Vertebrate Pest Research Unit

Orange, Australia

Vertebrate Pest Research Unit

Orange, Australia

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Sparkes J.,University of New England of Australia | Sparkes J.,Vertebrate Pest Research Unit | Sparkes J.,Invasive Animals Cooperative Research Center | Ballard G.,University of New England of Australia | And 9 more authors.
Oecologia | Year: 2016

Dogs (Canis familiaris) can transmit pathogens to other domestic animals, humans and wildlife. Both domestic and wild-living dogs are ubiquitous within mainland Australian landscapes, but their interactions are mostly unquantified. Consequently, the probability of pathogen transfer among wild-living and domestic dogs is unknown. To address this knowledge deficit, we established 65 camera trap stations, deployed for 26,151 camera trap nights, to quantify domestic and wild-living dog activity during 2 years across eight sites in north-east New South Wales, Australia. Wild-living dogs were detected on camera traps at all sites, and domestic dogs recorded at all but one. No contacts between domestic and wild-living dogs were recorded, and limited temporal overlap in activity was observed (32 %); domestic dogs were predominantly active during the day and wild-living dogs mainly during the night. Contact rates between wild-living and between domestic dogs, respectively, varied between sites and over time (range 0.003–0.56 contacts per camera trap night). Contact among wild-living dogs occurred mainly within social groupings, and peaked when young were present. However, pup emergence occurred throughout the year within and between sites and consequently, no overall annual cycle in contact rates could be established. Due to infrequent interactions between domestic and wild-living dogs, there are likely limited opportunities for pathogen transmission that require direct contact. In contrast, extensive spatial overlap of wild and domestic dogs could facilitate the spread of pathogens that do not require direct contact, some of which may be important zoonoses. © 2016 Springer-Verlag Berlin Heidelberg


Sparkes J.,University of New England of Australia | Sparkes J.,Vertebrate Pest Research Unit | Sparkes J.,Invasive Animals Cooperative Research Center | McLeod S.,Vertebrate Pest Research Unit | And 10 more authors.
Preventive Veterinary Medicine | Year: 2016

Currently, Australia is free from terrestrial rabies but an incursion from nearby Indonesia, where the virus is endemic, is a feasible threat. Here, we aimed to determine whether the response to a simulated rabies incursion would vary between three extant Australian dog populations; free-roaming domestic dogs from a remote indigenous community in northern Australia, and free-roaming domestic and wild dogs in peri-urban areas of north-east New South Wales. We further sought to predict how different management strategies impacted disease dynamics in these populations. We used simple stochastic state-transition models and dog demographic and contact rate data from the three dog populations to simulate rabies spread, and used global and local sensitivity analyses to determine effects of model parameters. To identify the most effective control options, dog removal and vaccination strategies were also simulated. Responses to simulated rabies incursions varied between the dog populations. Free-roaming domestic dogs from north-east New South Wales exhibited the lowest risk for rabies maintenance and spread. Due to low containment and high contact rates, rabies progressed rapidly through free-roaming dogs from the remote indigenous community in northern Australia. In contrast, rabies remained at relatively low levels within the north-east New South Wales wild dog population for over a year prior to an epidemic. Across all scenarios, sensitivity analyses revealed that contact rates and the probability of transmission were the most important drivers of the number of infectious individuals within a population. The number of infectious individuals was less sensitive to birth and death rates. Removal of dogs as a control strategy was not effective for any population modelled, while vaccination rates in excess of 70% of the population resulted in significant reductions in disease progression. The variability in response between these distinct dog groups to a rabies incursion, suggests that a blanket approach to management would not be effective or feasible to control rabies in Australia. Control strategies that take into account the different population and behavioural characteristics of these dog groups will maximise the likelihood of effective and efficient rabies control in Australia. © 2016


Sparkes J.,University of New England of Australia | Sparkes J.,Vertebrate Pest Research Unit | Sparkes J.,Invasive Animals Cooperative Research Center | Kortner G.,University of New England of Australia | And 9 more authors.
PLoS ONE | Year: 2014

Free-roaming dogs (Canis familiaris) are common worldwide, often maintaining diseases of domestic pets and wildlife. Management of these dogs is difficult and often involves capture, treatment, neutering and release. Information on the effects of sex and reproductive state on intraspecific contacts and disease transmission is currently lacking, but is vital to improving strategic management of their populations. We assessed the effects of sex and reproductive state on short-term activity patterns and contact rates of free-roaming dogs living in an Australian Indigenous community. Population, social group sizes and rates of contact were estimated from structured observations along walked transects. Simultaneously, GPS telemetry collars were used to track dogs' movements and to quantify the frequency of contacts between individual animals. We estimated that the community's dog population was 326±52, with only 9.8±2.5% confined to a house yard. Short-term activity ranges of dogs varied from 9.2 to 133.7 ha, with males ranging over significantly larger areas than females. Contacts between two or more dogs occurred frequently, with entire females and neutered males accumulating significantly more contacts than spayed females or entire males. This indicates that sex and reproductive status are potentially important to epidemiology, but the effect of these differential contact rates on disease transmission requires further investigation. The observed combination of unrestrained dogs and high contact rates suggest that contagious disease would likely spread rapidly through the population. Pro-active management of dog populations and targeted education programs could help reduce the risks associated with disease spread. © 2014 Sparkes et al.


Sparkes J.,University of New England of Australia | Fleming P.J.S.,University of New England of Australia | Fleming P.J.S.,Vertebrate Pest Research Unit | Ballard G.,University of New England of Australia | And 4 more authors.
Zoonoses and Public Health | Year: 2015

Summary: Australia is unique as a populated continent in that canine rabies is exotic, with only one likely incursion in 1867. This is despite the presence of a widespread free-ranging dog population, which includes the naturalized dingo, feral domestic dogs and dingo-dog cross-breeds. To Australia's immediate north, rabies has recently spread within the Indonesian archipelago, with outbreaks occurring in historically free islands to the east including Bali, Flores, Ambon and the Tanimbar Islands. Australia depends on strict quarantine protocols to prevent importation of a rabid animal, but the risk of illegal animal movements by fishing and recreational vessels circumventing quarantine remains. Predicting where rabies will enter Australia is important, but understanding dog population dynamics and interactions, including contact rates in and around human populations, is essential for rabies preparedness. The interactions among and between Australia's large populations of wild, free-roaming and restrained domestic dogs require quantification for rabies incursions to be detected and controlled. The imminent risk of rabies breaching Australian borders makes the development of disease spread models that will assist in the deployment of cost-effective surveillance, improve preventive strategies and guide disease management protocols vitally important. Here, we critically review Australia's preparedness for rabies, discuss prevailing assumptions and models, identify knowledge deficits in free-roaming dog ecology relating to rabies maintenance and speculate on the likely consequences of endemic rabies for Australia. © 2014 Blackwell Verlag GmbH.


Sparkes J.,University of New England of Australia | Sparkes J.,Vertebrate Pest Research Unit | Sparkes J.,Invasive Animals Cooperative Research Center | Ballard G.,University of New England of Australia | And 5 more authors.
Wildlife Research | Year: 2016

Context Dogs aid hunters in many parts of Australia. Because of close proximity, transfer of zoonotic disease between hunters, hunting dogs and wildlife can, and does, occur. Knowledge about cooperative hunting between humans and domestic dogs and interactions with wildlife in Australia is limited, but is necessary to improve zoonotic-risk mitigation strategies. Aims We aimed to describe the frequency and geographic distribution of hunting with dogs, and to document interactions between them and wildlife that could contribute to zoonosis transmission. Methods Australian hunters were invited via web-based hunting forums, hunting supply stores and government agency communications to complete an online questionnaire about their hunting activities. Key results Most of the 440 responding hunters resided on Australia's eastern coast. Pest animal management and recreation were their primary drivers for hunting with dogs. Most hunters used one or two dogs, and travelled ≥500km to target feral pigs, rabbits, birds and deer. Almost a quarter of respondents (N≤313) had lost a dog while hunting, but most (93%, N≤61) were reportedly recovered within a few hours. Half the respondents indicated that they had encountered wild dogs while hunting, and reported a range of consequences from non-contact interactions through to attacks on the hunting dog or hunter. Conclusions Australian hunters frequently used dogs to assist in hunts of birds and introduced mammals, particularly where access was difficult because of rough terrain or thick vegetation. Interactions between hunters and non-target animals such as wild dogs were common, providing potential pathways for the spread of diseases. Furthermore, hunting expeditions >500km from the point of residence occurred regularly, which could facilitate translocation of important zoonotic diseases between states and the creation of disparate foci of disease spread, even into highly populated areas. Implications Our improved understanding of hunting-dog use in Australia is essential to quantify the risk of disease transmission between wildlife and humans, identify transmission pathways and devise management plans to quash disease outbreaks. To promote rapid detection of exotic diseases, hunters should be encouraged to report unusual wildlife behaviour and interactions with their dogs. © The authors 2016.


PubMed | University of New England of Australia and Vertebrate Pest Research Unit
Type: | Journal: Preventive veterinary medicine | Year: 2016

Currently, Australia is free from terrestrial rabies but an incursion from nearby Indonesia, where the virus is endemic, is a feasible threat. Here, we aimed to determine whether the response to a simulated rabies incursion would vary between three extant Australian dog populations; free-roaming domestic dogs from a remote indigenous community in northern Australia, and free-roaming domestic and wild dogs in peri-urban areas of north-east New South Wales. We further sought to predict how different management strategies impacted disease dynamics in these populations. We used simple stochastic state-transition models and dog demographic and contact rate data from the three dog populations to simulate rabies spread, and used global and local sensitivity analyses to determine effects of model parameters. To identify the most effective control options, dog removal and vaccination strategies were also simulated. Responses to simulated rabies incursions varied between the dog populations. Free-roaming domestic dogs from north-east New South Wales exhibited the lowest risk for rabies maintenance and spread. Due to low containment and high contact rates, rabies progressed rapidly through free-roaming dogs from the remote indigenous community in northern Australia. In contrast, rabies remained at relatively low levels within the north-east New South Wales wild dog population for over a year prior to an epidemic. Across all scenarios, sensitivity analyses revealed that contact rates and the probability of transmission were the most important drivers of the number of infectious individuals within a population. The number of infectious individuals was less sensitive to birth and death rates. Removal of dogs as a control strategy was not effective for any population modelled, while vaccination rates in excess of 70% of the population resulted in significant reductions in disease progression. The variability in response between these distinct dog groups to a rabies incursion, suggests that a blanket approach to management would not be effective or feasible to control rabies in Australia. Control strategies that take into account the different population and behavioural characteristics of these dog groups will maximise the likelihood of effective and efficient rabies control in Australia.


McClelland K.L.,Conservation Policy Unit | Fleming P.J.S.,Vertebrate Pest Research Unit | Malcolm P.J.,Industry and Investment NSW
Australian Zoologist | Year: 2011

The Grey-headed Flying-fox, Pteropus poliocephalus, is listed as a threatened species in NSW, Victoria and nationally. The Grey-headed Flying-fox is a key species in maintaining forest ecosystems through the pollination of native trees and the dispersal of rainforest seeds. This threatened species is unique in that it is also recognised as a horticultural pest, predominantly in coastal orchards of south-eastern Australia. In times of native resource (pollen, nectar and rainforest fruits) shortage, flying-foxes are known to utilise commercial fruit crops. As such, the species is affected by control techniques employed by horticulturists to mitigate flying-fox damage, including shooting and netting. The NSW Department of Environment and Climate Change and the NSW Department of Primary Industries are working collaboratively to investigate flying-fox damage to commercial crops, quantify the levels of flying-fox damage (temporally and spatially), determine the factors contributing to trends in crop damage, and assess the effectiveness of mitigative measures employed by horticulturists to reduce flying-fox damage.The project is funded for two financial years through the Australian Government's Natural Heritage Trust Strategic Reserve funding and State Government contributions (cash and in-kind), and addresses several recovery actions of the draft National Recovery Plan for the Grey-headed Flying-fox. The project proposal was also strongly supported by the NSW Flying-fox Consultative Committee. The project commenced in October 2006 and focuses on commercial crops in the western Sydney Basin. To date (May 2007), preliminary evaluations have been conducted, including total yield loss, damaged fruit (including that specifically attributable to flying-foxes and birds), flyingfox crop visitation indices and crop architecture.These parameters will be compared throughout the fruit season across different stone fruit and apple crop types and between netted and unnetted crops to examine spatial and temporal trends. The process of establishing and implementing the collaborative project is discussed, within the framework of flying-fox conservation and management in NSW.


PubMed | Vertebrate Pest Research Unit
Type: Journal Article | Journal: The Journal of animal ecology | Year: 2015

Instrinsic variation in the availability of food to animal populations reflects the influence of foraging by the animals themselves. Instrinsic variation in food availability provides a link between population density, subsequent food availability and variation in the rate of population increase (r), operating through density-dependent food shortage. In contrast, extrinsic variation in food availability is caused by environmental influences on food or animal abundance, which are independent of animal foraging. Extrinsic variation in food availability is random relative to that arising through intrinsic shortage. Intrinsic and extrinsic variation in food availability can influence animal populations simultaneously. Intrinsic variation will impart a tendency towards an equilibrium between animal and food abundance. which will be progressively obscured by density-independent variation as the influence of extrinsic factors increases. This study used a large-scale field experiment, in which the density of food-limited feral pig (Sus Scrofa L.) populations was manipulated on six sites, to assess the relative influence of intrinsic and extrinsic variation in food availability. The experiment evaluated the influence of pig population density on r and the abundance of food resources measured as pasture biomass. It was predicted that if intrinsic shortages dominated variation in food availability, pasture biomass and r would decline with increasing pig density. If extrinsic factors dominated variation in food availability, pig density would have no systematic effect on either pasture biomass or r. If intrinsic and extrinsic sources simultaneously affected variation in food availability, higher pig densities would have no systematic effect on r, but would reduce pasture biomass. The simultaneous model predicts reduced pasture biomass because, in the absence of compensatory changes in other sources of variation, the effects of intrinsic and extrinsic factors will be additive. To examine further the degree of interdependence in pig and pasture abundance, a series of stochastic models of the grazing system were estimate and the feedback loop comprising the functional and numerical responses of feral pigs to variation in pasture biomass was manipulated. In the large-scale experiment, neither pasture biomass nor r declined with increasing pig density, suggesting that food availability was dominated by extrinsic factors. However, limitations of the experiment meant that a minor decline in pasture biomass may have gone undetected. Comparison of simulation models, which included and omitted pasture offtake by pigs, indicated that because they were less efficient grazers and persisted at lower average densities relative to other large herbivores, pigs had little influence on variation in pasture biomass.

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