Animal imagery has been part of the human effort to understand our place in the world since the beginning of recorded history. Through examining the role and use of animal imagery in the creation of cultural signals, I have developed a framework for my practice. Edgelands employs representations of feral animals as symbols for the “misfit” to emphasize the value of those who do not fit in. My experience as a woman in the field of metal work informs my material choice and process, subverting ironwork motifs and the purpose of gates and boundaries. Edgelands overlaps a series of material contradictions to begin the process of questioning the validity of commonly held delineations. The intersection of environmentalism, craft, and feminism is the space in which I interject the feral animal in an effort to reconcile aspects of my own experience as a misfit and learn about the world through making.

In this thesis I examine the population ecology of wild horses (Equus caballus) in the Australian Alps. Wild horses were first introduced into the Alps over 150 years ago. Paradoxically, they are a feral animal impacting on the environment, but are also a cultural icon. Managing wild horse populations is contentious and needs to be founded on knowledge of their population ecology. This is the first study of its kind in the Australian Alps and therefore has a broad focus. Four general areas were addressed: distribution, estimation of abundance and density, population dynamics and the influence of brumby-running. The study was conducted between 1999 and 2002 inclusive in the Australian Alps national parks, which form a contiguous protected area in south-eastern Australia from the Australian Capital Territory (ACT) in the north, through New South Wales (NSW) and into Victoria in the south. The current distribution of wild horses in the Australian Alps national parks is patchy. There are five major discrete populations in NSW and Victoria with the northern most population in Kosciuszko National Park (NSW) bordering on the ACT. A review of published material and oral history reveals historic influences on distribution. The presence of each population is associated with introductions by people. The distribution of some populations expanded after introductions and many have fluctuated over time. Distributions have been contained or reduced through control by people, natural events such as snow and drought and by geographical barriers. Park managers eliminated a population of wild horses in the ACT in the 1980s. Distributions have expanded in areas without active management (notably northern Kosciuszko National Park) and are likely to continue expanding under a policy of no management. In February and March 2001, abundance and density of wild horses were estimated by helicopter aerial survey in areas where the mapping showed horses to occur. This was the first time that these parameters have been estimated empirically. I compared three different aerial survey techniques (strip, mark-recapture and line transect) based on relative accuracy and precision and found that line transect analysis gave the highest, most precise estimate. Given that aerial surveys usually underestimate abundance, this method was also likely to be the most accurate. Mark-recapture over a 50m wide strip gave a similar result but lacked precision. Strip and mark-recapture techniques performed poorly over 200m strips because animals were missed. Numbers observed dropped off dramatically beyond the 50m strip. Line transect analysis (for both observers combined) gave an estimate of 5010 (+/- 1408SE) horses while mark recapture over 50 metres gave an estimate of 4915 (+/-2733SE). These estimates correspond to a density of 1.8 horses km-2 over the area surveyed (2789km2). The results suggest that aerial surveys of large mammals using a wide strip width (200m) and mark recapture analysis may seriously underestimate population density. The population dynamics and demography of wild horses were estimated at three sites, Big Boggy, Cowombat and Currango, every spring and autumn over 3 years. The sites were spread widely across the Alps with the aim of obtaining a broad understanding of population dynamics. The survey used Pollock�s robust design and natural markings were used to identify individuals. There was a seasonal spring peak in population size at Big Boggy with no clear seasonal trend at the other two sites. Mean wild horse densities determined at Big Boggy (2.01km-2) and Currango (2.13km-2) were not significantly (p<0.5) different to the density calculated in the aerial survey, whereas density was significantly higher at Cowombat (6.4 km-2). Census techniques were of limited use in estimating annual population growth rate because of low precision. Demographic analysis showed that none of the populations were increasing at the maximum intrinsic rate (l = 1.2), and the Big Boggy and Cowombat populations may be stable (l = 1.0/yr). There was an apparent trend of food limitation across the sites. Body condition was positively related (p<0.01) to pasture biomass. The Currango population was increasing (l = 0.09) associated with higher recruitment, body condition and pasture biomass than in the other two populations studied. The Cowombat population had the lowest annual finite rate of increase (l = 1.03), and horses at this site were in the poorest condition and pasture biomass was lowest. The Big Boggy population was intermediate between the two. Annual adult survival was constant in all populations at 0.91. Survival in the first three years of life was more variable with the average at each site ranging from 0.63/yr to 0.76/yr. An average of 0.26 female foals was born per adult female per year. Sensitivity analysis showed that population growth rate is most sensitive to changes in adult survival, followed by fecundity and then survival in the first three years of life. The dynamics observed at each site was representative of the demography of wild horses in other parts of the world and is typical for large mammalian herbivores. Brumby-running is a form of harvesting that is currently being used to control wild horses in the Alpine National Park (Victoria) and is soon to be trialled in Kosciuszko National Park (NSW). The effectiveness of brumby-running has not been assessed prior to this study. Data collected by the Alpine Brumby Management Association and predictive modelling were used to examine the influence of brumby-running on the wild horse population in Alpine National Park. Brumby-runners remove about 200 horses per year with a preference for young animals and adult females. More horses are caught in autumn (61/yr) and least in summer (30/yr) (p<0.05). Brumby-runners do not appear (p>0.05) to target horses in poor condition. One skilled brumby-runner caught an average of 1.16 horses/day, while his companions caught an average of 0.55 horses/day. Brumby-runners show behaviour analogous to social carnivores. Predictive modelling suggests that brumby-runners could suppress the population of wild horses in Alpine National Park similar to the effects of predators, or human harvesting of other large mammals. Selecting young animals in the harvest reduces the impact of harvesting on the population compared to unselective harvesting, while selecting adult females increases the predicted impact. There are several management recommendations based on the findings of this thesis that address concerns for both environmental impact and the cultural value of wild horses. The distribution of wild horses should not be allowed to expand further, and the size of the wild horse population should be prevented from increasing further. Other management recommendations that are more complex involve reducing some populations so that the level of environmental impact they are causing is acceptable. This requires a definition of �acceptable impact.� Finally managers should consider eradicating smaller populations.

This thesis is about making inference on the host status of feral ferrets in New Zealand for Mycobacterium bovis, the aetiological agent of bovine tuberculosis. The central question addressed is whether the rate of intra-specific transmission of M. bovis among ferrets is sufficient for the disease to persist in ferret populations in the absence of external, non-ferret sources of infection (inter-specific transmission). The question is tackled in three parts�firstly using model selection to identify suitable models for estimating the force of M. bovis infection in ferret populations; secondly applying statistical hypothesis testing to the results of planned manipulative field experiments to test the relationship between M. bovis infection in brushtail possums and that in ferrets; and thirdly using modelling to estimate intra-specific disease transmission rates and the basic reproductive rate (Ro) of M. bovis infection in ferrets. The model selection approach clearly identified the hypothesis of oral infection related to diet was, as modelled by a constant force of infection from the age of weaning, the best approximation of how M. bovis infection was transmitted to ferrets. No other form of transmission (e.g., during fighting, mating, or routine social interaction) was supported in comparison. The force of infection (λ) ranged from 0.14 yr-1 to 5.77 yr-1, and was significantly higher (2.2 times) in male than female ferrets. Statistical hypothesis testing revealed transmission of M. bovis to ferrets occurred from both brushtail possums and ferrets. The force of M. bovis infection in ferrets was reduced by 88% (λ=0.3 yr-1 vs. λ=2.5 yr-1) at sites with reductions in the population density of sympatric brushtail possum populations. A smaller decline in the force of infection resulting from the lethal cross-sectional sampling of the ferret populations was also demonstrated. The modelling approach estimated the basic reproductive rate (Ro) of M. bovis infection in ferrets in New Zealand to vary from 0.17 at the lowest population density (0.5 km-2) recorded to 1.6 at the highest population density (3.4 km-2) recorded. The estimates of Ro were moderately imprecise, with a coefficient of variation of 76%. Despite this imprecision, the Ro for M. bovis infection in ferrets was significantly less than unity for all North Island sites surveyed. Hence it is inferred ferrets are spillover hosts (0<Ro<1) for M. bovis infection in these environments. That is, M. bovis infection will progressively disappear from these ferret populations if the source of inter-specific transmission is eliminated. The estimates of Ro for M. bovis infection in South Island ferret populations were above one (the level required for disease establishment) for a number (5/10) of populations, though the imprecision made it impossible to ascertain whether Ro was significantly greater than one. The estimated threshold population density (Kt) for disease establishment was 2.9 ferrets km-2. It is inferred that, given sufficient population density (>Kt), the rate of intra-specific transmission of M. bovis among ferrets is sufficient for the disease to establish in ferrets in the absence of interspecific transmission. In these areas, ferrets would be considered maintenance hosts for the disease. Active management (e.g., density reduction or vaccination) of ferrets would be required to eradicate M. bovis from ferret populations in these areas, in addition to the elimination of sources of inter-specific transmission, particularly brushtail possums.

(1) Reliable measures of population abundance are essential for managing wildlife effectively. Aerial surveys provide a rapid and efficient means of surveying large mammals and many techniques have been developed to adjust for the inability to count all animals within transects. The probability of detection varies according to a range of factors which are important to consider when estimating density. Standardised survey methods developed in flat country are not readily transferable to steep terrain due to safety, access and difficulties delineating transect widths. Other methods have logistic constraints and must adhere to various other assumptions. (2) Density estimators are seldom examined using actual population size, hence their ability to correct for true bias is unknown. Studies that compare techniques are difficult to interpret because of the uncertainty of adherence to their respective assumptions. Factors influencing detection probability, estimators that correct for bias, the validity of their assumptions and how these relate to true density are important considerations for selecting suitable methods. The aim of this study was to obtain accurate and reliable methods for estimating the density of feral goats by improving predictions of detection probability, investigating the assumptions of aerial surveys, and examining the accuracy of 15 density estimators by comparing with total counts of feral goats. (3) Group size, vegetation and observer were the most important factors influencing the probability of observing a group of goats during aerial surveys. However, different approaches to analysing these data influenced the significance of variables and the predicted probabilities. Goat colour, type of helicopter, site and rear observer experience in hours were also found to be significant (P<0.05) when using likelihood equations based on all animals in the population rather than only those in the sample. The slope of the terrain was also shown to significantly (P=0.014) affect the probability of detection. (4) Indices are commonly used in wildlife management for their simplicity and practicality, but their validity has been questioned because of variable probability of detection. Results of this study suggest aerial survey indices are useful in monitoring a range of medium-sized mammal species across space and time if differences in detection probability between species, group size, vegetation and observer are considered and their effects are standardised. (5) An assumption of most sampling regimes that is fundamental but rarely examined is that animals are not counted more than once. In this study the behavioural responses of feral goats to helicopters were investigated as a basis for estimating the probability that goats were recounted. No long-term consequences were evident in feral goat behaviour of responses to helicopters. However, helicopter surveys were found to alter the structure of 42% of groups observed, with 28% of groups merging with others and 14% splitting into separate groups. Therefore, group size estimated from the air should not be considered as biologically important, and when estimating density, researchers should also avoid using group sizes determined from independent ground observations to correct group sizes determined from aerial surveys. Goats were also more likely to flush further when helicopters were within 150 m, which is close to or within standard helicopter strip widths. Substantial movement occurred between transects and 21% of goats were estimated to be available for recounting in adjacent transects. (6) Different detection probabilities between groups of goats may be particularly relevant when using double-counting, where multiple observers are �capturing� and �recapturing� animals in the same instant. Many analyses test and adjust for this �unequal catchability� assumption in different ways, with the approaches of Huggins and Alho allowing prediction of unique probability values for a range of co-variates. The approach of Chao attempts to correct for skewed distributions in small samples. The Horvitz-Thompson approach provides a useful basis for estimating abundance (or density) when detection probability can be estimated and is known to vary between observations according to a range of independent variables, and also avoids errors associated with averaging group size. (7) After correcting for recounting, the Alho estimator applied to helicopter surveys was the most accurate (Bias = 0.02) and reliable of all techniques, which suggests that estimates were improved by taking into account unconditional detection probability and correcting individual observations according to their characteristics. The positive bias evident in the Chao (Bias = 0.28) and Petersen (Bias = 0.15) aerial survey estimators may have been a result of averaging detection probability across all observations. The inconsistency and inaccuracy of the ground-based area-count technique emphasises the importance of other assumptions in density estimation, such as representative sampling and availability bias. The accuracy of index-manipulation-index techniques was dependent on the indices used. Capture-recapture estimates using mustering showed slight negative bias (Bias = -0.08), which was likely a result of increased probability of re-capture (i.e. trap happy). Ground-based capture-resight estimates were labour intensive and positively biased (Bias = 0.13), likely due to underestimating the area sampled, or overestimating the number of unmarked individuals with each sample. (8) Helicopter survey using double-counting is recommended for estimating the density of feral goats in steep terrain. However, consideration of recounting under intensive sampling regimes and adjustments for the factors that influence unconditional detection probability is required.

Merino sheep are the most numerous domestic livestock in Australia and feral goats are wide-spread and locally abundant in many of the regions where sheep are grazed. Foot and mouth disease (FMD) is a disease of ungulates that causes severe economic hardship to countries where outbreaks occur or where it has become endemic. In India, Africa, Greece and recently the United Kingdom and Eire, sheep and goats have been implicated in the spread and maintenance of FMD. In Australia, there are contingency plans (AUSVETPLANS) for dealing with an outbreak of FMD. Included in those plans are strategies for control of the disease in feral ungulates including feral pigs and feral goats. Modelling has provided assistance in developing strategies to combat outbreaks in feral pigs and for controlling outbreaks in domestic livestock. No models have been constructed to aid decisions about controlling FMD in feral goats where they co-occur with merino sheep. In Australia, the greatest densities of free-ranging feral goats and domestic livestock occur in the high rainfall zone (> 500 mm mean annual rainfall) along the eastern tablelands and adjacent slopes of the Great Dividing Range. Previous studies of feral goat biology, population dynamics and behaviour in Australia have concentrated on arid and semi-arid zones or on islands. Interactions between free ranging feral goats and merino sheep have not previously been studied in the high rainfall zone. My study investigated the ecological and behavioural characteristics of feral goats and their interactions with sympatric merino sheep at a high rainfall site in central eastern New South Wales. The population dynamics, biological and behavioural parameters of feral goats and sheep were then used to model FMD in such an environment. Deterministic temporal models and a new spatial stochastic model were used. Of particular interest were the rates of contact within and between subgroups of feral goats (termed herds and mobs), within and between subgroups of merino sheep (termed flocks and mobs), and between subgroups of the two species. Feral goats at the study site were found to be numerous (mean density = 34.94 goats km-2, from aerial surveys), in good condition, fecund and had high adult survival and low annual adult mortality (survival= 0.81�1.00) in the absence of harvesting and hunting. They had an observed instantaneous rate of increase of 0.112 per year. Annual rate of increase was similar to other sites in Australia without sustained harvesting pressure. Home ranges were small for both males (3.754 km², s.e. = 0.232, n = 116 goats) and females (2.369 km², s.e. = 0.088, n = 241 goats). From this and other Australasian studies, an inverse power function was found to be an excellent descriptor of the relationship between mean annual rainfall and female home range size. A resource selection function was fitted in a geographic information system to observational data of feral goats. The habitat selection of feral goats included a preference for wooded vegetation on eastern and north eastern aspects at higher elevations. The resource selection function was also used to set the probabilities of occurrence of feral goats in 1 ha areas of the landscape and these probabilities were used to generate heterogeneity in a spatial model of foot and mouth disease virus (FMDV) transmission. Daily per capita contact rates were estimated from observed contacts in the field where a contact between individuals was recognised when one approached within 1 body length ([approx] 1m) of another. The contacts between feral goats within herds were frequent and occurred at a rate of 6.96 (s.e. = 1.27) goat�goat contacts day-1. Sheep to sheep contacts were slightly less frequent (4.22 sheep�sheep contacts day-1, s.e. = 0.65) but both estimates were most likely negatively biased because of observer errors in estimating the number of individual animals coming in contact with observation subject (focal) animals. Contacts between herds of feral goats were not common and those between adjacent populations were fewer than 1 per year. In sheep, flock to flock contact was largely governed by husbandry practices and occurred at a mean daily rate of 0.0014 flock�flock contacts. Contacts between sheep and feral goats were less frequent but nonetheless common (2.82 goat�sheep contacts day-1, s.e. = 0.40). In feral goats the size of the mob in which focal goats were observed was found to be the most important factor in determining contact rates between individuals and a counter-intuitive inverse relationship was identified. Contacts were heterogeneous and density was not an important determinant of contact rates implying that, because of the uniformly high densities at the site, saturation had occurred. The temporal models of FMDV transmission showed that the rate of contact within and between species was such that FMD was predicted to spread rapidly throughout an infected herd or flock. Control strategies of intense culling of feral goats at the population level were predicted to allow the disease to persist at low prevalence, with a small peak corresponding to the annual lambing pulse in sheep. However, the same level of control (>90% reduction) at the herd level was predicted to eliminate FMD and allow the safe reintroduction of sheep. Extreme control that left very small groups (<3 individuals) may be counter productive because such small groups are likely to join the reintroduced sheep in an effort by the goats to meet gregarious urges. The spatial model was more reassuring. It predicted that FMD would die out in a mixed sheep and feral goat population in less than 90 days because of the low rate of herd to herd contact and herd to flock contact. For similar environments, the contingency planning consequences are that an outbreak of FMD introduced into feral goats from sympatric sheep is likely to be containable by removing all the sheep, determining the extent and likely range of the feral goats, then removing a substantial proportion of or eradicating each herd. Feral goats, being relatively sedentary, are unlikely to spread to adjacent populations and the disease will die out through lack of contact between herds and populations. Because feral goat home ranges overlap and are centred on one or two small catchments, a containment ring of feral goat control, set to encompass the home range of a target herd and that of adjacent herds, should be adequate to limit spread of FMD.

This thesis is concerned with studying aspects of the ecology of feral pigs in the wet-dry tropics of the Northern Territory. The data are needed for use in the management of feral pigs to reduce their agricultural and potential epidemiological impact. Particular emphasis is placed on collecting data needed for modelling foot-and-mouth disease in feral pigs, estimating agricultural damage caused by pigs and evaluating control techniques. All fieldwork was conducted in the Douglas Daly district of the Northern Territory.

The ability of feral herbivores to reduce the amount of food available to domestic livestock has rarely been quantified. This thesis seeks to examine the degree to which feral goats (Capra hircus) reduce the availability of pasture and shrub biomass for other herbivores. The interaction between feral goat populations and their food supply will be explored using a modelling approach. In addition to this it will also examine the cost of controlling goats and attempt to identify the cost efficient target densities for control operations. The implications of this information for management will be discussed. There are two ways an animal population can interact with its food supply, through: (1) intrinsic food shortages, and (2) extrinsic food shortages. Intrinsic food shortages occur when a negative feed-back loop exists between the animal population and their food supply. This means the animals affect the availability of their food and their food supply affects the dynamics of the animal population. Since the animals are affecting their own food supply it could be said that they will also affect the availability of that food to other herbivores if they consume the same species. Extrinsic food shortages occur when there is no feed-back from the animals to their food supply. Food availability is determined by extrinsic factors such as rainfall and is unaffected by the animal population. To determine how feral goats interact with their food supply several models will be examined, and these include: (1) single species models which use data from the animal population only. These have historically been used to identify density dependence which is commonly caused by the animal population being regulated through their food supply in the case of large herbivores, and (2) trophic models which incorporate data from at least two trophic levels in an ecosystem, in this case those being the animal population and the vegetation they are thought to consume. These models allow a more direct examination of the relationship between the feral goat population and their food supply. The various models were fitted to data collected on the field sites and the following results were obtained: (1) the dynamics of the feral goat populations could not be represented by single-species models. This was most probably due to the stochastic environment in which they lived causing the level of density dependence experienced by the goats to vary greatly masking its presence. (2) the rate of increase of the goat population could be predicted by the numerical response of rate of increase to pasture biomass. This demonstrated that food availability influenced the dynamics of the goat population. (3) goat density affected the availability of some species of shrub biomass. There was, however, no response seen in the availability of pasture species to changes in goat density. Since the study was conducted during a drought this is in agreement with other studies which indicated that goats will primarily browse during dry spells but switch to pasture species when conditions improve following rainfall. These results indicate that a negative feed-back loop does exist between feral goat populations and their food supply since the goats affected the availability of some shrub species and so they suffer intrinsic food shortages. This means goats have the ability to reduce the availability of food to other herbivores providing both are eating the same species. Cost-efficiency analysis showed that the cost of removing individual feral goats increases exponentially as density decreases because the search time per animal becomes greater. This relationship was used to construct a model that predicted the cost of achieving a target density. The model describing cost of control over density was also combined with a productivity model based on the numerical response of feral goats to pasture biomass to predict the cost of maintaining target densities under different environmental conditions. Using these models the most cost-efficient density identified was 11 goats/km2. From this study we can make the following conclusions: (1) feral goats have the ability to reduce the amount of shrub biomass available to other herbivores during dry conditions (2) their ability to influence the availability of pasture species remains unknown (3) given the cost of initial and ongoing control and the minimal benefits that result it would be difficult to justify controlling goats during a drought on the field sites.

Feral pigs, European wild boars and their crosses are ubiquitous and found in all ecological zones from Florida to California. These introduced animals are recorded in 39 US states and four Canadian provinces. Texas currently has an estimated population of 1-4 million pigs with the potential to exceed 4 million based on suitable habitat estimates. Feral pigs can modify local flora and fauna and cause significant physical damage with their rooting activities. They can also reintroduce parasites and pathogens to previously parasite and pathogen free herds of domestic cattle, horses, sheep, and goats. The two overarching objectives of this research were to determine what role feral pigs have in the maintenance and possible distribution of fleas, lice, and ticks common to the three wildlife districts; and if they serve as bridging hosts for the same (or other) arthropods and their natural hosts. The supporting objectives were to establish host records of fleas, lice, and ticks parasitizing feral pigs; determine species assemblies within each of the three wildlife districts; and to compare species assemblies among the wildlife districts. Feral pigs (564) were taken from June 2008 to March 2011 using box, corral, and panel traps in three wildlife districts. Two hundred fifty six fleas, Pulex porcinus (Jordan and Rothschild), were collected from all gender and age classes of feral pigs at the South Texas Plains wildlife district. No fleas were collected at either the Hill Country or Post Oak Savannah wildlife districts. This is the first report of these fleas on feral pigs. Lice and ticks were collected from all gender and age classes of feral pigs from all sample sites. Only hog lice, Haematopinus suis, were collected at all three sample sites. Seven species of ticks were collected from the three sites: Amblyomma americanum, A. cajennense, A. maculatum, Dermacentor albipictus, D. halli, D. variabilis, and Ixodes scapularis. Amblyomma cajennense was collected only at the South Texas Plains sample site; A. americanum and I. scapularis were collected only at the Hill Country and Post Oak sample sites. This study reports that feral pigs are serving as hosts for one species of flea, one species of lice and seven species of ticks common to Texas.

Demographic, biological and behavioural knowledge, together with information on the ecological interactions and impact of a species is fundamental to effective management of most mammal species. In this study, these aspects were investigated for a population of feral horses in the Namib Naukluft Park of Namibia, which lies within a part of the Namib Desert. An attempt was made to evaluate the justification of the continued existence of this exotic species in a conservation area, as well as to provide baseline information and recommendations regarding management of these horses. The study investigated the botanical component and grazing capacity of the area inhabited by the horses, as well as the demography and quality of life of the horses. The study further examined the possible negative impact the horses may have on the natural biodiversity of the area. Finally, it looked at the historic, scientific, aesthetic and economic values of the horses. The collected data was then used as a technical basis for the development of a draft management plan during a stakeholder workshop. The study proposed a range of grazing capacity values related to the total rainfall of the preceding twelve months, based on grass production in response to rainfall in different plant communities. The horses, as well as the native large herbivores, utilized the study area according to the patchy rainfall patterns typically found in the Namib Desert. The population size of the horses fluctuated between 89 and 149 over a ten year period. The social structure of the population was more significantly influenced by artificial interference than natural disasters which had implications on natality, mortality and genetic viability. Termite activity, measured as utilization of grass provided in bait boxes, did not correlate with horse density and seems, instead, to be influenced by soil properties. The results of ant and tenebrionid beetle species composition surveys and analyses did not indicate a significant negative impact from the horses on the study area. No indication could be found that the horses threaten the survival of any native species in the area or that they change the vegetation structure. It appears as if the biodiversity of the area is subjected to large natural stresses due to the continued and frequent desiccation in the desert environment. The impact of the horses is therefore probably minor to that of the climatic stochasticity. It also became apparent that the horses have developed significant historical, scientific and tourism value. The general public opinion is that the horses should be managed as a wild population with minimal artificial interference. / Thesis (Ph.D. (Zoology))--North-West University, Potchefstroom Campus, 2006.

No description available.