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Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.

Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.

Threat Abatement Plan for Competition and Land Degradation by Feral Goats

Biodiversity Group Environment Australia, 1999
ISBN 0 642 54634 7

Factors Affecting Goat Control

Commercial interests

Commercial interest in goats is based upon both a domestic goat industry and a wild harvest industry. Given that commercial harvesting of feral goats can reduce density, it is feasible to assume that such a measure has the potential to contribute to conservation objectives (Choquenot et al, 1995). While the presence of a commercial option for use of feral goats presents some opportunities for reducing costs of control it also presents a potentially confounding factor to effective control. Similarly the presence of a domestic goat industry also presents a confounding factor to management of feral goat populations by providing a potential source of new populations or reinfestation of controlled areas if the domestic stock are not adequately managed. The risks associated with both of these situations can be estimated and are amenable to management through appropriate actions.

Effective management of domestic goats depends on having adequate fencing and a maintenance regime to ensure that the fences are not breached. Domestic goat facilities near environmentally sensitive areas or areas which could act as refuges for escapees (for example broken ranges which are difficult to access) should be assessed for risk. The level of security required to keep the goats on the property should be determined by the level of risk posed by any potential escape. Currently no State or Territory has provision for such an assessment process.

Commercial use of feral goats can involve using field shot animals to supply a game meat market or live goats for a live export trade or to supply abattoirs producing meat for a chilled or frozen meat market. In addition, the development of a domestic goat industry has been partly supplemented with breeding stock derived from live captured feral animals. For the purposes of this plan the term 'wild harvest' is used to refer to both field shot animals and live captured animals which are immediately shipped off the property. Farmed or domestic animals are identified as being both bred and maintained in an enclosed system. Feral animals that are live captured and held on the property within goat proof yards to adjust to captive conditions, and maintained to match market demand and supply, are identified as ranched animals.

A significant problem with managing feral goats is the ambivalent attitude of many land managers. Feral goats are perceived as both a competitor to other livestock industries and a potential alternative source of income. The nature and significance of feral goat impacts on biological diversity is often unclear. This is particularly so where endangered or vulnerable species identified as being threatened by the presence of goats are not present. Such views must be resolved to enable clear management outcomes to be defined. For example, if feral goats are simply seen as a pest and competitor with other livestock industries, the desired management outcome will be to reduce numbers to the lowest level economically achievable. In contrast, where feral goats are seen as an economic resource, and managed to maximise income from them, the desired management outcome may be to maintain high densities of animals to maintain high offtake rates. In other words, the management outcomes in terms of population densities for these two management aims are diametrically opposed. The presence of feral goats on the conservation estate is generally seen as incompatible with the management of these areas for conservation of biological diversity and maintenance of normal ecosystem functioning. In these areas the desired management outcome is to reduce feral goat numbers to a level at which they have no significant impacts on these values.

Similar problems have arisen in the management of the commercial species of kangaroos where they are seen both as a pest and as a valuable natural resource. The significant difference with kangaroos is that they are native species for which the primary aim is to ensure their conservation throughout their distributional ranges. Management programs for these species have established two subsidiary aims: to mitigate damage caused by the species, and where appropriate to manage them as a sustainable natural resource. The Commonwealth has promoted a regional approach to kangaroo management. This allows the relative priority given to each of the two secondary aims to be adjusted to regional circumstances and priorities. By establishing the relative regional priorities of damage mitigation and sustainable resource use, the specific management outcomes in terms of population regulation can be specified and appropriate harvest quotas established.

A similar approach to management of feral goats would clarify the management aims for particular regions and enable land managers to coordinate their actions. It would also assist in establishing regional conservation priorities and integrating management of feral goats across all land tenures.

The development of an industry dependent upon a regular supply of feral goats is likely to lead to pressure to maintain densities of goats incompatible with sustainable land management. The Standing Committee on Agriculture and Resource Management at its meeting in October 1994 recognised this problem. It supported the development of industries based on the use of feral animals but agreed that such development should aim to eliminate rather than encourage the propagation of those species in the wild. The move from a wild harvest industry to a domestic goat industry is also more compatible with establishing and maintaining regular markets for goat products. The absence of a nationally agreed management framework for transforming the feral goat industry into a coherent domestic goat industry is a significant impediment to rational management of uncontrolled feral goat populations.

From a national perspective, it may be that commercial harvesting of feral goats is not a sufficient measure to control the population. This could be because of population dynamics and the fact that the industry cannot match market demand due to the variability of quality and supply of animals. Nevertheless, local control may be possible through commercial harvesting where access to markets, and adequate prices, allow reduction of feral goat numbers to very low levels.

To ensure that feral goat control and management integrates conservation and primary production outcomes, both the Australian and New Zealand Environment and Conservation Council and the Agricultural Resource Management Council of Australia and New Zealand should cooperatively develop national guidelines for the wild harvest of feral goats. These guidelines should also provide an agreed national policy framework for transforming the wild harvest industry into a domestic goat industry.

Legal status

Comments provided by a number of respondents to the draft threat abatement plan highlighted the problem of defining the transition from feral animal to domestic animal. Across Australia, the legal status of the feral goat varies. Commonwealth legislation identifies feral goats as contributing to a key threatening process but is otherwise silent on their legal status. Queensland, South Australia and Western Australia define feral goats as pests and prescribe actions to manage them. Other States and Territories do not define feral goats as a class and do not prescribe particular action for land managers. This lack of consistency in the legal definition of what constitutes a feral goat, and variation in the requirements imposed on land managers, impede actions to ameliorate their impacts on endangered species. It also impedes development of a national approach to commercial use of feral goats and transformation of a wild harvest industry into a domestic goat industry.

Cost efficiency

The level of control that may be achieved will be determined both by the cost of control and the funds available. Table 2 summarises the available data on the costs of various control techniques.

Management strategies including both helicopter shooting and mustering are thought to achieve the highest population reductions for the minimum net cost (Parkes et. al. 1996). In general, the cost of helicopter shooting rises exponentially with decreasing animal density (Parkes, 1993b; Maas and Choquenot, 1995). However, it is a very effective technique (as the population reductions indicate) and it can be used in all terrains except those with heavy vegetation. Mustering does not reduce goat populations to the same extent as helicopter shooting. However, this is offset by the lower cost, with cost effectiveness depending on the price of goats at the time.

Trapping, like mustering, may make a profit due to sale of captured animals, but can only be used during dry times in places where access to water can be controlled. The Judas goat technique is expensive and is only appropriate where protection of native species and ecological communities can only be achieved with extremely low goat densities. Ground based shooting is not appropriate as the primary means of control in a pastoral setting, because of high labour costs, but may be a useful supplement if conducted as a commercial wild harvest for game meat or hides. In densely vegetated areas, such as Tasmania's forests, it is the only available technique.

Table 2. A summary of the initial densities, levels of reduction and costs of various goat control techniques used in semi-arid environment.
Technique
Density/km2
% Reduction
Cost per Goat
Reference
Helicopter Shooting
6.22 45 3.95 Naismith, 1992
1.19 70 7.16 Parkes et. al. 1996
26.00 85 7.30 Maas and Choquenot, 1995
13.69 Shepherd, 1996
12.84 Shepherd, 1996
6.99 99 15.00 Henzell, 1984
1.85 13 19.70 Edwards et. al. 1994
14.50 49 2.91 Pople et. al. 1996
5.10 75 4.62 Pople et. al. 1996
4.75 100 19.10 Pople et. al. 1996
Mustering
40.00 80   Henzell, 1984
2.73 32 +1.00 Edwards et. al. 1994
23.00 26 +4.18 Brill, pers. comm
7.50 26 +3.50 Brill, pers. comm
+4.00 Parkes et. al. 1996
+1.93 Miller et. al. 1998
Trapping
    +5.90 Parkes et. al. 1996
      +2.08 Miller et. al. 1998
Ground Shooting
    2.94* Dodd and Hartwig 1992
  5.60 0 774.00 Edwards et. al. 1994
1.07 Frazer, 1992
Judas Goat
0.1-2.0 100 70.00 Henzell, 1992b#

*does not include the cost of labour;
# not based on an actual control campaign, but are a theoretical calculation;
+ income resulting from the sale of the feral goats

Animal welfare

Feral goat control techniques have raised concerns with animal welfare organisations particularly where captured goats are commercially used. The National Consultative Committee on Animal Welfare (NCCAW) considers it essential that animal welfare concerns be given equal weighting with other factors in assessing management options (O'Flynn, 1992). Both NCCAW (O'Flynn, 1992) and the RSPCA (Peters, 1992) opposed the capture and transport of feral goats as then practised because of high mortality rates.

Other techniques that are considered unsuitable on animal welfare grounds are denial of water as a means of killing animals; and trapping without prompt destruction or removal (Peters, 1992).

In 1991 the Standing Committee on Agriculture released a model code of practice entitled Feral Livestock Animals- Destruction or Capture, Handling and Marketing to promote the welfare of feral livestock animals which are captured or destroyed. Adherence to this code of practice is recommended when feral goats are commercially used or destroyed. Further improvements to animal welfare should be based on regular monitoring and assessment of the code's effectiveness.

Helicopter shooting is accepted as the most efficient method for killing feral goats in rough country and NCCAW notes that it can be a humane technique if done by appropriately trained and equipped marksmen (Peters, 1992; O'Flynn, 1992). Many Government agencies now require all personnel shooting feral animals from helicopters to undergo an approved training course.

To ensure the most humane methods are used animal welfare agencies should be consulted and involved in the design of feral goat management plans.

Water management

Artificial watering points are so numerous in the arid and semi-arid rangelands of Australia that their spacing is rarely more than 10 kilometres apart (James et. al. 1997). This water benefits all large herbivores, allowing them to survive in habitats that would not otherwise be suitable (Parkes et. al. 1996). This has led to a much greater total grazing pressure, which has irrevocably changed the character of the landscape (James et. al. 1997). Landsberg et. al. (1997) found that many native species were disadvantaged by providing water and recommended that artificial waters be closed to address this problem. Closing artificial water points is possible in conservation areas after unwanted herbivores have been removed by humane methods (Parkes et. al. 1996).

While the permanent closure of artificial water points may be an option on the conservation estate, it is not an option on land being managed for livestock production. In these latter areas the focus will need to be on improved management of water points to minimise waste and more effectively manage livestock and grazing pressure. Current efforts to cap the bores throughout the Great Artesian Basin are likely to contribute in time to more effective management of both domestic livestock and feral goats. In all cases the impact of improved management or closure of water points on non-target species would need to be assessed before taking this action.

Interaction with other herbivores

The presence of too many herbivores in an area can lead to overgrazing and land degradation. Whereas domestic livestock numbers can be actively controlled by land managers, there are a range of other herbivores, including feral goats and rabbits in particular, that may be significant contributors to total grazing pressure but are not as easy to control. These species are not normally considered in determining total stocking rates on an area but their numbers, combined with domestic livestock numbers, may exceed the safe stocking rates for the land. The impacts of these species will be most pronounced during drought when animals will be competing for declining food and water resources. Goats are known to persist longer than sheep or kangaroos during drought conditions and this is likely to exacerbate their contribution to land degradation.

As goats are generalist herbivores they can affect a wide range of plant species including grasses, forbs, herbs and perennial shrubs and trees. Parkes et. al. (1996) noted that the contribution of feral goats to total grazing pressure could be assessed by estimating the net annual aboveground productivity of vegetation eaten. Using this method, Parkes et. al. illustrate that goats at average densities of two per square kilometre consume 0.73 tonnes of dry matter per year, an order of magnitude less than average densities of rabbits (about 300 per square kilometre) that consume 10 tonnes of dry matter per year. Although this comparative figure may suggest that feral goats are only a minor contributor to land degradation, the fact that goats can survive on a wide range of plants means that their impacts may be greater than other herbivores' during periods of drought.

Decisions upon the effective allocation of resources to control feral herbivores in an area require a more detailed understanding of the interactions between the individual species.