Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact helpdesk@bioone.org with any questions.
Existing methods of reducing livestock depredation are heavily biased towards lethal control. However, criticism regarding the efficacy of such practices is rising. In Australia, over 200 years of lethal control has done little to resolve the conflict between dingoes (Canis dingo) and livestock producers. That is, killing dingoes does not necessarily prevent livestock losses. Rather than continuing with lethal control programs, there is an opportunity to shift to more innovative, effective and ethical non-lethal measures of protecting livestock from attacks. Traditionally, buffer zones (areas surrounding livestock enterprises or national parks where attempts are made to eradicate all dingoes entering that zone) have been put in place as a means to limit conflict. Although seen as more strategic than indiscriminately baiting over large areas, targeting dingoes in buffer zones does not necessarily remove problem animals. In addition, dingoes from outside baited zones eventually fill any territorial voids created. In order to break this cycle, we propose amending the traditional approach, so that instead of killing dingoes in these sensitive zones, they are excluded from production areas or otherwise discouraged from interacting with livestock (what we term ‘living buffer zones’). This can, in principle, be achieved through adoption of a suite of non-lethal management approaches, including aversive conditioning, which to-date has not been widely examined. In turn, resident dingoes conditioned to avoid livestock and/or livestock areas will maintain territories that largely exclude non-resident dingoes. Occasional ingress by transient dingoes will be met by the same exclusion and aversive strategies and are likely to quickly move on if harassed by resident dingoes. Such a strategy takes advantage of our ever-increasing knowledge of dingo biology and behaviour and leverages well established principles of animal learning. By funnelling funds currently spent on killing dingoes into experimental investigations of non-lethal approaches, we conclude that significantly more livestock will actually be saved.
Context. Trapping of small vertebrates during their active hot summer periods is vital for conservation and impact assessment studies. Animal Ethics Committees (AECs) protect wildlife by enforcing arbitrary but restrictive temperature limits for trapping.
Aims. Empirical data were gathered on the temperatures reached in different trap configurations to inform pragmatic ethical guidelines.
Methods. Temperature was measured inside small vertebrate traps at two Australian arid zone sites to generate data on the thermal consequences of: (1) trap design and external shading; (2) provision of protective refuge substrates; and (3) timing of trap clearing.
Key results. Shading and increased trap depth significantly reduced temperatures within pitfall traps. A conservative stressful upper temperature limit of 36°C was never exceeded inside deep, shaded, narrow pitfall traps at one study site and only between 1100 and 1300 hours on 3 days at the hotter site, despite ambient temperatures reaching over 42°C. By contrast, potentially lethal upper temperatures were reached in wider, shallower bucket pit traps on most days at both sites, even when optimal shading and refuge substrates were employed. Deployment of surface traps under vegetation and with additional shading significantly reduced maximum temperatures experienced. Temperatures inside shaded Elliott and funnel traps generally tracked ambient air temperatures and thus typically exceeded conservative threshold temperatures between 0700 and 1900 hours when ambient temperatures exceeded 36°C.
Conclusions. Temperatures experienced in optimal deep, shaded traps when ambient temperatures exceeded 40°C were 31°C lower than surface temperatures and similar to temperatures recorded at 20 cm below the soil surface, where many species would typically take refuge at these times.
Implications. Data suggest that deep (60 cm), narrow pitfall traps with elevated lids for shade and shelter substrate inside should enable trapping to be conducted safely in the study region during summer (December to February). This is even the case in extremely hot weather, as long as trapped animals are removed within 4 h of sunrise. Ecophysiological studies of thermal tolerance within optimum trap arrangements revealed by the present study will allow field ecologists and AECs to develop informed site-specific trapping protocols.
Context. Conservation management relies on baseline demographic data of natural populations. For Tasmanian devils (Sarcophilus harrisii), threatened in the wild by two fatal and transmissible cancers (devil facial tumour disease DFTD: DFT1 and DFT2), understanding the characteristics of healthy populations is crucial for developing adaptive management strategies to bolster populations in the wild.
Aims. Our analysis aims to evaluate contemporary reproductive rates for wild, DFTD-free Tasmanian devil populations, and to provide a baseline with which to compare the outcome of current translocation activities.
Methods. We analysed 8 years of field-trapping data, including demographics and reproductive rates, across 2004–16, from the largest known DFTD-free remnant population at Woolnorth, Tasmania.
Key results. Surprisingly, we found a dramatic and statistically significant decline in female breeding rate when comparing data collected from 2004–2009 with data from 2014–2016. Unfortunately we do not have any data from the intermediate years. This decline in breeding rate was accompanied by a subtle but statistically significant decline in litter sizes. These changes were not associated with a change in body condition over the same period. Furthermore, we could not attribute the decline in breeding to a change in population size or sex ratio. Preliminary analysis suggested a possible association between annual breeding rate and coarse measures of environmental variation (Southern Oscillation Index), but any mechanistic associations are yet to be determined.
Conclusions. The decline in breeding rates was unexpected, so further monitoring and investigation into potential environmental and/or biological reasons for the decline in breeding rate are recommended before the arrival of DFTD at Woolnorth.
Implications. Our results provide valuable data to support the conservation management of Tasmanian devils in their native range. They also highlight the importance of continued monitoring of ‘safe’ populations, in the face of significant threats elsewhere.
Context. Advances have been made in the development of reliable methods for estimating the abundance and density of large threatened mammalian predators, but there is little progress on developing population estimates for their principal prey. No standardised protocol for estimating prey populations exists, therefore different researchers use different methods. As such, there is little information on key prey species of the vulnerable snow leopard and this has hindered the preparation of effective snow leopard conservation plans.
Aims. This study aimed to establish an estimated seasonal baseline population abundance and density of blue sheep in the Lingzhi Park Range (LPR) of Bhutan’s Jigme Dorji National Park over winter (December to February) and summer (May to July). It also aimed to assess the number of snow leopard individuals that the current blue sheep population can sustain in the study area.
Methods. A refined double-observer survey method was used and involved walking transect lengths of 414 km in winter and 450 km in summer to estimate blue sheep abundance with the aid of 8 × 30 binoculars and 15 × 45 spotting scopes.
Key results. In total, 1762 (s.e. ± 199) blue sheep individuals were recorded in winter at a density of 8.51 individuals per km2 and 2097 (s.e. ± 172) individuals in summer at a density of 9.32 individuals per km2. Mean group size of blue sheep was 38.12 individuals (s.e. ± 6) in winter and 52.36 individuals (s.e. ± 4) in summer. LPR was estimated to sustain 11–17 snow leopards in winter and 15–21 in summer.
Key conclusions. LPR can be a hotspot for snow leopard conservation in western Bhutan and regionally in the eastern Himalayas, because the comparatively higher estimated blue sheep abundance and density supports possibly the highest density of snow leopards in Bhutan. The modified double-observer method used to assess blue sheep population estimates is inexpensive, robust and practical for the mountainous terrain of the Himalayas.
Implications. On the basis of this study, it is recommended that a refined double-observer method is adopted as a standard technique for estimating blue sheep populations in the snow leopard range countries of the Himalayas. Snow leopard conservation plans should, additionally, include efforts to minimise threats to blue sheep populations. This refined method is also highly applicable for future surveys of gregarious mammalian taxa, such as ungulates and primates, in difficult mountainous terrain elsewhere in the world.
Context. The study of the spatial variation in abundance of wild populations and the identification of factors explaining the observed patterns are key both to understand aspects of basic ecology and the effects of human activities. This is usually difficult to evaluate for low-density and widely distributed species, such as the lesser rhea (Rhea pennata pennata), an endemic bird from South America. Recent advances in spatial modelling such as the density surface models (DSM) combine distance-sampling procedures with modelling techniques to produce maps of spatial variation in abundance, and its relationship with predictive variables.
Aims. We aimed to analyse the spatial distribution and abundance of lesser rhea, and the variables that affect its abundance in Península Valdés (PV) Argentine Patagonia.
Methods. We conducted 338.4 km of ground surveys of lesser rheas in PV during the end of the Austral summer of 2015. Spatial models were constructed using DSM. Ecological and human-related variables were included in the models to account for variation in the abundance of animals at 4-km2 spatial resolution.
Key results. We estimated an overall density of 0.44 birds km–2 (CV = 32%) for the prediction area of 3320 km2. High values of normalised difference vegetation index, a correlate of plant productivity, were associated with increased numbers of lesser rheas. The location of ranch buildings, indicators of human presence, had a strong negative effect on lesser rheas, although their abundance increased at high sheep stocking rates.
Conclusions. As reported by previous studies in different sites, the abundance of lesser rheas in our study area was low. The use of DSM allowed a detailed examination of the spatial variation, as well as the variables involved and the uncertainty of the prediction.
Implications. The use of DSM techniques can be a useful tool for conservation planning and monitoring. Spatial, high-resolution data combined with knowledge on the factors affecting the number of animals are crucial to target specific conservation actions and monitor their results, and should allow government agencies to make better decisions concerning conservation-oriented management.
Context. The decline of Kentish plover (Charadrius alexandrinus) populations is related to a great variety of factors, including habitat loss, predators and human activities. In particular, predators have been identified as the main factor of low hatching success in many areas. However, few manipulative experiments have addressed this issue.
Aims. This study was designed to analyse the advantages, but also threats, of the protection measures commonly adopted in clutch protection programs.
Methods. Through camera traps, monitoring animal tracks and opportunistic observation we identified potential predators. Additionally, predation risk was assessed through simulated clutches. To improve hatching success, antipredator measures were adopted and their effectiveness analysed.
Key results. Our results show that under natural conditions, most simulated clutches will not complete the incubation period. Primary causes of hatching failure are predation, flooding, desertion and mechanical cleaning of the beaches, but another cause is accidental trampling. In this regard, protection measures greatly increased hatching success.
Conclusions. The use of clutch protection measures greatly increases hatching success in Kentish plovers. Nevertheless, protection measures are related to an increasing harassment of incubating adults, which could result in clutch desertion or adult predation.
Implications. Altogether, current results suggest that the efficiency of protection measures needs to be tested and adapted to each particular area; this is because there are a high number of correlated factors that might drastically affect the results in each case.
Context. Bioindicators are used for conservation prioritisation by means of spatial comparisons of a site value, or monitoring of ecosystem recovery or response to management. Spiders are characterised by their selection of quality habitats and guild responses to environmental change. However, they have only occasionally been used as bioindicators. Grammostola vachoni is an endemic tarantula that only occurs in the grasslands of the mountainous system in central Argentina and it is included in the Red List of the IUCN as Vulnerable.
Aims. In this study, we performed a characterisation of the microhabitat of G. vachoni at sites with different disturbance regimes and we analysed the potential use of this species as a bioindicator of mountain grassland health.
Methods. We determined the microhabitat characteristics around their refuges by mean of the soil parameters, as well as the composition and structure of vegetation and amount of refuge available.
Key results. We found significant differences in the number of individuals and the percentage of occupation between sites. No significant differences were recorded in the soil characteristics and occupation of G. vachoni but we found that the composition of vegetation, and the heterogeneity and diversity of plants are influenced by different disturbance regimes, altering the distribution of spiders.
Conclusions. Our results are consistent with those of other studies where the spiders have proved to be good bioindicators of different disturbances and we propose for the first time a Theraphosidae species for evaluating the state or health of a natural grassland.
Implications. The information reported in this study is very important to provide data for a future re-categorisation of G. vachoni for the Red List of IUCN. Also, we add new component of ecosystems for to use as indicator, open up the possibility for new research for the same and other species of a grasslands of the mountainous system.
Context. Terrestrial reptiles require varied thermal environments to promote optimal physiological performance, growth, reproduction, and survival.
Aims. Our study was designed to determine whether gap-based silvicultural practices offer suitable thermal environments for eastern box turtles (Terrapene carolina) by examining environmental temperature variation and body temperature of eastern box turtles in, and adjacent to, canopy gaps.
Methods. We recorded box turtle body temperature from 20 radio-tracked turtles and environmental temperatures (canopy gaps and undisturbed habitat) using temperature loggers from June to September 2014 in a managed forest after canopy gaps (0.28–1.13 ha gap–1) were created via gap-based silviculture.
Key results. Over the four-month study period, gap temperatures were generally higher than adjacent undisturbed microhabitats. Box turtle body temperatures were closely correlated with environmental temperatures in undisturbed habitat in June and July. Turtle body temperatures were, however, closely correlated with environmental temperatures in canopy gaps in August and September. In addition, box turtles in our study had activity areas that overlapped canopy gaps from 0 to 65%, depending on the individual. As percentage overlap of canopy gaps increased, turtle body temperatures were increasingly correlated with canopy gap temperatures. Furthermore, as percentage overlap of canopy gaps increased, daily mean body temperature records consistently stayed within the preferred box turtle body temperature range (20.2–26.2°C).
Conclusions. Our study suggests that gap-based silviculture can create thermally compatible environments for box turtles depending on the time of day and year, and that box turtles use these microhabitats to thermoregulate.
Implications. The application of relatively small-scale silvicultural practices (≤1 ha gap–1) that provide heterogeneity in forest structure, composition, and function may be a useful alternative to clearcutting and other intensive harvesting methods that are associated with declines in terrestrial reptile populations.
Context. Successful eradications of invasive rats from islands are paying tremendous conservation dividends, but failed eradications are economically and environmentally costly. For an eradication using rodenticides, every rat in every habitat must have sufficient exposure to toxic bait to receive a lethal dose. A post-operational review of a failed rat eradication on Wake Atoll, central Pacific Ocean, suggested that inadequate treatment of an intertidal habitat within the lagoon might have caused or contributed to the failure to kill all Polynesian rats (Rattus exulans), which have since recovered in number. This habitat could not be treated by aerial broadcast due to concerns about loss of bait to tidal action and perceived contamination of the marine environment.
Aims. In preparation for a second attempt, we developed two alternative bait application strategies to distribute enough bait for a long enough period of time to successfully target rats, while minimising bait entering the ocean.
Methods. We used camera traps and experimental bait provisioning methods to document rat foraging in the target habitat and uptake of bait. We developed two baiting strategy alternatives, and employed one of these strategies in a placebo bait application to demonstrate bait uptake by rats foraging within this tidally inundated habitat.
Key results. Our results show active foraging by rats in the target habitat. Provisioning of placebo bait by various means preventing bait spillage into the marine environment was followed by heavy feeding by rats and minimal bait interference by crabs.
Conclusions. We consider it likely that such a bait application strategy will be considered as an alternative during a future eradication attempt on Wake Atoll.
Implications. The techniques we explore here will be useful for rodent suppression in other wetland areas requiring rodent control while protecting sensitive aquatic resources.
Context. Small- and medium-sized native mammals have suffered severe declines in much of northern Australia, including within protected areas such as Kakadu National Park. Several factors have been implicated in these declines but predation, particularly by feral cats (Felis catus), has been identified as potentially the most direct cause of decline for many species.
Aims. We evaluated how prey frequency changed in cat and dingo scats in Kakadu from the early 1980s to 2013–15, with this period spanning a severe decline in the small- and medium-sized mammal fauna.
Methods. Chi-square test of independence and Fisher’s exact test were used to compare prey frequencies between dingoes and cats, and among years to assess significance of temporal change.
Key results. Small-sized native mammals were the prey item occurring at the highest frequency in scats for both dingoes and cats in the 1980s. Prey content in dingo and cat scats differed in the 2010s with macropods predominating in the scats of dingoes, and medium-sized native mammals predominating in cat scats. The frequency of occurrence of small-sized native mammals declined in both dingo and cat scats between the 1980s and 2010 sampling periods, while the frequency of occurrence of medium-sized native mammals remained constant in dingo scats and increased in cat scats.
Conclusions. Small mammals were a major component of the diets of both dingoes and cats in Kakadu in the 1980s, when small mammals were much more abundant. Despite marked reduction from the 1980s to the 2010s in the capture rates of both small- and medium-sized native mammals, some species continue to persist in the diets of cats and dingoes at disproportionally high frequencies. Both predators continue to exert predatory pressure on mammal populations that have already experienced substantial declines.
Implications. Although predation by feral cats is a major threat to small- and medium-sized native mammals, dingoes may also play an important role in limiting their recovery. Disturbance from fire and grazing by introduced herbivores has been shown to augment predatory impacts of feral cats on native mammals. Predation more generally, not just by feral cats, may be exacerbated by these disturbance processes. Management programs that solely focus on mitigating the impact of feral cats to benefit threatened species may be inadequate in landscapes with other significant disturbance regimes and populations of predators.
This article is only available to subscribers. It is not available for individual sale.
Access to the requested content is limited to institutions that have
purchased or subscribe to this BioOne eBook Collection. You are receiving
this notice because your organization may not have this eBook access.*
*Shibboleth/Open Athens users-please
sign in
to access your institution's subscriptions.
Additional information about institution subscriptions can be foundhere