Wildlife Research最新文献

Sus scrofa is a species that easily adapts to diverse environments and climatic zones. In urban and suburban spaces, its presence negatively impacts soil, crops, and animal production, posing health risks for other animals and even humans. Declared a national pest in Uruguay, it is one of the main predators of sheep. A deeper knowledge of its habitat, current distribution, and the environmental factors that influence its locations is required to develop an adequate programme to control its population.

To determine the spatial distribution of wild boars in Uruguay and its association with environmental factors concerning livestock production, on the basis of a survey administered to farmers.

The survey was completed by 2360 farmers, gathering information on the presence of wild boars and other wildlife animals on their farms, methods used for wild boar control, economic damages caused by the species, number of sheep, and types of land-cover besides pastures (native woodlands, shelter forests, pine plantations, and eucalyptus plantations).

Farms located in the Northeast region, with native woodlands and/or pine plantations, and larger than 500 ha were more likely to report the presence of wild boars. The presence of eucalyptus plantations did not affect the presence of wild boars in any region of the country. While the presence of sheep, free- ranging dogs, or wild boars on neighbouring farms affected the presence of wild boars, the existence of eucalyptus plantations showed no effect across any region of the country. On the other hand, the presence of wild boars increased in association with the presence of pampas foxes (Lycalopex gymnocercus).

These results provide valuable information regarding the current distribution of an invasive exotic ungulate, and factors influencing the probability of reporting its presence.

This information will serve as a starting point for future research analysing additional ecological and farm characteristics, as well as management strategies in sheep farms aimed at detecting, evading, dissuading and/or controlling this predatory species on the basis of its behaviour and environmental preferences.

Predator free havens are increasingly relied upon to preserve populations of imperilled species, yet despite their substantial cost, the success of these ventures is rarely critically evaluated.

Based on 12 years of population monitoring data, we report on the translocation of woylies (Bettongia penicillata ogilbyi) to Perup Sanctuary, a 423 ha predator-free haven in the south west of Western Australia.

We built spatially explicit capture–recapture models to estimate population density, population growth rates, and survivorship of woylies inside the sanctuary. Using these estimates, and additional demographic information, we aimed to show key drivers of population density, evaluate the establishment of the sanctuary population against predetermined translocation success criteria, and run simulations of different sampling designs to determine a robust sampling design for future monitoring of this population.

The population rapidly increased in the first 3 years (2010–2013), and then fluctuated around a density of ~0.9 woylies ha⁻¹ before declining slightly in recent years to ~0.6 woylies ha⁻¹. All translocation success criteria evaluated were met. The previous 3 months’ rainfall was a key driver of population density and body weight declined over time, indicating that the population may be regulated by food resources.

Woylies have established and persisted in Perup Sanctuary, and against the criteria, the translocation of woylies into Perup sanctuary is a success. Harvests from this population appear to have been sustainable. We discuss these findings in the context of the Perup Sanctuary, and recommend ongoing monitoring continue to ensure that the population remains viable and well managed.

We describe important considerations for the supplementation and harvest of fenced populations, including: the source of animals (selecting free-living individuals over captive ones); the timing of release (releasing more individuals early on may improve establishment probabilities); and rates of harvest (<30% of adults harvested per generation seemeded to be sustainable for woylies in this case). The results from this study can inform the ongoing management of this and other havened populations, to ensure they continue to benefit mammal conservation.

Early surveillance and the detection of incursions of species of biosecurity concern are a crucial component of an effective biosecurity system. Citizen science represents an opportunity to engage communities in biosecurity, and to provide mechanisms for citizen scientists to contribute to both monitoring the spread of species already present in country, and reporting new incursions.

To present an example of how citizen science is being used for environmental biosecurity surveillance in Australia and showcase the value of large data services such as the Atlas of Living Australia (ALA), as a connector between citizen science and management.

We detail how the alert email system was set up, using a bespoke solution implemented in the R programming language. The system works by querying the ALA database for species that match lists provided by management authorities. Alerts can be sent out at national, state/territory and local government scales, as well as defined spatial areas such as national park estates.

Twelve months in, the top source for alerts comes from iNaturalist (a popular global biodiversity citizen-science platform), with other contributions from a set of biodiversity-reporting applications. Over a 12-month period, the alerts service has provided notifications for over 150 species, including the first public record of an invasive species in Australia.

Systems such as the Biosecurity Alerts Service, provide impact through the connection between communities and decision-making.

Our findings showed how the advancement of citizen science is interconnected with the advancement of research infrastructure and will ultimately lead to greater scientific and management value of citizen-science data.

Determining and quantifying habitat selection of endangered species in peri-urban environments assists planners and managers to develop strategies and alternative conservation measures in the face of urban expansion and development. Sloane’s Froglet (Crinia sloanei), listed nationally as endangered in Australia, is a little-known species distributed within peri-urban environments, where foundational ecological information and the development of adequate conservation responses has been lacking.

(a) To determine a core calling period for Sloane’s Froglet and detection probabilities for occupancy surveys. (b) To understand and characterise the habitat that Sloane’s Froglet uses at the wetland and microhabitat scale.

We used generalised linear modelling and the information-theoretic approach to model habitat preferences for this species at two scales: the waterbody scale, and the microhabitat scale. We quantified the habitat characteristics of waterbodies occupied by Sloane’s Froglet in winter, its peak breeding period, by measuring the biophysical characteristics of 54 occupied and 40 unoccupied waterbodies. The microhabitat and relative spatial positioning of Sloane’s Froglet within waterbodies was examined at 54 calling sites in an area of one m squared around individual male Sloane’s Froglets and 57 randomly selected unused sites. Wetlands were surveyed multiple times to determine detection probabilities.

Model selection indicated that Sloane’s Froglet is 450 times more likely to occupy a waterbody when an adjacent ephemeral shallow overflow is present; and are more likely to be present when there is greater cover of small stem-diameter emergent vegetation and less bare ground on the bank. The microhabitat investigation of one m squared sites showed that Sloane’s Froglet’s calling sites are predominantly inundated, and at significantly shallower water depths, than unused sites. Sloane’s Froglet was found to always call from within the waterbody, distinguishing them from other sympatric Crinia species.

The habitat characteristics detailed provide information necessary for the management of Sloane’s Froglet and its habitat.

Housing and industrial development is occurring rapidly in Sloane’s Froglet habitat. The information provided here can be used to refine local and state government planning and better design appropriate responses. Indeed, results from this study are currently being used by agencies and environmental consultants when developing conservation plans and in the design of stormwater retention ponds in rapidly urbanising environments.

Feral cats are responsible for the decline and extinction of species globally. Predation by feral cats is identified in Australian legislation as a key threatening process. However, clear guidance to local land managers on feral cat management techniques and their impacts, limitations and potential costs can be difficult to find.

In this study, feral cat management experts from around Australia identified available management techniques and their average environmental, social, and economic impact for different ecoregions and land-use types.

We convened a 1-day structured elicitation workshop with 19 experts and five facilitators. Experts identified the techniques used for feral cat management; the effectiveness, impact, and cost of each method; and the key knowledge gaps associated with feral cat management. Facilitators aided in the design and format of the workshop, led the discussion at each stage and collated the results.

Experts identified the following 10 techniques currently used in Australia: aerial baiting; ground baiting; leghold trapping; cage trapping; shooting; tracking with detector dogs; tracking by Indigenous Rangers; habitat modification; resource modification; and exclusion fencing. In general, experts highlighted that permits, legislation and scale of application constrained many of these techniques. Aerial baiting was considered the most effective technique for reducing feral cat populations in natural and production systems. Cage trapping, shooting, or tracking with detector dogs were considered more effective in residential areas. For all techniques, efficacy estimates varied according to the following three broad vegetation structural regions: (1) deserts and xeric shrublands; (2) forests and woodlands; and (3) grasslands, savannas and shrublands. Techniques considered to have the lowest social tolerance and highest impact to non-target native species included aerial baiting, ground baiting and leghold trapping. Techniques considered to have high social tolerance and low impact on non-target species included tracking by Rangers, tracking with detector dogs, and habitat and resource modification.

Estimates of management action efficacy differ among land-use types and at least three vegetation structural regions. However, social licence, logistic and legislative constraints are the key drivers of the availability of methods for these areas.

Feral cat management programs should consider how program strategy can be prioritised on the basis of technique availability, region of use and expected impact.

Ecological surveillance monitoring typically targets multiple taxonomic groups by using standardised sampling across large spatial scales. Although surveillance monitoring confers advantages over hypothesis-driven monitoring in its broad taxonomic and spatial scope, the approach has been criticised for its disconnect from ecological management and failure to provide insights on the drivers of ecological change

To assess the adequacy of a plot-based general fauna-monitoring program for sampling reptiles as indicators of ecosystem health in a semi-arid upland region of the Northern Territory, Australia.

We surveyed reptiles at 90 sites, stratified between major landform and vegetation types, and using standard fauna-sampling methods, across the 2568 km² Tjoritja National Park in the MacDonnell Ranges. We compiled a full inventory of the reptile fauna of the study area and identified species with potential utility as ecological indicators. We then used single-season occupancy models and power analyses to evaluate the adequacy of sampling for detecting potential future changes in occupancy.

We detected 57 of the 68 reptile species known from the protected area, 17 of which are potentially useful indicators of ecological health, mostly related to fire management. There was insufficient power to detect moderate (50%) future changes in reptile occupancy for all but the single most detected species. For the two ecological indicator species with sufficient detections for occupancy modelling, a positive association with a keystone structure (dense spinifex grass) was confirmed. However, increasing detection probability or the number of surveys would result in only minor improvements in power to detect occupancy change in these species.

Although reptiles are potentially useful indicators of ecological health, particularly in relation to fire regimes, the number of sites required to detect future changes in reptile occupancy by using standardised plot-based monitoring in this protected area is prohibitively high.

Our results suggest that once ecological associations are understood, monitoring ecological health remotely by using techniques such as fire-scar mapping to track proportions of long-unburnt vegetation should be considered over labour-intensive surveillance monitoring for reptiles. Targeted monitoring of threatened and other reptile species of conservation or cultural concern may also be warranted.

Freshwater ecosystems rank among the most threatened environments on Earth. Monitoring aquatic and semi-aquatic species is vital to informing conservation of freshwater ecosystems. However, many semi-aquatic mammals can be difficult to detect with conventional survey methods.

We aimed to identify the most effective survey method for detecting an Australian semi-aquatic mammal, the rakali (Hydromys chrysogaster).

We compared rakali detection rates among camera-trapping, live-trapping and visual surveys, and tested the influence of camera angle, trap proximity to water and time of survey, across the Yanco Creek system in southern New South Wales.

Nocturnal spotlight surveys were the most effective method for detecting rakali, with most observations occurring while individuals were foraging or swimming in the water. Camera traps facing a floating platform and cage traps mounted on floating platforms performed better than those deployed on land. Downward-facing camera traps detected rakali three times more often than did forward-facing cameras. Trapping rakali was unreliable, with the species detected at fewer than half of the sites where presence was confirmed via visual observation and camera traps. For species absence to be determined with 95% confidence, 2–4 weeks of nightly trapping is required, compared with six nights of visual surveys or 12 nights for a platform-facing camera. Morning visual surveys were largely ineffective because of predominantly nocturnal rakali activity and difficulty in detecting signs in creek environments.

The likelihood of detecting rakali can be maximised through the use of nightly spotlighting and deployment of baited camera traps focussed on platforms or natural resting areas within a water body.

Understanding the effectiveness of each method is essential for developing species-appropriate protocols for population monitoring. Our findings present suitable options to be further explored among the 100-plus small (<1 kg) semi-aquatic mammals worldwide that share similar behaviours and characteristics to the rakali, many of which are threatened or data deficient.

Animal-borne devices can affect animal survival, reproduction, and behaviour through both the addition of weight and bulk and the direct effects of initial and subsequent capture. Researchers commonly employ a general rule of thumb that weight of the device must be less than 5% of bodyweight for terrestrial animals; however, this threshold has little empirical basis.

We evaluated the effects of environmental variables, repeated capture, and weight of animal-borne devices on bodyweight in free-ranging feral cats.

We recaptured feral cats at varying frequencies, wearing GPS and/or VHF collars that ranged from 0.29% to 4.88% of bodyweight, and recorded change in cat weight over time.

Collar weight as a percentage of bodyweight was not a significant predictor of feral cat weight change. Rather, change in bodyweight was best described by a negative relationship with an increasing temperature and number of captures, and a positive relationship with time since collar attachment.

Capture had a significant influence on feral cat weight but collar weights up to 5% of bodyweight did not significantly contribute to weight loss. However, the absence of control cats without collars hindered definitive conclusions on the effect of collar weight on cat weight change.

Researchers should space capture and handling events more than 30 days apart to reduce effects of weight loss from capture and handling. Researchers should also consider increasing collar weight and reducing frequency of capture (where collars are less than 5% of bodyweight), particularly if cat bodyweight is a parameter of interest.

The decline of the greater bilby (Macrotis lagotis), or Ngarlgumirdi (Yawuru), like other critical-weight range Australian mammals, is believed to be primarily due to the synergetic impacts of predation by feral cats and foxes, habitat disturbance caused by large introduced herbivores, and increases in the frequency and intensity of wildfires. Although it has been demonstrated that low-intensity prescribed burning mosaics in some habitats have the potential to benefit mammals, including Ngarlgumirdi, by creating habitat with sufficient vegetation cover, the contributions of specific fire-mosaic attributes to Ngarlgumirdi persistence remain unclear.

To elucidate the impacts of fire-mosaic attributes on the occupancy of Ngarlgumirdi on the Dampier Peninsula.

We used 2-ha sign-plot data collected by four Indigenous Ranger groups, in combination with 20 years of satellite-derived fire-history information to investigate the multiscale impacts of fire attributes on Ngarlgumirdi and feral cats (Felis catus) on the Dampier Peninsula in the West Kimberley region, a large, unfenced landscape in the most fire-prone section of the Ngarlgumirdi’s current range.

We found that Ngarlgumirdi was more common in areas that had a higher proportion of habitat that had not burnt for at least 3 years, whereas feral cats were less prevalent in these areas. Similarly, Ngarlgumirdi was less likely to occur in landscapes affected by frequent fires, whereas cats were more common there.

Our findings have highlighted the importance of decreasing fire frequency and increasing the extent of long-unburnt habitats (>3 years) for preserving Ngarlgumirdi on the Dampier Peninsula and mitigating ecological damage inflicted by feral cats. Findings were consistent across spatial scales (1-, 3-, 5- and 10-km radius from each monitoring site).

These results have demonstrated the potential of fire management to increase native species resilience in the absence of direct feral cat control methods. Further, they support a recent cross-tenure initiative led by Traditional Owners to implement fire management that aims to reduce large, frequent high-severity wildfires and increase areas of long-unburnt vegetation on the Dampier Peninsula.

Masked water snakes (Homalopsis buccata, Homalopsidae) thrive in the muddy edges of agricultural ponds and canals in densely populated areas of West Java, Indonesia, and are harvested by local farmers to protect fish stocks and to provide meat, skins, and medicines for commercial use.

Here, we aimed to quantify sexual dimorphism and reproductive biology of H. buccata, so as to deepen our knowledge of the species’ inherent ability to withstand commercial harvests.

We examined carcasses of 4286 snakes at six processing sites to quantify biological attributes (e.g. sexual dimorphism in body size and shape, seasonality of reproduction, fecundity, reproductive frequency), with emphasis on traits that affect the ability of snake populations to withstand this intensive harvesting.

The snakes we examined were primarily adults (<1% juvenile), with approximately equal numbers of males and females except in January (when females comprised >90% of specimens). Females grow larger than males, and they are more heavy-bodied but shorter-tailed than are males of the same snout–vent length. Reproduction is seasonal in both sexes, with testis volumes decreasing to a minimum over the period August to November (late dry season) when most adult-size females were gravid. Litter sizes ranged from 1 to 37 (mean 12), increasing with maternal body size, with ~75% of females reproducing each year.

On the basis of these results, we infer that the life history of H. buccata (viviparity, high fecundity, frequent reproduction, rapid maturation) renders it inherently resilient to harvesting, especially because that offtake is based on males as well as females. Because a lack of sustainability is evident only in hindsight, regular monitoring of the trade could assure that any problems are detected rapidly.

To further buffer these populations from the impact of harvest, hunting could be restricted during January (a time when gravid females are disproportionately vulnerable) and the largest snakes (females, with high fecundity and reproductive frequency) could be excluded from harvests.