Suchergebnisse

Context. Feeding strategies of large herbivores in snow-covered environments can be influenced by snow depth and snow quality. Common wombats, Vombatus ursinus, are large marsupial herbivores that occur in subalpine areas of Australia where they must dig through the snow to reach low vegetation. Deeper snow at higher elevations is considered to limit foraging and constrain their range, although there have been no quantitative studies investigating the influence of snow on their foraging behaviour. Aims. The present study examined how snow influenced the foraging behaviour of common wombats along a snow-depth gradient. Methods. During the 2008 winter season, snow tracks of 17 wombats were located within the subalpine zone, in a study area ranging from 1520 to 1850 m asl, and followed to record attributes of the snow cover and environment in relation to wombat activity. Key results. Wombats selected sites to feed where the snow was shallower, and deeper snow at feeding sites caused changes in foraging behaviour. Foraging occurred along fairly direct routes between burrows; however, as snow depth increased, wombats deviated more from their path to seek out suitable foraging sites. Most foraging occurred in shallow snow in open areas or where the snow had melted around the bases of trees, shrubs or boulders. About half (52%) of the feeding sites necessitated the wombats digging through the snow to reach low vegetation, predominantly the grasses of Poa spp. Digging craters for feeding occurred in snow depths up to 100 cm, although depths less than 35 cm were preferred. Some shrub species, such as dusty daisy bush, Olearia phlogopappa, that protruded from the snow, were also eaten where the snow was deeper. Dietary analysis confirmed that monocots made up the majority of the diet (93.3%), although some individuals consumed up to 26% dicots. Conclusions. The present study demonstrated that wombats can adjust to a snow-covered environment by altering both their foraging patterns and diet as snow depth increases. However, they will be limited where snow depths are consistently greater than 100 cm. Implications. Under future climate-change scenarios of declining snow cover, wombats may be able to forage and inhabit higher altitudes than where they currently occur, and this has implications for the grazing-sensitive alpine ecosystem. Predicting shifts in the range of other herbivores to higher altitudes will require knowledge of their species-specific foraging thresholds in snow, such as presented in this study.

Community-based wildlife postal surveys, which included the spotted-tailed
quoll, were undertaken in Eden, Port Stephens, Bellingen and Iluka. This
resulted in 68 records for spotted-tailed quolls for Eden, 40 for Port
Stephens, 39 for Bellingen and 7 for Iluka. Such a high number of records from
coastal New South Wales, with many on private lands, identifies postal surveys
as a major source of previously overlooked sightings. Spotted-tailed quolls
have declined in range by as much as 50–90% since European
settlement, which has seen them listed as a nationally vulnerable species.
There have been few surveys of spotted-tailed quolls in New South Wales due to
their difficulty of detection using standard field survey techniques, such as
cage trapping and hair tube sampling. Their unique appearance makes them an
ideal species to include in community-based surveys. Future use of these
surveys has the potential to contribute significantly to conservation programs
of spotted-tailed quolls that involve private lands and local support.

Analyses of the diets of Antechinus agilis and
A. swainsonii from Mumbulla State Forest examined
possible differences between species, sexes, logging treatment and aspect.
Taxa from 15 orders were identified in the diet, and were predominantly
terrestrial invertebrates. Overall, the dietary components were similar for
each species, but the frequencies taken showed some differences.
A. swainsonii ate more Diplopoda, Chilopoda and
Blattodea egg capsules, while A. agilis ate more weevils
(Coleoptera: Curculionidae). Male A. agilis ate more
coleopteran larvae, while females ate more Araneae. This difference in Araneae
in the diet between sexes of A. agilis was significant
in logged forest but not in unlogged forest. Female
A. swainsonii ate more Isoptera than did males. The
frequency of occurrence of lepidopteran larvae taken by
A. agilis differed across the three age-classes of
forest, with more taken in 26–34-year-old regrowth forest and none in
unlogged forest. Vertebrate remains – small skinks
(Lampropholis spp.) and feathertail glider
(Acrobates pygmaeus) – were found only in
A. agilis; these occurred infrequently in the diet.
These interspecific differences, sex differences and, most importantly,
differences between age classes of forest warrant further investigation,
particularly those relating to foraging patterns and prey availability.

Context. Nest boxes provide important nesting, denning and shelter sites for many fauna species worldwide, but we know little about the factors that influence the suitability of nest boxes for particular species. Such information is crucial in urban landscapes where natural hollows are scarce. Aims. The aim of this study was to record the use of nest boxes by sugar gliders (Petaurus breviceps), squirrel gliders (P. norfolcensis) and other fauna in a peri-urban landscape in northern Victoria and examine factors at multiple spatial scales that may influence nest-box use. Methods. We monitored the use of 102 nest boxes over three seasons in 2006. Attributes that may influence nest-box occupancy were measured at five different spatial scales: (i) landscape; (ii) the habitat beyond 20 m of the nest box; (iii) the habitat within 20 m of the nest box; (iv) the tree that the nest box was located in; and (v) the nest box. Key results. At the landscape scale, topography influenced nest-box occupancy with squirrel gliders using boxes in flat or gully areas, and sugar gliders using boxes in gully, mid-slope or ridge areas. For habitat beyond 20 m of the nest box, sugar gliders were more likely to occupy boxes with a higher density of surrounding nest boxes and a higher density of residential dwellings. Within 20 m of the nest box, boxes occupied by sugar gliders were more likely to occur in areas with a higher density of acacia shrubs and lower density of hollow-bearing trees, whereas the presence of acacia did not influence nest-box use by squirrel gliders. At the scale of the nest-box tree, boxes occupied by sugar gliders were more likely to be on smaller trees (based on height and diameter) and on box (e.g. red box Eucalyptus polyanthemos) species. The only nest-box characteristic to have a strong relationship with occupancy was date of establishment, with longer established boxes more likely to be occupied. Conclusions. Our study demonstrates that various factors influence nest-box use at different scales and nest boxes remain an important conservation and management tool in heavily modified landscapes. Implications. Land managers and groups should be aware that nest boxes may help to alleviate some of the negative impacts of the loss of hollow-bearing trees in low density urban areas, but nest-box use will vary depending on landscape context, habitat factors, box design, and the ecological traits of the target species. Each of these factors must be considered to maximise the conservation benefits of nest-box programs.

This paper reports a study of ground-dwelling, small mammals in coastal eucalypt forest in south-eastern Australia from 1970 through 2005. During this time, the study area burnt in an intense fire in December 1972 and was partially burnt in November 1980. Both fires were associated with prolonged drought. The mammals studied comprised two dasyurid marsupials, Antechinus agilis and A. swainsonii, two native murid rodents, Rattus fuscipes and R. lutreolus, and the introduced house mouse Mus musculus. After intensive sampling throughout the year from 1970 through 1972 to establish basic ecological and population parameters of the small mammal community, populations were sampled annually during late autumn and early winter before the onset of breeding. There were marked differences in the annual (autumn/winter) abundances of all species; numbers of A. agilis ranged from 4 to 142 individuals; A. swainsonii 0 to 43; R. fuscipes 4 to 54; R. lutreolus 0 to 11; M. musculus 0 to 23. Following the 1972 fire, numbers fell to the lowest level recorded during the study and each population subsequently disappeared from the plot between the 1973 and 1974 winter censuses. The less intense 1980 fire did not lead to extirpation, but numbers of A. agilis, A. swainsonii and R. fuscipes declined as drought conditions persisted through 1983. R. lutreolus occurred consistently only following the fires, when a grassy ground vegetation favoured by this species developed. Similarly, M. musculus colonised within two years of the fires and persisted on the plot for 3–4 years before disappearing. Following the fires, populations of the omnivorous R. fuscipes recovered first followed by the scansorial, insectivorous A. agilis and last by the fossorial, insectivorous A. swainsonii. Two primary conclusions emerged from this study. First, the intense fire of 1972 did not kill all the animals immediately, but led to the disappearance of each species from the plot over 18 months. Thus, intense fire had a delayed but catastrophic impact on small ground-dwelling mammals. The fluctuations in population levels, covering more than an order of magnitude, demonstrate that factors other than fire, such as rainfall and drought, drive the population dynamics of these small mammals. As stability and recovery are not features of local populations, long-term studies of benchmark populations are necessary to manage forest biodiversity.

In New South Wales, at least 28 species of native rodents have been recorded
since European settlement. Four of these are extinct nationally, six are
extinct in the State, six are vulnerable and four are endangered; only eight
remain non-threatened. Declines and losses have been greatest in central and
western New South Wales and least in the State's north-east. Neither
body weight nor habit are associated with status, but taxa such as
Rattus species with broad diets and habitat preferences
remain generally less threatened than ecological specialists. Threatening
processes affect all vulnerable and endangered species, with predation from
introduced carnivores, grazing from livestock, clearance of vegetation and
changed fire regimes being among the most severe. No species occur entirely on
reserved land, while two endangered species have no secure land tenure. A
program of survey, research, management and education is proposed to help
achieve recovery.

Context Loss and degradation of habitat from urban development is a key threat to the squirrel glider (Petaurus norfolcensis), because its distribution coincides where most people live in Australia. Squirrel gliders are known to occur in or around urban fringes where native vegetation is retained; however, little is known about specific anthropogenic factors that may affect their persistence. Aims We investigated the relative influence of biophysical and urban factors on the use of large hollow-bearing Eucalyptus trees, which are a key resource for squirrel gliders. The study was located in a typical urban growth area located in southern New South Wales. Methods A stratified random sampling approach was used to survey squirrel gliders in urban and rural areas. Infrared, motion-sensor cameras were placed in 34 selected trees for 17 nights to record squirrel glider occupancy and activity. Data on urban (e.g. light and noise pollution levels, road and housing density) and biophysical (e.g. tree height, hollow-bearing tree density, vegetation cover) variables were recorded at each survey tree. Data were statistically analysed using general linear modelling approaches. Key results Squirrel gliders were detected more frequently in the rural matrix (23.4% of camera trap-nights) than in urban areas (9.5%). Model results showed that tree height, and the distance to neighbouring trees, had a significant influence on the occurrence and activity of squirrel gliders. Road density and light pollution were included in 'best' models to explain glider activity (a negative influence), and noise pollution negatively influenced glider occurrence. Although gliders used large trees in both urban and rural areas, activity generally decreased as levels of urbanisation increased. Conclusions and implications Access to and availability of key resources such as tall, hollow-bearing trees is critical for gliders to persist in urban environments. Squirrel gliders will tolerate human stressors such as roads, noise and light pollution to a certain extent, but impacts on population viability remain largely unknown. Novel solutions need to be developed to lessen the effects of anthropogenic factors (such as light and noise) on patches of native vegetation retained in urban areas for conservation purposes.

The aim of this study was to examine the effects of fire on resource use by a population of koalas in remnant coastal forest. Fifty-five koalas were monitored regularly by radio-tracking for up to 35 months. The attributes of each tree in which the koala was sighted were recorded, giving a total of 8390 records. Analyses were undertaken on a range of ecological information. Regeneration of the forest began immediately following the fires and within three months koalas were seen among the epicormic growth. From a total 4631 trees used by koalas, 3247 (70%) were burnt. Observations of koalas feeding included 53% in burnt trees. Koalas changed trees frequently; individual trees were used once only on 3555 occasions (42% of all observations). Of all the trees used, 95% were used by only one collared koala; no trees were used by more than three koalas. Swamp mahogany (Eucalyptus robusta) was the tree species most frequently used by koalas, particularly at night and by breeding females. Koalas preferred trees of larger diameter (>30 cm) and used significantly taller trees during summer. This study has shown that resource depletion from intense wildfire is short-term for koalas because they utilise burnt trees within months of the fire for both food and shelter.

Context. Long-term studies are internationally recognised as an essential component of achieving ecologically sustainable forest management with respect to fauna. Aims. This study aimed to assess longer-term responses of small mammals to logging by returning in 1998 to our 1980–83 study sites in south-eastern New South Wales, Australia. Methods. Three age-classes of forest were surveyed: unlogged; 18–19-year-old regrowth; and 26–34-year-old regrowth. Key results. Rattus fuscipes remained affected by logging, and there were significantly fewer R. fuscipes males in logged, north-west-facing sites than at other sites, although the effect was less pronounced in 1998 than in 1980–83. Antechinus agilis females were significantly less numerous in south-east-facing, unlogged forest. This was not expected from the 1980–83 results. Antechinus swainsonii, which had disappeared following a fire in 1980, had returned to the forest by 1998. A. swainsonii females showed a significant preference for south-east-facing slopes and this relationship was consistent between logged and unlogged forest. No members of Mus musculus or Sminthopsis leucopus, which were present in 1980–83, were caught in 1998. Conclusions. As in the 1980s study, the responses of small mammal species to logging history were varied and species specific. Implications. In our study area, we predict that sustained logging for woodchips will continue to deplete its populations of small mammals. This adds to the case for a more robust and sustained approach to researching and managing our forest fauna.

A community-based postal survey (questionnaire and map) was undertaken in the Eden region of south-eastern New South Wales in 1991–92 to help determine the local distribution of koalas and to obtain information on which to base a regional plan of management for koalas. The 1198 replies from the II 600 households in the region represented all parts of the area surveyed. The survey responses suggest that koalas are rare in the Eden region, and that the number of koalas has been constantly low for the last four decades. The records are scattered both chronologically and geographically. National Parks and Nature Reserves have never been the stronghold of local koala populations, and freehold land, particularly farmland, is not a major reservoir of koalas. Most koalas reported were in, or adjacent to, State Forests, particularly Murrah–Berrnagui and Tantawangalo–Glenbog–Yurammie. These areas appear to contain the core of the surviving koala population of the region. An assessment of the vegetation where koalas were sighted indicated that dry forest is the preferred habitat. The once abundant and widespread local koala population of late last century has been reduced by habitat loss and fragmentation to a few small, isolated populations. This regional survey, which was undertaken by use of a carefully constructed questionnaire, revealed an invaluable source of records and contributed 70% of the records in the database used for this study. This study also laid a basis for assessing koala management options in south-eastern New South Wales.