Part III: Conservation and Management308
460,911 wild pigs were processed at locations requiring a federal
permit in Texas. The income earned by these landowners serves
to at least partially offset the negative damage caused by wild
pigs and helps to pay for ongoing control efforts (Higginbotham
2010, 2013).
Exclusion of wild pigs from an area can be an effective means
of reducing damages (e.g. to economically important agricul-
tural crops or ecologically sensitive areas). Exclusion is most
often accomplished through the use of fencing. Such barriers
consist of wire-mesh or electric fencing or combinations of the
two. However, with the requirement that such fencing be either
‘pig-proof ’ or ‘pig-resistant’, the cost of implementing this option
(i.e. construction and maintenance) can be very high. Because of
this financial constraint, fencing is typically employed to exclude
wild pigs from small areas (e.g. localized sensitive or fragile
environments or habitats). However, at least two projects have
been used to exclude wild pigs from large areas in California,
including the Pinnacles National Monument and Annadel State
Park (Barrett et al. 1988; McCann & Garcelon 2008). Exclusion
has also been used on the Channel Islands off of California dur-
ing pig eradication programmes (Lombardo & Faulkner 2000;
Schuyler et al. 2002; Parkes et al. 2010). Unfortunately, fencing
seldom provides a permanent control, because wild pigs are per-
sistent and will eventually find a way through almost any type of
fence over time (Barrett & Birmingham 1994; Reidy et al. 2008a;
Stevens 2010; Lavalle et al. 2011). Additionally, fencing can have
a negative impact on other wildlife species by restricting move-
ment/dispersal (Woodroffe et al. 2014).
Another potential form of exclusion entails the use of
repellents. While repellents have been successful for use with
some wildlife species, tests on wild pigs have had mostly mixed
results. A couple of technologies have showed promise; how-
ever, most repellents tested on wild pigs have proven to be
ineffective (Barrett & Birmingham 1994; West et al. 2009; USDA-
APHIS 2015).
The ultimate objective of management and control efforts
on wild pigs is to reduce the damage that these invasive animals
cause. A pilot project was undertaken in Texas to evaluate the
potential to abate wild pig damage on privately owned lands
(Higginbotham et al. 2008). On-site technical assistance (direct
control) was provided to landowners at three pilot sites while
group educational events (indirect control) emphasizing adop-
tion of efficient landowner-initiated control methods were con-
ducted state wide. Extension education directed at landowners
focused on the adoption of best management practices in order
to abate wild pig damage. That effort was able to decrease wild
pig damage collectively on 223,000 acres of land by 66 per cent
(Higginbotham et al. 2008; Higginbotham 2013).
Primarily because of the potential economic impacts to the
livestock industry, an important and growing component of
the management of wild pigs in North America has been dis-
ease monitoring. For example, USDA APHIS Wildlife Services
personnel collect biological samples from wild pigs killed in
the USA during operational control activities and from other
sources (e.g. hunter-killed animals). These samples are submit-
ted to diagnostic tests for various pathogens (e.g. classical swinefever, pseudorabies, swine brucellosis, and other diseases of
national interest). The current plan is to expand this national
disease monitoring programme to protect agriculture and
human health (USDA-APHIS 2015).
With the recent rapid expansion of wild pig populations
in North America and the accompanying increase in damage,
the laws and regulations associated with the management and
control of these animals have been rapidly evolving to address
this issue. As with most invasive species, the ability to suc-
cessfully manage or control these animals is dependent upon
supportive laws (Hamrick et al. 2011). In the USA the legal
status of wild pigs has largely shifted from that of a game ani-
mal to that of an invasive species. However, from a national
viewpoint, the laws associated with these wild pigs are widely
inconsistent, varying greatly between the federal and state
government perspectives, as well as among the numerous
states where these introduced animals exist. With issues
such as interstate transport, the legality of sport-hunting, the
game status between bordering states, and more, the diverse
assortment of laws pertaining to wild pigs is far from being a
national plan for success (Mayer et al. 2012). In general, these
legal changes have made the lethal harvest of these animals
easier. In a few cases, this has entailed the removal of wild
pigs as state-listed game animals. In contrast, six states (i.e.
Delaware, Kansas, Nebraska, New York, North Dakota, and
Tennessee) have eliminated the legal sport-hunting of these
animals. The reasoning for this action is that if wild pigs can
no longer be legally hunted as game animals, then there is no
incentive to illegally translocate them to new areas in the state
(Bevins et al. 2014; USDA-APHIS 2015).
Based on the aforementioned widespread consideration
of these animals as an undesirable invasive species, successful
eradications of wild pigs have occurred in North America. These
have included specific locations (e.g. both Annadel State Park
and Pinnacles National Monument in California), large offshore
islands (e.g. the California Channel Islands), and localized pop-
ulations in some states (e.g. Idaho, Illinois, Kansas, New York,
Oregon, South Dakota, Washington and others). Such efforts
have targeted either specific sites or populations in states where
these animals have only recently appeared (Barrett et al. 1988;
Lombardo & Faulkner 2000; Schuyler et al. 2002; McCann &
Garcelon 2008; Parkes et al. 2010; USDA-APHIS 2015).Research
Concurrent with this species’ population and range increase
over the last 10–15 years has been an increase in the volume
of research being conducted on wild pigs in North America.
Such efforts have been largely taking place in the USA (Mayer
& Brisbin 2009), but research work is beginning to increase in
both Canada and Mexico (e.g. Villarreal et al. 2010; Brook & van
Beest 2014). The overall goals of these research efforts have been
to improve wild pig control techniques, the characterization
and economics of the damage done by wild pigs, and our under-
standing of the biology/ecology of these animals as it relates to
their management..03012:52:20