Biodiversity KEY5 FACTS as hunting), as pasture grasses or as aquarium species Introduced (in the case of some marine species). They have also • Introduced species are been introduced accidentally, such as in shipments of recognised as a leading Species imported grain or in ballast water. cause of biodiversity loss Introduced plants, or weeds, can invade and world-wide. compete with native plant species for space, light, Trends water and nutrients and because of their rapid growth rates they can quickly smother native vegetation. • Rabbit numbers: a DECLINE since Similarly to weeds, many introduced animals compete introduction of Rabbit Haemorrhagic with and predate on native animals and impact on Disease (RHD, also known as calicivirus) native vegetation. They have high reproductive rates although the extent of the decline varies and can tolerate a wide range of habitats. As a result across the State. they often establish populations very quickly. •Fox numbers: DOWN in high priority Weeds can provide shelter for pest animals, conservation areas due to large-scale although they can provide food for or become habitat baiting programs; STILL A PROBLEM in for native animals. Blackberry, for example, is an ideal other parts of the State. habitat for the threatened Southern Brown Bandicoot. This illustrates the complexity of issues associated •Feral camel and deer numbers: UP. with pest control and highlights the need for control •Feral goat numbers: DECLINING across measures to have considered specific conservation Weed affected land – Mount Lofty Ranges the State. outcomes to be undertaken over time and to be Photo: Kym Nicolson •Feral pig numbers: UNKNOWN. accompanied by habitat restoration outcomes. Weeds can also increase the risk of wildfire and • Mundulla Yellows and Phytophthora can pose a serious threat to agriculture, forestry and cinnamomi: SPREADING. pastoralism. • Extent of terrestrial pest plants: INCREASING. Introduced fish pose a significant environmental problem for inland rivers and streams. Many were Goal introduced last century for recreational fishing and have subsequently spread into inland waterways, where they Minimal impact of pest animals and pest plants on compete with native fish for food and habitat and can primary industries, on natural ecosystems, and on have an adverse impact on water quality. public safety in South Australia. Some native plant and animal species become Animal and Plant Control Commission, Strategic pests if they are introduced to areas beyond their Plan 2001–2003 natural range. For example, the Cootamundra Wattle originating from the eastern states is invading What are the issues? bushland in South Australia. The aim of pest control is to reduce and maintain Species have been deliberately introduced to Australia pest density at levels where the benefits for specific for a wide variety of reasons including for use as garden conservation goals are maximised in comparison to plants, domestic or companion animals, for sport (such the costs of control. Pest control is most effective 104 INTRODUCED SPECIES Findings Making progress Naturally recurring outbreaks of Rabbit Haemorrhagic Disease (RHD) continue to hold rabbit numbers at greatly reduced levels across most of the State compared to before the introduction of RHD. Feral goat and fox numbers in the Flinders Ranges are generally low as a result of activities undertaken during Operation Bounceback, an ecological restoration program. This is having a positive impact on Yellow- footed Rock-wallaby populations and native vegetation condition. Biological control agents (insects and fungi) are being dispersed to assist in the management of Boneseed, Bridal Creeper, Gorse, Horehound, some species of Thistle and Salvation Jane, with positive results seen so far for the control of Horehound and Bridal Creeper. Rabbit in the Flinders Ranges Attention required Photo: Trevor Naismith Mundulla Yellows and Phytophthora cinnamomi pose a significant threat to our native plants. A major research program is investigating the causes, impact and management of Mundulla Yellows. A Threat Abatement Plan is being implemented for Phytophthora and there will be follow-up work to monitor its effectiveness and potential impact on native plants and animals. Despite control efforts, most terrestrial weeds remain a problem. Feral camel and deer numbers are increasing and there is, as yet, no coordinated approach to their control. The impact that introduced fish are having on the ecology of freshwater rivers, streams and the sea is poorly understood. Lack of understanding of appropriate management actions may risk the survival of some native fish, native aquatic plants and other aquatic animals and their habitats. There is limited information on the distribution of Mesquite, which occurs in scattered locations in the Far North. This weed has the potential to significantly impact on biodiversity and livestock industries. What more should we be doing? The Environment Protection Authority recommends that: 5.1 The level of research into Mundulla Yellows is maintained and enhanced to determine its cause, methods of spreading and impact on biodiversity. More research is required on the impact of Phytophthora cinnamomi on native plants and animals in South Australia. The effectiveness of risk management strategies for Phytophthora cinnamomi should also be monitored. 5.2 As a matter of urgency, integrated management programs for camels and deer be developed and implemented, incorporating involvement from all stakeholders. 5.3 The Operation Bounceback and Ark on Eyre programs are continued, and that these programs provide integrated models for all future introduced species management programs. 5.4 Measures are introduced to prevent the plant nursery industry from engaging in the sale of existing weeds, potential weed species and the spread of plant pathogens. 5.5 Programs are established to improve our understanding of the impact that introduced fish are having on the ecology of freshwater and marine environments. 5.6 Further research is undertaken to determine the extent of Mesquite in order to develop management strategies. where it is conservation outcome-focused – aimed at • Number of new incursions of pest plants reducing the impact of pests rather than simply and animals and responses (new indicator) reducing pest density. Newly emerging pest plants and animals See also chapters on Native Vegetation; and provide an additional threat to biodiversity. Threatened Species. Environmental indicators What is the current situation? PRESSURE INDICATORS PRESSURE INDICATOR: Distribution of • Distribution of key terrestrial and marine key terrestrial pest animals pest animals and plants (new indicator) The distribution of pest plant and animal species The most significant pest animals in South Australia that are known to be causing significant threats to that cause damage to the terrestrial environment are biodiversity provides an indication of the extent of rabbits, foxes, feral goats, deer, camels, cats and pigs. the impact that these species are having on the Competition and land degradation by rabbits and environment and on native plants and animals. feral goats, and predation by the European Red Fox Introduced species compete for resources often and feral cats have been recognised as key threatening to the detriment of native species. processes under the Commonwealth Environment STATE OF THE ENVIRONMENT REPORT 2003 105 5 Biodiversity KEY FACTS Protection and Biodiversity Conservation (EPBC) Act East, Mid North, Murraylands, Mount Lofty Ranges 1999. National Threat Abatement Plans have been and Kangaroo Island. • The European Rabbit is still produced for these species. See the State of the It is believed that numbers have increased our most widespread and Environment 2003 Supplementary Report for maps of over recent years as a result of escapes and some destructive pest animal. the distribution of key terrestrial pest animals. deliberate releases from deer farm enterprises, reduced hunting efforts and new habitats in European Rabbit Oryctolagus cuniculus •Positive results have been agro-forestry plantations. achieved for Yellow-footed This species is still Australia’s most widespread and Control is generally ad hoc although there have Rock-wallaby populations as a destructive pest despite the introduction of been some attempts by Animal and Plant Control result of feral goat and fox Myxomatosis and RHD. Rabbits are found throughout Boards to introduce cooperative control programs control in the Flinders Ranges. most of South Australia. involving landholders and recreational hunters. RHD is now common throughout the State •Bridal Creeper is considered following its introduction in 1995. It is estimated that Feral Camels Camelus dromedarius one of the most significant RHD has reduced rabbit numbers in South Australia by Feral camels occur in the Far North of the State. weed threats to biodiversity in more than 70% since its introduction, although the Following a number of good seasons it is estimated that South Australia. extent of the decline varies geographically across the their numbers have doubled over the last eight years. State. In high rainfall areas rabbit numbers do not An aerial survey of camels and other large feral appear to have declined and may have increased animals was conducted in 2002 in the Simpson Desert (Animal and Plant Control Board, pers. comm.). Region of South Australia (Axford et. al., 2002). The camel Traditional methods of control (poison