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The Effects of Abatement Efforts on Wild Pig Behavior


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The Effects of Abatement Efforts on Wild Pig Behavior
« on: April 13, 2018, 07:12:02 AM »
The following is the latest information from the Texas A&M Newsletter Spring 2018 feral hog studies.
Unfortunately I was unable to transfer it as a link of any kind, and had to copy it best I could.
For anyone who hunts hogs, its well worth the read.

Hunting Can Accelerate Wild Pig Birth Rates
It is generally accepted that sport hunting wild pigs will
not significantly reduce populations. Perhaps less
apparent is that human activities such as hunting can
induce evolutionary ramifications at both the population
and species level (Darimont et al. 2009). A good
example of this has been observed in deer species
(Odocoileus sp.); whereas high rates of trophy harvest
were shown to lead to smaller overall horn size and body
mass over time (Coltman et al. 2003). In wild pig
populations, though, high hunting pressure doesn’t
necessarily lead to reduced body sizes or smaller tusks.
Extensive monitoring of wild pig populations over 22
years found that high hunting pressure can actually cause
wild pigs to advance offspring birth rates by as much as
12 days per gestation cycle (Gamelon et al. 2011). This
acceleration in birth rate is further compounded by
increased conception rates of sows within their first year
of life when populations experience increased adult
mortality from hunting or other abatement efforts
(Gamelon et al. 2011). Essentially, wild pigs may breed
earlier and produce offspring more quickly when
subjected to hunting pressure. Given this novel survival
strategy, it becomes more understandable why a state like
Missouri banned completely the sport hunting of wild
pigs on conservation lands.
Instead of flushing, some wild pigs have adapted to evade helicopters
by holding within dense cover.
Wild Pig Adaptations to Aerial Gunning
Aerial gunning is an effective population reduction
strategy unless limited by topography or dense canopy
cover (Campbell et al. 2010). However, previous research
has shown that wild pigs can intelligently adapt their
behavior to avoid detection and flushing by helicopters
(Saunders and Bryant 1988). It might be assumed that
these animals would simply disperse from their home
range in response to aerial gunning efforts. In fact,
research indicated the opposite in that core area and home
range sizes did not alter either before or after enacting
aerial control (Campbell et al. 2010). Instead, wild pigs
can adapt to aerial gunning by seeking dense cover and
refusing to flush from it despite concerted efforts by the
pilot and crew.
Research indicated that wild pig sows subjected to high hunting
pressure had higher conception rates in their first year and
produced offspring up to 12 days sooner than normal gestation.
What is significant about this behavior is that until
relatively recently wild pig populations had not
encountered significant predation from above their line of
sight. Despite this, they have quickly adapted to be
capable of intelligently evading a formidable 5000 pound
“aerial predator” that otherwise would seem to have every
advantage. The intelligence and adaptability of wild pigs
are key factors that compound effective control (Sweeney
et al. 2003), and this is again evidenced by their potential
to learn to evade aerial gunning efforts.
Trap Aversion
Research has long documented trapping as an effective
population reduction technique, with 70-80% reductions in
populations having been reported using this technique
alone (Saunders et al. 1990, Vernes et al. 1999). However

wild pigs can adapt to avoid traps altogether for a variety
of reasons. This can occur due to the size and type of
trap used, but also can be attributed to inadvertently
“educating” wild pigs through incomplete captures. With
the exception of solitary adult males (boars), wild pigs
travel in social groups called sounders. When trapping
these animals, it is important to target and remove the
entire sounder in a single trapping effort. This is
generally accomplished through a process of pre-baiting
and conditioning the group over time to routinely enter a
trap large enough to contain the entire sounder. Corral
style traps are often best suited for this, and research
indicated this type of trap to be four times more effective
than conventional box traps (Williams et al. 2010). Box
traps, while valued for their portability, usually
only capture 1-3 animals at a time. No matter what type
of trap is used, incomplete captures can divide sounders
and cause remaining pigs to avoid traps in the future.
Wild pigs will attempt to escape traps if given the opportunity. Ensure
that traps are constructed properly and check traps at first light to
help minimize trap escape attempts. (Image Credit: Andy James)
In order to minimize learned trap aversion due to incomplete
captures, the goal of any trapping effort should be to target and
remove the entire sounder of wild pigs.
Trap Escape
Wild pigs can also adapt to escape traps, and individuals
that learn to do so often exhibit this behavior repeatedly.
Trap escapes can be accomplished through climbing,
rooting, exploiting trap design flaws and even jumping
considerable heights in excess of 4 feet. It is important
to construct and implement sound trap designs, and it is
equally important to check traps as soon as possible
following each trap night. Many experienced trappers
check their traps at first light and bring a firearm in order
to harvest any residual pigs that may be near the trap site
due to incomplete capture or escape. The Texas A&M
Natural Resources Institute recommends that corral traps
be constructed with four to six 16’ cattle panels that have
5’ panel height and 4” mesh in order to minimize trap
escapes. It is generally not necessary to bury or trench
paneling underground, but it is important not to leave any
gaps at ground level or near the head gate. Game cameras
can be integral in monitoring wild pig activity at traps
sites, and can also help to identify any modifications
necessary in order to minimize the potential for trap
Wild pigs exhibit a variety of behavioral responses to
abatement pressure. Their intelligence and adaptability can
complicate effective control, factors that are only
compounded by their extreme fecundity. It is important to
select appropriate strategies as well as to adapt control
techniques as necessary in order to minimize any potential
issues which can reduce the success of abatement efforts.
This can undoubtedly be easier said than done, as is
evidenced by the numerous and often remarkable ways in
which wild pigs can evade control efforts despite the best
technologies available to man. However, best management
practices including trapping, aerial gunning, strategic
shooting, snaring, and the use of trained dogs remain
proven tools that, when implemented in a combined
approach, can successfully abate the damages associated
with wild pigs.