Cities and nature may seem mutually exclusive, but the animal inhabitants, both native and introduced, from pets to pests, are a major component of city life. Using Sydney as an example, this paper takes a critical look at cities and nature, more narrowly zoology, with a long-term view, i.e. one with intergenerational equity in mind. In the rapid conversion of bush to farmland, then suburbs and industrial areas, flora and fauna have not been given a strong voice. We need a new ethic for this new urban ecosystem, one which encompasses dealing with exotic species, pests and vermin on the one hand, and relic native animal populations on the other. Plans for sustainability in environment, economics and society need to recognise that these are interrelated subjects, not separate entities. I argue that knowing the natural history of Sydney is integral to understanding the city, its history, and its sustainability.
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.
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.
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 Reviews of climate change in Australia have identified that it is imposing additional stresses on biodiversity, which is already under threat from multiple human impacts.
Aims The present study aimed to determine the contributions of several factors to the demise of the koala in the Eden region in south-eastern New South Wales and, in particular, to establish to what extent climate change may have exacerbated the decline.
Methods The study built on several community-based koala surveys in the Eden region since 1986, verified through interviews with survey respondents. Historical records as far back as the late 19th century, wildlife databases and field-based surveys were used to independently validate the community survey data and form a reliable picture of changes in the Eden koala population. Analysis of the community survey data used a logistic model to assess the contribution of known threats to koalas, including habitat loss measured as changes in foliage projective cover, fire, increases in the human population and climate change in the form of changes in temperature and rainfall, to the regional decline of this species.
Key results We found a marked, long-term shrinkage in the distribution of the koala across the Eden region. Our modelling demonstrated that a succession of multiple threats to koalas from land use (human population growth and habitat loss) and environmental change (temperature increase and drought) were significant contributors to this decline.
Conclusions Climate change, particularly drought and rising temperatures, has been a hitherto hidden factor that has been a major driver of the decline of the koala in the Eden region.
Implications Development of strategies to help fauna adapt to the changing climate is of paramount importance, particularly at a local scale.
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.
The present study demonstrates one solution to a problem faced by managers of species of conservation concern – how to develop broad-scale maps of populations, within known general distribution limits, for the purpose of targeted management action. We aimed to map the current populations of the koala, Phascolarctos cinereus, in New South Wales, Australia. This cryptic animal is widespread, although patchily distributed. It principally occurs on private property, and it can be hard to detect. We combined a map-based mail survey of rural and outer-urban New South Wales with recent developments in estimating site occupancy and species-detection parameters to determine the current (2006) distribution of the koala throughout New South Wales. We were able to define the distribution of koalas in New South Wales at a level commensurate with previous community and field surveys. Comparison with a 1986 survey provided an indication of changes in relative koala density across the state. The 2006 distribution map allows for local and state plans, including the 2008 New South Wales Koala Recovery Plan, to be more effectively implemented. The application of this combined technique can now be extended to a suite of other iconic species or species that are easily recognised by the public.
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.
This study summarises the results of a patchy, low-intensity hazard-reduction burn on the small mammals and lizards of Mumbulla State Forest and Biamanga National Park. About half of the study sites in the patchwork of alternate logging regrowth and unlogged forest had been burnt in April 1999. Prior to burning (winter 1998), there were significantly more Antechinus agilis in those north-west-facing sites that burnt in 1999, than in the south-east sites that burnt. By 15 months post-burning this trend had reversed, with more A. agilis in the burnt south-east sites. In contrast, burning had an initially positive effect on the abundance of Rattus fuscipes, with significantly more in the burnt south-east than burnt north-west sites four months post-burning compared with 1998 (pre-burning). This influence of aspect may be attributable to the fact that fires generally burn more intensely on the drier north-west slopes, removing more of the leaf litter and vegetative cover and making post-fire conditions harsher. Antechinus swainsonii became extremely scarce in the forest after the burning. Twenty months post-burning (summer 2000), there were significantly more Lampropholis delicata in the unburnt sites than in the burnt sites compared with 1999 (10 months post-burn). Lampropholis guichenoti were affected to a much lesser extent and recovered quickly, and Eulamprus heatwolei were generally unaffected by the burning. The hazard-reduction burn came 19 years after a high-intensity bushfire and logging operation in this forest. The results of the two fires were similar for the two Antechinus species and the Eulamprus species but contrasted for the other species. Hazard-reduction burning is widespread and accepted as a management tool and, following the New South Wales bushfires of 1994–95 and 2001–02, will probably increase in use. Our results, however, suggest that the biodiversity impacts of burning are complex and multidirectional, posing a significant challenge to conservation managers.
Context Global climate change will lead to increased climate variability, including more frequent drought and heatwaves, in many areas of the world. This will affect the distribution and numbers of wildlife populations. In south-west Queensland, anecdotal reports indicated that a low density but significant koala population had been impacted by drought from 2001–2009, in accord with the predicted effects of climate change.
Aims The study aimed to compare koala distribution and numbers in south-west Queensland in 2009 with pre-drought estimates from 1995–1997.
Methods Community surveys and faecal pellet surveys were used to assess koala distribution. Population densities were estimated using the Faecal Standing Crop Method. From these densities, koala abundance in 10 habitat units was interpolated across the study region. Bootstrapping was used to estimate standard error. Climate data and land clearing were examined as possible explanations for changes in koala distribution and numbers between the two time periods.
Key results Although there was only a minor change in distribution, there was an 80% decline in koala numbers across the study region, from a mean population of 59 000 in 1995 to 11 600 in 2009. Most summers between 2002 and 2007 were hotter and drier than average. Vegetation clearance was greatest in the eastern third of the study region, with the majority of clearing being in mixed eucalypt/acacia ecosystems and vegetation on elevated residuals.
Conclusions Changes in the area of occupancy and numbers of koalas allowed us to conclude that drought significantly reduced koala populations and that they contracted to critical riparian habitats. Land clearing in the eastern part of the region may reduce the ability of koalas to move between habitats.
Implications The increase in hotter and drier conditions expected with climate change will adversely affect koala populations in south-west Queensland and may be similar in other wildlife species in arid and semiarid regions. The effect of climate change on trailing edge populations may interact with habitat loss and fragmentation to increase extinction risks. Monitoring wildlife population dynamics at the margins of their geographic ranges will help to manage the impacts of climate change.
Context Habitat thresholds are the critical point(s), below which the probability of occurrence of a species declines. Identifying thresholds assists land managers to decide how much habitat is needed to conserve a species. However, for any given species, a threshold may not exist, or might occur at one scale but not at others, and it may differ across regions. The use of critical habitat thresholds can negatively affect populations if simplified conservation targets for habitat retention are prescribed. This problem is relevant to the koalas where there is evidence of habitat thresholds in mesic regions, but no studies of thresholds in semiarid regions.
Aims The aim of the present study was to investigate whether a threshold exists between the occupancy of a site by koalas and habitat variables at both the site and at four landscape scales in the semiarid Mulgalands Bioregion of Queensland, Australia.
Methods We modelled habitat relationships using standard and piece-wise logistic regression, and an information-theoretic approach, to determine whether the best model that explained the occupancy–habitat relationships was linear or had a distinct threshold. The site-scale variable was the percentage of primary eucalypt species. The landscape-scale variables included the amount of primary and secondary habitat, and an interaction between them.
Key findings There was a threshold relationship between the occurrence of koalas and the percentage of primary trees at the site scale. At the landscape scale, most threshold models failed to converge, and evidence pointed to a linear relationship between habitat amount and koala occupancy.
Conclusions Conservation actions for koalas in the Mulgalands Bioregion should concentrate on protecting the primary tree resource for koalas, namely, river red gums (E. camaldulensis). However, the maintenance or restoration of primary and secondary habitat to distances of 1000 m from the creek is important because of the linear relationship between koala presence and habitat amount.
Implications As habitat is lost in the semiarid Mulgalands Bioregion, koala occupancy declines. If known thresholds from mesic regions are used to define a minimum amount of habitat to be retained for koalas, conservation of local koala populations may well fail.
