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

<strong>animals</strong> due in part to its natural occurrence in some locally endemic plant species
(Twigg & King 1991). This enhances <strong>the</strong> target specificity <strong>of</strong> 1080 baiting campaigns
in <strong>the</strong>se areas, resulting in reduced potential for non-target <strong>impact</strong>s on native wildlife.
1080 ground baiting can be highly effective at reducing <strong>feral</strong> pig populations in <strong>the</strong>
field.
CSSP (yellow Phosphorous)
CSSP is also sometimes used in pig baiting, however <strong>the</strong> efficacy <strong>of</strong> CSSP in <strong>the</strong> field
<strong>and</strong> its potential <strong>impact</strong> on non-target species are somewhat unclear. CSSP is
generally used in an ad-hoc manner ra<strong>the</strong>r than in a coordinated campaigns since it is
available as a restricted ’take home’ poison. It is <strong>the</strong> only take home <strong>feral</strong> pig poison
registered in Australia, <strong>and</strong> as such, it is valuable to individual l<strong>and</strong> managers,
probably extending <strong>the</strong> area over which <strong>feral</strong> pigs are controlled. However, because <strong>of</strong>
this, <strong>the</strong> use <strong>of</strong> CSSP is <strong>of</strong>ten not coordinated <strong>and</strong> non-target <strong>impact</strong>s on scavenging
<strong>and</strong> carnivorous <strong>animals</strong> are probably high since no baiting strategy is used to reduce
this <strong>impact</strong>. The logistics <strong>of</strong> using CSSP are relatively low compared with o<strong>the</strong>r
ground based toxins since no free feeding is carried out with this method <strong>and</strong> <strong>the</strong> toxin
is relatively inexpensive. The major drawback to CSSP is that it compromises <strong>the</strong>
welfare <strong>of</strong> poisoned <strong>animals</strong>. A recent review by Lapidge & Cowled (2005) on
welfare issues in <strong>feral</strong> pig control concluded that CSSP caused <strong>feral</strong> pigs considerable
pain <strong>and</strong> in <strong>the</strong>ir opinion its use should be discontinued due to major animal welfare
concerns.
Warfarin
Warfarin is an anticoagulant to which <strong>feral</strong> pigs are reasonably sensitive. The
effectiveness <strong>of</strong> warfarin in controlling <strong>feral</strong> pig populations has been demonstrated
when used in grain over a number <strong>of</strong> consecutive days (Hone 1987, McIlroy 1989,
Saunders et al. 1990, Clarke 1993). Large decreases in <strong>feral</strong> pig numbers have
occurred in field trials, resulting in reduced environmental damage. Warfarin is
however, a toxin not supported for <strong>feral</strong> pig use by animal welfare societies, due to <strong>the</strong>
long time it takes for <strong>feral</strong> pigs to succumb to its effects. The use <strong>of</strong> warfarin in grain
can be labour intensive <strong>and</strong> impractical due to <strong>the</strong> requirement for repeat dosing <strong>and</strong>
<strong>the</strong> lack <strong>of</strong> an aerial delivery method. The effects <strong>of</strong> warfarin on non-target <strong>animals</strong>
<strong>and</strong> native communities are unclear. The control method efficiency <strong>of</strong> warfarin baiting
campaigns is high, <strong>and</strong> <strong>the</strong> qualities <strong>of</strong> <strong>the</strong> toxin <strong>and</strong> <strong>the</strong> baiting strategies employed
probably reduce <strong>the</strong> potential risks to non-target populations. The logistics <strong>of</strong> warfarin
baiting campaigns are relatively high compared with o<strong>the</strong>r ground baiting methods
because several consecutive doses <strong>of</strong> warfarin must occur for baiting to be lethal. A
‘one shot’ warfarin bait may improve <strong>the</strong> logistics <strong>of</strong> warfarin baiting campaigns, but
may increase <strong>the</strong> potential non-target <strong>impact</strong>s.
Trapping
Aside from poison baiting, trapping is one <strong>of</strong> <strong>the</strong> most widely used methods <strong>of</strong> <strong>feral</strong>
pig <strong>management</strong>. Although labour intensive, <strong>the</strong> technique can be pr<strong>of</strong>itable <strong>and</strong>
incorporated into daily l<strong>and</strong> <strong>management</strong> practices. The ability <strong>of</strong> this method to
control widespread <strong>feral</strong> pig populations is largely unknown. Trapping can produced
large decreases in <strong>feral</strong> pig populations, especially in small localised areas. The
effectiveness <strong>of</strong> trapping is determined by <strong>the</strong> attractiveness <strong>of</strong> <strong>the</strong> trap bait material,
<strong>and</strong> <strong>the</strong> rate at which <strong>feral</strong> pigs encounter traps. No assessment <strong>of</strong> <strong>the</strong> efficacy <strong>of</strong>
trapping as a broad-scale method <strong>of</strong> <strong>feral</strong> pig control has occurred. Trapping is
generally an expensive <strong>and</strong> time consuming means <strong>of</strong> <strong>feral</strong> pig control, with logistical
practicalities meaning that it is best applied to small areas <strong>of</strong> high agricultural or
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