Academic literature on the topic 'Bush rat (Rattus fuscipe)'

The reproductive seasonality of the bush rat (Rattus fuscipes greyi) was investigated in Scott Creek Conservation Park near Adelaide, South Australia, by catch and release trapping conducted at irregular intervals over a 4-year period in a population of higher density than previously reported for this species. A seasonal pattern in breeding activity was observed with the production of young in spring and summer (October-February) with a peak in December. There was seasonal variation in the testicular index of males with minimal values from April to June. Some animals may have retained the ability to mate throughout the year but there was no evidence of offspring surviving from any winter matings. Differences were seen in the timing and intensity of the non-breeding season between years. Possible causes of reproductive seasonality were seasonal changes in vegetative growth and the abundance of fungi and insects and predictive cues provided by seasonal changes in ambient temperature and photoperiod.

This study investigated the use of the grass-tree, Xanthorrhoea semiplana F.Muell. (family Xanthorrhoeaceae), for shelter by Rattus fuscipes (southern bush rat) in South Australia. Eight bush rats were radio-tracked for 4–8 days each. To identify the understorey shelters available to each animal, surveys were conducted using point-intercept sampling at 2-m intervals along transect lines. Grass-tree density was calculated in each area used by the radio-tracked animals, and canopy thickness of grass-trees selected for refuge was assigned a score; the availability of other potential shelters was also calculated. The results indicated that (1) R. fuscipes preferentially selected grass-trees over other understorey shelter; (2) the grass-trees chosen had thick canopy covers; (3) areas with high grass-tree densities were preferred for cover over areas with fewer grass-trees; and (4) grass-trees provided dense cover and, therefore, concealed burrows and nest sites.

Abstract Resource selection by animals influences individual fitness, the abundance of local populations, and the distribution of species. Further, the degree to which individuals select particular resources can be altered by numerous factors including competition, predation, and both natural- and human-induced environmental change. Understanding the influence of such factors on the way animals use resources can guide species conservation and management in changing environments. In this study, we investigated the effects of a prescribed fire on small-scale (microhabitat) resource selection, abundance, body condition, and movement pathways of a native Australian rodent, the bush rat ( Rattus fuscipes ). Using a before-after, control-impact design, we gathered data from 60 individuals fitted with spool and line tracking devices. In unburnt forest, selection of resources by bush rats was positively related to rushes, logs and complex habitat, and negatively related to ferns and litter. Fire caused selection for spreading grass, rushes, and complex habitat to increase relative to an unburnt control location. At the burnt location after the fire, rats selected patches of unburnt vegetation, and no rats were caught at a trapping site where most of the understory had been burnt. The fire also reduced bush rat abundance and body condition and caused movement pathways to become more convoluted. After the fire, some individuals moved through burnt areas but the majority of movements occurred within unburnt patches. The effects of fire on bush rat resource selection, movement, body condition, and abundance were likely driven by several linked factors including limited access to shelter and food due to the loss of understory vegetation and heightened levels of perceived predation risk. Our findings suggest the influence of prescribed fire on small mammals will depend on the resulting mosaic of burnt and unburnt patches and how well this corresponds to the resource requirements of particular species.

A population of Rattus fuscipes, in Sherbrooke Forest, Victoria, had a well defined breeding season. Mating occurred between November and January and the young were born between December and February. Juveniles were first captured in late February at approximately 1.5 months of age. The subadult age class displaced the parental age class in the population by the following August, so that almost all animals breeding in a season belonged to a single age class. The degree of home range overlap changed seasonally and could be related to changes in the proportion of amicable and agonistic behaviour judged from a series of contrived laboratory encounters. Diet consisted of both plant and insect material and changes in the proportion of these two components correlated with changes in survival. Measurements of 15 physiological parameters and organ weights, drawn at montly intervals indicated three periods during the life cycle when R. fuscipes exhibited heightened adreno-cortical activity. It is suggested that the development of territoriality in subadults during late autumn and possibly the decrease in abundance and quality of food in early winter, largely determine the size of the breeding population in late spring.

Conservation of small mammal species relies on an understanding of their habitat use. We used trapping surveys and telemetry to examine habitat selection and use by the broad-toothed rat (Mastacomys fuscus mordicus) and the bush rat (Rattus fuscipes) in an alpine resort in Victoria. M. fuscus occurred at low numbers, nesting in subalpine wet heathland and foraging in that habitat as well as small patches of disturbed woodland. In contrast, R. fuscipes was more common and nested in woodlands. Although foraging primarily in woodlands, R. fuscipes also foraged in all other available habitats. Both species showed strong selection for woodland fragments within ski runs. Although highly disturbed, these habitats may provide important habitat and connectivity between less disturbed and larger habitat patches.

The activity patterns and partitioning of time by four small mammal species, with a focus on the swamp rat (Rattus lutreolus) in north-eastern New South Wales, was investigated using camera trap data from two studies. Analysis was carried out on 1079 camera trap events over 1530 camera trap–nights or 36 720 h of camera trap deployment in the field. The activity patterns of Rattus lutreolus were distinctly diurnal with crepuscular peaks of activity but this differed between sites and when in the presence of competitors. The Hastings River mouse (Pseudomys oralis) and the bush rat (Rattus fuscipes) displayed typical bimodal patterns of nocturnal activity. Antechinus were mostly nocturnal but were occasionally active during the day. These data indicate that where species of Muridae co-occur, diurnal time partitioning by R. lutreolus may reduce competition for food resources. It also confirms the speculation that R. lutreolus displays diurnal behaviour, albeit dependent on the presence of other murids.

Snow is an important factor in the lives of flora and fauna in those regions where it occurs. Despite this, there is a relative lack of information about the ecological role of snow. In addition, on a global scale the majority of the research on snow ecology has been based in the boreal regions of North America and Eurasia. Insights from these areas may not extrapolate well to Australia. The distribution and physical characteristics of snow are highly variable both temporally and spatially. Its occurrence is affected by a range of factors acting at multiple scales. Working in snow covered areas, however, presents considerable practical problems, particularly for researchers attempting to sample organisms in the subnivean space between the base of the snowpack and the ground surface. As a result, most research has focused on small-scale projects because of logistical and animal-welfare issues. A technique was developed for this study for sampling small mammals beneath the snow using hairtubes fitted with bait and a removable adhesive surface that could be inserted into the subnivean space through a vertical PVC pipe. The technique provided a 39% detection rate with only 0.2% of tubes visited but not collecting hair samples. Using. this technique, it was possible to expand systematic sampling of small mammals in the subnivean space to larger scales at which snow cover can vary spatially and temporally particularly at the landscape scale. The main part of this research was conducted over two winters (2002-2003) at sites established in a series of valleys close to the Summit Road in Kosciuszko National Park, south-eastern Australia. Selection of sites was based on factors considered important in influencing the distribution of snow in the landscape and representative of the key vegetation types occurring in the subalpine zone. The resulting design consisted of 72 sites stratified by elevation (1501-1600 m, 1601-1700 m, 1701-1800 m), aspect (accumulating, ablating) and vegetation type (woodland, wet heath, dry heath, grassland) with each combination replicated three times. Each site consisted of three hairtube plots approximately 10 metres apart, at which small mammals were sampled. In addition, a range of biotic and abiotic factors including snow cover characteristics were measured throughout the winter at these same sites. In January 2003, a major bushfire burned 70% of the subalpine area of Kosciuszko National Park and damaged 83% of the sites established in 2002. As a result sampling during winter 2003 was limited to high elevation sites, along with a fifth habitat type (boulderfields). The snow cover that occurs in the main alpine and subalpine region of the· Snowy Mountains is primarily maritime in areas where there is sufficient accumulation, and ephemeral at lower elevations and ort higher ablating aspects. Maritime snow is generally deep (> lOOcm), with a density >0.30gcm-3, as a result of destructive metamorphism throughout the winter. The formation of depth hoar, which is considered to be important in acilitating the development of the subnivean space, does not occur under these conditions. Ephemeral snow is characterised by warm shallow snow that often melts before new snow is deposited. When snow was present, detections of dusky antechinus, Antechinus swainsonii and the bush rat, Rattus fuscipes were negatively correlated with snow depth and duration, and positively correlated with the complexity of structures and microtopography. At high elevations, detections were largely confined to boulderfields, and at mid- and low elevations, small mammals were detected primarily in habitats where the subnivean space was most extensive. Antechinus swainsonii and R. fuscipes responded differently to snow cover with the latter seeming better able to overwinter where snow cover was shallow and patchy. In contrast, A. swainsonii occurrence was correlated with the size of the subnivean space. The development of the subnivean space in the Snowy Mountains is dependent on the presence of structures such as shrubs, boulders and microtopographic features that are capable of supporting a snow layer above ground level. The temperature in the subnivean space was virtually constant beneath the snowpack, ranging between 0 and + 1 °C. When snow was patchy or absent, temperatures at ground level were highly variable with a minimum as low s -13°C and maximum as high as +47.5°C. Antechinus swainsonii and R. fuscipes were detected more regularly at sites that were thermally variable. At sites with deep and persistent snow cover (maritime snow), subnivean temperatures were stable, but small mammals were detected at low frequencies. At high elevations, boulderfields were favoured by small mammals during the nival period but were no different thermally from other habitats. The limitations imposed by snow cover on small mammals were further verified by a radio tracking study conducted during 2003 at Perisher Creek. That study investigated the home range size and activity patterns of R. fuscipes and A. swainsonii in relation to snow cover. Once continuous snow cover became established, the home range of both species contracted dramatically and there was an increase in home range overlap. Neither species showed any change in diurnal activity patterns. Rattus fascipes showed signs of social interaction during both seasons in contrast to A. swainsonii, which appeared to remain solitary. In winter, R. fuscipes nested communally at a single location, while during autumn the species appeared to use a number of nest sites. There was no significant change in daily activity patterns between autumn and winter in either species. R. fuscipes remained primarily nocturnal during both pre-nival and nival periods while A. swainsonii continued to be active throughout the diel cycle, although there was a slight shift in its peak activity time. Human activities can, have significant effects on the subnivean space and its residents. The physical characteristics of a range of modified snow types were investigated in the vicinity of several ski resorts in Kosciuszko National Park. Human activities associated with snow-based recreation, such as the creation of ski pistes, surface ski lifts and over-snow routes, involve compression of the snowpack and resulted in small or absent subnivean spaces and high snow cover densities compared to unmodified snow cover. To test the effects of the loss of the subnivean space on small mammals, the snowpack was experimentally compressed in high quality subnivean habitats. Detections of R. fascipes and A. swainsonii declined by 75-80%. Burnt sites from the 2002 study were used in 2003 to investigate the effect of removing vegetation on the subnivean space, to simulate the loss of structure associated with ski slope preparation. There was a significant reduction (p<0.0001) in the size of the subnivean space compared to unburnt sites regardless of habitat type. The key conclusions of the work reported in this thesis are listed below: • Snow conditions in the Australian Alps are markedly different from those of higher northern latitudes and altitudes. As a result, conclusions about snow/fauna interactions based on research in regions with particular snow cover types need to be carefully considered before attempting to extrapolate generalisations to other parts of the world. • The subnivean space can be formed either by passive or active processes. The former occurs when there are sufficient competent structures to permit the support of the snow pack above the ground surface, while the latter refers to the ability of small mammals to actively tunnel through relatively low density snow (depth hoar) and thus create their own subnivean space. In Australia the passive process dominates. • The widely held assumption that small mammals are dependent on the thermally stable conditions in the subnivean space was not confirmed. Rattus fascipes and A. swainsonii survive in the Australian Alps because they are able to exploit thermally variable environments. • Management of human activities in nival areas should focus on avoiding disturbance in areas where a subnivean space forms, particularly in high quality winter habitats such as boulderfields. • Global warming resulting from climate change is likely to provide conditions in the Australian Alps that favour an expansion of the distribution and population of R. fuscipes and A. swainsonii, but nival endemics such as Burramys parvus and possibly Mastacomys fuscus may be at a disadvantage. • The extent of alpine and subalpine environments in Australia will decrease in future, imposing greater pressure on a shrinking resource and raising the possibility of conflict between user groups and conservation imperatives.