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infected <strong>and</strong> sterilised rabbits required for population decline is much lower than if only one antigen were used. No species o<strong>the</strong>r than <strong>the</strong> rabbit would be at risk, because <strong>the</strong> system would possess double species-specificity, <strong>the</strong> species-specific virus <strong>and</strong> <strong>the</strong> species-specific reproductive antigens. The concept is a humane method <strong>of</strong> rabbit control in that it reduces rabbit numbers without increasing <strong>the</strong> incidence <strong>of</strong> myxoma infection. It is a long-term project that will require years <strong>of</strong> research <strong>and</strong> development. An effective virus would need to be approved for release by <strong>the</strong> Office <strong>of</strong> <strong>the</strong> Gene Technology Regulator (OGTR) after exhaustive investigations into its stability, species-specificity <strong>and</strong> safety. For such an immunocontraceptive virus to be effective it must produce a long-lasting immune response. Initially it would be advantageous if <strong>the</strong> virus could provoke an adequate immune response in a second infection in rabbits that have had myxomatosis previously. Effective dissemination <strong>of</strong> <strong>the</strong> virus into <strong>the</strong> field in Australia will be a formidable challenge, because it will need to be able to spread <strong>and</strong> infect a high proportion (more than 80 percent) <strong>of</strong> rabbits in competition with existing field strains <strong>of</strong> myxoma virus (Parer et al. 1985). Breeding by <strong>the</strong> European rabbit flea, a major vector <strong>of</strong> myxoma virus is linked intimately with <strong>the</strong> breeding <strong>of</strong> rabbits (Mead-Briggs 1977). Therefore, flea populations may decline after <strong>the</strong> introduction <strong>of</strong> an immunocontraceptive virus. Intensive annual introductions <strong>of</strong> <strong>the</strong> immunocontraceptive virus may be needed, <strong>and</strong> this would add significantly to <strong>the</strong> cost. A substantial reduction in fertility may eliminate rabbits from marginal habitats, such as subalpine areas, where females produce only 15 young per year (Gilbert et al. 1987). In environments more favourable to rabbits, an effective immunocontraceptive virus would make <strong>the</strong> rabbit problem more amenable to solution by conventional techniques. The rate at which wild rabbits would be selected for genetic resistance to <strong>the</strong> modified virus is not known. Research by <strong>the</strong> Pest Animal Control CRC has discovered encouraging results with <strong>the</strong> achievement <strong>of</strong> temporary anti-fertility in up to 70 percent <strong>of</strong> female rabbits. However, permanent infertility has proved elusive <strong>and</strong> <strong>the</strong> investment into this research will be scaled down <strong>and</strong> not carried forward into <strong>the</strong> new Invasive Animals CRC. Integrated control It is clear from <strong>the</strong> information provided above that when any one technique <strong>of</strong> rabbit control is used in isolation it is less effective than when two or more techniques are carefully combined (Cooke 1993). When reliance is placed on only one technique <strong>and</strong> follow-up control is not implemented, <strong>the</strong> initial gains made in controlling rabbits are soon lost; as rabbits will readily recolonise an area in <strong>the</strong> absence <strong>of</strong> any fur<strong>the</strong>r control (Parer & Milkovits 1994, Williams & Moore 1995). Integrated rabbit control in Australia normally involves a significant reduction <strong>of</strong> <strong>the</strong> population, followed by harbour destruction <strong>and</strong> subsequent follow-up control. The initial population reduction may be brought about by an effective outbreak <strong>of</strong> myxomatosis or RCD, poisoning, or even a drought. Techniques such as harbour destruction, poisoning, warren ripping, <strong>and</strong> fumigation may be effective in keeping rabbit populations low (Williams et al. 1995). Cooke (1993) demonstrated <strong>the</strong> value in following up an effective myxomatosis epidemic with ripping in South Australia. A property where warrens were ripped following a large decline in rabbit numbers remained almost rabbit free many years later, but a nearby property that was not ripped, experienced high rabbit numbers 132
again soon after, even though myxomatosis re-occurred at both sites in <strong>the</strong> following year. Similar results were obtained from a study in central Australia that assessed <strong>the</strong> <strong>impact</strong>s <strong>of</strong> ripping warrens on rabbit persistence (Dobbie 1998). Williams et al. (1995) proposed <strong>the</strong> following hypo<strong>the</strong>tical integrated control scenario based on biocontrol <strong>and</strong> current techniques. If an effective immunosterilising virus can be produced <strong>and</strong> approved for release, <strong>and</strong> if permission is given to release RCD, simultaneous <strong>and</strong> intensive release <strong>of</strong> both viruses over very large areas would seem to be an effective strategy for <strong>the</strong> following reasons: <strong>of</strong>ten high proportions <strong>of</strong> adult rabbits have antibodies to myxoma virus; RCD could kill <strong>the</strong>m within a few days; <strong>the</strong> immunosterilising myxoma virus <strong>the</strong>n could kill or sterilise young rabbits. An intensive maintenance warren ripping program could take maximum advantage <strong>of</strong> epizootics <strong>of</strong> myxomatosis, RCD or both. A follow-up warren ripping program, or a tactical poisoning program for areas <strong>of</strong> dense rabbit-infested scrub, is an essential component <strong>of</strong> such a strategy <strong>of</strong> integrated biological control. Bulloo Downs warren ripping In his report on making <strong>the</strong> most <strong>of</strong> RCD, Cooke (2003) provided an economic example <strong>of</strong> rabbit control utilising warren ripping after a RCD epizootic. His account <strong>of</strong> <strong>the</strong> Bulloo Station control results was based on data provided by David Berman (2001) from <strong>the</strong> Queensl<strong>and</strong> Department <strong>of</strong> Natural resources <strong>and</strong> Mines. It highlights how integrated strategic <strong>management</strong> can be <strong>the</strong> most effective form <strong>of</strong> control in <strong>the</strong> long-term. An extract <strong>of</strong> <strong>the</strong> report states: “Many l<strong>and</strong>holders in <strong>the</strong> rangel<strong>and</strong>s do not rip <strong>the</strong>ir warrens because <strong>the</strong>y ei<strong>the</strong>r can’t afford <strong>the</strong> up-front costs or believe ripping to be uneconomic. However, at Bulloo Downs in south-west Queensl<strong>and</strong>, <strong>the</strong>y are showing that <strong>the</strong> cost:benefit <strong>of</strong> warren ripping can be greatly improved by focussing on key rabbit refuge areas ra<strong>the</strong>r than treating <strong>the</strong> whole property. Over 30,000 warrens were ripped in an area <strong>of</strong> about 95 square kilometres over 18 months at a cost <strong>of</strong> $1,462 per square kilometre. The aim is to knock out <strong>the</strong> rabbits’ drought refuge warrens by ripping all areas within one kilometre <strong>of</strong> permanent water. If all drought refuge areas can be ripped, rabbit numbers may be pushed low enough that <strong>the</strong>y will not recover well after drought, with dingoes, myxomatosis <strong>and</strong> RHD potentially keeping numbers low. If this proves to be <strong>the</strong> case, $240,000 in ripping costs will have removed <strong>the</strong> <strong>impact</strong> <strong>of</strong> rabbits from 2,500 square kilometres with an estimated cattle production benefit <strong>of</strong> over $500,000 per year. In marked contrast, <strong>the</strong> cost <strong>of</strong> ripping all warrens on Bulloo Downs would be over $6 million! There also seem to be clear environmental benefits from ripping ra<strong>the</strong>r than just relying on myxomatosis <strong>and</strong> RHD. An experimental warren ripping trial showed that native <strong>animals</strong> were still reduced by <strong>the</strong> presence <strong>of</strong> rabbits, even though myxomatosis <strong>and</strong> RHD were active. Ripping stopped <strong>the</strong> <strong>impact</strong> <strong>of</strong> rabbits almost immediately, with <strong>the</strong> numbers <strong>of</strong> some small native mammals doubling within two months.” Strategies Resources will never be sufficient to deal with all rabbit <strong>management</strong> problems so strategic allocation <strong>of</strong> resources to give <strong>the</strong> best outcome for threatened species conservation must occur. Localised rabbit control in specific areas <strong>of</strong> high conservation concern, particularly around populations <strong>of</strong> threatened species, should be 133
Page 1:
Review of<
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Contributors Andrew Norris Pest Ani
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3.7.36 Common Myna (Acridot
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Table of figures F
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Section 2 Introduction Feral <stron
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Amanda Dimmock, QD
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Section 3 A status review o
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3.4 Birds Thirteen (or 14) species
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Information on the
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Summary A rodent that contributes t
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Dingoes can become a threat to wild
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The significance of</strong
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macropods and b<st
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^Lasiorhinus krefftii North
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Perceived threat Geopsittacus occid
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conservation areas. It is less clea
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Table 8 Rare species found in <stro
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Competition Several examples are re
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In truth, camels do substantial dam
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the Tanami. Buffal
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The situation today Buffalo numbers
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qualify under IUCN criteria as enda
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3.7.16 Goat (Capra hircus) Summary
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Drakonorchis drakeoides Hinged Drag
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3.7.19 Red Deer (Cervus elaphus) Su
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Impacts Much is known about <strong
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Distribution Ostriches have won <st
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nest in tree hollows along
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Distribution The skylark is found i
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Distribution The blackbird is wides
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Land, and<
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have been translocated to o
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esources. Significant investment in
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many native species (Clarke et al.
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spread across the
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Section 4 Legislative framework 4.1
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protection, as long as it falls wit
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Native Vegetation Conservation Act
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ehabilitate existing native vegetat
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suppression, which is the</
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al. 1986, 1987). The use of
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5.1.4 Mustering Commercial musterin
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etal. (1997) found that many native
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the vaccine <stron
Page 90 and 91: Where possible, integration <strong
Page 92 and 93: strategy, relative cost-effectivene
Page 94 and 95: Fencing Feral buffalo have a reputa
Page 96 and 97: 5.3 Management of
Page 98 and 99: Summary of <strong
Page 100 and 101: time comes for the
Page 104 and 105: Individual tracking Tracking is a l
Page 106 and 107: SA - Currently cats are not widely
Page 108 and 109: Method of control
Page 110 and 111: Aerial shooting Aerial shooting can
Page 114 and 115: 80% of export was
Page 116 and 117: ensuring effective treatment <stron
Page 118 and 119: the lower cost, wi
Page 122 and 123: conservation value rathe</s
Page 124 and 125: effort on the cont
Page 128 and 129: follow transect lines, one kilometr
Page 130 and 131: as a refuge from predators. Removal
Page 134 and 135: was completed it was the</s
Page 136 and 137: warren structure amenable to recolo
Page 138 and 139: Poisons Traditionally, strychnine,
Page 142 and 143: of high priority.
Page 144 and 145: Method of control
Page 148 and 149: technique can allow for cost-effect
Page 152 and 153: In South Australia, between 30 <str
Page 156 and 157: % respondents 100% 90% 80% 70% 60%
Page 158 and 159: a) b) Figure 3. a) Extent o
Page 160 and 161: Figure 4 Response frequency for lik
Page 162 and 163: distribution of <s
Page 164 and 165: Section 7 Key problems and<
Page 166 and 167: • Goats degrading temperate woodl
Page 168 and 169: conservation problems in Europe <st
Page 170 and 171: message that camels are a valuable
Page 172 and 173: In the Koolatong R
Page 174 and 175: environmental degradation’ (Nor<s
Page 176 and 177: ecause dingo and d
Page 178 and 179: Various control methods have been a
Page 180 and 181: Pascale Taplin, an Indigenous L<str
Page 182 and 183: Lack of a Strategi
Page 184 and 185: eradicated after seeing the
Page 186 and 187: In some situations, payment <strong
Page 188 and 189: could have led to better protocols
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Game hunting is a growing business,
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Much as we might like it, t
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conservation outcome. In such a sit
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community consultation and<
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• Have the non-t
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provide opportunities for strategic
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Section 9 Priorities for investment
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contacted for exact locations <stro
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way. Achilles heel research should
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efficient in any given situation. R
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west Queensland re
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Crossland, MR, 199
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Forsyth, DM, and P
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Lange, RT, and Gra
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Morgan, LA and But
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Parkes, JP, 1990, Feral goat contro
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Van Rensberg, PJJ, Skinner, JD, <st
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Appendix A Ferals animals</
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Indigenous lands I
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Appendix B Stakeholder survey form
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222
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224
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226
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Appendix C Database on past NHT fun
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Lachlan Rehabilitation of</
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Northern Territory
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Cape York Ambiilmungu-Ngarra tradit
Page 244 and 245:
Wet Tropics Expansion and</
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Avon Protecting and</strong
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