Perameles Nasuta Research Articles

When Does an Alien Become a Native Species? A Vulnerable Native Mammal Recognizes and Responds to Its Long-Term Alien Predator

The impact of alien predators on native prey populations is often attributed to prey naiveté towards a novel threat. Yet evolutionary theory predicts that alien predators cannot remain eternally novel; prey species must either become extinct or learn and adapt to the new threat. As local enemies lose their naiveté and coexistence becomes possible, an introduced species must eventually become ‘native’. But when exactly does an alien become a native species? The dingo (Canis lupus dingo) was introduced to Australia about 4000 years ago, yet its native status remains disputed. To determine whether a vulnerable native mammal (Perameles nasuta) recognizes the close relative of the dingo, the domestic dog (Canis lupus familiaris), we surveyed local residents to determine levels of bandicoot visitation to yards with and without resident dogs. Bandicoots in this area regularly emerge from bushland to forage in residential yards at night, leaving behind tell-tale deep, conical diggings in lawns and garden beds. These diggings were less likely to appear at all, and appeared less frequently and in smaller quantities in yards with dogs than in yards with either resident cats (Felis catus) or no pets. Most dogs were kept indoors at night, meaning that bandicoots were not simply chased out of the yards or killed before they could leave diggings, but rather they recognized the threat posed by dogs and avoided those yards. Native Australian mammals have had thousands of years experience with wild dingoes, which are very closely related to domestic dogs. Our study suggests that these bandicoots may no longer be naïve towards dogs. We argue that the logical criterion for determining native status of a long-term alien species must be once its native enemies are no longer naïve.

Short-term response of the long-nosed bandicoot, Perameles nasuta, and the southern brown bandicoot, Isoodon obesulus obesulus, to low-intensity prescribed fire in heathland vegetation

Context Prescribed burning is routinely performed within the Sydney Basin as a method of fire-hazard mitigation. Despite the widespread use of prescribed fire, knowledge of the impact of prescribed fire on most fauna species remains unclear. This is particularly the case for bandicoot species. Aims To determine the impact of a low-intensity prescribed fire on the survival of the long-nosed bandicoot, Perameles nasuta, and the southern brown bandicoot, Isoodon obesulus obesulus (hereafter abbreviated to I. obesulus), immediately after the fire and at 5 weeks, 5 months and 13 months following the fire. To document the spatial ecology and nesting requirements of I. obesulus and P. nasuta before and after fire. Methods One I. obesulus and seven P. nasuta (five female and two male) individuals were radio-tracked. Animals were tracked before, during and following a hazard-reduction burn to assess the impact of fire on home range, survival and nesting behaviour. Key results Post-fire survival of P. nasuta and I. obesulus was high and the population remained stable up to 5 months following the fire. All animals tracked within the burn area (three female P. nasuta) survived the passage of fire. The home range for one male I. obesulus was found to be 2.35 ha 50% kernel-density estimate (KDE) and 12.35 ha 95% KDE. Female P. nasuta (n = 5) had a home range of 1.3 ha ± 0.2 s.e. 50% KDE and 7.5 ha ± 1.7 s.e. 95% KDE. Male P. nasuta (n = 1) had a home range of 1.1 ha 50% KDE and 6.5ha 95% KDE. Nesting for both species tended to occur in dense vegetation, with a slight shift to non-combustible refuge sites post-fire. Animals tended to maintain exclusive and relatively stable core home ranges, although overlap of non-core home ranges was common. Conclusions The survival of bandicoots following a low-intensity hazard-reduction fire was high in the short term; however, further research is required to determine how the components of a fire regime affect native species, in particular peramelids. Implications Hazard-reduction fires should be used with caution to manage the isolated and endangered northern Sydney population of I. obesulus, so as to ensure the persistence of this species.

A review of the nutrition of Australian peramelid marsupials

European settlement has had a dramatic impact on the distribution and abundance of peramelid (bandicoot and bilby) marsupials. Predation and competition from introduced species and altered habitat have been implicated in their decline or extinction. Bandicoots and bilbies inhabit a broad range of habitats in Australia. Research on the distribution, morphology, gastrointestinal histology, lactation, metabolism and nutritional physiology of extant peramelid species has increased in the last few decades. This paper provides a review that encompasses recent nutritional-based research. Peramelid research is mostly limited to only three species – Isoodon macrourus, Perameles nasuta and Macrotis lagotis – which prevents effective comparisons between species. Peramelids are broadly classified as omnivores and possess relatively uncomplicated gastrointestinal tracts. The caecum is the region of greatest diversity among species. The relatively large caecum of Chaeropus ecaudatus supports the theory that this species may have been the only herbivorous peramelid. The caecum of M. lagotis is less pronounced than other species and is continuous with the proximal colon. M. lagotis also has a longer total colon length, which aids water conservation to ensure survival in an arid environment. Temperate-zone species such as I. macrourus, I. obesulus and P. nasuta are more similar to each other with respect to gastrointestinal morphology than either C. ecaudatus or M. lagotis. Additional research on the morphometrics of the gastrointestinal tracts of P. gunnii, P. bougainville, P. eremiana, M. leucura and I. auratus would enable further comparisons to determine whether differences are a result of geographic distribution, habitat preference or variation between genera and/or individual species. Currently, histological information of the gastrointestinal tract is limited to the small intestine of P. nasuta and I. macrourus. The histology of the small intestine of the weaned juvenile I. macrourus more closely resembles that of P. nasuta pouch young than P. nasuta adults. The younger bandicoots possessed villi whereas in the adult P. nasuta and I. macrourus villi were arranged in a zig-zag formation. The reason for the zig-zag formation of the villi and the function it may serve remains unclear. Detailed nutritional research on captive M. lagotis, I. macrourus and P. nasuta indicate that the two temperate-zone species – I. macrourus and P. nasuta – are more similar to each other than to the arid-dwelling M. lagotis. Detailed nutritional studies are required on all species, both free-living and captive. Experimental diets do not always accurately reflect a natural diet, which means that results from captive studies may not reflect the situation for free-living animals. The hindgut of peramelids is the main region for retention of digesta, and presumably where microbial digestion occurs. However, no studies have been undertaken to examine the microflora of the gastrointestinal tract of bandicoots or the bilby. As captive husbandry is an important tool in conservation management, it should also improve their successful maintenance in captivity by the provision of diets that better meet their nutritional requirements.

Are less vocal rainforest mammals susceptible to impacts from traffic noise?

Context Traffic noise is believed to cause road avoidance and other barrier effects in a variety of wildlife species, and to force changes to call pitch or loudness in others; however, this has never been tested in the absence of other road impacts. Noise impacts on species that do not frequently vocalise are also poorly understood. We investigated traffic-noise impacts on the following three rainforest mammals that do not often vocalise: Hypsiprymnodon moschatus, Uromys caudimaculatus and Perameles nasuta. These species have previously been observed to exhibit varying levels of road avoidance. Aims To determine whether traffic noise affects movement and behaviour of medium-sized, ground-dwelling rainforest mammals in the absence of other road-associated variables and potential impacts. We hypothesised that noise impacts would be greatest for species previously shown to avoid roads. Noise impacts on these less vocal species compared with more vocal species is also discussed. Methods In north-eastern Queensland, Australia, mammals captured at least 500 m from any road were tracked after fitting with spool-and-line equipment. On noisy nights, traffic noise at levels similar to a busy highway was played continuously throughout the night from a line of 12 speakers mounted on trees. Speakers were silent on quiet nights. Key results Traffic noise caused no increase in avoidance of the speaker line and was not a barrier to movements across the line. Overall, movement paths on noisy nights appeared similar in pattern (tortuosity) to those of quiet nights. At a finer scale, movements of H. moschatus and P. nasuta became more tortuous later in the track, suggesting a return to normal foraging behaviour and possible habituation to the noise. Conclusions These three species with varying levels of previously recorded road avoidance, did not respond negatively to traffic noise. There was, however, a suggestion of habituation by H. moschatus and P. nasuta in response to the noise. Implications The demonstrated lack of response to traffic noise in these less vocal species means that traffic noise is unlikely to cause road avoidance or barrier effects. Instead, lack of response and possible habituation to traffic noise may increase vulnerability to road mortality.

Habitat-dependent population regulation in an irrupting population of long-nosed bandicoots (Perameles nasuta)

We used isodars to analyse habitat-dependent population regulation by long-nosed bandicoots Perameles nasuta during an irruption and subsequent population crash in three habitats (heath, woodland and forest) at Booderee National Park, south-eastern Australia. Specifically, we aimed to see whether patterns of habitat-dependent population regulation matched a priori estimates of quantitative and qualitative differences between habitats. We also tested if habitat preference changed between the increasing and decreasing phase of the irruption as predicted by the reciprocating dispersal theory. Quantitative differences in habitat quality were indexed by the relative abundance of the main food of long-nosed bandicoots (terrestrial invertebrates), while qualitative differences were indexed by the availability of refuge from predation (vegetation understorey density). One index of fitness, body weight, was highest in forest, and lowest in heath, suggesting an ideal despotic model of habitat selection. Over the entire course of the irruption, there was density-dependent habitat selection with forest and woodland both quantitatively superior to heath. This reflected the overall abundance of invertebrates with highest abundance in woodland and forest and less in heath. Isodar analysis also revealed that although forest was quantitatively better than heath and equivalent to woodland it was qualitatively poorer than either habitat. Heath had a higher density of understorey than woodland and woodland having a higher density of understorey than forest giving crossover population regulation. When the increasing and declining phase of the irruption were analysed separately, no habitat was quantitatively superior to any other during either phase. The lack of switching in preference between habitats from the increasing to the declining phase of the irruption and the virtual absence of any dispersal by adults, does not support the reciprocating dispersal hypothesis.

Serologic-based Investigation of Leptospirosis in a Population of Free-ranging Eastern Grey Kangaroos (Macropus giganteus) Indicating the Presence of Leptospira weilii Serovar Topaz

Eastern grey kangaroos (Macropus giganteus) are one of the most abundant large macropodids sharing the landscape with humans. Despite this, little is known about the prevalence of Leptospira carriage within this species and the role that they may partake in the transmission of this disease in Australia. The sera of 87 free-ranging eastern grey kangaroos, captured in the Warragamba Catchment Area, Sydney, Australia, from June 2004 to November 2006, were screened against a reference panel of 22 Leptospira serovars using the microscopic agglutination test (MAT). Leptospiral antibodies were detected in 47% (41 of 87) of serum samples collected. Leptospira weilii Topaz, a newly emergent serovar in Australia, was detected in all seropositive kangaroos (41 of 41; 100%). The sex and tail-fat body condition index of kangaroos appeared to have no significant effect on the exposure to the disease. This serologic-based study is the first reported for L. weilii serovar Topaz in New South Wales, to our knowledge, having previously been isolated only in humans and two other animal species (bovine and long-nosed bandicoot [Perameles nasuta]) in Western Australia and Queensland. The potential role of eastern grey kangaroos in the maintenance and zoonotic spread of the disease to livestock and humans is discussed.

Detection of medium-sized ground-dwelling mammals using infrared digital cameras: an alternative way forward?

Infrared digital cameras were used to examine temporal detection rates of medium-sized ground-dwelling mammals in a coastal woodland landscape. From three successive deployments at fixed stations, a range of mammals was detected, including three target species: the long-nosed bandicoot, the long-nosed potoroo and the southern brown bandicoot. Reporting rates of target species were largely consistent and in some cases high. The swamp wallaby was the most commonly detected species, ranging from 47–67% of cameras on any given deployment. Long-nosed bandicoots were detected at 37–53% of cameras, long-nosed potoroos 13–23% and southern brown bandicoots 10–17%. In total, bandicoots and potoroos were detected at 23 of 30 sites (77%) while forage-diggings of these mammals were universally present. There were differences in the detection rate of bandicoots and potoroos in relation to 24-hourly cycles: all three species were less likely to be detected between dawn and dusk than dusk and dawn. Otherwise, with few exceptions, the rate at which bandicoots and potoroos were detected over time within a deployment did not vary markedly. Infrared digital cameras offer great potential as sampling devices for bandicoots and potoroos because of their greater detection efficiency relative to other techniques.

Heading for greener pastures? Defining the foraging preferences of urban long-nosed bandicoots

The impact of urbanisation is delayed for many species, as populations that manage to survive the initial loss of habitat gradually decline throughout the urban–bushland mosaic. Yet many species’ chances of persistence within urban areas can be increased through relatively simple management techniques, and an understanding of how remnant populations use the interface between urban and natural landscapes is therefore crucial to their long-term management. Here we examine the habitat preferences of a semi-urban population of long-nosed bandicoots (Perameles nasuta) that inhabits a matrix of urban open lawn and dense native heath macrohabitats. We radio-tracked animals in these two distinct macrohabitats and compared the microhabitat features between core and peripheral areas of home ranges. Core and peripheral areas did not differ in their characteristics for either macrohabitat; however, individuals showed a high level of fidelity to distinct foraging patches. We then related microhabitat features to an index of foraging activity using generalised linear modelling and found that diggings were more abundant in areas with moist, soft soils close to cover. Soil softness and moisture were experimentally increased via artificial watering on selected sites. After only 10 days there were significantly more diggings on watered than non-watered sites. Thus, bandicoots appear to be a matrix-sensitive species, using some open grass areas of the matrix but requiring the vegetation cover of remnant bush. We suggest, however, that artificial watering and additional cover may be one way to increase foraging opportunities to make this, and other semi-urban, populations matrix-occupying, and thus facilitate bandicoot persistence in the urban mosaic.

The impact of fox control on the relative abundance of forest mammals in East Gippsland, Victoria

Predation by European red foxes is believed to be the major cause of the extinction and decline of a large number of native medium-sized terrestrial mammals in Australia. We examined the impact of poisoning of foxes on the relative abundance of a group of medium-sized mammals in an experiment conducted in three large forest blocks in south-eastern Australia. The blocks consisted of paired sites, as follows: one site where poison baiting was used to control foxes (treatment site) and one where foxes were not controlled (non-treatment site). At all six sites, the population responses of a range of mammals were measured, and compared between treatment and non-treatment sites. The relative fox abundance, as indexed by bait-take, declined during the course of the study at treatment sites and to a lesser extent at non-treatment sites. The decline in bait-take at non-treatment sites was most likely due to treatment sites acting as ecological traps, so that reduced intra-specific competition attracted foxes from non-treatment to treatment sites, where they were subsequently poisoned. There was a significant treatment effect for the abundances of total mammals, long-nosed potoroos, southern brown bandicoots and common brushtail possums, with higher abundances at treatment sites than at non-treatment sites. Common ringtail possums increased in abundance during the course of the study, with no significant difference between treatment and non-treatment sites. There was no significant effect of time or treatment on the abundance of long-nosed bandicoots. The increase in the abundance of native mammals at treatment sites was most likely due to a lower predation pressure by foxes brought about by fox control, and the smaller increase in abundance in non-treatment blocks was likely due to the ecological-trap effect because of fox baiting at treatment sites. The present study demonstrated that broad-scale fox control can lead to increases in the abundance of native mammals in forested habitats, without recourse to aerial baiting or fences. The study also demonstrated that the influence of fox control on the fox abundance can extend well beyond the perimeter of the area baited.

Attitudes to native bandicoots in an urban environment

Urbanization along the eastern seaboard of Australia has increased the potential for conflict between humans and wildlife. The northern suburbs of Sydney are home to the southern brown (Isoodon obesulus) and the long-nosed bandicoot (Perameles nasuta). Both are known to enter yards of home owners causing a disturbance to yard plantings and an interaction with domestic pets. Understanding the driving factors behind the public’s perception of bandicoots will enable wildlife managers to develop effective and socially acceptable conservation strategies. Six hundred and thirty questionnaires were distributed to the residents bordering Ku-ring-gai Chase and Garigal National Park in Sydney, Australia, to assess the sources of conflict. Eighty-three percent of respondents had experienced bandicoot interactions and 27% had experienced interactions on a daily basis. This interaction with bandicoots influenced respondents’ perception of a bandicoot as a nuisance or pest. The age of the resident and pet ownership status also influenced respondents’ attitudes. Contrary to anecdotal reports, there was an overall positive response from the community. The information gained from this survey will inform the development community-based management strategies for the bandicoots of northern Sydney.

Contrasting mammal responses to vegetation type and fire

The response of terrestrial mammals and arboreal marsupials to past burning history as well as a year prior to, and then for 4 years after, a major wildfire in 2003 at Booderee National Park, Jervis Bay Territory was quantified. The present study encompassed extensive repeated surveys at a set of 109 replicated sites stratified by vegetation type and fire history. It was found that most species exhibited significant differences in presence and abundance between major vegetation types. Detections of long-nosed bandicoot (Perameles nasuta) increased significantly in all vegetation types surveyed, in both burnt and unburnt areas. Temporal patterns in captures of three species of small mammals (bush rat (Rattus fuscipes), swamp rat (Rattus lutreolus) and brown antechinus (Antechinus stuartii)) showed a trend for lower numbers of captures on burnt sites compared with unburnt sites. Three species of arboreal marsupials, common ringtail possum (Pseudocheirus peregrinus), greater glider (Petauroides volans) and common brushtail possum (Trichosurus vulpecula), were moderately common and all showed marked differences in abundance between vegetation types. Whereas P. peregrinus and P. volans exhibited a temporal decline between 2003 and 2006, T. vulpecula exhibited a general increase from 2003 levels. However, arboreal marsupial responses did not appear to be directly fire related.

Population responses of small and medium sized mammals to fox control at Jervis Bay, southeastern Australia

At Jervis Bay, strategic pest programmes to control the Red Fox Vulpes vulpes have been in place on the Beecroft Weapons Range (BWR) Beecroft Peninsula, New South Wales since 1995 and Booderee National Park (BNP) Bherwerre Peninsula, Jervis Bay Territory since 1999. As an integral component of the BWR plan, monitoring terrestrial and arboreal mammals has been carried out and demonstrated a significant increase in the abundance of Common Ringtail Possum Pseudochelrus peregrinus, Long-nosed Bandicoot Perameles nasuta, and Bush Rat Rattus fuscipes. There was no significant change in the abundance of Brown Antechinus Antechinus stuartii, Sugar Glider Petaurus breviceps or Black Rat (R. raltus). At BNP changes in population abundance of mammals were not monitored, but a comparison of the abundance of terrestrial mammals between the fox baited BNP and the adjacent un-baited Jervis Bay National Park (JBNP) showed Long-nosed Bandicoots, Bush Rat and Brown Antechinus to be in higher abundance in BNP than JBNP. Scat analysis further supported this finding (Roberts et aI, 2006), We assert that these combined findings are evidence that terrestrial native fauna have responded positively to continued fox control on both peninsulas, thus proving that measuring prey responses are a positive measure of success for strategic pest control programmes.

Diet of the tiger quoll (Dasyurus maculatus) in south-eastern Australia

Analysis of 338 tiger quoll scats from tableland moist forest in south-eastern New South Wales found that the greater glider was the major prey species occurring in 54.1% of scats and contributing an estimated 51.01% of the biomass consumed by tiger quolls. Medium-sized (0.5–5 kg) mammals were the most important prey group by occurrence (53.9%), frequency (66.0%) and estimated biomass contribution to diet (62.93%). Other medium-sized prey taken by tiger quolls included: long-nosed bandicoot, rabbit, brushtail possum and ringtail possum. Macropods and wombats were also present in the scats and had been presumably taken as carrion. There was no significant difference in the diets of male and female tiger quolls. Tiger quolls were recorded hunting greater gliders in their tree hollows during the day, hunting rabbits in their burrows both during the day and at night and were observed eating road-killed macropods and wombats around dawn and dusk.

Diet of the spotted‐tailed quoll (Dasyurus maculatus) in eastern Australia: effects of season, sex and size

AbstractThe diet of spotted‐tailed quolls Dasyurus maculatus (Marsupialia: Dasyuridae) in the north‐eastern tablelands of New South Wales was investigated by faecal analysis. Medium‐sized mammals (500–6999 g) formed the bulk of the faecal content, in terms of both volume and frequency of occurrence. The most frequently consumed vertebrates were the greater glider Petauroides volans, rabbit Oryctolagus cuniculus, bandicoots Perameles nasuta and/or Isoodon macrourus, red‐necked pademelon Thylogale thetis, ringtail possum Pseudocheirus peregrinus, and brushtail possums Trichosurus vulpecula and/or T. caninus. Insects were also eaten frequently, but birds and reptiles occurred relatively infrequently in the diet. The seasonal variation in diet was marked, with insects and reptiles being consumed more frequently, and mammals less frequently, in summer than in winter. This seasonal pattern was also mirrored by the relative volumes of mammals and insects consumed. The results obtained here indicate that the spotted‐tailed quoll is an opportunistic predator, consuming a wide variety of taxa and apparently varying its diet to take advantage of short‐term fluctuations in prey abundance. The extremely high proportion of mammals in the diet identifies D. maculatus as a hypercarnivore, or meat specialist. The importance of tree hollow‐nesting mammals in the diet indicates that the preservation of hollow‐bearing trees should aid the conservation of D. maculatus. Future dietary studies of the species should sample over extensive time periods and involve concurrent monitoring of prey populations.

Does baiting influence the relative composition of the diet of foxes?

The changes in the diet of foxes (Vulpes vulpes) in the Jervis Bay Region was assessed following a long-term baiting program by analysing the composition of fox faecal excreta (scats). In all, 470 fox scats were collected between April and August 2003 from two baited sites, Booderee National Park (BNP) and Beecroft Peninsula, and from two unbaited sites in the southern and northern parts of Jervis Bay National Park (SJBNP and NJBNP respectively). Diet was compared between these sites and mammalian diet was also compared from scats collected before baiting in 1996 and after baiting in 2000 at Beecroft Peninsula and in 2001 at Booderee National Park. In 2003, the most common species consumed by foxes was the common ringtail possum (Pseudocheirus peregrinus), except at unbaited NJBNP, where the swamp wallaby (Wallabia bicolor) was the most frequent dietary item. Significant dietary differences were found between unbaited and baited sites, with the long-nosed bandicoot (Perameles nasuta) and P. peregrinus featuring more in the diet of foxes from the baited sites. Marked increases in the frequency of occurrence of P. peregrinus and P. nasuta in fox scats occurred from before baiting through to after baiting. Relative fox abundance, as indexed by the number of scats collected per kilometre, was lowest in Booderee, followed by Beecroft, then SJBNP, with NJBNP having the highest relative abundance of foxes. We suggest that baiting did affect the diet of foxes on both peninsulas and that the dietary changes across baiting histories were intrinsically related to an increase in abundance in some taxa as a result of relaxed predator pressure following sustained fox control. However, the lack of unbaited control sites over the whole study precludes a definitive conclusion.

Responses of four Critical Weight Range (CWR) marsupials to the odours of native and introduced predators

In Australia many critical weight range (CWR) species are threatened by predation from the introduced Red Fox Vulpes vulpes. Understanding how these prey species respond to native predators such as the Tiger Quoll Dasyurus maculatus, and comparing their responses to foxes is important in understanding why fox predation is such a problem. Many northern hemisphere mammalian species have developed responses to the odours of the main species which prey upon them. The situation in Australia remains unclear. We looked at the effect of scenting traps with the faeces of the Tiger Quoll and the Red Fox on the capture rates of four species of CWR marsupials, the Long-nosed Bandicoot Perameles nasuta, the Southern Brown Bandicoot Isoodon obesulus, the Northern Brown Bandicoot I. macrourus and the Common Brushtail Possum Trichosurus vulpecula. None of these species responded to fox odour. However despite low capture rates, Northern Brown Bandicoots and Common Brushtail Possums were captured significantly more often i...

Seasonal changes in the diet of the long-nosed bandicoot (Perameles nasuta) assessed by analysis of faecal scats and of stable isotopes in blood

The diet of long-nosed bandicoots (Perameles nasuta) on the central coast of New South Wales, Australia, was examined over two summers and two winters using a combination of faecal scat analysis for food fragments and stable isotope analysis (ratios of 13C/12C and 15N/14N) of blood. Isotope ratios in blood overlapped most strongly with those in invertebrate prey, and varied much less between seasons than did those in most dietary items, suggesting that the assimilated diet of long-nosed bandicoots is dominated by invertebrates throughout the year. Invertebrate remains dominated collected faeces in both seasons, even though the availability of invertebrate prey was higher in summer. Thus both techniques indicated that long-nosed bandicoots were primarily insectivorous year-round. Faecal scat analysis indicated that invertebrate eggs were more abundant in summer than winter. At a finer scale, spiders, orthopterans, lepidopteran larvae, ants, leaf material (non-grass monocot) and seeds were more abundant in summer, while cicada larvae, roots, fungi, grass leaves and Acacia bract (small modified leaves appearing as scales) were more abundant in winter. Subterranean foods (cicada larvae, plant roots and hypogeous fungi) were more abundant in winter and more abundant in the diet of males than of either lactating or non-lactating females.

Effects of diet change on carbon and nitrogen stable-isotope ratios in blood cells and plasma of the long-nosed bandicoot (Perameles nasuta)

Carbon (C) and nitrogen (N) stable isotopes offer a powerful tool for assessing the extent of tissue assimilation of dietary components. However, the method relies on knowledge of diet–tissue isotopic discrimination and how quickly diet shifts become apparent in various tissues. In the present study, blood plasma and blood cells, tissues that are easily obtained under field conditions, were used to validate the stable isotope method over a period of 4–5 weeks using captive long-nosed bandicoots (Perameles nasuta). Diet–tissue discrimination effects appeared to be small. For C, derived diet–tissue isotopic discriminations were 1.4‰ for blood plasma and –0.2‰ for blood cells. For N the values were 2.8‰ and 2.1‰, respectively, and were independent of the nitrogen content of the food. C and N turnover measurements in the blood plasma and cells of the bandicoots indicated that blood plasma provides dietary information integrated over a period of ~3 weeks, whereas blood cells give an impression of the assimilated diet over a period of as much as half a year. These turnover rates were low compared with the little information available for birds and eutherian mammals, and probably relate to the typically low metabolic rate of marsupials.

Effects of rainforest fragmentation on non-flying mammals of the Eastern Dorrigo Plateau, Australia

This paper describes the non-flying mammals recorded in warm-temperate rainforest fragments on the Eastern Dorrigo Plateau of New South Wales, Australia, and investigates the importance of landscape and habitat factors in determining their richness and abundance. Thirty-three rainforest fragments, ranging in size from 0.15 to 996 ha, and five sites within continuous rainforest, were surveyed. Mammal species were detected by live-trapping, spotlighting, diurnal transect walks and nest boxes. Vegetation surveys were carried out within fragments, and landscape parameters such as area and disturbance were measured on-site, via aerial photographs, and through discussion with land-owners. Nineteen species of non-flying mammals were recorded, the most common being two possums ( Trichosurus vulpecula, Pseudocheirus peregrinus), a peramelid ( Perameles nasuta), two native ( Melomys cervinipes, Rattus fuscipes) and one introduced ( Rattus rattus) species of rodent and a dasyurid ( Antechinus stuartii). Mammal species richness overall was linked overwhelmingly with landscape parameters, particularly fragment area. Analyses of abundance were carried out on small mammal species only. The most important variables for A. stuartii were related to habitat, in particular structures used for nesting. Rattus fuscipes and M. cervinipes were restricted largely to fragments above 1 ha in area, and exhibited complex relationships with several habitat variables. Larger species of mammals were lost progressively from small fragments probably because their spatial requirements could not be met. Protection of existing remnants and establishment of links between these remnants and continuous forest may slow attrition of the region's mammalian fauna.

Seasonal energetics of the long-nosed bandicoot (Perameles nasuta) in coastal New South Wales

Water-turnover rates and field metabolic rates were measured in long-nosed bandicoots (Perameles nasuta) near Newcastle, New South Wales, over two summers and two winters. Water-turnover rates were higher in lactating than in non-lactating females, and higher in winter than in summer, possibly because of a relatively high proportion (50%) of females at or near peak lactation in one winter. There were no significant differences in field metabolic rates between seasons or among groups (males, lactating females and non-lactating females). The overall field metabolic rate of the long-nosed bandicoot was within 9% of the predicted value for a marsupial of its size, and similar to rates reported for most other bandicoots, both temperate and arid-zone species. Its overall water-turnover rate was within 18% of the predicted marsupial value, but higher than values reported for arid-zone bandicoot species. Comparison with other data indicates that seasonal changes in water-turnover rate are related to changes in reproductive status (especially lactation), as in this study, but for field metabolic rate, seasonal changes are related to changes in water status and thus productivity of the environment.