m area was searched on foot for sign of the species. A helicopter was used in an aerial survey to identify bilby diggings from an altitude of 15–20 m while travelling at a speed of 30–40 knots along a predefined transect. The results for each method were stratified in relation to latitude and substrate to facilitate comparison of the efficacy of each technique. The fixed transects returned the least number of bilby records for most effort. The aerial transect technique resulted in few (<4%) false negative records but a sizeable (42%) number of false positive records. It is suggested that the aerial survey technique combined with ground-truth survey plots would provide reliable information on the extent of occurrence and status of the bilby in the remote spinifex deserts of central Australia.

Abstract ContextFeral cat is a favoured food item in some Australian Indigenous communities. We describe how cats are hunted and whether cat hunting can contribute to the persistence of threatened species. AimsTo determine whether cat hunting by expert trackers has the potential to be an effective method of managing predation impacts on threatened species at key sites. MethodsWe recorded all cats captured on the Kiwirrkurra Indigenous protected area (Kiwirrkurra IPA) over a 5-year period by offering incentive payments for hunters to report their catch. For a subset of hunts, we measured the duration and distance of the hunt. We compared the frequency of occurrence of cat tracks in 2-ha track plots between the hunting zone and more remote, unmanaged areas. At a finer scale, we compared cat presence at bilby burrows inside and outside the hunting zone. Key resultsIn all, 130 cats were removed from the Kiwirrkurra IPA from 2014 to 2019. Hunts took an average of 62min to complete and a team of four hunters could catch up to four cats in a single day. Although cats still occurred throughout the hunting zone, we found that cat detections at track plots were less likely in the areas where cats were hunted. Long-term data suggest that threatened species have persisted better in areas where there is an active presence of hunters. ConclusionsCat hunting by Indigenous tracking experts is an efficient method of despatching cats at localised sites. Following footprints on foot facilitates the targeting of individual cats that are hunting at threatened species burrows. More rigorous studies are required to determine whether cat hunting significantly reduces predation on threatened species, or whether there are other co-benefits of maintaining a presence of hunters in the landscape (such as fine-scale fire management) that are more important for the persistence of vulnerable prey. Implications Wherever open sandy substrates occur, there is potential to employ Indigenous expert trackers to assist with the removal of problem cats, such as, for example, to complete cat eradication inside fenced reintroduction sites, or at times of peak prey vulnerability, such as breeding events or after bushfires.

Context Prescribed burning is widely adopted as a conservation-management tool, with priorities largely being the protection of fire-sensitive plant communities, threatened fauna habitat and minimising the risk and impacts of broad-scale wildfire. However, an improved understanding of the ecological mechanisms that underpin species responses to fire will assist the development and refinement of prescribed-burning practice. Aims To examine the effect of fire on burrow-system occupancy and breeding success at different spatial and temporal scales for a threatened skink, Liopholis kintorei. Methods Experimental burns simulating different fire types (clean burn, patchy burn and no burn) were conducted at 30 L. kintorei burrow systems that were selected from within a 75-ha focal study area. Burrow-system occupancy was monitored daily for 1 month, then monthly for an additional 3 months. Breeding success was assessed once at all 30 burrow systems. Eight additional 1-km2 sites within L. kintorei habitat that had experienced some degree of fire 2 years earlier were selected from across Newhaven Wildlife Sanctuary. Burrow-system occupancy and breeding success of L. kintorei at these sites was assessed once. Key results There was no significant effect of fire on burrow-system occupancy 1 month after experimental burns; however, burrow-system occupancy was significantly higher at unburnt sites 4 months after experimental burns and 2 years post-fire. Breeding success was significantly higher at unburnt sites than at clean-burnt and patchy-burnt sites. Conclusions Fire adversely affects L. kintorei, as demonstrated by a higher proportion of unoccupied burrow systems and fewer successful breeding events post-fire, particularly when all ground cover is lost. Implications Because fire is an inevitable and natural process within arid-zone spinifex grasslands, the primary habitat for L. kintorei, we recommend prescribed-burning practices that aim to maximise ground cover by reducing the frequency, intensity and size of fires. More specifically, we recommend fire exclusion from key sites within distinct localities where L. kintorei is known to be locally abundant. Depending on the size of these key sites, there may also be a need to construct strategic fire breaks within sites to ensure that any unwanted ignitions do not result in the loss of all vegetation cover.