2.1
Feral deer, pigs and goats in Australia are responsible for a range of environmental, social and economic impacts. The committee heard that feral animal populations are a threat to Australia's biodiversity, agriculture and social amenity, and can have severe impacts on the condition of Australia's natural resource base. Pest animal populations also pose a significant challenge to containing and eradicating exotic pests and diseases, and can spread diseases to both animals (native and farmed) and humans.
2.2
This chapter details the specific risks and impacts of these species, as shown in evidence to the committee.
Impacts of feral deer populations
2.3
Submitters and witnesses identified various environmental, economic and social impacts of feral deer populations in Australia.
Overview of environmental impacts
2.4
The Department of the Environment and Energy submitted that the impacts of feral deer on the environment can include:
reducing or changing the abundance and diversity of plant species through browsing and grazing;
destroying saplings by rubbing against them, trampling or eating;
spreading weeds into new areas;
competing with native herbivores (such as kangaroos and wallabies) for feed, water and shelter;
contributing to erosion and water quality degradation through trampling, wallowing and faecal contamination;
altering soil properties and nutrient cycling;
hindering revegetation programs; and
carrying diseases and pathogens.
2.5
The department noted that the presence and severity of each of these impacts in Australia is variable between the six species of deer and the particular sites where the deer are living. It stated further that, as the abundance of deer is increasing across Australia, consequentially the impacts listed above are occurring to a greater number of sites or species, or to a greater degree.
2.6
The Centre for Invasive Species Solutions noted that the full extent of feral deer risks and impacts in Australia have not yet been established, however impacts on environmental, agricultural and community assets has been well researched and documented internationally.
2.7
CSIRO submitted that there is very little published research on the biodiversity impacts of introduced deer in Australia. Evidence of deer impacts in Australia is largely observational in nature, or from small-scale, short-term, single‑species case studies that do not quantify community- or ecosystem-level impacts. Few studies published in the Australian context have experimentally partitioned the impacts of deer from those of other native and introduced herbivores.
2.8
CSIRO commented that the lack of understanding about the environmental impacts of deer represents 'a critical information gap that may hamper the development of effective management responses and potentially hinder broader public acceptance of control actions should they be required'.
Impacts of feral deer on specific species and ecological communities
2.9
The environmental impacts of feral deer affect various flora and fauna species in Australia. The Victorian Government's Victorian Deer Control Strategy notes that sambar deer are considered a threat to at least 13 threatened flora species and 12 threatened ecological communities in the state, and that more than a thousand species of flora and fauna would benefit from deer control efforts across the state.
2.10
Feral deer impacts can also have broader deleterious consequences for specific threatened ecological communities in Australia. For example, the negative impacts of feral deer were noted in a 2017 draft national recovery plan for the littoral rainforest and coastal vine thickets of Eastern Australia, an ecological community listed as critically endangered under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). This draft plan stated that grazing and browsing by feral sambar, hog and rusa deer 'has been shown to detrimentally impact the ecological community on both a local and landscape level'. Further:
These activities can result in structural modification, erosion and altered species composition within Littoral Rainforest. Rubbing causes direct physical damage to established trees, while browsing prevents regeneration of Littoral Rainforest canopy and understorey species and creates gaps in the vegetation which allows colonisation by weeds. This has occurred in the area near Genoa River, in Victoria… When infestations are severe these weeds are contributing significantly to the collapse of the existing Littoral Rainforest patches through the smothering of shrubs and young trees. Severe damage to Littoral Rainforest has also been observed from Twofold Bay in NSW to the Gippsland Lakes in Victoria. Persistent infestations are documented as causing the local loss of rainforest species and whole sections of mature rainforest in Victoria... In the Royal National Park in NSW, herbivory by Rusa deer has led to a 54% reduction in understorey plant species richness in sites were deer densities are high and caused a 75% reduction in cover of the threatened plant magenta lilly pilly.
2.11
The Victorian National Parks Association commented on some of the impacts of feral deer in Victoria:
Rainforest communities across the state are already seriously impacted, often browsed bare from ground level to a deer's reach height, taking out mosses, ferns, fungi and epiphytic orchids etc. State and federally listed alpine communities, such as moss beds and snowpatch communities, are suffering more than they did under licensed cattle grazing, because deer arrive much earlier each year, soon after snow‐melt, when those vegetation communities are at their most vulnerable.
2.12
The committee received numerous submissions from individuals, community groups and local councils documenting the environmental impacts of feral deer in particular local regions. Some examples include:
fallow deer damaging native vegetation and dispersing weed species' seeds throughout Waite Conservation Reserve, a grassy woodland area and nationally endangered plant community located in the foothills of the Mt Lofty Ranges near Adelaide;
increasing populations of sambar, fallow and red deer degrading the last remaining wild habitat of the Helmeted Honeyeater in the Yellingbo Nature Conservation Reserve in Victoria; and
rusa deer killing or significantly damaging large numbers of native trees and plants in Stanwell Park in New South Wales.
2.13
The Victorian National Parks Association noted that impacts from feral deer can exacerbate other pressures affecting environmental systems:
[D]eer impacts are an additional stress to already highly stressed systems. Many sources have acknowledged that, faced with fragmentation, an increasing suite of invasive plants and animals and harmful fire regimes, our native ecosystems require increased management of any potentially controllable impacts and the avoidance of any future impacts. Increasing climate change impacts, in particular, call for greater efforts from land managers to control as many threats as we can, to give ecosystems the necessary increased resilience.
Deer have now overlaid an additional impact not anticipated by any threat modelling known to us.
Risks relating to disease and pathogens
2.14
Feral deer are currently a reservoir for various diseases found in Australia, as well as potential vectors of novel diseases should they enter and spread into Australia.
2.15
As of 2013, 16 diseases had been identified in feral deer in Australia. These include two diseases which are able to be transmitted to humans, hydatidosis and leptospirosis.
2.16
A 2019 review of introduced deer and their potential role in disease transmission to livestock in Australia found that deer 'have the potential to play a significant role in the epidemiology of multiple livestock diseases', both those that are currently present in Australia (endemic diseases), and those that are absent but have the potential to become established in the future (exotic diseases).
2.17
Examples of endemic diseases which can be transmitted by feral deer include:
cattle ticks, for which feral deer can act as hosts, and transport and transmit those ticks to cattle in tick-free areas; and
Bovine Johne's disease, a wasting disease caused by the bacterium Mycobacterium paratuberculosis, which has been detected in feral deer in Australia and can be transmitted from deer to domestic livestock.
2.18
Feral deer are listed as being susceptible to a range of exotic diseases, including Aujeszky's disease, surra, brucellosis, bovine tuberculosis, foot‑and‑mouth disease, rabies and bluetongue.
2.19
There are several examples worldwide where populations of wild deer have been directly implicated in disease transmission to domestic livestock, including: the ongoing transmission of bovine tuberculosis to livestock populations in New Zealand and the USA; and an outbreak of foot-and-mouth disease in livestock in Bulgaria in 2011.
2.20
The Tasmanian Department of Primary Industries, Parks, Water & Environment (DPIPWE) commented on these issues in the Tasmanian context:
DPIPWE is collaborating with the Centre for Invasive Species Solutions through a project that seeks to understand the genetic diversity of wild fallow deer to improve modelling of their likely impact as transmission agents for exotic diseases. The results of this work would help prioritise response strategies to an exotic disease incursion for which wild fallow deer may be a vector.
There is some speculation within the farming community as to the role of wild fallow deer in transmitting diseases such as ovine Johnes Disease and ovine footrot. To date, there is no science-based evidence to understand the role of wild fallow deer in transmitting these diseases across the landscape under Tasmanian conditions.
2.21
Mr Ted Rowley, a landholder near Jindabyne in NSW, emphasised that the biosecurity risks associated with feral deer can affect the ability of farmers to market and sell their produce:
The continued presence of feral deer amongst domestics herd animals also increases the difficulties in maintaining herd and business 'bio secure status'. Bio secure status declarations are required by marketing authorities, processors and supply chains for meat and fibre products. Meat and fibre market value chain stakeholders are increasingly mandating 'bio secure' supply chains where quality of product and disease/contaminate standards have to be proven to be maintained at a high level. As a farmer we need to make statutory declarations that biosecurity plans have been developed and implemented and this is becoming increasingly difficult as the presence of feral deer becomes more entrenched in the landscape.
Our deer group has invested major resources in attempting to control feral deer populations across our landscape. Feral deer species however, have a unique characteristic among vertebrate pest animals in their ability to learn, after one or two exposures, avoidance behaviour to the particular control technique employed. They also adapt behaviour readily and convey the survival behaviours across generations. Deer escalate their ability to resist control rapidly and this makes meeting biosecurity standards very difficult and expensive.
Agricultural, economic and social impacts
2.22
Feral deer can cause various impacts on agricultural enterprises, including through:
grazing on crops, pasture, fruit and vegetable crops;
competing with livestock for food;
creating biosecurity risks for livestock;
trampling crops and fouling water sources resulting in losses of productivity;
reducing the capacity for alternate land uses (for example, carbon sequestration);
expenditure of time repairing damage; and
the financial costs of managing deer impacts.
2.23
Deer also affect managed native and pine forestry plantations through browsing and antler rubbing.
2.24
The full extent of feral deer impacts on agricultural activity across Australia is largely unquantified at the present time, with published evidence to date being predominantly anecdotal.
Landholder awareness of feral deer as a problem in their area
2.25
The Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) conducted a national survey in 2016 of agricultural land managers about pest and weed management.
2.26
The survey, which canvassed 6470 land managers across Australia, found that approximately 13 per cent of respondents were aware of the presence of feral deer on their property in the last 12 months, with around 15 per cent of these respondents considering feral deer to be a major problem on their property.
Evidence from submitters and witnesses about local and regional impacts
2.27
The committee heard evidence from submitters and witnesses about local and regional impacts in this regard. For example, the Adelaide and Mount Lofty Ranges Natural Resource Management Board submitted:
From a local impact perspective, deer are regularly implicated in primary production impacts ranging from occasional minor nuisance (occasional minor tree-crop browsing), to regular (fence damage and grazing competition) and sometimes severe (market garden crop trampling, resulting in thousands of dollars of lost income per event in the northern horticultural area).
2.28
Nillumbik Shire Council, located on Melbourne's north-east fringe, stated that rural landowners in Nillumbik are reporting increasing damage by deer to vineyards, orchards and rural grazing businesses. Impacts noted by landholders in this area included water spoilage, erosion, damage to fences, tree crops, vines and shelterbelts and an increased struggle to achieve good pasture via rotational grazing.
2.29
Mr Rowley and Ms Jo Roberts submitted that, based on experience in their district, graziers 'can expect a reduction in stocking capacity of up to 50 per cent' as deer spread and build in numbers. They explained further:
We have on our farm an estimated 200 Fallow deer per night, despite intensive ground shooting over many years. If you take a Dry Sheep Equivalent (DSE) as 60 kg live weight that means we have 20 additional breeding cow equivalents of deer on our small property alone. We estimate our costs from deer impact and management are around $25,000 a year. Neighbours to the south who have properties several times our size multiply this figure by five or six times and are suffering huge losses in grazing not to mention biosecurity risks, environmental damage, water quality impacts and public safety.
2.30
Another grazier located in the south east region of NSW high country estimated that deer impacts are conservatively costing $100 000 annually across their farming operation, and provided one example of the impacts as follows:
We have an 80-hectare paddock located at the south east of our property that is pasture improved and fertilised. It is lightly timbered with several water sources. Ten years ago, this paddock ran 50 breeding Herefords without any feed supplementation. That equates to $50,000 annual income.
At present, this paddock cannot run 20 Hereford breeding cows due to the continual pressure from deer. We need to feed these 20 cows hay and feed blocks and this year we are seriously considering to wean calves early which is solely attributed to the pressure from deer.
The boundary fence needs to be continually repaired, deer foul dams and our cows compete with deer for scarce water resources. Deer also help themselves to the cattle's hay and feed blocks. Even though there are no sheep in this paddock, if walked through you would think it ran 1000 wethers. Deer scatts are in abundance across the whole paddock. It is quite astounding.
The bottom line cost to our farming business equates to at least $30,000 per annum (lost income and costs) from this paddock alone.
2.31
Mr Simon Cameron, a Tasmanian wool grower, submitted that the impost of feral deer on his property reduces his farm output by 10 to 15 per cent, at a financial loss of about $50 000 per annum. Mr Cameron described the main impacts of deer on his property to the committee:
In terms of wool production, the main impact is through competition for feed. This revolves around the number of deer I'm hosting. It's difficult to put an accurate number on them. I generally work backwards from the number that we're culling each year. That gives me an approximation—the equivalent of about 500 sheep that I can't carry. That's about 10 per cent of the flock on my land. In terms of other aspects to farming, there's obviously the infrastructure damage. There's also a concern that, when you're trying to rest a paddock, it's an ideal time for deer to take over... We also have the spread of weeds through deer, and this is quite evident. If you follow deer tracks or you come across deer carcasses, there are frequently weeds growing around the carcasses. Keeping the bush clear of that sort of unwanted growth is a major task.
2.32
The Tasmanian Farmers and Graziers Association noted that it had conducted a survey of 250 of its members on the cost of deer impacts on farms, which resulted in an estimated indicative annual cost in the range of $10 to $80 million across the survey group.
2.33
Tallangatta Valley Landcare Group estimated that landholders in this area of regional Victoria experience losses due to feral deer predation of pastures in excess of $2 million per annum.
2.34
Submitters highlighted that, in addition to financial impacts on livestock producers and landholders caused by damage to crops and horticultural industries, significant emotional and psychological stress can be incurred. For example, Mr Rowley and Ms Roberts submitted:
Feral deer are having a major impact on vegetation regeneration and recruitment in natural and planted areas, including significant areas of publicly funded Landcare plantings. Having plants survive rabbits and hares only to be demolished by deer after eight years establishment is heart breaking.
Impact on regeneration projects and carbon sequestration
2.35
The committee heard that feral deer can severely impact attempts to implement landscape regeneration projects, and can limit other productive land uses such as carbon sequestration initiatives.
2.36
Dr Neil Davidson, Restorative Ecologist, Greening Australia, provided information about the impact of deer on a landscape-scale restoration project, called the Island Ark Project, within Tasmania's Midlands biodiversity hotspot:
So far, Greening Australia has strategically revegetated or restored 1,800 hectares of native woodland, along two biodiversity corridors across the Midlands, at a total cost of about $11 million. A major problem in this work has been the damage done by feral deer. Deer browse the tree seedlings when they're first planted, and they ringbark stems and smash branches of well-established saplings five to 15 centimetres in diameter. The damage occurs in the lead-up to the rutting season, when deer rub their antlers on trees to remove the felt from them. But they also crash their antlers in woody shrubs.
…
As a result of this experience, Greening Australia has had no option but to cage trees that are at risk of browsing damage by deer, at a cost of $50 to $100 per cage. That raises the total cost of restoration at a hectare level to $6,000 per hectare, probably doubling the cost. Where they are vulnerable, we enclose the genetic trials with a deer-proof fence, costing about $35 a metre. That translates to a cost of $50,000 to enclose 17 hectares to conduct our genetic trials.
2.37
Dr Davidson concluded that deer in high numbers are 'a major destructive influence in government funded biodiversity restoration projects, greatly increasing the cost of landscape restoration in susceptible areas, leading to an unnecessary extra impost on the public purse'.
2.38
Dr Davidson noted further that the presence of high numbers of deer and the high cost of dealing with the damage they cause in Tasmania mean that 'Tasmania is not competitive with mainland Australia when it comes to attracting money for plantation plantings of trees for carbon offset and biodiversity', and discourages farmers from conducting environmental restoration on their properties.
2.39
Dr Elisa Raulings, National Programs and Science Lead at Greening Australia, commented further that despite trialling four different deer control measures, Greening Australia has 'been unable to bring the cost of revegetation down to a point where it becomes cost-effective for our investors' in areas of high deer density in Tasmania:
[D]eer are a major destructive force in restoration in high-density locations across Tasmania and also Australia. There are no sufficient control methods at the moment that we are able to use to drive the cost down to a point where we are able to plant cost effectively. We know that emerging carbon markets have very significant potential to drive a lot of investment into Tasmania in the future, but until we are able to address the deer issue, we will be unable to direct a lot of resources to Tasmania without significant other investment.
2.40
Dr Raulings explained the potential income streams that can be lost for farmers whose properties cannot sustain tree planting programs due to deer impacts:
[Farmers are] missing out in a couple of key ways. One is the direct payment that we pay the landholders to put trees on their land. Carbon offsets come with different types of leasing arrangements, but farmers basically, at the end of the day, get some sort of incentive, and it depends on the carbon landscape in which their farm is. But they receive a payment to have those trees on those farms, and depending on the arrangement and the agreement they also might get a payment for maintaining those farms for 25 to 100 years. So there's a direct payment they're missing. We've seen in other locations that that's really a very good incentive for people to start diversifying their product stream, so, they can have cattle grazing in the understorey and getting money from milk, for example, but they can also have an income stream from the trees and the overstorey. That's something that's very attractive to farmers.
The last one is actually the productivity benefits themselves… [T]here are some direct productivity benefits associated with having trees on farms.
2.41
Greening Australia noted that it has a goal of working with a minimum of 700 Tasmanian landholders to achieve its target of restoring 15 000 hectares of land across Tasmania by 2030, and stated:
Unless we can find a suitable strategy to mitigate the cost of deer in revegetation, these targeted 700 Tasmanian farmers will, in addition to being directly impacted by deer…also lose out on diversified income streams through carbon offset funding and the productivity benefits associated with trees on farms.
2.42
Mr Rowley commented on these issues in the context of his own property near Jindabyne:
Our attempts to establish areas of grasslands, woodlands or forest areas now are problematic as the areas need protection from grazing and browsing feral deer for at least 12 years. Either a combination of 2 metre high substantial posts and 2.2 metre high mesh fences are needed around each tree or area or a feral deer proof fence needs to erected around the area. This increases costs greatly and effectively means we now do not invest in revegetation.
More importantly our attempts to build partnerships with carbon sequestration companies and potentially earn income from carbon sequestration on our farm have been abandoned as the presence of feral deer renders carbon sequestration tree or grassland planting very difficult. The greatest concern is that our attempts to protect and enhance existing areas of woodland, grassland and forest that would sequester carbon on our land is made impossible with the presence of feral deer in substantial numbers.
Impacts on indigenous cultural heritage
2.43
The Victorian Deer Control Strategy notes concern over the risks posed by deer to cultural heritage sites and values:
For example, the Gunaikurnai Land and Water Aboriginal Corporation and the Dja Dja Wurrung Clans Aboriginal Corporation are both seeking to tackle the impacts of deer (and other large invasive herbivores) at ten sites in Gippsland and six sites in Central Victoria, respectively. The identified impacts of deer at these sites include soil compaction and erosion, damage to native plant species and competition with native species for grazing in grassy, shrubby and herb-rich woodlands.
Damage caused through vehicular incidents
2.44
Feral deer also pose a threat to community safety as a traffic hazard. Deer‑vehicle-collisions are a significant documented issue in other jurisdictions such as the United States and the United Kingdom, and are becoming an increasing problem in parts of Australia.
2.45
There are few, if any, published analyses of the occurrence and type of deer‑related traffic incidents in Australia. Data that is available includes, for example, statistics released from police reports in the Wollongong Local Government Area showing that between 2005 and 2017, there were 107 motor vehicle accidents involving deer in that region. Of these, 90 were rated as 'serious' incidents, including 28 resulting in personal injuries and one death.
2.46
Submitters and witnesses provided further contextual evidence for the traffic threat caused by deer in areas of high deer abundance. For example, Yarra Ranges Council stated that resident communications to council 'indicate an increasing number of deer‑car collisions, with the risk of fatalities from a deer‑vehicle collision high'. It submitted further:
Traffic accidents may pose the largest financial cost of wild deer in the Yarra Ranges. Deer can be 240kg, with a higher centre of gravity than native animals, providing a greater potential to cause serious damage in vehicle collisions and increased likelihood of fatalities. RACV have deer listed as #5 on the most frequently hit animal resulting in a claim. There has been an increase in deer-vehicle-collisions throughout Yarra Ranges causing substantial costs in vehicle repairs and imminent risk of significant injury or fatality.
2.47
Meander Valley Council, located in northern Tasmania, reported to the committee a significant increase in deer-related traffic incidents and sightings in recent years, including one collision relating in a fatality.
2.48
Friends of Royal, a not for profit organisation with the goals of protecting, preserving and appreciating the Royal National Park north of Wollongong, commented on the prevalence of deer as a traffic hazard in the park:
On the roads in the park it is common to see the carcass of dead deer from road kills. The impact of large 80 to 120 kg animals on a car can be extensive. Impacts can send them through the windscreen. Deer are cryptic in nature and commonly rest during the day and feed at night. It is at night when the deer become the greatest hazard to motorists. The deer at such times are difficult to spot due to their greyish brown pelage and along with the twisting narrow roads of the Park, often seem to spring from nowhere and into the path of the vehicle. The deer have no traffic sense and can freeze to some extent in the headlights. At times they often try to move across a road in single file to enter the bush as a car approaches. It is now a common experience to drive through the Royal National Park of a day time and see deer road kills.
Impact on rail networks
2.49
In addition to collisions with road vehicles, submitters also noted the impact of deer interactions with trains, and rail networks more broadly.
2.50
A report prepared for Wollongong City Council noted that between the 2010‑11 financial year and 2016, more than 212 deer were struck by trains in the Northern Illawarra region. The estimated cost per annum in that period for these incidents was 'in the order of $145 000 for incident call-outs, $242 000 in the economic costs of delays and an unquantified financial cost for repairing trains'.
2.51
Further reporting from Sydney Trains in October 2017 showed that there had been more than 30 collisions involving deer wandering onto the rail corridor over the previous 12 months, with 24 of these collisions occurring in the Illawarra region; and that more than $1 million had been spent on fencing 'in a futile bid to stop them crossing tracks along the south-coast rail line'.
Domestic and public nuisance
2.52
Feral deer can create a domestic and public nuisance, particularly in suburban areas, and have been blamed for 'damaging gardens, small crops and fruit trees, knocking over rubbish bins, wrecking turf, chasing dogs and competing with domestic livestock (usually horses) for feed'. In extreme cases, horses have reportedly been gored by stags whilst being chased away from feed.
2.53
Wollongong City Council submitted that nearly 50 per cent of residents in deer-affected areas of the Wollongong Local Government Area had reported damage to their property, with costs of up to $5000 per year for some properties.
2.54
Yarra Ranges Council commented that interactions with deer in populous environments presents safety risks, and noted examples from its region including: a male stag being trapped in a school ground requiring euthanasia during school hours; and another deer causing over $100 000 damage to a funeral home.
Potential impacts on urban water supplies
2.55
Yarra Ranges Council submitted that Cryptosporidium and Giardia parasites with the potential to cause disease in humans 'have been detected at low levels in deer faecal pellets in Sydney and Melbourne drinking water catchments'. It stated further that if Melbourne's water supply had to be treated for Cryptosporidium it is estimated to cost up to $740 million, and that Melbourne Water 'is investing significantly into deer control and deterrents within their water catchments in Yarra Ranges currently, with the potential to require significantly more if deer populations cannot be reduced'.
Economic impact of recreational deer hunting and commercial harvesting
2.56
Some submitters commented that the economic and social benefits of recreational hunting must be accounted for in any discussion of the impacts of feral deer in Australia. The Australian Deer Association submitted that hunting is an important social, cultural and economic activity.
2.57
It was noted that a 2014 report commissioned by the Victorian Department of Environment and Primary Industries found that deer hunting was estimated to directly contribute $57 million to the Gross State Product (GSP) of Victoria in 2013, with flow-on impacts of a further $85 million in GSP, including significant contributions to local regional economies.
2.58
Some submitters to the inquiry, however, questioned the economic benefit of recreational hunting of deer, when contrasted with the costs to agriculture and the environment posed by feral deer. For example, the Victorian National Parks Association submitted that while recreational hunting may contribute $142 million per year to the Victorian economy, this is significantly less than the $1 billion per annum generated through tourism to Victoria's parks, which are facing significant negative impacts from the growing feral deer population.
2.59
Participants at a 2016 National Wild Deer Management Workshop summarised this issue as follows:
Reaching a balanced understanding of the total economic impacts of deer requires the input and cooperation of many stakeholders… Because the policy space for deer management is often contested (game resource versus pest), it is important that the total costs are considered in an economic analysis… Since the economic benefits are an important part of the total economic impacts of deer, we propose that there needs to be detailed cost benefit analyses that consider the total impact and not just a positive or negative perspective. This will help inform policy.
2.60
Broader issues relating to recreational hunting of feral deer are discussed further in Chapter 4.
2.61
The committee also took evidence from Wild Game Resources Australia (WGRA), a company that operates in Queensland, New South Wales and Victoria harvesting feral deer for commercial sale (both as a pet food product and as a venison product for human consumption). Company representatives told the committee that its operations currently provide growing employment opportunities for accredited shooters, as well as workers in its meat processing facilities. Further, landholders who agree to have WGRA shooters harvest deer on their properties can receive income of around $500–$1000 per night of harvesting, based on a per kilogram fee for each animal that is removed.
Risks and impacts of feral pig populations
2.62
Feral pigs are a serious environmental and agricultural pest across Australia. CSIRO noted that many impacts of feral pigs have only come to light in recent decades following the expansion of their range, for example, predation of aestivating Bogong moths in parts of the Australian Alps.
Environmental impacts
2.63
The environmental impacts of feral pigs in Australia include: predation of animals; consumption of plants and soil organisms; and habitat change and degradation due to the destruction of plants, reduced plant regeneration, soil erosion and changes in soil structure; and the spreading of weeds.
2.64
The national Threat Abatement Plan (TAP) for predation, habitat degradation, competition and disease transmission by feral pigs (Sus scrofa) lists eight ecological communities, 63 threatened animals and 85 threatened plants impacted or potentially impacted by feral pigs. This includes six of the 20 threatened birds listed in the Australian Government's Threatened Species Strategy.
Competition impacts and predation of native species
2.65
Feral pigs compete with and predate native animals in Australia. Native fauna preyed upon by feral pigs include earthworms, amphipods, centipedes, beetles and other arthropods, crustaceans, snails, frogs, lizards, snakes, the eggs of the freshwater crocodile, freshwater turtles and their eggs, marine turtle eggs and hatchlings, and small ground-nesting birds and their eggs.
2.66
CSIRO noted that micro-endemic (localised) species and species that form nesting aggregations are at particular risk of significant impact from pig predation.
Habitat change and degradation
2.67
Habitat degradation is mostly a consequence of pigs digging up soils, grasslands and forest litter as they forage or 'root' for subterranean food items such as roots and fungi. Moist soils particularly attract digging activities. Rooting activity is damaging at the ecosystem level: directly damaging the ground and vegetation and impacting plant species richness; increasing run‑off, erosion and water quality; influencing soil chemistry and fungal and microbial life; and slowing regeneration.
2.68
The Invasive Species Council noted that soil disturbance by pigs may have 'hidden' ecological impacts, including: disruption of nutrient and water cycles; altered soil micro-organism and invertebrate populations; altered plant succession; and erosion.
2.69
Feral pig impacts are associated particularly with wetlands and riparian (that is, riverbank) ecosystems, which are their preferred habitats, leading to impacts on water quality such as water turbidity and dissolved nutrient levels.
2.70
Feral pig disturbance can be locally extensive, such as in or around swamps and lagoons, and may be associated with sites modified by people, or close to roads, tracks and watercourses. Foraging can result in obvious large expanses of deeply turned over or rooted soil in highly profitable foraging patches. More commonly, damage is distributed discontinuously throughout a broad area, such that a few sites experience high levels of damage while many sites have little.
2.71
Ms Patricia Jeffers from Cairns, appearing in a private capacity, gave the committee a local example of landscape degradation, explaining the connection between feral pigs, land management, and sediment run-off into the Great Barrier Reef:
[C]ameras have captured what's happening down in the rainforest creek at the bottom of the hill. This is a cow pasture. It's all rainforest, and this little creek, about 500 metres down, runs into the Barron River. The pigs need water all the time… So they get down into the creek and they wallow, and they dig for mussels and prawns and things. We used to have six-foot tall water plants down in this rainforest creek 10 years ago, but now we've got nothing. The banks are all turned up; they're all just mud. We get about a metre of rain in our wet system. There are no plants holding the banks together, and all of that rain washes down into the creek, down into the Barron River and eventually out onto the Great Barrier Reef.
2.72
CSIRO noted that the precise effects of pig ecosystem engineering are not well understood and most likely differ broadly among different habitats and ecotypes, with further study required to better understand these impacts in the Australian landscape.
Spreading weeds and plant pathogens
2.73
The presence of feral pigs often results in increases in weed abundance, although whether this is through passing seeds in faeces, spreading seeds attached to fur, creating localised nutrient enrichment through urine and faeces, or simply by creating ground disturbance in which weeds can take root, is not certain.
2.74
Feral pigs can act as reservoirs for disease and they are implicated in the spread of plant pathogens. Soil-borne plant pathogens that can be spread by feral pigs include: Phytophthora cinnamomi, which causes plant dieback in a range of native, ornamental, forestry and horticultural plants; and the Panama Disease TR4 fungus, which causes wilting and eventually death of banana plants.
2.75
Mr Leon Collins, Deputy Chair of the Australian Banana Growers' Council, commented on a Panama Disease outbreak in Far North Queensland:
The banana industry is now having a great battle with the world's worst banana disease: Panama disease tropical race 4… It is easily spread by wild animals, including pigs, on any part of their bodies. It's spread by wallabies, people, machinery and also overland water flow.
Now we have discovered it on four separate farms in the Tully area. The first one was purchased by Banana Growers in conjunction with a grant from government. It was shut down immediately. We thought that would be the best thing to stop the spread of TR4 in the Tully River Valley. These four farms are all within the Tully River Valley, nothing outside of it yet, so containment. Since then we've had three other neighbouring farms and the last one across the river that have succumbed and had positive tests. Feral pigs come out of the nearby national park. They are living in the rainforest, coming out and feeding in the farming infrastructure. A lot of our pigs only eat fruit; they are not carrion eaters, so they have grown up on [a] completely vegetarian diet.
We believe strongly—I have seen it with my own eyes in the tracks since 2015 the spread of this disease—and I am in no doubt, as are most people up here, the pigs have been the major vector spreading it between these farms in Tully. Banana farmers are participating in a coordinated feral pig control program of aerial shooting, trapping and ground control. We first started off in July 2017. Since then we have taken out of the Tully River Valley in the TR4 treatment area just over 6,000 feral pigs.
Impacts and risks relating to animal disease and pathogens
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Feral pigs are carriers of 14 endemic diseases, 11 of which are diseases able to be transmitted from pigs to humans (zoonotic diseases), with an additional zoonotic disease carried by ticks infesting pigs.
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The Department of Agriculture highlighted several of these diseases in its submission:
A number of diseases carried by feral pigs can affect both livestock and human health, such as: leptospirosis, through contact with the urine of infected feral pigs; porcine brucellosis, through handling raw feral pig meat; and sparganosis, through eating inadequately cooked meat. There are also additional biosecurity risks to human health from zoonotic diseases such as rabies or Japanese encephalitis which can be transmitted from deer, pigs or goats to people.
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The two most common zoonotic diseases isolated from feral pig populations are leptospirosis and brucellosis. Brucellosis, a potentially serious bacterial infection, is currently endemic in both the Queensland and New South Wales feral pig populations and can be transferred to humans and other livestock. Pig hunters and their dogs are particularly at risk, with a 17 fold increase in identified cases in dogs New South Wales between 2011 and 2015. Ninety percent of these cases were in dogs that had participated directly in pig hunting activities.
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CSIRO highlighted the role of pigs as vectors of several parasitic diseases that may cause problems in humans and are transmitted when pigs contaminate drinking water supplies, namely: Giardia; Cryptosporidium; and Balantidium coli (of which feral pigs are the only known vector).
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Feral pigs are susceptible to become reservoirs of many exotic diseases should they enter Australia, including: foot-and-mouth disease, bovine tuberculosis, classic swine fever, Aujeszky's disease, African swine fever, pseudo-rabies, swine vesicular disease, and porcine reproduction and respiratory syndrome.
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CSIRO cautioned in its submission that it is difficult to assess the level of risk associated with population-level outbreaks of exotic disease resulting from individual feral pigs becoming infected. This is due to various factors, including the unreliability of disease detection in feral pigs in Australia, and poor understanding of disease transmission between pigs under Australian conditions and the degree of connectedness between pig populations with changing seasons.
African swine fever
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An emerging threat to Australia's pig herd is African swine fever (ASF), which is a contagious viral disease of domestic and wild pigs that has established itself in Asia and parts of Europe and continues to spread. ASF has no vaccine and kills about 80 per cent of the pigs it infects. The Department of Agriculture, Water and the Environment notes:
ASF has never occurred in Australia. Its changing distribution means it’s a significant biosecurity threat to our country. An outbreak would be devastating for our pig production and health. It would also damage our trade and the economy.
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On 11 December 2019 the Australian Government announced $66.6 million to address the immediate threat of ASF, including more biosecurity officers and detection dogs at Australian airports.
Agricultural impacts from feral pigs
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Submitters noted that in horticultural and agricultural land, landholders suffer both direct and indirect monetary losses due to feral pigs.
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Direct losses arise from: pigs foraging on, rooting and trampling crops, resulting in crop destruction or reduced crop yield (including grains, sugarcane, vegetable and fruit crops); predation of livestock (in particular, lambs); damaging infrastructure such as fences, bores, drainage and irrigation, and roads and airfields; and competition with livestock for pasture.
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Direct pig control measures (for example, paying professional shooters to eradicate feral pigs) can also be costly for landholders. Preliminary results from ABARES' 2019 National Pest Animal and Weed Landholder Management Survey estimates that the total yearly expenditure on feral pig management by private landholders (agricultural establishments) is $47.7 million.
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CSIRO summarised indirect agricultural costs resulting from feral pigs as follows:
Indirectly, pig destruction might cause a shift in produce prices, with a flow-on cost increase to consumers. Farmers might switch to a crop that is less palatable to the pigs, but that also might earn less money per hectare. There are also flow-on effects of pig damage to infrastructure, such as machinery damaged on pig-rutted grounds, or slowed transport.
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Dr Heather Channon, National Feral Pig Management Coordinator, informed the committee that 'in 2002 the damage bill for feral pig activity, including infrastructure costs to agriculture, was conservatively estimated to be in excess of $100 million per year'.
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A review of the cost of pest animals in NSW and Australia released in 2016 estimated that, in the 2013–14 financial year, production losses to agricultural industries across Australia due to feral pig impacts amounted to $14.4 million. This included estimated losses of $4.9 million for wool producers, $2.9 million for sheep-meat farmers and $6.6 million for broad-acre wheat and barley producers.
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This analysis found that more than 90 per cent of this impact was felt in NSW, with an estimated $13.5 million in losses in that state.
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Agricultural lobby group AgForce Queensland recently estimated that feral pigs cost the agriculture sector in that State more than $70 million in 2018 alone.
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ABARES' national survey of agricultural land managers' pest and weed management in 2016 found that approximately 24 per cent of land managers surveyed were aware of the presence of feral pigs on their property in the previous 12 months, with around 32 per cent of these respondents considering that feral pigs were a major problem on their property.
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The geographic spread of land managers in the survey who reported feral pigs on their property is shown at Figure 2.1.
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The committee heard that local councils also invest significant resources to help control feral pig populations. Mr Travis Sydes, Regional Natural Asset and Sustainability Coordinator, Far North Queensland Regional Organisation of Councils, told the committee that Cairns Regional Council currently spends in the order of $250 000 annually on feral pig control, with expenditure by local governments in the broader Wet Tropics area totalling nearly $650 000.
Risks from disease outbreaks linked to feral pigs
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Exotic diseases, should they become established in Australia, have the capacity to seriously affect Australian agriculture through direct losses and loss of international markets. The Department of the Environment and Energy has noted that the economic impact of feral pigs 'would be severe in the case of outbreaks of exotic disease, particularly foot-and-mouth disease'. It explained further:
The Australian Bureau of Agricultural and Resource Economics and Sciences (ABARES) has modelled the cost of hypothetical foot-and-mouth disease outbreaks in Australia. It estimated that two small foot-and-mouth disease outbreaks in Queensland and Victoria would result in revenue losses of between $5.6 billion and $6.2 billion (in present value terms) over 10 years, depending on the response strategy used. In the event of a large multi-state foot-and-mouth disease outbreak, ABARES estimated revenue losses of between $49.3 billion and $51.8 billion (in present value terms) over 10 years.
…
If there were a foot and mouth disease outbreak in Australia, feral pigs could contribute to the persistence and transmission of the disease, because they are highly susceptible to the virus, they are abundant in northern Australia, they are often in close contact with livestock, and they are highly efficient amplifiers and transmitters of the virus. The wide range of landscapes/habitats in which feral pigs occur also makes it difficult to predict the spread and persistence of a foot and mouth disease outbreak.
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Australian Pork Limited (APL), the peak national representative body for Australian pig producers, submitted that feral pigs present a very real threat to the Australian pork industry because of their ability to transfer disease to domestic herds. It observed that Australia's commercial pig herd is free from many of the crippling diseases that affect major pig producing countries in Europe, Asia and the Americas, and that this status helps ensure Australian pork can remain competitive and desirable in export markets.
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APL noted that recent outbreaks of disease in feral pig populations in Belgium had resulted in significant and ongoing impacts on the pork industry in that country, and observed that Australia would be similarly affected should an exotic disease outbreak occur here:
The arrival of an exotic disease in the Australian feral pig population would likewise be devastating for the Australian pork industry. International biosecurity protocols typically rely on countries to prove 'freedom from disease' through evidence. Whilst commercial pig populations can be isolated and culled in the event of a disease outbreak, no such opportunity is possible with feral pigs, which can traverse significant distances and spread disease not only within their own populations, but to commercial pigs also.
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By way of example, APL estimated that if an outbreak of porcine reproduction and respiratory syndrome (PRRS) were to occur in feral pigs in Australia and spread to the commercial pig herd, this would add an estimated $77 million per annum to the cost of production for the pork industry, due to the need to undertake control and eradication measures. An ASF outbreak was estimated to cost the pig industry more than $2 billion.
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Ms Margo Andrae, Chief Executive Officer of APL, commented further at a public hearing:
Feral pigs are a very real threat to the Australian pork industry. Feral pigs share the same biological traits as domesticated pigs and can transfer disease through domestic herds. Today we face some of our greatest threats from diseases spreading throughout the world, like the global movement of African swine fever, which has resulted in the disruption of more than 30 per cent of the global pig population. The feral pig herd poses just as great a threat to the Australian natural environment and native wildlife. It is a significant threat to Australian agriculture and has been for many decades. From an animal perspective, an African swine fever or, for that matter, foot and mouth disease outbreak in Australia would be devastating. For producers and employers, the lasting financial, social and emotional devastation would be akin to the worst kind of natural disaster. From an on-property perspective, producers know the front gate is their last line of defence. On-farm biosecurity measures, which already represent best practice, are now at unprecedented levels. Producers are determined to secure their farms and their herds and their family's livelihoods.
Social and cultural impacts
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CSIRO noted that for remote and regional Aboriginal and Torres Strait Islander communities, pig rooting can affect vehicle access to their traditional lands as well as the values of culturally important wetlands, and can damage culturally important places and species. Further, pigs can also limit Aboriginal and Torres Strait Islander Peoples' access to foods through the damage they cause to the environment as well as their predation on the same food sources such as yams, roots, tubers and turtles.
Risks and impacts of feral goat populations
Environmental impacts
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As generalist herbivores, goats are able to colonise a wide range of habitats. Similarly to other grazing animals, feral goats can affect native flora and fauna by:
browsing and grazing on native vegetation, thereby preventing regeneration;
overgrazing, which causes soil erosion;
competing with other species for food and shelter;
introducing weeds through seeds carried in their dung; and
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The Invasive Species Council noted that goats are highly efficient herbivores, able to eat almost any vegetation, including foliage, bark, twigs, flowers, fruits, roots, plant litter and seeds on the ground. It explained further:
There are few plants that [goats] don't eat. They can significantly alter the composition of plant communities and, because they can survive on low‑nutrient fibrous vegetation and tolerate drought conditions, goats can cause irreversible changes to plant communities. They can stand on their hind legs or partially climb trees to browse, and are able to access difficult habitats such as rugged gorges, breakaways and stony ranges, which often support rare remnant assemblages of plants and animals.
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The Adelaide and Mount Lofty Ranges Natural Resources Management Board submitted that a particular concern in that region is the tendency of feral goats to inhabit relatively small areas of steep, rocky terrain:
[T]his has the effect of concentrating their impacts (browsing, trampling etc) to already fragile environments prone to disturbance and erosion. In particular, several of these areas include habitat for nationally rated orchids and regionally rated bird species.
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Mr Sydes of the Far North Queensland Regional Organisation of Councils drew the committee's attention to the impact of feral goats on offshore islands within the Great Barrier Reef, which often contain very significant species and populations and are also connected directly to the reef:
Feral goats, particularly in concentrated populations, have the ability to denude a whole island of vegetation, causing significant soil erosion as well as the direct impact on the vegetation itself and the flow-on ecosystem impacts from there.
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There are 99 threatened plants and 11 threatened animals impacted by feral goats in Australia. This includes the malleefowl, which is listed in the Australian Government's Threatened Species Strategy. The Invasive Species Council noted that habitat degradation and resources competition by feral goats is a significant threat for at least six threatened rock wallaby species or subspecies in Australia.
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Feral goats are prone to a number of diseases currently present in Australia, including Q fever, tetanus, leptospirosis, brucella melitensis, hydatids, pulpy kidney, blackleg, and various parasitic worms. Feral goats may also harbour and transmit several significant exotic diseases in the case of an outbreak, including foot and mouth disease, rabies and rinderpest.
Agricultural and economic impacts
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Negative impacts from feral goats on agricultural enterprises occur primarily because goats compete for feed resources with farmed sheep and cattle in semi-arid areas.
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ABARES' national survey of agricultural land managers' pest and weed management in 2016 found that approximately seven per cent of land managers surveyed were aware of the presence of feral goats on their property in the previous 12 months, with around 20 per cent of these respondents identifying feral goats as a problem on their property.
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The geographic spread of land managers in the survey who reported feral goats on their property is shown at Figure 2.2.
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A review of the cost of pest animals in NSW and Australia released in 2016 estimated that in the 2013–14 financial year, production losses to agricultural industries across Australia due to feral goat impacts amounted to $6.8 million. This included estimated losses of $4.3 million for wool producers, $0.3 million for sheep-meat farmers and $2.2 million for beef cattle farmers.
Commercial goat harvesting
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Australia is also home to a significant commercial goat meat industry. This industry includes both farmed goats and harvested wild (feral) goats. The national TAP for unmanaged goats articulates this distinction further:
[T]he term 'wild harvest' refers to both field shot animals and live captured animals that are immediately shipped off the property. Farmed or domestic animals are identified as being both bred and maintained in an enclosed system. Goats are identified as ranched or 'managed' animals if they are captured live and held on the property within goat-proof yards to adjust to captive conditions, and maintained to match market demand and supply.
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Feral goats are valued by some landholders as a harvestable resource, particularly during periods of high goat prices. The majority of goat meat in Australia is harvested from semi-wild rangeland goats, with a 2017 survey of goat meat producers in New South Wales finding that 71 per cent of enterprises operated in this manner, with only 29 per cent operating a managed or semi-managed farming enterprise.
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The goat industry in Australia slaughtered 1.54 million head in 2018, a reduction of 20 per cent from 2017 due to poor seasonal conditions. Approximately 90 per cent of goat meat produced in Australia is exported, while around 10 per cent is utilised domestically. The vast bulk of exported goat meat (around 98 per cent) consists of frozen whole carcasses, with the remaining proportion consisting of live goat exports.
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Australian goat meat exports were valued at $182.6 million in 2018, down from approximately $257 million in 2017. The CSIRO commented in its submission that ABARES trade data shows Australia is the largest global exporter of goat meat because of harvesting from feral goat populations.
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The interaction between commercial considerations for agricultural enterprises harvesting feral goats, and imperatives to reduce the threats to biodiversity created by the presence of feral goats, is discussed further in Chapter 4.