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4.2 Pest animals

Summary points

• Pest animals are a threat across the Australian landscape.
• Elimination of most pest animals in not possible - we need to focus on effectively manage their impacts.
• In NSW parks, pest animals are reported by park managers as the second most common threat to park values.
• Strategic prioritisation of pest animal management occurs for all parks through regional pest management strategies.
• Park managers report they are stopping pest animal impacts from increasing in over 94 per cent of the park system by area and are concentrating on controlling the remaining impacts.
• Collaborative actions with neighbours are essential for successful pest control.

Introduction

Pest animals damage aquatic and terrestrial ecosystems. Introduced predators, such as foxes and feral cats, can decimate populations of native species and are believed to have caused the extinction of a number of native prey species. Introduced herbivores, such as feral goats, rabbits and deer, can cause extensive damage to native vegetation and soils through grazing, trampling and digging. They can suppress native herbivore populations by competing for food. They can also support high densities of introduced predators, which then also prey on native species. Pest animals continue to have an effect on many threatened species: across NSW, 28 pest animal species have been identified as posing a threat to at least one endangered and/or vulnerable species (Coutts-Smith & Downey 2006). Some of these pest animals are an issue across the state, while others are becoming an increasing problem (see the cane toad case study).

Pest animals can also degrade sites of cultural significance, such as Aboriginal rock art sites or historically significant structures. Furthermore, pest animals such as wild dogs and feral pigs pose a major threat to agriculture, prey upon native species and contribute to soil erosion.

Some pest animal species have been listed as key threatening processes under the Threatened Species Conservation Act 1995.

Status and trends

Pest animals are a threat across the Australian landscape. As shown in the DECCW Protecting our national parks from pests and weeds report, species such as foxes occur throughout NSW, while feral goats and pigs can be found in large parts of western NSW. Pest animals simply do not observe land management boundaries.

The most cost-effective way to manage pest animals is to prevent initial incursions. DECCW works with other agencies to prevent the introduction of new pest into the wild and to respond rapidly when new incursions occur. The Australian Government and Industry and Investment NSW have the lead roles for 'biosecurity' and emergency responses to new incursions.

Many pest species, however, are already widely established in NSW and their complete eradication over wide areas of different land tenure is rarely practicable e.g. foxes and wild dogs. It is therefore necessary to prioritise pest management efforts and allocate resources to those areas where they will be of greatest benefit. The NSW Fox Threat Abatement Plan (Fox TAP) is a good example of how control effort has been prioritised. The targeted Fox TAP identifies 81 priority sites for fox control across NSW and includes recovery actions for 34 threatened species (11 mammals, 15 birds and eight reptiles). Fox control and/or monitoring of threatened species populations are in place at most of these sites, in collaboration with other agencies, community groups and private landholders. The Fox TAP is currently being reviewed and a revised plan will be available in 2010.

DECCW undertakes extensive planning across the NSW park system to prioritise and manage pest animal impacts. All parks within the system are covered by a regional pest management strategy, which aims to maximise the effectiveness of pest animal management through regional programs and cooperative approaches with neighbours. These strategies also recognise that management needs to reflect the extent to which the pest animal is distributed and that different approaches need to be applied depending upon whether the threat is localised or widespread. For more information on how the NSW Government is managing invasive species impacts, see the NSW Invasive Species Plan 2008 - 2015.

In NSW parks, pest animals are reported by park managers as the second most common threat to park values: 62 per cent of all parks identify pest animals as a threat to values that needs to be actively managed. Like other threats, however, pest animals are not uniformly distributed across NSW parks, their extent varying due to the nomadic nature of many species.

Park managers report that impacts from pest animals to park values are being effectively managed (impacts are negligible, diminishing or stable) in 94% of the park system. Planning processes, such as threat abatement plans and regional pest management strategies are used to identify priorities for managing pest animal threats. Other processes, such as regional operations plans, are in place to support park managers in implementing pest animal management programs.

Monitoring is an ongoing component of many of our pest animal management programs to ensure they are delivering the desired outcomes. For example, a key component of the Fox TAP is monitoring the response of priority threatened species and foxes to control activities. Best Practice Guidelines for monitoring responses are being developed as part of revisions to the Fox TAP.

Effective management actions require collaborative approaches with other agencies, private land managers, land holders and community groups. DECCW is a major contributor to a number of cooperative programs, such as the implementation of the NSW Invasive Species Plan, which identifies state-wide priorities for managing both pest animals and weeds, and the NSW Natural Resource Management Monitoring, Evaluation and Reporting (MER) Strategy, as it relates to biodiversity conservation. These strategies guide DECCW's management of pest animal impacts into the future and are illustrative of our successful relationships with other land managers working towards a common goal.

Future directions

Priorities for pest management within the park system are identified in the Threatened Species Priorities Action Statement, regional pest management strategies and the State of the Parks report titled "Protecting our national parks from pest and weeds". Some of the priorities identified in these documents include:

• Lead implementation of the NSW Invasive Species Plan as it relates to biodiversity conservation.
• A revised Fox TAP to be released in 2010. Its implementation will be a priority to protect 34 threatened species identified as being most at risk from fox predation.
• Prepare a Threat Abatement Plan for feral goats. Develop and implement cost-effective methods for monitoring goat density and biodiversity response to goat control to demonstrate the effectiveness of management programs.
• Protect priority threatened species from the impacts of other pest animals listed as key threatening processes such as feral pigs, deer and rabbits.
• Work with the Department of Industry and Investment, Livestock Health and Pest Authorities and wild dog control associations to minimise stock losses caused by wild dogs. At the same time develop more effective and/or alternative methods for controlling wild dogs e.g. M44 ejector device and llamas as guard animals.
• Contribute to research that improves our understanding of the interactions between climate change, biodiversity and pest animals.
• Work with other agencies and the community to prevent the spread of cane toads into new areas (coastal areas south of Yamba); continue to promote the Trap that toad teacher resource to NSW school students; undertake regular cane toad surveys on the North Coast to gain a better understanding of the distribution of cane toads; undertake regular community-based 'musters' to reduce cane toad populations at priority sites.
• Identify priorities for the control of feral cats based on the fauna most susceptible to cat predation; identify priority sites for feral cat control based on these priorities in anticipation of new feral cat control methods becoming available.

Further information

• The NSW DECCW website has extensive information on pest animals in NSW including links to research activities that DECCW is involved with. Species specific information is also available for agricultural pests, cane toads, feral bees, feral cats, feral deer, feral goats, feral horses, feral pigs, foxes, introduced ants, introduced rats, plague minnow, rabbits and wild dogs.
• See the "Conserving and managing natural and cultural values across the landscape" chapter of our DECCW Annual reports for examples of recent pest animal and weed management actions.
• Protecting our national parks from pest and weeds(2006).
• The NSW State of the Environment Report: Section 7.3 'Reserves and Conservation'
• NSW Invasive Species Plan, which provides actions that aim to prevent and effectively manage the introduction and spread of invasive species.
• Coutts-Smith, A.J. & Downey, P.O. (2006). Impact of Weeds on Threatened Biodiversity in New South Wales, Technical Series no.11, CRC for Australian Weed Management, Adelaide.

Case study

Managing feral goats in Western NSW

Goats are an introduced species in Australia and feral populations have become established from escaped domestic stock. Feral goats can cause significant environmental impacts, such as grazing and browsing causing changes to vegetation cover and their hard hooves enhancing soil erosion. Feral goats are considered a major threat to biodiversity in NSW. They are believed to impact on 94 threatened species, populations and communities listed under the NSW Threatened Species Act; fourth after lantana, foxes and feral cats (see 'The threat posed by pest animals to biodiversity in New South Wales').

Feral goats are found throughout NSW, but population characteristics differ across the state due to differences in climate, topography and land use. Home ranges for feral goats increase as rainfall decreases, thus feral goats are more nomadic and have larger home ranges in particularly arid areas. In eastern parts of the state, feral goats are limited by humans and wild dogs and occur at high density in areas of native vegetation in rugged terrain where they can escape these predators. In western NSW, the lower population density of humans and wild dogs have allowed for contiguous populations of feral goats across the rangelands.

In these areas, it is food and, more importantly, water that limits the distribution of feral goats. As a result, trapping at artificial watering points can be very effective at removing large numbers of goats with minimal effort once the traps are constructed. In the far north west of NSW near Bourke, contractors engaged by DECCW have removed over 23,000 goats from four remote reserves during 2009. Due to its success this program was extended into 2010.

The provision of artificial watering points such as ground tanks and bores however, has led to the establishment of neighbouring populations throughout the arid and semi-arid rangelands. Challenges therefore exist with areas being rapidly reinvaded after control activities have taken place. Eradication of these goat populations is therefore virtually impossible.

One potential solution to reducing reinvasion is to manipulate feral goat access to water. Research by DECCW in Nocoleche Nature Reserve and Mutawintji National Park shows that feral goats concentrate between one and two and rarely more than three kilometres from water. By manipulating access to artificial watering points to force goats to travel more than three kilometres, either through decommissioning or the strategic use of fences, large areas of conservation reserves may become unsuitable for goats without affecting native species (such as kangaroos) that have evolved for these naturally more water-restricted environments.

DECCW is currently investigating the effectiveness of manipulating access to artificial watering points to control feral goats in Culgoa, Gundabooka and Paroo-Darling National Parks and Nocoleche Nature Reserve in Western NSW. DECCW is looking at the responses of feral goats, kangaroos and emus to fencing watering points, cutting drainage lines and constructing eight kilometre stretches of goat-proof fencing in areas where artificial watering points occur on nearby neighbouring properties. Animals are monitored through visual driving transects and established 100m dung count transects in spring and autumn before and after water manipulations. Determining how goats change their behaviour in response to water manipulation is only the first step in investigating this approach.