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

Poisons
Traditionally, strychnine, phosphorous <strong>and</strong> arsenic were used for poisoning rabbits.
1080 has generally replaced <strong>the</strong> use <strong>of</strong> <strong>the</strong>se chemicals in most parts <strong>of</strong> Australia.
1080 is cheap <strong>and</strong> is used where <strong>the</strong>re is little risk <strong>of</strong> poisoning dogs, sheep or cattle.
1080 is rapidly eliminated from <strong>animals</strong> that consume a non-lethal dose, presenting a
negligible risk to people who consume meat from stock from areas treated with 1080
poisoned baits (Eason 1992). Concerns about sublethal ingestion leading to bait
shyness <strong>and</strong> non-target <strong>impact</strong>s have led to <strong>the</strong> study <strong>of</strong> alternative poisons such as
pindone <strong>and</strong> second generation coagulants (Oliver et al. 1982, Crosbie et al. 1986,
Mead et al. 1991, Eason & Jolly 1993). Pindone is a chronic anticoagulant poison
which requires several consecutive doses, but does have an effective antidote. Pindone
is relatively expensive <strong>and</strong> is used in areas close to human settlement where <strong>the</strong>re is
significant risk <strong>of</strong> poisoning dogs or people. In Western Australia <strong>the</strong> use <strong>of</strong> pindone
is carefully controlled, <strong>and</strong> specific prescriptions require its careful use in <strong>the</strong> presence
<strong>of</strong> certain native species, especially large macropods. Experience has shown that
marsupials are very sensitive to this toxin (Martin et al. 1991, Martin et al. 1994).
Second generation coagulants are comparatively expensive <strong>and</strong> will continue to
receive little use whilst 1080 is cheap <strong>and</strong> effective to use.
One-shot baiting
Conventional poisoning methods rely on pre-feeding with non-poisoned bait prior to
laying poisoned bait. The one-shot oats technique requires no pre-baiting, relying on
rabbits becoming accustomed to eating <strong>the</strong> oat bait while consuming <strong>the</strong> non-poisoned
grains, before encountering <strong>the</strong> ‘one in a hundred’ oat grain containing more than
sufficient 1080 poison to kill it. The two techniques were equally effective when
tested under similar conditions in South Australia during summer/autumn, but not
during <strong>the</strong> winter/spring breeding season (Cooke 1968). One-shot oats also proved
less effective than conventional poisoning during <strong>the</strong> rabbit breeding season in o<strong>the</strong>r
trials (Gooding 1968). Where rabbits are not bait shy, <strong>the</strong> one-shot oat technique may
achieve kills as high as those achieved in eastern Australia by conventional 1080
poisoning. One-shot oats poisoning was used for three years in South Australia. Its
use was discontinued because <strong>of</strong> severe non-target losses (Williams et al. 1995).
Tarbaby
The ‘tarbaby’ technique is a possible alternative to baiting. This uses a toxin mixed
with grease, which is placed down <strong>the</strong> entrance <strong>of</strong> <strong>the</strong> burrow. Rabbits which pass
through <strong>the</strong> grease will attempt to groom <strong>the</strong>mselves by licking <strong>the</strong> grease from <strong>the</strong>ir
fur <strong>and</strong> will <strong>the</strong>reby ingest <strong>the</strong> toxin. The high concentration <strong>of</strong> 1080 required
precludes its use with this technique. Combining second generation anticoagulants
with tarbaby may overcome this obstacle. The technique could have a useful but very
specific role as a follow-up technique to destroy rabbits in rocky areas. Trials have
shown that this technique performs poorly in light s<strong>and</strong>y soils, such as those found in
Western Australia (Williams et al. 1995).
Myxomatosis
Myxomatosis, a disease specific to leporids, is caused by myxoma pox virus which
was released into Australian wild rabbit populations in 1950. Initially it caused
extremely high mortality, but <strong>the</strong> virus quickly attenuated (weakened) <strong>and</strong> rabbits
with a genetic resistance to <strong>the</strong> disease became more common. Rabbits that survive
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