Wildlife Research最新文献

Accurate monitoring data on species presence and distribution are crucial for effective conservation management. Environmental DNA (eDNA)-based techniques, in which species are detected from trace amounts of DNA found throughout the environment, are promising tools that may complement traditional monitoring methods and improve detection. However, imperfect detection is a feature of all survey methods that should be properly assessed so that the probability of detecting a target species’ DNA at a site where it is present (i.e. the sensitivity of the method) can be determined. The spot-tailed quoll (Dasyurus maculatus), a carnivorous marsupial found in eastern Australia, is a difficult species to detect as it is rare and has large home ranges, often in remote and difficult to access habitat.

In this study, we aimed to evaluate the feasibility of using eDNA soil analysis as a viable alternative or complement to traditional monitoring techniques for detecting spot-tailed quoll.

We developed a species-specific assay and validated it using synthetic oligos, tissue samples and soil collected from a captive quoll enclosure. We then assessed the assay on natural environment soil samples taken from the Snowy River region from communal quoll defecation sites (latrines) and from broader quoll habitat. We used amplification success data to model the concentration of quoll DNA in soil from different site types and calculate the sensitivity of our assay.

Sensitivity was highest at latrine sites, but decreased sharply when sampling just 1 m away. In non-latrine habitat, the positive amplification rate was too low to allow for meaningful statistical analyses, suggesting that a prohibitively large number of samples would need to be analysed for detection probabilities to be adequate for routine monitoring programs.

Overall, we found that low sensitivity was driven by the low concentration of spot-tailed quoll DNA at many of the surveyed sites.

Given that quoll latrines can usually be identified from the accumulation of scats, and scats themselves can be sampled for DNA, we suggest that eDNA analysis of soil is unlikely to offer improvements over current spot-tailed quoll monitoring methods.

The deleterious impacts of cat predation on wildlife have been well documented. Additionally, unowned cats may act as reservoirs of disease important to public and companion animal health and their proclivity for roaming and fighting enables effective disease transmission. Urban environments support the highest human populations and companion animal densities, increasing the potential for disease transmission from unowned cats to people and pets. However, there is little data on the prevalence of pathogens in unowned cat populations.

This aim of this research was to establish baseline prevalence data for priority pathogens in an urban population of unowned cats.

One hundred unowned cat cadavers were collected from the Brisbane City Council region, Queensland, Australia. Blood and additional organ or tissue samples were collected post-mortem. Diagnostic methods for pathogen detection included use of real-time polymerase-chain reaction, commercially available rapid enzyme-linked-immunosorbent assay, lavage and faecal flotation.

Pathogen carriage was found in 79% (95% CI 71, 87%) of sampled cats. In total, 62% (95% CI 52, 72%) of cats showed evidence of co-carriage of two or more pathogenic organisms. The overall prevalence found for pathogens and parasites investigated were: Toxoplasma gondii, 7% (95% CI 2, 12%); Coxiella burnetii, 0.0% (95% CI 0, 0%); feline immunodeficiency virus, 12% (95% CI 6, 18%); feline leukaemia virus, 0.0% (95% CI 0, 0%); and gastrointestinal parasites, 76.8% (95% CI 68, 85%).

This study reports contemporary prevalence data for these pathogens that have not previously been available for unowned cats of south-east Queensland. High rates of gastrointestinal parasitism observed throughout the study population prompt concerns of a general increase in pathogenic prevalence, especially in comparison with that of owned domestic cats, as per previously published literature. The presence of signs of fighting is an important risk factor for increased likelihood of infection.

Data produced from this study contribute to informing cat management efforts throughout urban regions. Continued and expanded investigations, considering prevalence and risk factors of pathogens important to human and companion animal health, are recommended for the south-east Queensland area and beyond.

Mule deer (Odocoileus hemionus) are a species of social, economic and cultural importance that are experiencing a population decline throughout much of their range. Factors such as disease, landscape-level changes in nutritional output of forage species, winter habitat degradation, habitat fragmentation, competition for resources with both domestic and wild ungulates, and predation have all been implicated in the decline. Recently, summer habitat quality in Oregon has been identified as a potentially strong limiting factor for mule deer population performance. Competition and habitat degradation from feral horses (Equus caballus) have been proposed as factors potentially exacerbating existing habitat limitations for mule deer.

The aim of this study was to investigate factors affecting mule deer summer range occupancy within a study area that experienced both wildfires and the presence of feral horses.

We deployed 72, 77 and 75 camera traps throughout the Murderers Creek and Northside wildlife management units located in north-eastern Oregon during summer 2019, 2020 and 2021 respectively. We used an occupancy modelling framework to build and evaluate models of mule deer summer range occupancy related to competition, vegetation and abiotic variables.

Our final model set included four covariates: (1) an index of feral horse use; (2) whether the site was disturbed by wildfire; (3) distance to forest edge; and (4) eastness of the site. Model averaging indicated that mule deer probability of occupancy was negatively related with increased feral horse use and distance to forest edge, and positively related to eastern slopes and sites within a wildfire perimeter.

Our results add to the growing body of literature indicating that wildfires in forested ecosystems benefit mule deer and add to the limited body of literature indicating that feral horse use of a site negatively impacts mule deer.

Managers should incorporate fire into forest restoration projects when possible to benefit mule deer. Where feral horses and mule deer overlap, increased management of feral horse herds could potentially benefit mule deer. Lastly, our research showcases the utility of camera traps coupled with occupancy modelling to answer research questions that, in the past, were mainly answered through radio collaring.

The distribution of the threatened greater bilby (Macrotis lagotis) has significantly contracted since the introduction of feral cats and foxes. To counteract these threats, bilbies have been reintroduced to multiple feral predator exclosures and offshore islands across Australia.

The aims of this study were to monitor the reintroduction of bilbies to the feral predator exclosure at Currawinya National Park and assess three hypotheses: (1) captive-born founders would establish stable home ranges and utilise habitats similar to those of wild-born bilbies in the exclosure; (2) founders would maintain adequate body condition and weight, enabling the survival of >50% of founders at 12 months post-release; and (3) the population would rapidly increase in the absence of feral predators, due to the high reproductive potential of bilbies.

We used VHF/GPS telemetry to compare home range size and habitat use of 12 founders and 11 wild-born bilbies. Founders were monitored intensively to assess reproductive success, weight, body condition and survival. Pouch activity was monitored to examine reproductive output. Spatially explicit capture–recapture modelling was used to estimate population density/size.

The population rapidly increased to >450 bilbies after 3 years, and founder survivorship was high (70% at 12 months post-release). Male founder home ranges (248.46 ha ± 97.22) were comparable in size to wild-born males (216.74 ha ± 54.19), but female founder home ranges (51.23 ha ± 12.22) were significantly larger than wild-born females (20.80 ha ± 2.94) (P = 0.04). The doubling of the population between 2021 and 2022 may have resulted in the contraction of female home ranges. Reproductive output decreased significantly in 2022, indicating that reproduction may be density-dependent at high densities. There was a significant relationship between track counts and population estimates, indicating that track counts are a reliable method for estimating population size inside the exclosure.

This reintroduction has been highly successful to date, demonstrating that bilbies are an adaptable species capable of rapid population growth in the absence of feral predators.

Bilbies are a model species for reintroductions to feral predator exclosures due to high survival rates, reproductive output, dietary flexibility and the ability to utilise a broad range of environments.

Increased populations of wild boar (Sus scrofa) in many ecosystems have raised concern regarding the impacts of this species on ecosystems and biodiversity. The relationship between other wildlife and wild boars is not yet fully understood, due to a lack of studies on whether and how other wildlife avoid wild boar interference.

This study aimed to investigate the impact of wild boars on the temporal resource utilisation of silver pheasants (Lophura nycthemera).

Eighteen infrared camera stations were deployed during the survey period of May 2020 to April 2022. We utilised avoidance–attraction ratios for evaluating the temporal interaction between silver pheasants and wild boars. We also used a kernel density for measuring their daily activity patterns and interspecific overlap. We simultaneously analysed the impact of human activities on silver pheasants as the reference basis for evaluating the degree of interference by wild boars.

The total survey effort was 1620 camera days, resulting in a total of 3451 independent detections. The silver pheasants showcased avoidance of both wild boars and human activities (avoidance–attraction ratios were both significantly greater than 1; P < 0.05). The highest degree of temporal overlap was observed between silver pheasants and human activities (Δ = 0.711), followed by wild boars (Δ = 0.615). They both depicted a significant difference in temporal ecological niche differentiation (P < 0.05).

Our results indicated that wild boars had a significant impact on the temporal resource utilisation of silver pheasants. The presence of wild boars significantly prolonged the recurrent reappearance time of silver pheasants in the same location. To avoid potential interference from wild boars, silver pheasants maximised activity frequencies during low activity periods of wild boars.

This study provides useful information for understanding the relationship between wild boars and other wildlife that inhabited the same areas. Future research will need to investigate both individual and combined impacts of wild boars and human activities on other wildlife.

Elevated mesopredator populations can pose a threat to species of conservation concern.

We sought to evaluate the effectiveness of raccoon removal on their abundance and on Blanding’s turtle nest success.

We used an index of raccoon abundance generated from camera-trap data and information on the success of Blanding’s turtle nests to compare adjacent control and raccoon-removal sites.

Raccoon detections were more frequent and abundance index values were higher at control sites than at the removal site. However, Blanding’s turtle nest success did not differ between control and removal sites, likely because of differences in nest location and camera proximity.

The efficacy of raccoon removal for Blanding’s turtle conservation may vary with nest habitat characteristics and can benefit from a priori knowledge of nesting areas.

Mesopredator removal can be beneficial to species of conservation concern, provided it occurs in areas of greatest impact.

Fire has played an integral role in regulating patterns of biodiversity for millions of years. However, anthropogenic disturbance and climate change has altered fire activity – driving increases in both fire severity and scale. The effect fire now has on the persistence of biodiversity is poorly known, especially for frogs. Studies examining frog responses to fire usually have small sample sizes, focus upon small geographic areas and are based on low-severity fires, which can mean results are not applicable to high-severity fires, such as those expected under future climate change.

Our aims were to examine (1) persistence of frog species, measured by species richness, up to 18 months post-fire, and (2) the effects of varying fire severity on frog species richness and recovery, where we expected higher fire severity to lead to lower species richness after fire.

Using large-scale citizen science data from the Australian Museum’s FrogID project, coupled with remotely sensed fire data, we present a spatially and taxonomically broad analysis examining post-fire recovery responses for Australian frog species after the 2019/2020 ‘Black Summer’ bushfires.

We reveal no overall decrease in the species richness of Australian frogs both in the short- and long-term post-fire. Furthermore, species richness did not decline with increasing fire severity. Instead, species richness and its response to fire was highly site-specific.

We provide evidence that widespread and common Australian frog species have persisted post-fire in most sites and concluded that this is potentially due to their ability to shelter from fire adequately and/or La Niña-driven high rainfall offering conditions conducive to breeding activity and persistence.

We show how citizen science provides critical data for conservation, especially in response to unprecedented disturbance events, such as the 2019/2020 megafires. Our research also highlights the need for ongoing and targeted scientific monitoring, especially for less common or threatened species.