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A report in Wildlife Research, that koalas are extinct in most of the Eden region as a result of climate change, logging and clearing, is mistaken. Its recommendation, that logging should cease in a climate refuge where, supposedly, the last koalas persist, has been adopted by Government. Koalas are unlikely to benefit. It would be better to conduct radio-tracking studies of koalas in this area and in the wider region to inform their future management.
The koala (Phascolarctos cinereus) occupies a broad range of eastern and southern Australia, extending over tropical coastal, semiarid inland and temperate regions. In many areas koala populations are under threat, in particular from the direct and indirect effects of ongoing habitat destruction due to increased urbanisation and other anthropogenic processes. Climate change presents additional threats to the integrity of koala habitats because many species of food and non-food trees have narrow climate envelopes and are unable to adapt to altered temperatures and rainfall. Climate extremes also produce physiological stresses in koalas that may increase the likelihood of outbreaks of chlamydiosis and other diseases. Climate change–related increases in the relative content of toxic chemicals in leaves are further stresses to the koala after ingestion. In addition, populations that originated from a small number of founder individuals are at potential risk due to their relatively low genetic diversity. Strategies that maintain residual habitat fragments and promote the construction of new refugia are now being formulated. Modelling of the impact of habitat metrics on koala distribution is providing important information that can be used in the rehabilitation of koala refugia. In future these models could be augmented with metrics that describe koala homeostasis to inform local conservation strategies. These considerations are also relevant for the maintenance of other taxa in the wider ecosystem that are also at risk from habitat destruction and climate change.
Assessments of the conservation status of koalas and trends in their population have been based on mostly unstated false assumptions about their pre-European status and on notions that either they were naturally regulated by their predators, chiefly Aborigines and dingoes, or that they somehow ‘self-regulated’ their fecundity. Closer examination of their ecological history suggests that frequent mild burning by Aborigines maintained eucalypt forests having fewer, mostly healthy trees, fewer young trees, canopies comprising mostly hard and dry leaves with low nutrient content, and, consequently, very few koalas. European explorers did not see them because they were solitary animals occupying large home ranges. After burning was disrupted, koalas responded to increased food resources in dense new growth of eucalypts and in stressed trees continually turning over new foliage. An export skin industry flourished. When their food resources were depleted by clearing or ringbarking of new growth and/or death of declining stands during droughts, koalas crashed back to low levels. Koalas continue to irrupt and decline through much of their range according to changing land management. Wildlife managers should re-assess their status and their management from a clear historical and ecological perspective.
Context. Assisted colonisation has the potential to protect species from intractable threats within their historical ranges. The Australian mainland subspecies of the eastern barred bandicoot (Perameles gunnii) is extinct in the wild, with surviving populations restricted to small sites protected by predator–barrier fences. PVA modelling shows that a self-sustaining bandicoot population would require an area free of the introduced red fox (Vulpes vulpes) of at least 2500 ha. French Island is outside the historic range of the species, but is fox-free and contains around 9000 ha of potentially suitable habitat.
Aims. This study will assess the suitability of French Island as a potential site for a self-sustaining eastern barred bandicoot population by conducting a 1-year assisted colonisation trial to assess habitat use, body condition and survival.
Methods. Between July and September 2012, 18 adult bandicoots were released. We radio-tracked bandicoots using intraperitoneal radio-transmitters for up to 122 days and trapped fortnightly.
Key results. The release group met the three measures of success: (1) appropriate habitat use; (2) recovery of post-release bodyweight; and (3) founder survival exceeding 100 days. Habitat use and body condition throughout the trial reflected that of mainland populations, and seven bandicoots survived longer than 100 days. Mortality was greatest in the first month, with veterinary investigations confirming two deaths due to cat predation, two deaths from toxoplasmosis and one unknown cause of death. Bandicoots that survived longer than 100 days occupied higher, drier ground than those that did not. Toxoplasmosis cases were associated with lower topographic position on the site.
Conclusions. Our results suggest that French Island provides suitable habitat for the establishment of a population of eastern barred bandicoots. On French Island, toxoplasmosis was identified as an important source of mortality in addition to cat predation, and warrants further investigation.
Implications. Given the costs and challenges of predator control and the maintenance of predator exclusion fences, assisted colonisation to one or more fox-free islands remains the most viable option to establish self-sustaining bandicoot populations. Our results highlight the value in conducting trial releases ahead of major translocations.
Context. Wolverines (Gulo gulo) are harvested for fur in northern Canada; however, the impacts of harvest are poorly known. Additionally, wolverine population data are largely absent for much of their northern range. Demographic data collected from harvested wolverines provide information on the vulnerability and variability of different sex and age cohorts to harvest, which, in turn, may have implications for harvest sustainability.
Aims. We examined the temporal variability of different sex and age cohorts in wolverine harvest among years, and within the harvest season, in Yukon, Canada. We also examined the pregnancy status of female wolverines in relation to the harvest date, so as to evaluate the impact of the harvest-season length on breeding wolverines.
Methods. We determined the sex and age composition of harvested wolverines via dissections of 655 carcasses collected from 2005 to 2014. We determined the reproductive status and fetal measurements for female wolverines via dissections of reproductive tracts.
Key results. The harvest consisted mostly of males, particularly of young individuals. The sex ratio of harvested animals did not fluctuate significantly, but we observed variation in the age structure among years. The age structure varied within the harvest season (November to March), with a greater proportion of adults being harvested in late winter. Active gestation was evident in females harvested after mid-January, and near-term or postpartum females were harvested during late February and March.
Conclusions. Late winter harvest is likely to have a more significant impact on populations than is early winter harvest, because of increased harvest of adults and breeding females. Wolverine harvest season extends to the onset of the denning season in late February and March, indicating a concern for ethical harvest.
Implications. Limiting the legal harvest season to early winter may contribute to improved harvest sustainability and protection of breeding wolverines in northern latitudes.
Context. Land-use change may represent a major driver for wildlife population trends in most ecosystems all over the world. In addition to land abandonment and forest management transformation in remote areas of developed countries, such as the European mountains, the intensification of human activities has, by and large, affected the settlement opportunities for wildlife species.
Aims. What changes occurred in the structure and extent of land use between 1973 and 2011 in the Central Eastern Alps, Italy? Are the abundance indices of roe deer (Capreolus capreolus) and red deer (Cervus elaphus) driven by these landscape transformations? Is there any relationship between the increase in red deer and the decrease in roe deer abundance?
Methods. The study was conducted in a 1335-km2 area (Central Eastern Alps, Italy). Through GIS photo interpretation techniques and patch analysis tools, we determined land-use changes between 1973 and 2011. Correlations between environmental modifications and climatic conditions, as well as between roe and red deer abundance indices (i.e. catch per unit effort (CPUE) and hunting bag data, respectively) were investigated for the 1973–2011 period by implementing linear mixed models.
Key results. The metrics thus calculated revealed a homogenisation of the woodland area and a general landscape simplification. By examining the effects of the climatic factors supposedly affecting population growth rate, roe and red deer trends seemed to be driven also by land-use evolution. Indeed, in the 1973–2011 period a negative trend in the availability of open areas below the tree line (–4.6%) and of agricultural zones (–1.9%) seemed to disfavour roe deer, while a fast increase in woodlands ( 7.8%), scrublands ( 3.3%) and canopy cover ( 7.9%) was reported to be concomitant to red deer range expansion and density increase. Moreover, red deer growth rate impacted on roe deer population dynamics.
Conclusions and implications. Given the ongoing land-use changes, their effect on roe and red deer population trends and the competition issue between them, these results may help managers to apply an effective adaptive-management planning technique for target locations to keep the ecosystem balanced.
Context. Cryptic (i.e. secretive, elusive or well camouflaged) species are often very challenging to accurately survey. Because many cryptic species are threatened, the development of robust and efficient survey methods to detect them is critically important for conservation management. The swamp skink (Lissolepis coventryi) is an example of an elusive and threatened species; it inhabits densely vegetated, wet environments throughout south-east Australia. The swamp skink occurs in peri-urban areas and faces many human-induced threats including habitat loss, introduced predators and environmental pollution. Effective and reliable survey methods are therefore essential for its conservation.
Aims. This study aimed to review the current swamp skink survey guidelines to compare the detection success of Elliott traps with two alternative methods: passive infrared cameras (camera traps) and artificial refuges.
Methods. Detection probabilities for the swamp skink were compared using Elliott traps, artificial refuges and camera traps at two known populations on the Mornington Peninsula, Victoria, Australia.
Key results. Artificial refuges and camera traps were significantly more successful than Elliott traps at detecting swamp skinks.
Conclusions. Elliott traps are currently regarded as the standard technique for surveying swamp skinks; however, these traps were the least successful of the three methods trialled. Therefore, the use of Elliott traps in future swamp skink presence–absence surveys is not recommended.
Implications. Many previous surveys utilising Elliott traps have failed to detect swamp skinks in habitats where they are likely to occur. Our findings suggest that at least some of these past surveys may have reported false absences of swamp skinks, potentially resulting in poor planning decisions. A reduction in the reliance on Elliott trapping is likely to increase future swamp skink detection success, broaden our understanding of this cryptic species and aid conservation efforts. Our results emphasise that it is essential to regularly review recommended survey methods to ensure they are accurate and effective for target species.
Context. Many institutions of wildlife management and their hunting constituents tend to value ungulates over large carnivores, in part due to financial incentives associated with ungulate hunting over carnivore hunting. This system benefits from mythology that presents large carnivores as competitors for antlered male ungulates most prized by the hunting community.
Aims. We explored puma (Puma concolor) foraging and prey selection in two study areas in the Rocky Mountains, USA, to test whether pumas were competing with human hunters for antlered elk (Cervus elaphus) and mule deer (Odocoileus hemionus).
Methods. We employed GPS technology to track pumas and document their prey. We measured population- and individual-level selection by comparing prey killed by pumas to two estimates of prey availability: (1) landscape-level as determined by annual agency game counts; and (2) total prey killed by marked pumas.
Key results. Pumas in both study systems killed small numbers of antlered elk and mule deer. Pumas exhibited avoidance of mature elk, instead strongly selecting for elk calves over any other age or sex class. Pumas in both systems also selected for mule deer fawns; however, they also exhibited small positive selection (Jacob’s index of 0.08 in CO and 0.11 in WY on a scale of 0.0–1.0) for antlered mule deer.
Conclusions. In terms of numbers killed, pumas were not a competitor with human hunters for either antlered species. In terms of prey selection, pumas showed that they may be greater competition for rare antlered mule deer but not for antlered elk. In both study sites, antlered elk and deer remained at levels at which they could perform their ecological functions.
Implications. Our results highlight the fact that the overhunting of large carnivores over competition for antlered ungulates is mostly unfounded; we should instead focus management, media attention and conservation science on disentangling the complex ecology driving localised declines of mule deer, elk and other important ungulate resources, many of which are anthropogenic in nature and can be addressed.
Context. Accurate surveying and monitoring of biodiversity provides essential baseline data for developing and implementing effective environmental management strategies. Land managers in arid zones face the challenge of managing vast, remote landscapes that support numerous cryptic species that are difficult to detect and monitor. Although researchers and land managers are using an increasingly wider variety of monitoring techniques to detect and monitor species, little is known of the relative effectiveness and comparative costs of these techniques.
Aims. The present study simultaneously assessed the efficacy of three popular monitoring techniques utilised in the spinifex sand plains of arid Australia, namely, live trapping, sign surveys and passive infrared (PIR)-camera trapping.
Methods. We explored variations in capture rates and species richness for each technique and compared initial and on-going costs of the techniques over time.
Key results. Sign surveys detected the greatest number of species and groups overall. Detectability of small mammals and reptiles, as a target group, was greater using PIR cameras, although the probability of detection by each technique varied among specific species. PIR cameras were initially the most expensive technique; however, the low ongoing costs of maintaining cameras in the field meant that they became the most cost effective after eight survey periods.
Conclusions. Each of the techniques tested here showed biases towards the detection of specific groups or species in the spinifex sand-plain habitat of Australia. Regardless, PIR cameras performed better at detecting the greatest diversity of target species and financially over time.
Implications. To accurately survey species across vast areas and climate variations, studies often extend over long time periods. Many long-term studies would be likely to benefit financially from the increased deployment of PIR cameras alongside or in place of live trapping surveys, with little impact on the ability to monitor the presence of most species in the region.
Context. Conflicts between wildlife and humans have occurred for millennia, and are major drivers of wildlife decline. To promote coexistence, Botswana established buffer zones called wildlife-management areas (WMAs) adjacent to National Parks and Reserves where communities assume stewardship of wildlife and derive financial benefits from it. In contrast, communities outside WMAs are generally excluded from these benefits despite incurring ‘coexistence costs’, including crop damage and livestock depredation, although they may receive compensation for these losses.
Aims. To investigate the perceptions and actions of a livestock farming community outside (but surrounded by) WMAs in northern Botswana, especially in relation to predator management.
Methods. We conducted standard-format interviews with 62 heads of households (cattleposts), and evaluated responses using descriptive and multivariate statistics.
Key results. Almost half (46%) of respondents expressed negative perceptions of predators, with 67% reporting losses to predation. After disease, predation was the most commonly reported source of livestock losses. Increased age of the head of household was the strongest predictor of reported predation. Few households employed husbandry beyond kraaling at night, but some (21%) reported conducting lethal control of predators. Reported use of lethal control was independent of the household experience with predation and whether they derived financial benefits from wildlife. Instead, households with larger herds were more likely to report using lethal control, despite the most educated farmers tending to have larger herds. Lethal control was almost twice as likely in households previously denied government compensation for losses (42%) than in those granted compensation (23%). Perhaps as a result of perceived failures of the government compensation scheme, most households (91%) supported the development of an independent insurance program, with 67% expressing willingness to pay a premium.
Conclusions. Our results challenge the assumption that deriving financial benefit from wildlife increases tolerance. A measurable disconnect also exists between the willingness of a household to employ lethal control and their experience with predation, suggesting that lethal control was used pre-emptively rather than reactively.
Implications. Efforts must be made to connect the financial costs incurred during farming alongside wildlife with the financial benefits derived from wildlife. Where compensation schemes exist, timely payments may reduce retaliatory killing.
Context. Knowledge of the movements and space-use patterns of wildlife is crucial for implementation of effective conservation and management actions. Such information can be difficult to obtain, especially from hard-to-capture or far-ranging taxa. Global-positioning-system (GPS) receivers that have remote data-acquisition capability via satellite-communication networks offer an effective means of tracking highly mobile animals; however, often the equipment and operational costs of these devices are prohibitive.
Aim. To evaluate the operational performance and potential of an inexpensive, commercially available satellite-download GPS receiver that can be easily modified for use on wildlife, and to demonstrate its utility for revealing novel information on individual animal movements in an important wildlife management context.
Methods. We added external batteries and supplementary waterproofing to ‘off-the-shelf’ SPOT Trace® GPS receivers (∼$120 USD; Spot LLC, Covington, LA) that transmit recorded location data to users through the Globalstar satellite network. We then deployed these devices on eight wild black swans (Cygnus atratus) inhabiting a large inland marine harbor adjacent to Auckland International Airport and assessed the GPS units’ operational performance and overall cost effectiveness.
Key results. During field trials with the tracking devices lasting up to 25 days we were able to collect thousands of precision location observations from the swans without the need for recapture. Cost-per-fix was only ∼$0.04 USD – up to an order of magnitude lower than some satellite-download GPS receivers manufactured specifically for wildlife. We provide novel information about the swans’ patterns of activity, movement, space-use, habitat preferences and responses to actions taken by airport staff to scare problem individuals from threat zones.
Conclusions. User-modified satellite-download GPS devices can be a highly cost-effective means of tracking the movements of animals.
Implications. Knowledge of where and when swans present the greatest likely threat to air traffic and how they respond to displacement from restricted areas near the airport will be useful in devising threat-management plans. The ready availability of affordable remote-download GPS receivers will provide many new opportunities to study the movement and/or space-use patterns of wildlife and incorporate such information into a broad range of research and management programs.
Context. The cane toad (Rhinella marina), a native species of central and southern America, was introduced to Australia in 1935 as a biocontrol agent after a complex history of prior introductions. The population rapidly expanded and has since spread through much of the Australian landmass, with severe impacts on the endemic wildlife, primarily via toxicity to predators. The invasion process has taken its toll on the cane toad, with changes in the immunological capacity across the Australian invasive population.
Aims. To investigate the immunogenetic underpinnings of these changes, we studied the diversity of the Major Histocompatiblity Complex (MHC) genes in introduced cane toad populations.
Methods. We studied the diversity of two MHC genes (the classical class I UA locus and a class II DAB locus) and compared these with neutral microsatellite markers in toads from the Australian site of introduction and the Australian invasion front. We also included toads from Hawai’i, the original source of the Australian toads, to infer founder effect.
Key results. Diversity across all markers was low across Australian and Hawai’ian samples, consistent with a reduction in genetic diversity through multiple founder effects during the course of the successive translocations. In Australia, allelic diversity at the microsatellite markers and the UA locus was reduced at the invasion front, whereas all three alleles at the DAB locus were maintained in the invasion-front toads.
Conclusions. Loss of allelic diversity observed at the microsatellite markers and the UA locus could be the result of drift and bottlenecking along the invasion process, however, the persistence of DAB diversity warrants further investigation to disentangle the evolutionary forces influencing this locus.
Implications. Through the use of different molecular markers, we provide a preliminary description of the adaptive genetic processes occurring in this invasive population. The extremely limited MHC diversity may represent low immunogenetic competence across the Australian population, which could be exploited for invasive species management.
Context. Due to their important ecological roles, predators are increasingly being suggested as targets for biodiversity studies investigating how they respond to landscape change and transformation. But there is limited literature investigating our capacity to accurately monitor changes in their occupancy.
Aims. To test the efficacy of playback surveys for monitoring owls as a basis for investigating change in owl occupancy over time. We ask whether playback is an effective tool, and whether it can be optimised to improve its utility.
Methods. Using the urban–forest interface of Melbourne, Australia, as a case study, we used playback techniques to survey for the presence of three owl species: the powerful owl (Ninox strenua); southern boobook (Ninox boobook); and eastern barn owl (Tyto javanica). Sites were repeat surveyed at least 16 times throughout the year and occupancy models were developed to establish how season and temperature influence nightly detection probabilities of owls.
Key results. All three species of owl were detected through playback survey approaches, but the detection probabilities varied greatly between species and across seasons and temperature conditions. Eastern barn owls are poor candidates for playback surveys due to their low detection probabilities. The southern boobook and powerful owl are responsive to playback, but detection probabilities are influenced by season and/or temperature conditions. To optimise survey approaches, southern boobooks should be surveyed during spring and summer and the powerful owl should be surveyed on nights where the minimum temperature is near 20°C.
Conclusions. Although there is considerable interest in using predators such as owls to monitor biodiversity impacts associated with landscape change, poor detection rates can limit their utility. However, optimising survey approaches that consider shifting detection probabilities under different conditions such as time of year or temperature may improve the utility of predators as surrogates in biodiversity monitoring.
Implications. Optimising survey approaches for owls considerably reduces the window of opportunity in which to conduct surveys. To counter this, the intensity of survey effort needs to be increased during key periods. The use of highly trained citizen science teams may be one effective way of delivering such an approach.
Context. Contact rates are a key determinant of disease transmission. Territorial behaviour has generally been considered to limit contact between European rabbits occupying different warrens, particularly during the breeding season.
Aims. We investigated warren use by subadult rabbits during a period of low population density to determine their potential role in transmission of rabbit haemorrhagic disease and myxomatosis.
Methods. Subadult rabbits were radio-collared in late summer and relocated twice-weekly for 25 weeks, during which time they grew to adult size and breeding commenced.
Key results. Rabbits of both sexes used an average of four warrens each on a regular basis, even after older rabbits had commenced breeding. Warrens used by individual rabbits formed a continuously overlapping, irregular array. Subadult rabbits did not belong to separate social groups that utilised separate groups of warrens.
Conclusions. Subadult or young adult rabbits did not display the same territorial warren fidelity that had been previously described for rabbits. They have potential to carry pathogens between warrens at a landscape scale.
Implications. Movement of subadult rabbits between warrens is therefore likely to play a critical role in disease transmission, particularly when population density is low. This may help to explain the prevalent seasonality of RHD epizootics in spring when first-born litters of each breeding season typically reach that size.
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