Chapter 28: Introduced wild pigs in North America307
that state. Mengak (2012) reported a total of > $81 million for
‘damage to crops or crop related damage and damage to items
other than crops (e.g. timber, food plots, lease values, etc.)’ in
41 of the 159 counties in Georgia. Shi et al. (2010) estimated
~$75 million for ‘damage to crops’ statewide in Alabama in 2009.
Very localized or single-incident damage costs have also been
identified. Engeman et al. (2004) calculated an estimated $1–4
million for wild pig damage to 5.4 ha of exposed basin marsh
based on wetland ‘damage valuation’ (i.e. dollar amount spent in
mitigation attempts to replace lost wetland resources). A single
incident at Jacksonville International Airport in Florida resulted
in the total loss of a $16 million F-16 fighter jet, which had been
caused to crash during takeoff after a collision with two wild
pigs that were attempting to cross the runway in front of the jet.
Based on the estimated valuation of domestic livestock indus-
tries in the USA, a devastating foreign animal disease outbreak
(e.g. African swine fever, classical swine fever, foot and mouth
disease) could cost that country billions of dollars in losses in
headcount, productivity, or sales (Mayer & Brisbin 2009).
Management
The successful management of these animals in North America
and elsewhere is a multifold challenge. As an intelligent and
secretive ecological generalist and opportunistic omnivore with
a high reproductive potential, the basic biological makeup of this
extremely destructive invasive species accounts for most of this
challenge. If one wanted to ‘design’ the most difficult invasive
species to control, it would be the wild pig. Combine that with
a lack of truly viable control options and the complication of
the sport-hunting component, and this issue presents an almost
insurmountable task. This has all been exacerbated by a general
lack of awareness of this problem by the private citizenry on the
continent. Until recently, this had been reflected in a similar lack
of awareness by governmental agencies; however, since 2010
that latter situation has begun to change. Being a problem on a
continent scale, Canada, Mexico and the USA have recognized
this common issue and begun to establish international efforts
to deal with this problem across borders (USDA-APHIS 2015).
Historically, local management objectives with respect to
this invasive species in North America have encompassed a
spectrum from benign inattention to total eradication. This
includes those private lands or governmental entities that con-
tinue to promote wild pigs as a game species. This full range
of management regimes is still variously practised at present
throughout the continent.
In contrast to the aforementioned spectrum of management
regimes, wild pigs are currently considered to be and managed
as a destructive invasive species in most places where they are
found on the continent. Therefore, the most common manage-
ment objectives with respect to these wild pigs would centre
on the control or reduction in either the numbers of these ani-
mals present or the damage that these animals cause in a given
area. Such efforts would individually or collectively include
lethal removal, exclusion, supplemental feeding, damage abate-
ment, and public outreach/education (Mayer & Brisbin 2009;
West et al. 2009; Hamrick et al. 2011). Although government
agencies conduct a number of these management actions within
their jurisdictions, most lands occupied by invasive wild pigs in
North America are privately owned. For such actions to be suc-
cessful on a continental scale, private landowners will have to
either provide access to these agencies or personally finance and
implement control actions themselves to reduce the numbers
of these animals and their damage (Rollins et al. 2007; USDA-
APHIS 2015).
Population control in the form of lethal removal is unques-
tionably the most common management technique practised
on wild pigs in North America. This variously includes control
shooting (i.e. conducted on foot, from vehicles or from planes/
helicopters), trapping (i.e. using box, cage, pen or corral traps,
and wire snares), and dogging (i.e. use of trained hunting dogs
to either bay or catch pigs). The successful application of these
lethal removal techniques is dependent upon the terrain, avail-
able manpower and funding, experience of the persons con-
ducting the action and the management objectives for the wild
pig population in a particular area. Typically, successful wild pig
control programmes entail a combination of these techniques to
remove pigs (Mayer & Brisbin 2009; West et al. 2009; Hamrick
et al. 2011).
Sport-hunting is also considered to be a component of lethal
removal techniques used in some areas (Stevens 2010); however,
given the relatively small mean annual removal rate of a wild pig
population through the use of this technique (i.e. 22.8 per cent;
Mayer 2014), sport-hunting is generally not considered to be an
effective management tool for controlling this species (West et al.
2009). In contrast, recreational hunting was reported to reduce
wild pig damage to sensitive wetland sites in Florida (Engeman
et al. 2007). Lastly, in areas where sport-hunting has been enlisted
by government agencies as a form of wild pig population control
by the public, this action has often been followed by an increase
in the illegal translocation and release of these animals to create
new local hunting opportunities (Bevins et al. 2014).
In another form of lethal control, classical swine fever was
introduced multiple times during the 1940s and 1950s into the
wild pig populations on Santa Cruz and Santa Rosa Islands off
of the coast of California in an effort to reduce the numbers of
these animals. Each introduction was followed by observation
of large numbers of dead or dying pigs. However, these popu-
lations recovered and surveys conducted in 1987 determined
that the virus was no longer active on these islands (Nettles et al.
1989; Mayer & Brisbin 2008).
In a few locations, economic incentives have been imple-
mented to increase the lethal removal of these animals. For
example, private- and government-sponsored bounty systems
have been tried in Alabama, Alberta, Michigan, South Carolina
and Texas (J. J. Mayer, unpublished data). However, these bounty
programmes have done little to control the numbers of these
animals. In addition, such programmes are also susceptible
to fraud and abuse (e.g. turning in domestic pig tails obtained
from commercial slaughterhouses to collect bounty fees; Bevins
et al. 2014). In another example, privately owned ‘buying sta-
tions’ scattered across Texas and Oklahoma pay landowners
for live wild pigs based on the animals’ weights, with the largest
pigs bringing the highest prices. From 2004 to 2009, a total of.03012:52:20