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Context. The global benefits of increased renewable energy production may come at a cost to local biotic communities and even regional ecosystems. Wind energy developments, in particular, are known to cause bird and bat mortalities, and to fragment habitat for terrestrial vertebrates within developed project areas. Effects on species sensitive to wind turbines (and increased prevalence of species tolerant to this disturbance) might alter community-level patterns of occurrence, with potentially detrimental changes to wildlife habitat and ecosystem health.
Aims. The present study assessed whether wind energy developments produced downstream ecological costs. Specifically, community composition and diversity were compared between wind farms and nearby areas without energy development.
Methods. Traditional diversity measures and non-metric multidimensional scaling (NMDS) were used to map ecological dissimilarity across four wind farms and five reference (control) areas in Southern California, USA.
Key results. Wind farms had more noise and road disturbance than sites without turbine installations. Noise and disturbance were correlated with reduced plant richness, particularly for endemic plant species and, conversely, with increased non-native plant richness. Animal communities at wind farms were less diverse, with fewer species and lower evenness relative to reference areas with minor or no disturbances. Wind farms had fewer rare and unique species and, for some species of avian predators, encounter rates were lower at wind farms.
Conclusions. Renewable wind energy may indeed cause shifts in local communities. Although wind farms still supported many of the same species found in natural areas, suggesting that renewable wind energy facilities can provide useable habitat for some wildlife, these communities were also less rich and diverse.
Implications. Non-native species were more prevalent at wind farms, which may then facilitate further invasions into surrounding habitats. In addition, reduced overall plant and predator diversity at wind farms, and lower encounter rates for specific taxa (particular birds), may significantly affect community structure and function.
Context. Multi-use management of global forests has seen even-aged, high-stem density regrowth represent >50% of the world’s forest cover. Large areas of river red gum (Eucalyptus camaldulensis) forests have declined in ecological condition. Thinning has been promoted as a tool to reduce competition in dense, young stands of E. camaldulensis regrowth, yet responses of forest structure and fauna to large-scale thinning are largely unclear.
Aims. To establish a before-after-control-impact experiment to assess responses of forest structure and fauna to large-scale (compartment-level; ∼440 ha) silvicultural thinning.
Methods. We measured immediate (<2 yrs) responses of forest structural components (living, dead and hollow-bearing stem densities, coarse woody debris (CWD) density and volumes and ground cover) and components of biodiversity (bats, birds, volant insects and non-volant mammals) before and after thinning within five control and three impact compartments.
Key results. Thinning reduced stem density by approximately two-thirds and was associated with a substantial increase in activity and richness of bats and a change in bat species composition. There was no change in richness for birds and non-volant mammals, nor insect biomass in relation to thinning. However, thinning affected composition of non-volant mammals, with the common brushtail possum (Trichosurus vulpecula) and red fox (Vulpes vulpes) less active post-thinning at impact plots relative to control plots. Thinning reduced the density of dead stems, though these were predominantly small (∼13 cm diameter at breast height over bark, or dbhob) and mostly lacked hollows. Hollow-bearing tree density was not affected by thinning. Although thinning increased CWD densities, volume of CWD did not change, indicating that thinning contributed small-sized CWD. Thinning did not affect densities of hollow- and fissure-bearing CWD or ground cover, which was low (<7%) in control and impact plots. There were no other negative effects on biodiversity detected.
Conclusions. Short-term fauna responses to thinning were generally neutral or positive.
Implications. Ongoing monitoring is required to detect long-term changes that may result from colonisation or altered breeding success after thinning. We recommend that some unthinned stands should be retained throughout the landscape to provide a mosaic forest structure suitable for a diverse fauna.
Context. Tourism is becoming one of the largest and fastest growing industries in many countries. Increasing tourism exerts serious impacts on the habitats of wildlife in nature reserves.
Aims. To ascertain how tourism affects the habitat of the Chinese giant salamander (Andrias davidianus), especially water quality and population size.
Method. An experiment was conducted to investigate the influences of different tourism disturbance intensities on the habitat quality and population size of the Chinese giant salamander in the Hunan Zhangjiajie Chinese Giant Salamander National Nature Reserve. Habitat characteristics, water physicochemical properties and microbial abundance were analysed, and population size estimated.
Key results. The results showed that high levels of tourism disturbance (>100 000 visitors per year) had negative effects on habitat quality. These effects included increased noise and abundance of aquatic microbes, increased concentration of total nitrogen (TN) and total phosphorus (TP) and a reduction of dissolved oxygen (DO) in water. The abundance of Escherichia coli could be regarded as an indicator of tourism disturbance on Chinese giant salamander.
Conclusions. It is concluded that: (1) the habitats were much noisier with increasing numbers of tourists, which might directly reduce the population size; (2) tourism indirectly disturbs the salamander population by increasing TN and TP, and reducing DO in the water; and (3) tourism might take in pathogenic microbes to the water habitats, which could cause disease for the salamander population.
Implications. Although tourism development might reduce local poverty, such efforts must consider the deterioration of habitats for wildlife, especially for this endangered animal species. Moreover, the intensity of tourism disturbance needs be reduced (by controlling the number of tourists) to achieve the coordinated development of tourism and wild animal protection.
KEYWORDS: European red fox, global positioning system (GPS), Kalbarri National Park, Notamacropus eugenii, remote sensing, translocation, Vulpes vulpes
Context. Fauna translocations are a tool for improving the conservation status of threatened species. Reviews of translocations undertaken in Australia and globally have reported that many fail because of predation by exotic predators. The outcome of ∼40% of translocations was unknown, often owing to inadequate post-release monitoring. Monitoring methods such as global positioning system data-loggers can provide valuable information on survival, habitat use and sociality, and can be particularly useful for cryptic species.
Aims. The present study used global positioning system (GPS) data-loggers and VHF radio-transmitters to evaluate the success of a reintroduction of the tammar wallaby and measured survival, short-term home-range, habitat use and proximity between reintroduced individuals (as a proxy for association).
Methods. Sixty-nine tammar wallabies of captive and wild stock were reintroduced to Kalbarri National Park (KNP) following long-term and broad-scale fox control, with nine receiving GPS data-loggers, and 16 receiving VHF radio-transmitters. Wallabies were intensively monitored for up to 11 months post-release. Mortalities were investigated using DNA identification and field necropsies.
Key results. In total, 16 of the 25 collared wallabies died within 11–319 days of release. Ten of the sixteen deaths were from predation. Home-range areas were larger than those reported elsewhere. Wallabies utilised long-undisturbed vegetation with a dense canopy cover during crepuscular periods. These areas were likely sought as refuge from predation and thermal extremes. During the main feeding period, a mosaic of recently burnt (i.e. ∼1 year) and >10 years since last disturbance was important.
Conclusions. The reintroduction was not considered successful because two-thirds of the collared wallabies died within 1 year of release and, therefore, the success criteria were not met.
Implications. Despite long-term fox control in KNP, the majority of collared wallaby deaths were a result of fox predation. This highlights the inherent difficulty of establishing populations of some species in the presence of introduced predators. Additional research could assist in determining appropriate control levels for introduced predators, to help ensure the success of future translocations of this species. Consideration should be given to the prey naivety of source animals, prey-switching by introduced predators, and short-term supplementary feeding to assist population establishment.
Context. The broad concepts and generalisations that guide conduct of applied ecology, including wildlife management, have been reviewed and synthesised recently into 22 prescriptive and three empirical principles.
Aims. The aim of this study was to use these principles to evaluate three on-ground wildlife management programs and assess the utility of the principles themselves.
Key results. Case studies of long-term management of national park biodiversity impacted by feral pigs (Sus scrofa), and of conservation and harvest of red kangaroos (Macropus rufus) and mallards (Anas platyrhnchos), were selected to provide a representative range of management objectives, spatial scales and land tenures, and to include both native and introduced species. Management documents and a considerable scientific literature were available for all three programs. The results highlight similarities and differences among management activities and demonstrate the 25 principles to differing degrees. Most of the prescriptive principles were demonstrated in both the management and the scientific literature in all three programs, but almost no use was made of the three empirical principles. We propose that use of the prescriptive principles constitutes evidence that these programs meet both societal and scientific expectations. However, the limited use of the empirical principles shows gaps in the three programs.
Conclusions. The results suggest that evaluating other wildlife management programs against the principles of applied ecology is worthwhile and could highlight aspects of those programs that might otherwise be overlooked. Little use was made of the empirical principles, but the the Effort–outcomes principle in particular provides a framework for evaluating management programs.
Implications. The effort–outcomes relationship should be a focus of future applied research, and both prescriptive and empirical principles should be integrated into wildlife management programs.
Context. Accurate estimates of population density are a critical component of effective wildlife conservation and management. However, many snake species are so secretive that their density cannot be determined using traditional methods such as capture–mark–recapture. Thus, the status of most terrestrial snake populations remains completely unknown.
Aim. We developed a novel simulation-based technique for estimating density of secretive snakes that combined behavioural observations of snake road-crossing behaviour (crossing speed), effort-corrected road-survey data, and simulations of spatial movement patterns derived from radio-telemetry, without relying on mark–recapture.
Methods. We used radio-telemetry data to parameterise individual-based movement models that estimate the frequency with which individual snakes cross roads and used information on survey vehicle speed and snake crossing speed to determine the probability of detecting a snake, given that it crosses the road transect during a survey. Snake encounter frequencies during systematic road surveys were then interpreted in light of detection probabilities and simulation model results to estimate snake densities and to assess various factors likely to affect abundance estimates. We demonstrated the broad applicability of this approach through a case study of the imperiled southern hognose snake (Heterodon simus) in the North Carolina (USA) Sandhills.
Key results. We estimated that H. simus occurs at average densities of 0.17 ha–1 in the North Carolina Sandhills and explored the sensitivity of this estimate to assumptions and variation in model parameters.
Conclusions. Our novel method allowed us to generate the first abundance estimates for H. simus. We found that H. simus exists at low densities relative to congeners and other mid-sized snake species, raising concern that this species may not only have declined in geographic range, but may also occur at low densities or be declining in their strongholds, such as the North Carolina Sandhills.
Implications. We present a framework for estimating density of species that have traditionally been considered too secretive to study at the population level. This method will greatly enhance our ability to study and manage a wide variety of snake species and could be applied to other secretive wildlife species that are most frequently encountered during road surveys.
Content. Native communities of herbivores have evolved fundamental dietary niches that avoid or minimise competition; the introduction of exotic species can change dietary niches, cause overlap in resource use, and result in competition for resources.
Aims. We compared niche breadth, overlap in diet, and quality of diet between introduced sika deer and native white-tailed deer in Maryland, USA. We investigated these changes in free-ranging populations where both species are allopatric as well as when they are sympatric.
Methods. We used microhistological analysis of faecal samples to determine the percentage of resources used by sika deer and white-tailed deer, as measured between geographical areas of similar habitat quality. We compared resource use specifically by controlling for harvest pressure and resource availability, which are known to alter resource use other than the presence of an additional deer species.
Key results. We observed a significant resource overlap (range 63–88%) between species. In the presence of sika deer, white-tailed deer displayed an increased niche breadth (108%) and a lower diet quality (17%). Sika deer consumed the same resources that comprised 78% of white-tailed deer diet. Unlike other native ungulates that have dietary overlap with white-tailed deer, sika deer is neither temporally nor geographically segregated in habitat use.
Conclusions. Resource overlap and changes in niche breadth and diet quality during sympatry strongly denote dietary competition between sika deer and white-tailed deer. This competition results in white-tailed deer altering the dietary selection, thereby consuming lower-quality forage.
Implications. White-tailed deer are concentrate selectors and require higher diet quality than do sika deer, which can tolerate diets higher in fibre, consistent with their classification as intermediate feeders. A decrease in the nutritional quality of resources used by white-tailed deer could contribute to the decline of white-tailed deer over time and allow the continued spread of sika deer.
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