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

conservation value ra<strong>the</strong>r than larger, remote areas. However, once <strong>feral</strong> pig trapping
materials are purchased <strong>and</strong> traps are established, <strong>the</strong> costs <strong>and</strong> time taken for
subsequent trapping campaigns are reduced significantly. New technology, such as
shape recognition trapping may improve <strong>the</strong> applicability <strong>of</strong> this method. Research is
required to assess <strong>the</strong> applicability <strong>of</strong> trapping to broad-scale <strong>feral</strong> pig control. The
practice has <strong>the</strong> advantage <strong>of</strong> being highly target specific <strong>and</strong> providing a means <strong>of</strong>
<strong>of</strong>f-setting <strong>the</strong> cost <strong>of</strong> <strong>the</strong> control efforts.
Commercial harvesting
In total since 1998, between 140 000 <strong>and</strong> 332 000 <strong>feral</strong> pigs have been inspected
annually at game meat processing plants in Australia (Lapidge & Cowled 2004
unpublished). These rates <strong>of</strong> commercially harvested pigs, although significant when
applied to some local areas are small in comparison to <strong>the</strong> total numbers <strong>of</strong> <strong>feral</strong> pigs
in Australia. Commercially harvested pigs are sourced from accredited field
harvesters who utilise dogging, ground shooting <strong>and</strong> trapping to source <strong>the</strong> pigs
Ground shooting
Hunting by non-commercial hunters <strong>and</strong> commercial harvesters using ground
shooting, dogging <strong>and</strong> trapping can have a significant localised reduction on <strong>feral</strong> pig
numbers. Generally, <strong>the</strong> benefits <strong>of</strong> hunting <strong>and</strong> harvesting <strong>feral</strong> pigs are unquantified.
A criticism <strong>of</strong> hunting as a control method is that non-commercial <strong>and</strong> commercial
hunting may hold <strong>feral</strong> pig numbers at a point where <strong>the</strong> benefits <strong>of</strong> hunting exceeds
<strong>the</strong> cost <strong>of</strong> hunting. The ability <strong>of</strong> hunting <strong>and</strong> harvesting to reduce <strong>feral</strong> pig <strong>impact</strong>s
on conservation outcomes is unknown. In some areas <strong>the</strong> methods have markedly
reduced <strong>feral</strong> pig populations, however, <strong>the</strong> efficacy <strong>of</strong> <strong>the</strong> method is reduced by
deliberate introductions <strong>and</strong> decreasing returns in hunted areas. The method is
generally inexpensive to apply since hunters <strong>and</strong> harvesters will <strong>of</strong>ten volunteer <strong>the</strong>ir
time. The method may be difficult to apply in remote areas <strong>and</strong> can result in <strong>feral</strong> pig
translocations. The non-target effects <strong>of</strong> hunting <strong>and</strong> harvesting have not been
researched (escape <strong>of</strong> hunting dogs, <strong>feral</strong> pig translocations), but if conducted
responsibly <strong>the</strong>y should be low.
Aerial shooting
Aerial shooting is a method which can deliver rapid <strong>and</strong> large reductions (up to 80%)
in <strong>feral</strong> pig numbers across extensive areas in appropriate habitats, including remote
locations. However, <strong>the</strong> technique can be expensive, generally is undertaken in
isolation, <strong>and</strong> <strong>the</strong> effect can be short-lived. It is highly target specific <strong>and</strong> can be cost
effective. The main disadvantages are that <strong>the</strong> method is not applicable to all habitats
<strong>and</strong> is expensive when <strong>feral</strong> pigs are in low densities. Aerial shooting is especially
useful to extend <strong>feral</strong> pig control to remote or inaccessible areas <strong>and</strong> is one <strong>of</strong> <strong>the</strong>
efficacious techniques available for use over broad areas in many areas <strong>of</strong> Australia.
However, aerial shooting is not effective in all habitats, such as mountainous or
heavily forested areas. The target specificity <strong>of</strong> aerial shooting is extremely high <strong>and</strong>
<strong>the</strong> logistical practicalities are relatively easily met.
Fencing
Fencing can be a useful method <strong>of</strong> <strong>feral</strong> pig <strong>management</strong> through reducing or
eliminating <strong>impact</strong>s on small, valuable areas. Its use is however expensive <strong>and</strong> time
consuming <strong>and</strong> is generally limited to small areas or isl<strong>and</strong>s to allow eradication <strong>and</strong>
exclusion. Ongoing maintenance requirements can be high. Fencing will potentially
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