Suchergebnisse

We know little about the availability of potential prey and patterns of prey consumption by Ningaui yvonneae in a natural environment. This information is important to understanding how the species is able to exploit its semiarid environment. Here, we examine the diet of N. yvonneae inhabiting a semiarid mallee community in South Australia using a combination of faecal analysis and observations of nocturnally foraging animals. Prey consumption was compared with the availability of prey types in the environment, and comparisons made between habitat components, across seasons and between sexes. N. yvonneae was found to include a range of prey types in its diet, with 11 invertebrate taxa recorded from direct observation and eight of these detected in the scats. Prey taxa consumed most often by freely foraging ningauis were Araneae, Blattodea and Orthoptera, while those most commonly detected in scats were Hymenoptera and Araneae. In comparison, 22 invertebrate taxa were recorded in pitfall traps, although many of these were recorded infrequently. Taxa most commonly recorded in traps were Hymenoptera, Collembola, Coleoptera and Acariformes. Observational data also indicated that consumption of prey taxa differed significantly between sexes and among seasons. Males generally consumed a more diverse array of prey, with both observational and scat data showing that they were more likely to consume Hymenoptera and Isoptera, while females were more likely to consume Lepidoptera and Hemiptera. Variability between seasons was evident in consumption of invertebrate grubs (recorded only during 'growth'; February–April), Orthoptera (recorded most often during 'breeding', August–October), and Araneae (recorded more often during 'maturation', May–July). However percentage occurrence data from the scats lacked this seasonality, possibly because of the smaller array of prey taxa recorded. N. yvonneae captured prey from all available habitat components, with five of the most frequently recorded prey taxa being recorded from all components. Leaf litter and Triodia were the most commonly recorded capture sites (45% and 22% of captures respectively), and males and females used the habitat components in a similar manner. Although N. yvonneae is like many other dasyurids in having a largely generalist insectivorous diet, comparisons of prey consumed with their availability in the environment indicated that individuals did show some selectivity towards certain taxa, particularly Blattodea, Orthoptera, Chilopoda, Lepidoptera and Araneae.

This study uses analysis of faecal pellets to assess the diet of the bilby (Macrotis lagotis) in an area spanning over 230 000 km2 in the Tanami Desert, Northern Territory. More specifically, we examine the link between diet composition, bilby prevalence and the landscape variables of fire, rainfall and substrate. Seed promoted by fire, particularly of Yakirra australiense, was found to be one of the most important components of the diet and constituted ~36% of the relative abundance of identifiable food particles. Bulb from Cyperus bulbosus was also an important component of the diet (18.5% relative abundance). Invertebrates accounted for 39% of the identifable food particles, and termites and beetles were the most common types. Bulb and seed formed a greater component of the diet in the central part of the study area where bilbies were more prevalent. Conversely, invertebrates were more dominant in the bilby diet on the northern and southern periphery of the Tanami Desert. Substrate type and antecedent rainfall associated significantly with the amount of seed from fire-promoted plants and total plant contained in the diet. Time since fire was an additional factor associated with the abundance of dietary fire-promoted seed. This suggests that the spatial and temporal variability of these landscape variables play an important role in controlling the availability of seed and bulb resources used by the bilby, and thus affect bilby prevalence. The results support the proposition that seed and bulb plant foods are exploited opportunistically and invertebrates, especially termites, are relied upon when plant food resources are scarce. Furthermore, the findings indicate that fire management could be used as a means to increase the favourability of habitat for the bilby in parts of its current range.

Autecological data were collected on southern populations of the yellow-footed antechinus (Antechinus flavipes), during a wider study on the persistence of this species in a highly fragmented landscape of the southern Mt Lofty Ranges, South Australia. Data are presented to provide information on this species in the southern part of its range, to present a comparison with populations in other, more northern regions, and to provide an insight into the species' persistence in a fragmented system. Resulting recapture rates lend support to the presence of a male-biased dispersal strategy, which is the first published indication of such a strategy for the species. New information was also recorded for nest sites, with most sites occurring in tall Xanthorrhoea semiplana tateana, and only 33% found in tree cavities. Other results showed mostly comparable population densities and weights with other, more northern populations. However, differences were apparent with respect to juvenile dispersal behaviour and, to some extent, breeding times. Within-study populations also showed variation with regard to weights, density and breeding times. Forest animals were lighter, were largely of lower population densities, and were generally later breeders than animals that inhabited patches and strips of remnant vegetation. Such differences in weight and density may have been due to favourable 'edge effects' in patches and strips, while variations in breeding times may be due to local climatic or habitat factors. The life-history strategies and tolerance of habitat edges shown by A.�flavipes (presently and historically) provide some explanation for the species' persistence in this fragmented system.

In this study we examine broad-scale factors affecting the distribution of the yellow-bellied glider (Petaurus australis australis) in the southern Australian state of Victoria. Using the bioclimatic analysis and prediction system, BIOCLIM, and vegetation-suitability mapping, we assessed the potential distribution of the species at the time of European settlement and compared it to the current distribution. BIOCLIM revealed that P. a. australis is most likely to occur in areas with mean annual rainfall >600 mm and mean annual temperature between 6°C and 14.5°C. Much of its current distribution is skewed to the eastern half of the State, and our results emphasise a disjunction between western and eastern Victorian populations that is attributed to unsuitable climate and vegetation for the species. This indicates that P. australis in the west was most likely separated from eastern Victorian P. australis long before European settlement. Our results also indicate that isolated P. australis populations in south-western Victoria represent fragments of what was probably a much more widely distributed population when European settlement took place. Owing to the highly restricted distribution of suitable remnant native vegetation, these westernmost P. australis populations should be a high priority for future research and conservation work.

Linear forest clearings created by utility corridors have the potential to fragment landscapes, create edge effects and isolate populations of plants and animals. Here, we investigated the impact of utility corridors on small terrestrial fauna inhabiting Nangwarry Native Forest Reserve, south of Penola in south-eastern South Australia. Twelve sites straddling linear clearings of two widths (1.5 and 4.2 m) were surveyed over 2 years with 53 traps arranged as five transects at each site. This resulted in a total of 933 captures of 18 vertebrate species, including four amphibians, eight reptiles and six mammals. Propensity for capture near edges v. interiors, distances moved between recaptures and willingness to cross linear clearings varied among species, and was not related to taxa groups. For example, the small skink Bassiana duperreyi was extremely mobile and crossed tracks regularly. At the other extreme, the frog Neobatrachus pictus was more likely to be caught on interior transects and was never recorded moving between captures. The small dasyurid Antechinus flavipes was the most regularly caught species, and made both short- (<50 m) and long-distance (>1500 m) movements, with longer moves made by dispersing juveniles. Movements by this species often involved clearing crossings, although these were more likely when time between recaptures was longer, particularly for females. However, the overall rate of crossings for this species was not different from that expected if movements were random. In conclusion, the relatively narrow utility corridors studied here did not appear to affect the mobility of the majority of vertebrates significantly, with approximately half of the 85 movements recorded being of animals crossing a clearing, and no significant difference between the proportion crossing the wider (4.2 m) and the narrower (1.5 m) clearings. The present study is one of only a handful investigating movement patterns in reptiles and amphibians, particularly in relation to disturbances. However, sample sizes were small for some species, and future work should focus on those species that look to be either particularly mobile or sedentary, and encompass responses to the wider (up to 15 m) permanent tracks in the region.

This study provides the first assessment of the diet of the yellow-bellied
glider (Petaurus australis) in the south-west portion of
its range near the Victorian–South Australian border. Examining its diet
in this region is viewed as being fundamental to understanding the ecological
requirements of the species. Observations were conducted over a five-year
period on gliders from five distinct groups. Sap was the most important food
item throughout the year and accounted for 83% of 407 feeding
observations. Each group of gliders used up to 21 different trees for sap, but
during any sample period only 1–8 trees were used. This represents a
vastly different pattern of use of sap trees to that described in any earlier
study. Some trees were visited more often than others, and these tended to be
heavily scarred, indicating use over many years. Other food types were
arthropods and honeydew and, to a lesser extent, nectar. This study also
revealed that the yellow- bellied glider is not dependent on a diversity of
tree species nor on a winter-flowering species. We provide a review of the
diet of the yellow-bellied glider throughout its range. This shows that the
yellow-bellied glider is reliant on sap as a food resource but particularly so
at both ends of its geographic range. The reason for this is unclear, but
there is definitely a need for further study of sap-flow patterns in
eucalypts.

Context Many of Australia's threatened mammals were once widespread across the continent and present in both arid, semiarid and temperate habitats. However, data on breeding biology can be lacking for some climatic regions due to local extinctions of populations. The breeding biology of the greater bilby (Macrotis lagotis) has previously only been studied in captive colonies or free-ranging arid zone populations. Between 1997 and 2005, captive-bred bilbies were released at two sites in temperate South Australia. These populations provided an opportunity to determine whether bilbies adopt a seasonal reproductive strategy in the temperate zone, where this species has not been present since the early 1900s. Aims To determine the season of births, litter size and female reproductive potential in two free-ranging populations of the bilby in the temperate zone of South Australia. Methods Bilbies were regularly cage-trapped at Venus Bay Conservation Park and Thistle Island between August 2007 and April 2010 to obtain data on reproductive activity in both populations. Key results Births of pouch young in both populations occurred in winter (June–August), spring and early summer, but not between February and mid-May. Males had a significantly smaller mean testes size relative to head length in late summer, when breeding activity ceased. Average litter size at pouch emergence was between 1.00 and 1.47 pouch young, with females producing up to three litters per annum. The mean head length of females that successfully raised twins was significantly larger than that of females who raised a single pouch young. Conclusions The seasonal breeding pattern observed in the present study differs from that of year-round reproductive activity in captivity and the arid zone. The present study suggests that female body size influences fecundity, and that releasing large females at the start of the breeding season in temperate areas may maximise the initial rate of increase of a translocated bilby population. Implications The present study suggests previously widespread species such as the bilby can adapt their reproductive strategy to suit local conditions. Cessation of breeding in autumn, as observed in this study, has also been observed in other bandicoot species in southern Australia.

Abstract
Context Translocations have been widely used to re-establish populations of threatened Australian mammalian species. However, they are limited by the availability of sites where key threats can be effectively minimised or eliminated. Outside of 'safe havens', threats such as exotic predators, introduced herbivores and habitat degradation are often unable to be completely eliminated. Understanding how different threats affect Australian mammal populations can assist in prioritising threat-management actions outside of safe havens.
AimsWe sought to determine whether translocations of the greater bilby to two sites in the temperate zone of South Australia could be successful when human-induced threats, such as prior habitat clearance, historic grazing, the presence of feral cats and European rabbits, could not be completely eliminated.
Methods Greater bilbies were regularly cage trapped at two translocation sites and a capture–mark–recapture study was used to determine survival, recruitment and population growth at both sites.
Key results Our study showed that bilbies were successfully translocated to an offshore island with a previous history of grazing and habitat clearance, but which was free of exotic predators. At a second site, a mainland exclosure with feral cats and European rabbits present, the bilby population declined over time. Adult bilbies had similar survival rates in both populations; however, the mainland bilby population had low recruitment rates and low numbers of subadults despite high adult female fecundity.
ConclusionsThe results indicated that past grazing and habitat clearance did not prevent the bilby population on the offshore island establishing and reaching a high population density. In the mainland exclosure, the low recruitment is probably due to feral cats predating on subadult bilbies following pouch emergence.
Implications The results demonstrated that the bilby, an ecologically flexible Australian marsupial, can be successfully translocated to sites with a history of habitat degradation if exotic predators are absent. At the mainland exclosure site, threat mitigation for bilbies should focus on control or eradication of the feral cats. The control of European rabbits without control of feral cats could lead to prey-switching by feral cats, further increasing predation pressure on the small bilby population.