Jordan O. Hampton

Illegal translocation and genetic structure of feral pigs in Western Australia

Abstract Unlike many regions in the world where wild pigs (Sus scrofa) are threatened, in Australia they are a significant invasive species. As such, the molecular ecology of feral pigs was investigated to understand their social and population genetic structure. Samples from 269 adult animals were collected over their distribution in southwestern Australia. Using 14 highly polymorphic microsatellite markers, we identified 7 inferred feral pig populations that had moderate heterozygosity (mean = 0.580) and displayed a high level of differentiation (mean RST = 0.180). In revealing the genetic structure of feral pigs, we detected anomalies in the putative origin of some individuals. Samples from these animals were collected from 2 main areas: recently colonized regions that were previously uninfested, and established feral pig populations, where animals from geographically isolated areas had been introduced. In the latter, these corresponded to areas that were in close proximity to public road access and towns. Given the large distances immigrants were found from their population of origin (from 50 to > 400 km), the generally low levels of dispersal of southwest feral pigs, and the grouping and sex of these pigs, we suggest that these individuals have been deliberately and illegally translocated to supplement recreational hunting stocks. Additionally, we could not detect any genetic contribution in these feral pigs from domestic pig herds, suggesting that the deliberate release of domestic pigs to restock feral populations is relatively uncommon. Our molecular data allowed some inferences regarding the success or lack thereof of current management practices, and offered considerable insights into the dynamics of the feral pig populations and identification of “new” approaches that may allow for better control of this highly destructive species.

The sociogenetic structure of a controlled feral pig population

In Australia, the feral pig (Sus scrofa) is a significant vertebrate pest that has an impact on agricultural production, public health and ecosystem integrity. Although feral pigs are controlled throughout much of their range, little is known about the impact that these control programs have had on the social biology, structure and the dispersal of pigs. To begin to address this, we collected demographic data and genetic samples from 123 feral pigs culled during a regional aerial shooting program over 33 pastoral properties in the semi-arid rangelands of southern Queensland, Australia. Sampling was carried out after two years of extensive control efforts (aerial 1080-baiting) and the samples therefore represented a controlled, persecuted population with a bias towards young animals. The analysis of 13 microsatellite loci suggested that females will accept multiple matings, females form loose mobs that appear to be highly dynamic social groups, and males will travel large distances between mobs. These data indicate that feral pigs in this population had a high level of social contact and form a single open population with no evidence of genetic (population) structuring. Such information may be important to integrate into management strategies, particularly the development of contingency plans regarding the spread of wildlife diseases.

A preliminary genetic study of the social biology of feral pigs in south-western Australia and the implications for management

A combination of demographic and genetic data was collected from 354 feral pigs (Sus scrofa), caught using standard trapping methods in south-western Australia, to provide preliminary information on their social biology. This included attempts to identify the putative parentage of 172 juvenile and foetal pigs, characterisation of the genetic mating system observed, and examination of the demographics of those individuals captured by current trapping methods. Findings revealed that in south-western Australia (a) feral pigs displayed moderately polygynous, but not polyandrous, mating behaviour, (b) breeding boars were significantly heavier than non-breeding boars, (c) the most reproductively successful boars, large individuals weighing >90 kg, moved the furthest in order to secure paternity, and (d) that a large proportion of breeding adults, particularly boars, were not captured under the standard trapping method employed. Ultimately, these data may be useful for the improvement of existing control programs, and exotic disease preparedness strategies.

Prevalence of Zoonotic Pathogens from Feral Pigs in Major Public Drinking Water Catchments in Western Australia

Australia has the largest number of wild pigs in the world. Their pronounced impacts on agriculture and biodiversity make the estimated 23 million feral pigs one of Australia’s most important vertebrate pest species. The foraging and wallowing behavior of pigs can markedly increase the turbidity of water supplies, but more importantly, they can transmit and excrete a number of infectious waterborne organisms pathogenic to humans. Their persistence in drinking water catchments also makes them potentially significant reservoirs for zoonotic pathogens. In this study, important protozoan parasite pathogens, such as Giardia, Cryptosporidium, Balantidium, and Entamoeba, were detected from the feces of feral pigs caught in metropolitan drinking water catchment areas. All are potentially important waterborne human pathogens that pose a major threat to drinking water quality. Fortunately, the overall prevalence in feral pigs appears to be relatively low, with ≤13% of pigs detected with parasites. In this study, we combined the findings from the parasitological analysis with the use of 14 highly informative DNA markers to define a series of highly structured populations that indicated very little movement of feral pigs between the populations. The implication of this pattern is that any public health risk may spread very slowly between populations, but may be much higher within watercourses. This study represents an innovative and important new approach to drinking water source protection in Australia.

Measuring the Demographic and Genetic Effects of Pest Control in a Highly Persecuted Feral Pig Population

Abstract Substantial efforts have been made to identify the most effective practices for the control and management of invasive vertebrate pest species, such as the feral pig (Sus scrofa). We investigated the demographics, abundance, and molecular ecology of a persecuted feral pig population that was subjected to control. We then applied methodologies to determine if we could retrospectively quantify any changes in the population structure or dynamics of these pigs. Feral pig demographic and abundance parameters indicated that in this population of feral pigs, there were very few detectable changes between the two aerial culling years. We observed this despite environmental conditions being optimal for control. Genetic results indicated that pigs culled in the latter 2004 cull were genetically identical to those pigs that inhabited the area a year earlier. The genetic population was geographically larger than the sample area. These findings indicate that the recovery in feral pig density witnessed in the controlled area was not a result of reinvasion from a separate, genetically distinct population, but rather, it was the result of reinvasion from feral pigs outside the study area but within the same genetic population. Importantly, we were unable to detect any recent genetic bottlenecks. This approach has considerable potential for auditing the effectiveness of control programs of pest species and assessing the feasibility of impacting upon or locally eradicating many other free-ranging pest species.

Integrating animal welfare into wild herbivore management: lessons from the Australian Feral Camel Management Project

The Australian Feral Camel Management Project (AFCMP) was initiated in 2009 to manage the growing impacts of feral camels (Camelus dromedarius) in Australia. One of the most important considerations for the project was achieving high standards of animal welfare and demonstrating this to stakeholders and the public. The novelty of feral camels as an invasive species meant that relatively little was known about the animal welfare aspects of the available management techniques. To address this knowledge gap, quantitative animal-based assessment tools were developed to allow independent observers to perform repeatable in situ field auditing of the two main control methods used: aerial (helicopter) shooting and live capture (mustering and transport for slaughter). Although observation protocols allowed most stages of aerial shooting (in situ killing) to be assessed, not all stages of live capture operations could be assessed (namely transport and slaughter at ex situ abattoirs) due to the limitations of the jurisdiction of the Australian Feral Camel Management Project. For assessments that were performed, audit results were made available to project partners to allow procedures to be reviewed and published through peer-reviewed literature to improve transparency. Empirical evidence produced through the audit system was also used to refine humaneness ranking assessments comparing management methods. We present the lessons learnt through the animal welfare approach of the AFCMP to assist future wild herbivore management programs.

Quantitative analysis of animal-welfare outcomes in helicopter shooting: a case study with feral dromedary camels (Camelus dromedarius)

Abstract Context. Helicopter shooting is a common and effective tool for reducing overabundant wildlife populations. However, there is little quantitative information on the humaneness of the method, leading to uncertainty in wildlife-management policy. There is, subsequently, a need for an improved understanding of the welfare implications of helicopter shooting. Aim. A study was undertaken to infer the humaneness of helicopter shooting for a case study species, the feral dromedary camel (Camelus dromedarius). Methods. Seven post-mortem studies (n = 715) and one ante-mortem study (n = 192) were undertaken during routine helicopter shooting programs of free-ranging camels. In these studies, we measured four animal-welfare parameters to allow inference on the humaneness of the technique. These parameters were time to death, instantaneous death rate (proportion of animals for which time to death = 0), wounding rate and location of bullet-wound tract. We also modelled these welfare variables against hypothesised explanatory variables to assist improvement of future programs. Key results. The mean wounding rate was 0.4%, and the killing efficacy of the technique was 99.6%. Mean time to death was 4 s, and mean instantaneous death rate was 83%. Each animal displayed a mean 2.4 bullet-wound tracts, with 75%, 63% and 35% of animals shot at least once in the thorax, cranium and cervical spine, respectively. Regression analysis revealed that the identity of the shooter and the nature of the local vegetation were the most important factors associated with an animal experiencing an inferred instantaneous death or not. Conclusions. Helicopter shooting of feral camels produces a very low wounding rate and rapid time to death. Shooter identity is the most important consideration for determining animal-welfare outcomes. Improvements to the humaneness of programs can be made by increasing the rigour of shooter selection and training. Implications. Wildlife killing methods must be demonstrated to be humane to receive public support; however, few shooting methods are objectively examined. Helicopter shooting can be independently examined and operators assessed. Adoption of this examination template may allow continual improvement by industry as well as increasing societal acceptance of helicopter shooting.

How Does a Carnivore Guild Utilise a Substantial but Unpredictable Anthropogenic Food Source? Scavenging on Hunter-Shot Ungulate Carcasses by Wild Dogs/Dingoes, Red Foxes and Feral Cats in South-Eastern Australia Revealed by Camera Traps

There is much interest in understanding how anthropogenic food resources subsidise carnivore populations. Carcasses of hunter-shot ungulates are a potentially substantial food source for mammalian carnivores. The sambar deer (Rusa unicolor) is a large (≥150 kg) exotic ungulate that can be hunted throughout the year in south-eastern Australia, and hunters are not required to remove or bury carcasses. We investigated how wild dogs/dingoes and their hybrids (Canis lupus familiaris/dingo), red foxes (Vulpes vulpes) and feral cats (Felis catus) utilised sambar deer carcasses during the peak hunting seasons (i.e. winter and spring). We placed carcasses at 1-km intervals along each of six transects that extended 4-km into forest from farm boundaries. Visits to carcasses were monitored using camera traps, and the rate of change in edible biomass estimated at ∼14-day intervals. Wild dogs and foxes fed on 70% and 60% of 30 carcasses, respectively, but feral cats seldom (10%) fed on carcasses. Spatial and temporal patterns of visits to carcasses were consistent with the hypothesis that foxes avoid wild dogs. Wild dog activity peaked at carcasses 2 and 3 km from farms, a likely legacy of wild dog control, whereas fox activity peaked at carcasses 0 and 4 km from farms. Wild dog activity peaked at dawn and dusk, whereas nearly all fox activity occurred after dusk and before dawn. Neither wild dogs nor foxes remained at carcasses for long periods and the amount of feeding activity by either species was a less important predictor of the loss of edible biomass than season. Reasons for the low impacts of wild dogs and foxes on sambar deer carcass biomass include the spatially and temporally unpredictable distribution of carcasses in the landscape, the rapid rate of edible biomass decomposition in warm periods, low wild dog densities and the availability of alternative food resources.

A systematic review of the impacts and management of introduced deer (family Cervidae) in Australia

Abstract. Deer are among the world’s most successful invasive mammals and can have substantial deleterious impacts on natural and agricultural ecosystems. Six species have established wild populations in Australia, and the distributions and abundances of some species are increasing. Approaches to managing wild deer in Australia are diverse and complex, with some populations managed as ‘game’ and others as ‘pests’. Implementation of cost-effective management strategies that account for this complexity is hindered by a lack of knowledge of the nature, extent and severity of deer impacts. To clarify the knowledge base and identify research needs, we conducted a systematic review of the impacts and management of wild deer in Australia. Most wild deer are in south-eastern Australia, but bioclimatic analysis suggested that four species are well suited to the tropical and subtropical climates of northern Australia. Deer could potentially occupy most of the continent, including parts of the arid interior. The most significant impacts are likely to occur through direct effects of herbivory, with potentially cascading indirect effects on fauna and ecosystem processes. However, evidence of impacts in Australia is largely observational, and few studies have experimentally partitioned the impacts of deer from those of sympatric native and other introduced herbivores. Furthermore, there has been little rigorous testing of the efficacy of deer management in Australia, and our understanding of the deer ecology required to guide deer management is limited. We identified the following six priority research areas: (i) identifying long-term changes in plant communities caused by deer; (ii) understanding interactions with other fauna; (iii) measuring impacts on water quality; (iv) assessing economic impacts on agriculture (including as disease vectors); (v) evaluating efficacy of management for mitigating deer impacts; and (vi) quantifying changes in distribution and abundance. Addressing these knowledge gaps will assist the development and prioritisation of cost-effective management strategies and help increase stakeholder support for managing the impacts of deer on Australian ecosystems.

FIELD IMMOBILIZATION OF FERAL ‘JUDAS’ DONKEYS (EQUUS ASINUS) BY REMOTE INJECTION OF MEDETOMIDINE AND KETAMINE AND ANTAGONISM WITH ATIPAMEZOLE

The Judas technique is a method used for landscape control of feral donkeys (Equus asinus) in northern Australia. Central to the success of any Judas program is the safe, efficient, and humane attachment of the telemetry device. For feral donkeys, this involves the use of field immobilization. We examine the replacement of the current chemical capture agent, succinylcholine, with contemporary immobilization agents to achieve positive animal welfare outcomes. A combination of medetomidine and ketamine delivered by remote injection from a helicopter was used to capture 14 free-ranging feral donkeys for the fitting of telemetry collars in Western Australia in November 2010. Dose rates of 0.14 mg/kg medetomidine and 4.1 mg/kg ketamine were appropriate to immobilize animals in 9 min (±SD=3). Mean recovery time (total time in recumbency) was 21 min (±14). All animals recovered uneventfully after being administered atipamezole, a specific antagonist of medetomidine, intramuscularly at 0.35 mg/kg. Physiologic parameters were recorded during recumbency, with environment-related hyperthermia being the only abnormality recognized. No significant complications were encountered, and this drug combination represents an efficient approach to capturing wild donkeys. This new method allows a rapid, safe, cost-effective approach to the immobilization of feral donkeys for use as Judas animals. This drug combination will replace the relatively inhumane succinylcholine for the field immobilization of feral donkeys.