Rattus Villosissimus Research Articles

Plague Rat or Anopheles: Health Disasters and Home Improvement in Late Colonial Java

When plague broke out in Java in 1911, the Dutch responded with home improvement in an attempt to widen the distance between human residents and the rodent host of this disease. Over the following thirty years, home improvement was implemented on a tremendous scale—resulting in the reconstruction of over 1.6 million houses. After the mid-1920s, however, home improvement was gradually implicated in facilitating malaria transmission instead: effectively replacing one set of disease mortality with another. In this article, I trace how this correlation came to light and was responded to. The case of woningverbeteringsmalaria, I suggest, offers a case study for us to reflect on how health priorities were set, how developmentalist colonial policies designed to counter one threat often generated others, and understand how advances in understanding the human-animal relations underpinning health gradually broadened from linear transmission theories into broader ecological models.

Tree-cavity formation in the mature subtropical forests of Yambaru, Okinawa Island

ABSTRACT Tree-cavities are considered as key components that support multiple species, including endemic ones, in subtropical forests in Yambaru, the northern area of Okinawa Island, Japan. Here, we established two study plots in mature subtropical forests in Yambaru and surveyed for tree-cavities with depths ≥ 10 cm. The density of tree-cavities was 198 per ha, which is exceptionally high compared with tree-cavity densities reported by other studies. Among the three key tree species (Castanopsis sieboldii, Schima wallichii, and Distylium racemosum), no tree-cavities were observed in S. wallichii in the study plots. In both C. sieboldii and D. racemosum, the probability of tree-cavity presence increased as the diameter at breast height (DBH) increased. In addition, the probability of tree-cavity presence on D. racemosum started to increase at smaller DBH stage compared with that on C. sieboldii. Distylium racemosum often had multiple tree-cavities per stem. Excavated cavities were rare across all species, and decay cavities were dominant. We detected the activity of the endangered Ryukyu long-haired rat (Diplothrix legata) in two cavities, both of which had similar features: a stem DBH of about 43 cm and volumes of 0.09–0.16 m3. In the Yambaru area, the preservation of large-diameter stems that will form tree-cavities is critically important for maintaining forest ecosystem health and should be considered when implementing forest management plans, especially for D. racemosum, which is rich in cavities and likely plays multiple ecological roles.

A nomadic avian predator displays flexibility in prey choice during episodic outbreaks of rodents in arid Australia.

In environments driven by unpredictable resource pulses, populations of many consumer species experience dramatic fluctuations in abundance and spatial extent. Predator-prey relationships in these acyclic systems are poorly understood in particular with respect to the level of prey specialisation shown by nomadic predators. To understand the dynamics of such a system I examined the response to rodent outbreaks by the letter-winged kite (Elanus scriptus) in the Simpson Desert, Australia; a region that experiences major pulses in primary productivity, driven by unpredictable rainfall events. The kite feeds on small mammals and is the only night-hunting species in the Accipitridae. Letter-winged kites irrupted in the area on only three occasions during 20years of sampling (1999-2019) and remained for a maximum of 20months. Each period of kite occupation occurred only during the increase and/or peak phase of rodent population cycles (which occurred three times during the study). During each period kite diet was dominated by small (10-50g body mass) quadrupedal rodents (Pseudomys australis, P. hermannsburgensis, Mus musculus). Abundance of these species varied across the three outbreaks and kites typically captured them in proportion to availability. The large body mass (134g) long-haired rat (Rattus villosissimus) was abundant during one outbreak but was infrequently consumed. The bipedal spinifex hopping-mouse (Notomys alexis) was within the kites' favoured prey size range (35g) but was consistently avoided. The flexibility in prey selection by letter-winged kites appears to be an important adaptation for survival and reproduction by species exploiting acyclic rodent outbreaks.

Diets of mammalian carnivores in the deserts of north-eastern South Australia

We studied diets of feral cats (Felis catus), dingoes (Canis familiaris) and red foxes (Vulpes vulpes) in desert environments in north-eastern South Australia by analysing prey remains in opportunistically-collected scats. Four major landscapes were sampled (Simpson Desert, Sturt Stony Desert, Strzelecki Desert – Cooper Creek and Diamantina River) which yielded 238 cat scats, 298 dingo scats and ten fox scats. There was some overlap in prey eaten by cats and dingoes, but their diets were significantly different because cats typically ate small prey such as small mammals, small lizards and birds, while dingoes ate larger prey like domestic cattle, kangaroos and large reptiles. The few fox scats collected suggested fox diets were more similar to cat than dingo diets. Scat composition also differed significantly between landscapes irrespective of predator, with landscapes differing both in diversity and relative abundances of prey consumed. We detected several species in scats that are threatened with extinction either nationally (dusky hopping mouse, Notomys fuscus, and crest-tailed mulgara, Dasycercus cristicauda) or regionally (desert mouse, Pseudomys desertor, and long-haired rat, Rattus villosissimus), adding valuable knowledge to the distribution of these mammals and demonstrating the value of predator scat analyses in mammal surveys of Australian deserts.

150 years of mammal extinction and invasion at Koonchera Dune in the Lake Eyre Basin of South Australia

Koonchera Dune is a prominent sand ridge fringed by a complex of ephemeral swamps and open plains on the edge of Sturt Stony Desert, northeastern South Australia. In 1931 mammalogist Hedley Herbert Finlayson rediscovered the desert rat-kangaroo or ngudlukanta (Caloprymnus campestris) here, and also captured lesser bilby or yallara (Macrotis leucura), bilby (Macrotis lagotis), and plains mouse (Pseudomys australis). This was the last time any of these mammals were recorded at Koonchera; ngudlukanta and yallara are globally extinct, the bilby is extinct on mainland South Australia, and the plains mouse is listed as vulnerable throughout its diminishing range. Prior to these and other recent extinctions totalling a minimum six species, we estimate that Koonchera supported at least 24 native mammals. In 2018 and 2019 we surveyed mammals here, detecting 11 native mammals including three rare or threatened species: fawn hopping mouse (Notomys cervinus), dusky hopping mouse (N. fuscus), and long-haired rat (Rattus villosissimus). We also detected seven introduced species, including feral cat (Felis catus), fox (Vulpes vulpes), European rabbit (Oryctolagus cuniculus), and feral pig (Sus scrofa). Physically, Koonchera and the Lake Eyre Basin region is much the same as Finlayson would have found it in 1931, but our work shows a proliferation of feral and introduced species and a decline of native mammals, especially medium-sized Critical Weight Range (CWR) species. If Koonchera and the surrounding landscape is to hold on to its remaining native mammal diversity, coordinated management of threats, principal of which is predation by cats and foxes, and impacts on vegetation and soil from a host of introduced herbivores, is required.

Resource pulses affect prey selection and reduce dietary diversity of dingoes in arid Australia

Abstract In Australia, the dingo Canis lupus dingo is the largest terrestrial predator. Dingoes contribute to ecological processes and functions throughout their continental geographic range. Their generalist diet enables daily energetic requirements to be met even in the resource‐limited deserts of central Australia, where irregular rainfall drives extreme fluctuations in mammal assemblages. Given that predation is a primary driver of declining mammal populations and failed reintroductions, it is necessary to understand the dietary intake of the continent's apex predator if conservation outcomes are to be achieved. We performed a meta‐analysis of the mammalian composition of the dingo's diet throughout Australia's arid zone, an area covering c. 5.4 million km2. We used 25 data sets from 11 studies to measure the effects of resource booms and anthropogenic disturbance (pastoralism) on diet. We explored whether the probability of prey species occurring in the diet was related to the size of the prey or to prevailing conditions. We also investigated the similarities in diet between dingo populations from across the arid zone, and how dietary overlap was affected by opposing land uses. Dingoes primarily consumed medium‐sized (35–5500 g) and large (>5500 g) mammals, whereas most small mammals (<35 g) were consumed infrequently, or not at all. The composition of the diet changed dramatically during resource booms to exploit irruptive prey species such as long‐haired rats Rattus villosissimus (native; 144 g) and house mice Mus musculus (introduced; 20 g). During resource booms, the consumption of large mammals decreased significantly, whereas the occurrence in the diet of medium‐sized mammals remained high. The diversity of species consumed by dingoes was significantly lower during boom periods than during non‐boom periods. The dingo's heightened consumption of hyper‐abundant species has the potential to release many non‐target species from direct predation pressure during boom times. This could be advantageous for remnant and reintroduced populations of mammals, which are especially susceptible to predation.

A new species of sucking louse Hoplopleura villosissima n. sp. (Psocodea: Phthiraptera: Hoplopleuridae) and a new host record of the spiny rat louse Polyplax spinulosa Burmeister, 1839 (Psocodea: Phthiraptera: Polyplacidae) from the long-haired rat Rattus villosissimus Waite (Rodentia: Muridae) in Australia

BackgroundThe sucking louse fauna of endemic Australian rodents has been under-studied for decades. Sixty-five species of native rodents have been recorded in Australia. However, only 11 species of lice have been reported from 11 species of endemic Australian rodents.ResultsWe describe a new species of sucking louse, Hoplopleura villosissima Wang (Psocodea: Phthiraptera: Hoplopleuridae), and report a new host record of the spiny rat louse, Polyplax spinulosa Burmeister, 1839 (Psocodea: Phthiraptera: Polyplacidae), from the long-haired rat, Rattus villosissimus Waite (Rodentia: Muridae), which is endemic to Australia.ConclusionsThis study is the first record of sucking louse from R. villosissimus and the first record of a species of Polyplax Enderlein, 1904 from an endemic Australian rodent. This study brings the total number of sucking louse species in endemic Australian rodents from 11 to 13. Previously, only the introduced brown rat, Rattus norvegicus Berkenhout and the black rat, Rattus rattus Linnaeus were recorded as the hosts of P. spinulosa in Australia. Because R. villosissimus overlaps with R. rattus in distribution but not with R. norvegicus, we propose that P. spinulosa transferred to R. villosissimus from R. rattus.

Diet of the feral cat, Felis catus, in central Australian grassland habitats during population cycles of its principal prey

Foraging theory predicts that animals should forage so as to maximize their net rate of energy gain or to minimize their risk of starvation. In situations where prey numbers fluctuate dramatically, theory predicts further that foragers will eat ‘optimal’ prey when it is abundant but expand their diet to include other prey types when the optimal prey is scarce; this is the alternative prey hypothesis. Here, we test this prediction by analyzing the diet of a mammalian predator, the feral house cat Felis catus, during periods of scarcity and abundance of the long-haired rat Rattus villosissimus. We also investigate whether the body condition of feral cats differs during different stages of the prey population cycle. Feral cats were shot during culling operations in semi-arid grassland habitats in central Queensland, Australia, and the stomach contents later identified. We found that the body condition of feral cats did not differ between phases of the prey population cycle, but the diets of cats culled when long-haired rats were scarce were significantly more diverse than when this rodent was abundant. Rats comprised about 80 % of cats’ diet by volume and frequency of occurrence when they were present, whereas birds, reptiles and invertebrates comprised the bulk of the diet when rats were not available. We conclude that, whilst feral cats are often thought to be specialist predators, they may be better considered as facultative specialists that will shift their diet in predictable ways in response to changes in the abundance of primary prey.

Sperm preservation by freeze-drying for the conservation of wild animals.

Sperm preservation is a useful technique for the maintenance of biological resources in experimental and domestic animals, and in wild animals. A new preservation method has been developed that enables sperm to be stored for a long time in a refrigerator at 4°C. Sperm are freeze-dried in a solution containing 10 mM Tris and 1 mM EDTA. Using this method, liquid nitrogen is not required for the storage and transportation of sperm. We demonstrate that chimpanzee, giraffe, jaguar, weasel and the long-haired rat sperm remain viable after freeze-drying. In all species, pronuclei were formed after the injection of freeze-dried sperm into the mouse oocytes. Although preliminary, these results may be useful for the future establishment of “freeze-drying zoo” to conserve wild animals.

Experimental evidence that feral cats cause local extirpation of small mammals in Australia's tropical savannas

Summary Small mammal species are declining across northern Australia. Predation by feral cats Felis sylvestris catus is one hypothesised cause. Most evidence of cat impacts on native prey comes from islands, where cat densities are often high, but cats typically occur at low densities on mainland Australia. We conducted a field experiment to measure the effect of predation by low‐density cat populations on the demography of a native small mammal. We established two 12·5‐ha enclosures in tropical savanna in the Northern Territory. Each enclosure was divided in half, with cats allowed access to one half but not the other. We introduced about 20 individuals of a native rodent, Rattus villosissimus, into each of the four compartments (two enclosures × two predator‐access treatments). We monitored rat demography by mark‐recapture analysis and radiotracking, and predator incursions by camera surveillance and track and scat searches. Rat populations persisted over the duration of the study (18 months) in the predator‐proof treatment, where we detected no predator incursions, but declined to extinction in both predator‐accessible compartments. In one case, cat incursions were frequently detected and the rat population was rapidly extirpated (<3 months); in the other, cat incursions were infrequent, and the population declined more gradually (c. 16 months) due to low recruitment. We detected no incursions by dingoes Canis dingo, the other mammalian predator in the area. Synthesis and applications. This is the first study to provide direct evidence that cats are capable of extirpating small mammals in a continental setting, in spite of their low population densities. This finding supports the hypothesis that predation by feral cats is contributing to declines of small mammals in northern Australia. The conservation management of native small mammals in northern Australia may require intensive control of cat populations, including large cat‐free enclosures.

Perfect storm: Demographic responses of an irruptive desert mammal to prescribed burns following flooding rain

AbstractExtreme climatic events are expected to increase in frequency and magnitude in future and to have powerful effects on the organisms and ecological communities that experience them. In arid Australia flooding rains trigger flushes in primary productivity that allow ephemeral irruptions of consumer organisms, but they also provide conditions for ‘perfect storms’: wildfires that are carried by flood‐stimulated increases in fuel load. Here we describe demographic responses of the long‐haired rat Rattus villosissimus to flood rains and prescribed burns in the Mitchell grass downs of central Queensland, Australia, during a broad‐scale irruption of this species in 2011. Populations were sampled on three trapping grids on two occasions before and two occasions after control burns in April 2011, and compared with populations sampled at the same times on three further grids that remained unburnt. Rat populations declined temporarily just after the fires, but survival, sex ratio, body condition, reproduction and other demographic parameters remained unaffected by the burn treatment. The temporary declines in rat numbers on the burnt grids were probably caused by resource shortages, but subsequent increases in rat numbers suggest that these impacts were not severe. If small‐scale prescribed burns reduce the chance of landscape‐wide wildfires taking hold, we suggest that they should effectively allow long‐haired rats to weather perfect storms in future.

Diet of the feral cat, Felis catus, in central Australian grassland habitats: do cat attributes influence what they eat?

The house cat Felis catus was introduced to Australia as a pet and means of rodent control over 200 years ago, but now has established feral populations and has become a serious threat to native wildlife. Using stomach content analysis of 73 feral cats from semi-arid grassland habitats in Queensland, Australia, we aimed to identify dominant prey groups in the cats' diet and to explore associations between the diversity of prey eaten and attributes of the cats including body size, condition, sex, age and coat colour. We also sought to determine any relationships between cat size and the size of the dominant prey in the diet, the long-haired rat Rattus villosissimus. Mammals and reptiles were the dominant prey, with R. villosissimus occurring in 60 % of samples and comprising more than half of all prey by volume. Birds and terrestrial invertebrates were the next most important contributors to the diet, but fish, frogs and freshwater crustaceans also were surprisingly well represented. The dietary diversity of cats was largely unrelated to any of the cat attributes that we measured, although a positive relationship emerged between cat head width and the range of prey types eaten. Our study was conducted during a population irruption of R. villosissimus and confirms that cats are able to exploit an abundant focal prey resource when the opportunity occurs. Further research now is needed to explore associations between diet and cat attributes during periods when rats are scarce.

Desert small mammal responses to wildfire and predation in the aftermath of a La Nińa driven resource pulse

AbstractIn arid Australia, flooding rains associated with the La Nińa phase of El Niño/Southern Oscillation (ENSO) prompt dramatic pulses of primary productivity, which in turn result in irruptions of rodents and their predators. When it is dry, the dense vegetation produced by extreme rainfall events can fuel extensive wildfires. In this study we investigated the effects of a wildfire that followed exceptional rainfalls associated with the La Niña event of 2010–2011 on small mammal assemblages in a stony (gibber) desert ecosystem in central Australia. When the study commenced in July 2011, there was dense grass cover and rodents, particularly, Rattus villosissimus occurred at high abundance. Mammalian predator activity was high throughout the study period and predators primarily consumed rodents. A wildfire in October 2011, reduced grass cover but there was no effect of fire on the abundance or species richness of small mammals, immediately after the wildfire or 11 months after the wildfire. Following the fire event, grass cover increased on both burnt and unburnt grids, but did not reach the levels recorded prior to the wildfire. Small mammal abundance and species richness declined steadily during the study irrespective of the occurrence of wildfire. At 6 and 11 months after the wildfire there was no difference in grass cover on burnt and unburnt grids and Rattus villosissimus were absent. Our results show that the removal of vegetation by wildfire was not a major driver of small mammal assemblage structure in this stony desert ecosystem. Our results are consistent with the predictions of ecosystem organization models that describe switching trophic control along gradients of resource productivity and support the notion that the decline of small mammals was driven by the onset of top‐down control by abundant predators coupled with diminished availability of food resources.

Extreme rainfall events predict irruptions of rat plagues in central Australia

AbstractA general understanding of the factors that regulate populations remains a central goal for ecologists, and species that increase rapidly to plague numbers followed by equally sudden crashes in abundance are particularly intriguing. Throughout central Australia, the long‐haired rat, Rattus villosissimus, is largely absent in dry times, but can irrupt into plague numbers after heavy rains. Using historical data we first relate the occurrence of plagues to exceptionally high rainfalls, and using live‐trapping records from rat irruptions in 1991 and 2011 in the eastern Simpson Desert, we then investigate the population structure at the plague front. In doing so, we ask if long‐haired rat plagues irrupt from multiple refugia, if young males are first to disperse and whether the rate of dispersal is rapid. Annual rainfall in the year preceding a plague successfully predicted the probability of an outbreak, with an 80% chance of a plague occurring after an annual rainfall of 750 mm. Trapping grids closest to drainage lines to the south of the study area had greater captures of long‐haired rats. Enhanced rat numbers in proximity to drainage areas suggested that the irruptive process unfolded from the south and demonstrated the existence of multiple refugia. In contrast to the resident fitness hypothesis, there was no difference in captures between the sexes or age‐classes of long‐haired rats. Heavier animals were caught at the invasion front, presumably because they could travel larger distances than smaller individuals, suggesting that larger individuals were maximizing their fitness by dispersing first to new resources. Captures of long‐haired rats were highest at the beginning of the irruption in both 1991 and 2011, suggesting rapid colonization. Although rare in occurrence, rodent population irruptions and the resulting dispersal across large areas, which may persist for a few years, can thus extend the domain of influence of exceptional rain years well into the future.

Molecular Species Identification of Predators of Endangered Species on Okinawa-Jima Island

The ‘Yambaru’, a subtropical rainforest of northern Okinawa-jima Island, Japan, has a diverse and complex biota. It is particularly important habitat for many endangered species, such as the Ryukyu long-haired rat (Diplothrix legata), the Okinawa spiny rat (Tokudaia osimensis), the Okinawa rail (Gallirallus okinawae), the Ryukyu black-breasted leaf turtle (Geoemyda japonica), Ishikawa’s frog (Odorrana ishikawae), and others. These species are all threatened with extinction, due mainly to habitat destruction, poaching, and negative effect by introduced species. In the Yambaru, carnivores that prey on these endangered species were once absent. The human-introduced predators, such as the domestic dog (Canis lupus familiaris), the domestic cat (Felis catus), and the Javan mongoose (Herpestes javanicus), seem to be the greatest threat to the endangered fauna of the Yambaru. For example, the wild population of Okinawa rail is in decline (from 1,500–2,100 birds in 1985 to 820–1,300 birds in 2006) due to habitat loss and predation by stray dogs and cats (Ozaki 2008). In recent years, the mongoose’s distribution has expanded into the Yambaru area (Ozaki et al. 2002). Therefore, predation of the endangered animals in the Yambaru is likely to increase. To establish an effective predator control program, one must first identify the predator species, because a proper trapping system must be selected for predator eradication. Therefore, the identification of predator species is essential if there were multiple predator species in geographical area of predator eradication activities like a Yambaru area. However, predator identification is difficult because direct observations of predation are rare, and often a predator’s bite marks are not distinctive. We focused instead on predator saliva remaining on the carcass. Saliva has long been used as an important source of DNA in human forensics (Butler 2005). Recently, DNA from saliva has been used to investigate livestock predation (Williams et al. 2003; Sundqvist et al. 2008). Unfortunately, the amount of DNA that can be extracted from predator saliva on prey is extremely small and is mixed with large amounts of prey DNA. Additionally, when the prey is a wild animal, several days usually pass before the carcass is discovered, during which the DNA tends to degrade. For all these reasons, effective predator control requires a DNA-based method of predator identification that is both highly sensitivity and highly species-specific. Here, we report a technique to identify predators from salivary DNA remaining on prey carcasses. First, we designed species-specific nested primers for the cytochrome b gene of dogs, cats and Javan mongooses and developed two PCR methods to identify predators, a species-specific nested PCR and a multiplex nested PCR that included multiple species-specific primer pairs in a single reaction. We applied them to predator species identification using skin, hairs or feathers of prey animals. Specifically, we tested our protocol on carcasses of the Ryukyu long-haired rat, the Okinawa rail, the white-breasted waterhen (Amauromis phoenicurus), and the Okinawa woodpecker (Sapheopipo noguchii).

The mammal fauna of the Sir Edward Pellew island group, Northern Territory, Australia: refuge and death-trap

Context Australian islands have provided a major conservation refuge for many native mammals; however, conversely, island populations may also be highly susceptible to the introduction of novel threats. Nearby islands subject to different arrays of threats or different timing of arrival of those threats may provide a natural experiment, offering particular insight into the relative impacts of different threats to Australian mammals more generally. Aims The present study sought to document the native mammal fauna occurring on the main islands of the Sir Edward Pellew group, Northern Territory, and the changes in that fauna over a ~50-year period, and to seek to identify those factors that have contributed to such change. Methods In different combinations, the five main islands (and three smaller islands) were subject to standard wildlife survey methods in 1966–67, 1988, 2003, 2004–05, and 2009–10. Sampling procedures were not identical in all periods; however, a measure of abundance (trap success rate) could be calculated for all sampling. This conventional survey approach was complemented by documentation of ethno-biological knowledge. Key results For many species, these islands held populations of biogeographic or conservation significance. However, there has been a major loss or decline of mammal species from most islands. Extirpation is difficult to prove; however, we consider it most likely that the important regional populations of brush-tailed rabbit-rat (Conilurus penicillatus), northern quoll (Dasyurus hallucatus), northern brush-tailed phascogale (Phascogale pirata), common brushtail possum (Trichosurus vulpecula) and canefield rat (Rattus sordidus) have been lost from these islands, and that northern brown bandicoot (Isoodon macrourus), western chestnut mouse (Pseudomys nanus), pale field-rat (Rattus tunneyi) and long-haired rat (Rattus villosissimus) have been lost from most of the islands on which they formerly occurred. Some species–island combinations are known only from the ethno-biological record, and the loss of these populations probably mostly occurred in the period 30–50 years ago. Many other declines and losses occurred in the period between the second (1988) and third (2003) survey. The loss of the northern quoll from Vanderlin Island occurred in 2008. No single factor unambiguously accounts for the declines, although the introduction of cats (Felis catus) provides the best fit to the pattern of decline. A notable exception is the extirpation of northern quoll on Vanderlin Island, which is closely linked to the colonisation of that island by cane toads (Rhinella marina). Conclusions The Sir Edward Pellew group of islands have lost much of their formerly high conservation significance for native mammals over the past 50 years, mostly because of introductions of cats, and to a lesser extent, natural colonisation of the islands by cane toads. Implications The present study has provided some insight into the relative impacts of a range of factors that have been considered as possibly implicated in the decline of native mammals on the northern Australian mainland, with most support being offered here for a primary role for predation by feral cats. The study has also demonstrated the need for better quarantining of islands with significant conservation values. The comprehensive natural colonisation of these islands by cane toads offers a further lesson, of most importance to managers of islands in north-western Australia currently just beyond the range of toads.

Additional records of small mammals in northern South Australia

Analysis of prey remains found in predator scats is a valuable tool for assessing the distribution and status of small mammal populations. As part of a large-scale dingo research project in northern South Australia, the prey remains found in 1845 dingo scats were analysed. A range of species were identified as expected, though, of particular interest, additional records of Rattus villosissimus, Notomys fuscus and Pseudomys australis were obtained. Our R. villosissimus records confirm the contemporary range of this species in the north-eastern pastoral zone, while our N. fuscus records support other recent records of this species in the same area. Our P. australis record indicates that an isolated population of this species exists in the Strzelecki Desert, ~400 km east of the nearest known population. The status of these populations remains unknown, including the risk of dingo predation to them.

Using the diet of the barn owl (Tyto alba) as an indicator of small vertebrate abundance in the Channel Country, south-western Queensland

The diet of the barn owl (Tyto alba) was determined by analysing pellets and bulk pellet debris found in the ruins of Baryulah Homestead, south-western Queensland. Nine species of mammal, at least eight bird, five reptile and three frog species were identified. The majority of prey consisted of small mammals and was dominated by Mus musculus, which accounted for almost 40 Prey Unit percent (PU%) of all prey. Rattus villosissimus was an important secondary prey species, which, due to its comparatively large mass, contributed 21.79 PU%. Other native mammals were present in low frequency only. Reptiles (primarily geckos) were more abundant than expected, collectively contributing >15 PU%, suggesting that they were an important component of the barn owl’s diet.

Relative importance of plague rodents and dasyurids as prey of barn owls in central Australia

We examined the diet of the barn owl in three bioregions of arid Northern Territory; two in upland areas, the other on the Barkly Tableland. Owls from the MacDonnell and Petermann Ranges fed predominantly on rodents. At both sites, Mus musculus was the dominant prey both in terms of frequency and prey units, with Pseudomys hermannsburgensis an important secondary item. Notomys alexis was an important secondary item in the MacDonnell Ranges. These results support previous research in highlighting the importance of plague rodents in the diet of barn owls in arid Australia. In contrast to the samples from the upland sites, the Barkly Tableland sample was composed mostly of the dasyurid marsupial Sminthopsis macroura, with only one rodent captured. The absence of the long-haired rat, Rattus villosissimus, from the sample, despite the species being a favoured prey item of the barn owl that undergoes population irruptions at the collection site, suggests that the sample was collected during a non-plague period. Our study is the first to record a marsupial species as the major prey of the barn owl. This finding suggests that barn owls can switch to other prey when populations of rodents crash.

Climatic modelling of the Australian distribution of the grass owl (Tyto capensis): is there an inland population?

The Australian distribution of the grass owl (Tyto capensis) is poorly understood. It has been proposed that there are two centres of distribution: a resident coastal population in the north-east, and a less stable inland population from which there is Australia-wide dispersal when good seasons are followed by deteriorating conditions. We analysed records of the grass owl and modelled its bioclimatic profile and distribution, which was typically subtropical, warm to hot humid with no dry season or a dry winter. This predicted a north-east sub-coastal to coastal, permanently occupied, core distribution for the owl. We found no evidence for a permanent or isolated inland population, nor for inland populations being the sole source of dispersers, as has been suggested previously. Most inland and northern records were made in the 1970s when grass owls colonised the arid inland, the Kimberley and the far north of the country in association with events leading to the flooding of Lake Eyre. The data suggest that grass owls disperse from their core range after exceptionally good breeding seasons to areas made temporarily favourable by exceptional rainfall or flooding, only to disperse again when conditions become drier. These dispersal events are not tied uniquely to outbreaks of the long-haired rat (Rattus villosissimus), but to a variety of terrestrial prey with dynamic life histories driven by rainfall.