Introduction
1.1
On 18 September 2018, the Senate referred to the Environment and Communications References Committee for inquiry and report by the second sitting Wednesday in February 2019:
The impact of feral deer, pigs and goats in Australia, and national priorities to prevent the problems worsening for the natural environment, community and farmers, including:
(a)
the current and potential occurrence of feral deer, pigs and goats across Australia;
(b)
the likely and potential biosecurity risks and impacts of feral deer, pigs and goats on the environment, agriculture, community safety and other values;
(c)
the effectiveness of current state and national laws, policies and practices in limiting spread and mitigating impacts of feral deer, pigs and goats;
(d)
the efficacy and welfare implications of currently available control and containment tools and methods, and the potential for new control and containment tools and methods;
(e)
priority research questions;
(f)
the benefits of developing and fully implementing national threat abatement plans for feral deer, pigs and goats; and
(g)
any other related matters.
1.2
On 12 February 2019, the Senate granted an extension of time to report until 17 September 2019. The inquiry lapsed at the end of the 45th Parliament. On 23 July 2019, the Senate agreed to the committee's recommendation that this inquiry be re‑adopted in the 46th Parliament, with a final reporting date of 17 September 2019. The Senate subsequently granted a number of further extensions of time to report, with a final reporting date of 19 May 2021.
1.3
All evidence previously received for this inquiry during the 45th Parliament has been accepted as evidence to the committee's re-adopted inquiry.
Conduct of the inquiry
1.4
In accordance with its usual processes, the committee advertised the inquiry on its website, and wrote to relevant organisations to invite submissions. The committee received 69 submissions in the 45th Parliament and seven in the 46th Parliament. A list of submissions to the inquiry is at Appendix 1.
1.5
In the 45th Parliament the committee held a public hearing in Melbourne on 20 November 2018. In the 46th Parliament the committee held public hearings in Canberra on 21 July, 22 July and 14 October 2020, and in Launceston on 24 November 2020. The names of witnesses who appeared at the hearings are at Appendix 2.
1.6
The committee thanks those who made submissions and appeared at public hearings for their input to the inquiry.
Structure of the report
1.7
This report consists of six chapters, as follows:
The remainder of Chapter 1 provides an overview of the prevalence of feral deer, pigs and goats in Australia.
Chapter 2 details evidence about the risks and impacts of feral deer, pig and goat populations.
Chapter 3 outlines the laws, policies and practices in place at the Commonwealth and state and territory levels in Australia for the management of feral deer, pigs and goats.
Chapter 4 discusses the effectiveness of currently available control and containment tools and methods utilised in Australia for these pest species.
Chapter 5 examines priority areas for further research in the management of feral deer, pigs and goats, and looks at options for improving nationally coordinated management and control processes for these species.
Chapter 6 sets out the committee's conclusions and recommendations.
Current and potential occurrence of feral deer, pigs and goats in Australia
1.8
This section provides information on the current occurrence and impact of feral deer, pigs and goats in Australia, as well as the potential expansion in numbers and concomitant impacts if these feral populations are not effectively managed.
Mapping and understanding the occurrence of feral deer, pigs and goats
1.9
National mapping of the occurrence of feral deer, pigs and goats was last conducted in 2011, as part of a broader study examining the occurrence of 23 nationally relevant pest animal species. This study drew on a range of datasets from national, state or territory governments and other non‑government databases. The resultant mapping provides an indication of where these species may be present currently.
1.10
State and territory governments, regional natural resource management organisations and other groups monitor and map the occurrence of feral deer, pigs and goats on their land. Some jurisdictions undertake regular surveys which provide an indication of the changes in distribution of these species over time.
1.11
The Department of the Environment and Energy submitted that ongoing monitoring of the impacts of feral species allows for management activities to be targeted at the right time and place, and as such is more important than knowing the occurrence or absolute abundance of these species.
General population dynamics of introduced species
1.12
CSIRO noted in its submission that the progress of introduced herbivore species colonising new ranges tends to follow a specific pattern; these populations typically undergoing dramatic growth, followed by a population crash, then partial recovery to a lower density that fluctuates based on the seasons. This phenomenon is termed an ungulate 'irruption'. CSIRO explained further:
[T]he impact of invading populations tends to be highest in the early phases as the invading populations approach their peak, and highly palatable food resources are exhausted… Feral pig, wild deer and goat populations introduced to new ranges exhibit…irruptive behaviour, with the time from introduction to peak density as long as several decades. For example, peak densities of feral pigs were seen in many regions of NSW in the early 1970s, whereas in East Arnhem Land peak densities didn't occur until the late 1990s early 2000s as these populations were founded much more recently. Deer are yet to reach peak densities in much of their current range.
Occurrence of feral deer in Australia
1.13
Deer were initially introduced to Australia in the 19th century for hunting purposes; however more recently, accidental releases from deer farms and deliberate translocations and releases by hunters have augmented their spread. Six species of introduced deer (fallow, sambar, red, rusa, chital and hog) are found distributed across Australia, with all states and territories having at least one species present. An overview of each species from the abovementioned 2011 national mapping study is at Table 1.1.
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(Scientific name)
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Fallow deer
(Dama dama)
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Introduced and released around 1830 during European settlement. Widespread in south-eastern Australia and in parts of Tasmania. Can become serious pests when in high numbers as seen in New Zealand. A threat to biodiversity and a potential risk of exotic disease.
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Sambar deer
(Cervus unicolor)
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Introduced to Victoria in 1860s. Originally from Asia and can cause environmental damage through grazing of vegetation and erosion. A threat to biodiversity and a potential risk of exotic disease.
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Red deer
(Cervus elaphus)
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Introduced to Australia and native to Asia, Europe and North Africa. Known to cause serious habitat damage. In New Zealand, red deer have caused severe damage to vegetation and seedling recruitment. A potential host of exotic disease.
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Rusa deer
(Cervus timorensis)
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Introduced from SE Asia to Australia. Can cause significant environmental damage. Well known to Royal National Park, NSW. Occur in QLD, SA and NSW. May be a potential risk of exotic disease.
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Chital deer
(also called spotted deer)
(Axis axis)
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Introduced to Australia from Sri Lanka and India in early 1800s. Have increased in range in the wild substantially in the recent decade. Known to occur on some islands. A threat to biodiversity and a potential risk of exotic disease.
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Hog deer
(Cervus porcinus)
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Introduced to Australia in 1860s by the Acclimatisation Society of Victoria. Originally from SE Asia and the smallest of the deer species in Australia. A threat to biodiversity and a potential risk of exotic disease.
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1.14
The potential range of each deer species in Australia is far greater than their present distribution. Researchers mapping the potential distribution of feral deer in 2016 noted that current distributions of deer are 'largely an artefact of historical locations of liberation and escape' rather than because deer populations in Australia have reached equilibrium. Potential distribution maps from this study indicate that all feral deer species except rusa could occupy almost the entire continent, and they currently occupy less than 5–10 per cent of their potential range (see Figure 1.1).
1.15
It is anticipated that existing wild deer species in eastern Australia will progressively colonise nearly the entire eastern seaboard, Great Dividing Range and the western slopes. Colonisation of a new area by deer is a complex process, and 'is likely to be driven by interactions among fire, native vegetation modification, primary production, climate change, human population growth and associated human–wildlife interactions'.
1.16
CSIRO noted that in the long term, competition between deer species is likely to occur, and that the ultimate ranges of the various deer species may look very different to those currently observed; these inter-specific competitive pressures, as well as land use, are seen as the most likely determinants of the final distribution of deer species in Australia.
1.17
CSIRO observed that colonisation of new ranges would occur 'as a result of natural spread and deliberate release', noting that past experience suggests that release of deer into the wild will continue to occur despite the best efforts of authorities:
The general observation is that wherever there are farmed deer there are often escaped deer, with deer farm escape/releases accounting for 35 per cent of herds in Australia as of 2004 and 38 per cent of recent populations in New Zealand — there appears to be no such thing as deer reliably "contained behind wire" as escapes are common.
1.18
Feral deer are increasingly becoming a problem in peri-urban and urban areas in Australia. CSIRO submitted that sambar and rusa deer are particularly tolerant of human disturbance, and are adept at inhabiting such environments; for example, rusa deer are currently well established in the 'leafy' western suburbs of Brisbane and the Sutherland Shire south of Sydney, while sambar deer are well established in the Yarra Valley in Melbourne.
1.19
The Centre for Invasive Species Solutions, a pest animal Research, Development & Extension collaboration involving 17 government, industry and research provider partners in Australia, submitted that the mapping studies at Figure 1.1 show 'in stark detail the potential distribution of feral deer across the Australian landscape' and demonstrate the need for a nationally coordinated approach to the management of deer and their impacts and to prevent them from reaching the full extent of their potential range.
Distribution of feral deer at state and territory level
1.20
Submitters to the inquiry provided further detail about the distribution of feral deer species at the state and territory level, and their increasing numbers in recent years. In particular, information on feral deer distribution in Victoria, New South Wales, Queensland, South Australia and Tasmania was highlighted.
Victoria
1.21
Four species of deer are well established in Victoria. Sambar is the most commonly found species, with significant coverage primarily in the eastern half of the state. Red deer are prominent in the Grampians National Park in the west of the state. Fallow deer have populations present in various area of the state, and Hog Deer have a limited distribution and are found in coastal areas of Gippsland (see Figure 1.2).
1.22
The four species of deer found in Victoria frequent 'many different habitat types from heavy forest, rough mountainous terrain to more open-country including semi-open scrublands, pine plantations and open grazing land'.
1.23
The overall number of deer present in Victoria is not clearly established, with the state government noting that estimates of deer numbers range from several hundred thousand up to one million wild animals or more. Some submissions to the inquiry argued that even the upper estimate of one million deer in Victoria could be conservative.
1.24
According to the Victorian Government's Victorian Deer Control Strategy, reports suggest that 'deer distribution and abundance, particularly of Sambar and Fallow Deer, have rapidly increased in recent years and are consequently having an increased impact on a range of values'. Further:
There is also evidence deer are spreading to new areas across Victoria at a rapid rate. While the exact number of wild deer is unknown, there are a number of theories that explain their relatively rapid spread. Increases in deer have been, in part, attributed to fire, natural dispersal, deliberate releases and farm escapes, while urbanisation has led to a greater number of human observations and interactions with deer.
1.25
Several submitters commented on recent increases in specific areas of Victoria, particularly in areas extending from the east and northeast fringes of Melbourne. For example, Yarra Ranges Council submitted that monitoring from two ecologically significant council reserves in that local government area was showing four to five times the number of deer in 2018 compared with previous years.
New South Wales
1.26
Six species of deer have established wild populations in NSW: fallow and red deer are the most commonly found species in eastern NSW, followed by rusa and chital deer, with sambar and hog deer mostly present in south-east NSW. Feral deer distribution across NSW in 2020 is shown at Figure 1.3.
1.27
The geographic area inhabited by deer in NSW has expanded in recent years; the distribution of deer species increased by around 30 per cent from 2005 to 2009 across the NSW coast and tablelands, and increased by at least a further 30 per cent between 2009 and 2016.
1.28
Data released in 2020 by the NSW Department of Primary Industries notes that in 2020, feral deer species were recorded across 180 443 square kilometres, or 22 per cent, of NSW, which represents a significant increase from the feral deer distribution of 138 000 square kilometres recorded in 2016. Fallow deer are the most widespread and numerous feral deer species in NSW, and increased their distribution by 60 per cent between 2016 and 2020.
1.29
Deer are increasingly present in some urban areas of NSW; for example, Wollongong City Council submitted that Wollongong is a high abundance location for feral deer, with the local deer population increasing despite a deer management strategy being in place since 2011.
Queensland
1.30
The Queensland Government's Feral deer management strategy 2013–18 notes that chital, red, rusa and fallow deer have become established in various parts of the state as a result of historical releases of animals in the late nineteenth and early twentieth centuries, with populations still centred mainly in the areas where historical releases occurred. This strategy estimated that about 30 000 feral deer were present in Queensland in at least 20 populations. Estimated distributions in Queensland as of 2008 are shown at Figure 1.4.
South Australia
1.31
Estimates of overall feral deer numbers in South Australia are not available, however the South Australian Government indicates that feral deer numbers in the state have increased since the government's first policy on feral deer was released in 2006. Indicative distribution of feral deer species in southern South Australia is shown at Figure 1.5.
1.32
Findings from aerial surveys in 2016 indicated that fallow and red deer populations in south east South Australia increased by 30 per cent and 16 per cent per year respectively. The South East Natural Resources Management Board submitted that feral deer are a major pest problem in the area, with distribution of feral deer now widespread across the region.
1.33
The Adelaide and Mount Lofty Ranges (AMLR) Natural Resources Management Board submitted that fallow deer are almost ubiquitous across the Mount Lofty Ranges east of Adelaide, with numbers increasing substantially between 2007 and 2016. Red deer are also present in isolated populations in the AMLR region. The Nature Conservation Society of South Australia submitted that anecdotal evidence indicates fallow and red deer are also increasing in numbers across the Northern and Yorke Natural Resource Management regions of South Australia.
1.34
The Kangaroo Island Natural Resources Management Board noted that a feral population of fallow deer had built up on the island following unintentional releases of farmed deer in the 1990s; however, a sustained culling program over a period of 12 years has now successfully eradicated feral deer from Kangaroo Island.
Tasmania
1.35
Fallow deer were introduced to Tasmania for recreational hunting in the 1830s and established populations in central and eastern areas of the state. Natural population increase and release of animals from deer farms has resulted in deer populations spreading from their original core range, increasing interaction with high value agricultural pursuits, urban environments and conservation areas. By the early 2000s, the estimated fallow deer population across Tasmania was around 20 000–30 000; this had increased from estimates of 7000–8000 in the 1970s.
1.36
Modelling studies published in 2015 found that without active management beyond current policy settings, abundance of fallow deer in Tasmania is estimated to increase substantially in the 10 years to 2025. The study stated that, uncontrolled, the fallow deer population in Tasmania could exceed one million animals by the middle of the 21st century.
1.37
The Tasmanian Government provided a geographical map of estimated fallow deer range in the state in its submission, shown at Figure 1.6.
1.38
A 2017 report of a Tasmanian Legislative Council committee into wild fallow deer in the state found that there was no science based quantitative estimate of the wild fallow deer population in Tasmania. As part of its response to this report, the Tasmanian Government committed to undertake a comprehensive state‑wide census of wild fallow deer in Tasmania.
1.39
The government subsequently commissioned a baseline aerial survey of wild fallow deer population in central and north‑eastern Tasmania, which was undertaken in September to October 2019. The survey data estimated a population of 53 660 wild fallow deer in the 19 905 square kilometre survey area, with an average estimated density of deer within the survey area of 2.7 deer per square kilometre.
1.40
The survey report estimated that the wild fallow deer population has increased by around 5.4 per cent per year over the period 2006 to 2019, even in the presence of takes (removals) of approximately 10 000 to 30 000 deer per year. It stated that, removing the effect of take, the annual growth rate of the wild fallow deer population for the period 2006 to 2019 would have been around 27 per cent per year.
1.41
The Tasmanian Department of Primary Industries, Parks, Water & Environment informed the committee that the next stage of the overall deer census project is to estimate wild deer abundance in other areas of the state, including the Tasmanian Wilderness World Heritage Area, parks and reserves, 'over the next two years using camera traps and citizen science, [with these] being methodologies best suited to surveying low and very low animal populations'.
1.42
The survey work being undertaken aims to provide baseline data against which the impacts of future management strategies can be assessed.
1.43
Professor Chris Johnson, an ecologist and conservation biologist at the University of Tasmania, told the committee that the deer population in Tasmania has the potential to expand significantly:
A recent census tells us that the current deer population is about 54,000. It is a large number, but I'd suggest that it could get much bigger. If we allow for geographic spread and an increase in density, half a million deer or more in Tasmania is not implausible over the next few decades.
1.44
Professor Johnson noted that deer have started to make incursions, in small numbers, into the eastern side of the Tasmanian Wilderness World Heritage Area (WHA), and argued that eliminating deer from the WHA should be a high priority goal for deer control measures in Tasmania. Professor Johnson stated further:
[E]ven quite simple models of the potential distribution of deer have them occupying most of the World Heritage area and all the way across to the west coast. It's hard to predict exactly what they would do to the World Heritage area if they got into it, but it would almost certainly be significant damage.
Occurrence of feral pigs in Australia
1.45
Pigs were first introduced into Australia with the First Fleet as a food resource. The spread of pigs then followed the pattern of European expansion, and as pigs were kept in semi-feral conditions many were able to escape and form feral populations. The feral pig population was firmly established by the late 19th century with thousands being shot in New South Wales.
1.46
Feral pigs belong to the same scientific species as domesticated pigs, sus scrofa, and as such interbreeding can readily occur. Feral pigs in Australia are smaller, leaner and more muscular than domestic pigs, with more pronounced snouts, longer and coarser hair, and prominent tusks (in males). Regional populations of feral pigs vary in physical size, shape and colour. While size is highly variable, adult feral pigs generally range up to 115kg for males and 75kg for females.
1.47
Feral pigs are now among the most abundant and widespread terrestrial mammals in Australia, and are particularly widespread in the tropical north of the country. Significant gaps in our spatial knowledge of species distribution and abundance for feral pigs continue to exist. The most recent nation-wide estimate of the distribution of feral pigs across Australia was provided in a 2008 report, which estimated that feral pigs inhabit approximately 45 per cent of mainland Australia (see Figure 1.7). In 1990, by contrast, this estimated area was 38 per cent of the mainland.
1.48
In 1990 it was estimated there were between 3.5 million and 23.5 million feral pigs in Australia. There are no up-to-date estimates of the feral pig population; however, the Australian Bureau of Agricultural Resource Economics and Sciences (ABARES) was contracted in mid-2020 to update population distribution and density maps, supported by information provided by all states and territories. The outcomes of this research will be provided by June 2022.
1.49
The Department of Environment and Energy notes that the range of estimates for the feral pig population in Australia varies greatly, partly because of the difficulty in estimating their numbers, but also because their populations can fluctuate widely in response to variations in environmental conditions and the availability of food and water. For example, recent modelling developed by CSIRO research indicates that in northern Australia, habitat suitability for feral pigs is significantly seasonally affected, with a four-fold increase in suitable habitat during the annual wet season.
1.50
Feral pigs are able to rapidly build populations in good conditions, with two litters of up to 10 piglets every 12 to 15 months. Conversely, prolonged drought can result in feral pig numbers declining significantly with high piglet mortality, and adult mortality of up to 50 per cent of the population.
1.51
Pig populations in Australia continue to expand due to both natural spread and illegal introductions. They have expanded beyond their initially predicted range into areas of New South Wales, Queensland, the Northern Territory and Western Australia which do not correspond to their most suitable climate and habitat characteristics. Despite this expansion of range into areas that were not assessed as suitable habitat, pigs have not yet expanded into the full extent of their predicted range in other areas of these states. Feral pig populations tend to expand their range slowly, between 2km and 4km per year.
1.52
Climate matching indicates that there are extensive areas of Australia which pigs could occupy in the future. These include large parts of central and eastern Tasmania, the Eyre Peninsula, the south-east of South Australia, and south‑west Western Australia. CSIRO submitted that the wild pig is a 'habitat generalist', and observed that the most pertinent question when considering feral pig population distribution is "why aren't pigs present?" in a given location, as opposed to "why are they present?".
1.53
The only hard environmental boundaries limiting the potential spread of feral pig populations are:
access to permanent water year-round (a limitation often met in the Australian context through the availability of artificial water sources spread throughout pastoral lands);
harsh winter conditions, with pigs unable to cope with excessive (above 50cm) winter snow depth; and
access to water and thermal refuges such as riverine woodlands in extremely hot weather.
1.54
CSIRO noted that its research has recently developed a spatially-explicit, resource-based modelling framework aimed at generating improved seasonal and regional-scale knowledge of feral pig distributions, which has already been applied to several areas of Australia.
Estimates of specific regional feral pig populations
1.55
The committee heard evidence on feral pig populations in some specific regions.
Kakadu National Park
1.56
Kakadu National Park estimate current numbers of feral pigs are more than 120 000, predominantly in the floodplain region and areas of the lowland region that are seasonally inundated by water.
Kimberley region
1.57
A 2009 study estimated the future distribution of a recently introduced, expanding feral pig population in the remote Kimberley region of north‑western Australia. This modelling indicated that feral pigs could expand their distribution, by natural dispersal alone, to occupy 61 950km2 (approximately 70%) of suitable habitat within the study area.
Cape York Peninsula
1.58
Mr Travis Sydes, Regional Natural Asset and Sustainability Coordinator, Far North Queensland Regional Organisation of Councils spoke about the distribution of feral pigs on Cape York:
If we first look at the distribution of feral pigs on Cape York with a product like FeralScan or look at the national mapping of feral pigs, you will see that, really, from Cairns north on the cape—the pointy bit on top of Queensland—pretty much all of that has the highest density of feral pigs anywhere in Australia. They are existing over a landscape which ranges from rainforest remnants and islands coming down the east coast from the Lockerbie Scrub to the Iron Range et cetera down the East Coast. Those rainforest ecosystems there are particularly vulnerable. Some of those contain southern cassowary and other very sensitive species as well.
1.59
Mr John Gavin, Chief Executive Officer, Cape York Natural Resource Management, also spoke of the difficulties in estimating numbers in this area:
The largest populations are believed to occur on the cape. It's pretty much Cape York-wide, with some of the survey work that's been done showing them across the entire cape. Things like the freshwater wetlands on Cape York are prime habitat for feral pigs. They're widespread. One of the problems that we have in terms of coordinating management is that there isn't really good data on the distribution or the numbers. Even the estimate of number ranges between three million and 24 million, which is a huge range. As we move down into the wet tropics…we have significant numbers through the wet tropics world heritage area. Then we also get particular higher density amounts in the coastal plains and the coastal wetlands that occur throughout the wet tropics region.
Occurrence of feral goats in Australia
1.60
Goats were introduced into the Australian mainland with the arrival of the First Fleet in 1788, and through numerous further introductions since. Through a combination of escapes, abandonment and deliberate release, feral goats have now spread across most of Australia. The presence of watering points for livestock has allowed goats to occupy arid and semi-arid rangeland areas, as well as higher rainfall areas.
1.61
Feral goat population numbers are difficult to estimate as goats are nomadic and occupy terrain that is difficult to survey. In addition, feral goat populations fluctuate with environmental conditions, and with the utilisation of goats for commercial sale. In favourable conditions, feral goats have multiple offspring, and populations can increase by up to 50 per cent each year.
1.62
The estimated population of goats in Australia's rangeland areas, based on aerial surveys, grew from 1.4 million goats in 1997 to an estimated 4.1 million in 2008, and then decreased to an estimated 3.3 million in 2010. Other estimates of the total goat population in Australia have ranged up to 6 million.
1.63
Estimated distribution of feral goats across Australia as of 2008 is shown at Figure 1.8. Approximately 70 per cent of the feral goat population occurs in New South Wales, where there were an estimated 2.95 million animals in 2011. This compares to estimates in other states as follows:
491 000 feral goats in Queensland in 2010;
322 000 feral goats in South Australia in 2011; and
150 000 feral goats in Western Australia in 2011, declining from a peak of 1.5 million in 2005.
1.64
The distribution of unmanaged goats is limited by several factors, including: type and nutritional quality of vegetation; availability of shelter; availability of water during dry times; occurrence of parasites and diseases; and predation from dingoes and wild dogs in areas where these predators occur.
1.65
CSIRO noted that of these factors, the two biggest influences on the distribution and abundance of feral goats in Australia are predation by dingoes and wild dogs, and control measures by humans (including fencing). In the absence of predation, goats are capable of colonising virtually all of Australia other than desert areas without permanent water. These factors mean that the future distribution of feral goats 'will likely be determined by land manager (both public and private) decisions'.
1.66
The most recent national threat abatement plan (TAP) for feral goats, introduced in 2008, aims to prevent unmanaged goats colonising new areas in Australia, although a review of the TAP in 2013 considered that it was failing in this regard.