Review of the management of feral animals and their impact on ...

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have been translocated to <strong>of</strong>fshore isl<strong>and</strong>s to provide <strong>the</strong>m with security from toads. The brush-tailed phascogale, a smaller carnivorous marsupial, may also be at risk (Nor<strong>the</strong>rn L<strong>and</strong> Council 2004). This species had become rare in <strong>the</strong> Nor<strong>the</strong>rn Territory even before <strong>the</strong> arrival <strong>of</strong> toads (Woinarski et al. 2001). Birds rarely die from toad consumption, <strong>and</strong> no bird species is thought to have declined because <strong>of</strong> toads. Many birds have learned to utilise toads by consuming <strong>the</strong>ir non-toxic parts. Goannas decline dramatically in numbers when toads invade. Populations recover many years later, but whe<strong>the</strong>r <strong>the</strong>y reach <strong>the</strong>ir original densities remains unknown. Similar statements apply to frilled lizards. Various snakes, including red-bellied black snakes, brown snakes <strong>and</strong> death adders, die if <strong>the</strong>y ingest toads. Red-bellied black snakes <strong>and</strong> death adders remain uncommon in areas supporting toads, <strong>and</strong> <strong>the</strong>ir populations may be permanently suppressed by toad numbers. One snake, <strong>the</strong> keelback, can eat small toads, <strong>and</strong> it <strong>of</strong>ten prospers in wetl<strong>and</strong>s where toads are common. Freshwater crocodiles <strong>of</strong>ten die after eating toads. However, freshwater crocodiles are not declining in Queensl<strong>and</strong> where toads are common. Cane toad eggs <strong>and</strong> dead tadpoles proved lethal to <strong>the</strong> tadpoles <strong>of</strong> desert tree frogs, dwarf tree frogs <strong>and</strong> ornate burrowing frogs. Tadpoles appear to be unable to detect <strong>the</strong> toxins in toad eggs. In Queensl<strong>and</strong>, where toads are very common, frog numbers may be suppressed to some degree, but native frogs do not disappear from sites when toads are present. Cane toad eggs <strong>and</strong> tadpoles prove lethal to some fish but not o<strong>the</strong>rs. Fly-specked hardyheads, b<strong>and</strong>ed grunters, spangled grunters <strong>and</strong> purple-spotted gudgeon are poisoned but various o<strong>the</strong>r fish, including saratoga <strong>and</strong> common archerfish, are not. No declines in fish numbers have been recorded, although no monitoring <strong>of</strong> fish has taken place. Cane toad eggs <strong>and</strong> small tadpoles are lethal to some native invertebrates that prey on <strong>the</strong>m but prove harmless to o<strong>the</strong>rs. Snails, water beetle larvae, backswimmers <strong>and</strong> leeches die after consuming <strong>the</strong>m. Water scorpions, giant water bugs, dragonfly larvae, freshwater prawns, crabs, crayfish, wolf spiders, ants are unharmed. The o<strong>the</strong>r <strong>impact</strong>s <strong>of</strong> toads, resource competition <strong>and</strong> predation, appear to be less significant. Competition In New South Wales <strong>the</strong> green tree frog is thought to have declined in areas supporting toads, which may reflect competition; however, green tree frogs are sometimes common in sites supporting toads. Crossl<strong>and</strong> & Alford (1998) found that cane toad tadpoles can compete significantly with <strong>the</strong> tadpoles <strong>of</strong> <strong>the</strong> ornate burrowing frog. Toads produce far more eggs than most frogs, but competition is only likely when breeding sites are limited, which is usually not <strong>the</strong> case. Ornate burrowing frogs remain common in many sites that support toads. Where toads are abundant <strong>the</strong>y <strong>of</strong>ten dominate hiding places under logs <strong>and</strong> o<strong>the</strong>r cover (Covacevich & Archer 1975). They probably inconvenience o<strong>the</strong>r <strong>animals</strong> seeking cover in <strong>the</strong>se situations. However, snakes <strong>and</strong> lizards will <strong>of</strong>ten share shelter 56
with cane toads <strong>and</strong> <strong>the</strong> level <strong>of</strong> competition is not likely to be <strong>of</strong> great significance except in certain habitats. Competition for food is not thought likely at <strong>the</strong> adult stage. Dietary studies show that toads mainly eat beetles, ants <strong>and</strong> termites, <strong>and</strong> that <strong>the</strong>y are not obvious competitors with native frogs. But toad tadpoles (‘toadpoles’) do compete with native tadpoles in small pools. This competition would be unlikely to lead to extinctions but it might reduce frog numbers at some sites. Predation Although cane toads are occasionally reported eating frogs, snakes, lizards, birds, mice <strong>and</strong> o<strong>the</strong>r vertebrates, dietary studies, based upon dissecting large number <strong>of</strong> toad stomachs, indicate that beetles, termites <strong>and</strong> ants are <strong>the</strong>ir main foods. It seems very unlikely that any prey species has become rare because <strong>of</strong> toad predation at ei<strong>the</strong>r <strong>the</strong> adult or tadpole stage. Summary Cane toads are <strong>of</strong>ten claimed to have a devastating <strong>impact</strong> upon biodiversity. Laboratory experiments demonstrate that toads <strong>and</strong> <strong>the</strong>ir eggs <strong>and</strong> tadpoles are poisonous to many predators. But surveys <strong>of</strong> toad-invaded areas show that nearly all predators survive alongside toads, albeit sometimes at reduced densities. The evidence suggests that predator populations sooner or later learn to avoid toads. This does not mean that <strong>the</strong> <strong>impact</strong> <strong>of</strong> toads should be downplayed. Impact should not be measured only by <strong>the</strong> loss <strong>of</strong> species. Feral <strong>animals</strong> <strong>of</strong>ten have a wide range <strong>of</strong> <strong>impact</strong>s upon ecosystem functioning. Cane toads are sometimes <strong>the</strong> most abundant vertebrate within a habitat, <strong>and</strong> <strong>the</strong>ir <strong>impact</strong>s can be wide ranging, as noted above. The cumulative effects <strong>of</strong> cane toad poisoning, competition <strong>and</strong> predation can represent a substantial <strong>impact</strong> upon ecosystem functioning, especially when it leads to reduced numbers <strong>of</strong> predators such as quolls, goannas <strong>and</strong> snakes. The <strong>impact</strong> upon nor<strong>the</strong>rn quolls is <strong>the</strong> most serious <strong>impact</strong> <strong>of</strong> toads yet recorded. In some regions <strong>of</strong> Queensl<strong>and</strong>, quolls occur alongside toads, although mainly in rocky <strong>and</strong> upl<strong>and</strong> situations where quolls probably have little contact with <strong>the</strong>m. In o<strong>the</strong>r areas, quolls disappeared soon after toads arrived <strong>and</strong> <strong>the</strong>y have never returned. The nor<strong>the</strong>rn quoll is now listed federally as endangered. Permanent declines in populations <strong>of</strong> frog-eating snakes are ano<strong>the</strong>r significant <strong>impact</strong>. Declines in goannas may be a third <strong>impact</strong>, but <strong>the</strong> evidence for this is less convincing: goanna densities are not easy to monitor. Fish 3.7.40 Common Carp (Cyprinus carpio) Summary Carp are widespread throughout sou<strong>the</strong>rn Australia where <strong>the</strong>y dominate <strong>the</strong> aquatic fauna. Although perceived as <strong>the</strong> number one introduced fish threat to inl<strong>and</strong> waterways, <strong>the</strong> extent <strong>of</strong> negative <strong>impact</strong>s this species has is still unclear. They have been implicated in reduction <strong>of</strong> water quality, destruction <strong>of</strong> aquatic vegetation, spreading disease <strong>and</strong> parasites, undermining banks <strong>and</strong> competition for food 57
Page 1:
Review of<
Page 4 and 5:
Contributors Andrew Norris Pest Ani
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3.7.36 Common Myna (Acridot
Page 8 and 9:
Table of figures F
Page 10 and 11:
Section 2 Introduction Feral <stron
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Amanda Dimmock, QD
Page 14 and 15: Section 3 A status review o
Page 16 and 17: 3.4 Birds Thirteen (or 14) species
Page 18 and 19: Information on the
Page 20 and 21: Summary A rodent that contributes t
Page 22 and 23: Dingoes can become a threat to wild
Page 24 and 25: The significance of</strong
Page 26 and 27: macropods and b<st
Page 28 and 29: ^Lasiorhinus krefftii North
Page 30 and 31: Perceived threat Geopsittacus occid
Page 32 and 33: conservation areas. It is less clea
Page 34 and 35: Table 8 Rare species found in <stro
Page 36 and 37: Competition Several examples are re
Page 38 and 39: In truth, camels do substantial dam
Page 40 and 41: the Tanami. Buffal
Page 42 and 43: The situation today Buffalo numbers
Page 44 and 45: qualify under IUCN criteria as enda
Page 46 and 47: 3.7.16 Goat (Capra hircus) Summary
Page 48 and 49: Drakonorchis drakeoides Hinged Drag
Page 50 and 51: 3.7.19 Red Deer (Cervus elaphus) Su
Page 52 and 53: Impacts Much is known about <strong
Page 54 and 55: Distribution Ostriches have won <st
Page 56 and 57: nest in tree hollows along
Page 58 and 59: Distribution The skylark is found i
Page 60 and 61: Distribution The blackbird is wides
Page 62 and 63: Land, and<
Page 66 and 67: esources. Significant investment in
Page 68 and 69: many native species (Clarke et al.
Page 70 and 71: spread across the
Page 72 and 73: Section 4 Legislative framework 4.1
Page 74 and 75: protection, as long as it falls wit
Page 76 and 77: Native Vegetation Conservation Act
Page 78 and 79: ehabilitate existing native vegetat
Page 80 and 81: suppression, which is the</
Page 82 and 83: al. 1986, 1987). The use of
Page 84 and 85: 5.1.4 Mustering Commercial musterin
Page 86 and 87: etal. (1997) found that many native
Page 88 and 89: 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
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80% of export was
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ensuring effective treatment <stron
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the lower cost, wi
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5.8 Management of
Page 122 and 123:
conservation value rathe</s
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effort on the cont
Page 126 and 127:
5.9 Management of
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follow transect lines, one kilometr
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as a refuge from predators. Removal
Page 132 and 133:
Summary of <strong
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was completed it was the</s
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warren structure amenable to recolo
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Poisons Traditionally, strychnine,
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infected and steri
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of high priority.
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Method of control
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5.11 Management of
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technique can allow for cost-effect
Page 150 and 151:
Summary of <strong
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In South Australia, between 30 <str
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Summary of <strong
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% respondents 100% 90% 80% 70% 60%
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a) b) Figure 3. a) Extent o
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Figure 4 Response frequency for lik
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distribution of <s
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Section 7 Key problems and<
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• Goats degrading temperate woodl
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conservation problems in Europe <st
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message that camels are a valuable
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In the Koolatong R
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environmental degradation’ (Nor<s
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ecause dingo and d
Page 178 and 179:
Various control methods have been a
Page 180 and 181:
Pascale Taplin, an Indigenous L<str
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Lack of a Strategi
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eradicated after seeing the
Page 186 and 187:
In some situations, payment <strong
Page 188 and 189:
could have led to better protocols
Page 190 and 191:
Game hunting is a growing business,
Page 192 and 193:
Much as we might like it, t
Page 194 and 195:
conservation outcome. In such a sit
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community consultation and<
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• Have the non-t
Page 200 and 201:
provide opportunities for strategic
Page 202 and 203:
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
Page 210 and 211:
west Queensland re
Page 212 and 213:
Crossland, MR, 199
Page 214 and 215:
Forsyth, DM, and P
Page 216 and 217:
Lange, RT, and Gra
Page 218 and 219:
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
Page 230 and 231:
222
Page 232 and 233:
224
Page 234 and 235:
226
Page 236 and 237:
Appendix C Database on past NHT fun
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Lachlan Rehabilitation of</
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Northern Territory
Page 242 and 243:
Cape York Ambiilmungu-Ngarra tradit
Page 244 and 245:
Wet Tropics Expansion and</
Page 246 and 247:
Avon Protecting and</strong
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