FERAL PIGS KING RANCH BLUESTEM AXIS DEER

ALIEN INVADERS!
Feral pigs
are not
dangerous,
but like all
wild animals
will defend
themselves
if cornered
or harassed.
What is an invasive species?
An “invasive species” is a species that is non-native (alien) to an ecosystem and
causes, or is likely to cause, economic or environmental harm. Invasive species are
persistent. They grow, or reproduce, and spread rapidly, encroaching on large areas.
They threaten the survival of native plants and animals and are very costly to control.
Exotic animals in Texas are unprotected, non-game
animals. They may be taken by any means or
methods at any time of year. A hunting license and
landowner permission are required to hunt them.
Native plants and animals are products of
thousands of years of evolving specific
characteristics allowing them to fit into certain
ecosystems. Eliminating a native from its habitat
affects soil organisms, insects, birds, mammals,
and other plants that depend on that native
species. Alien invaders upset the whole balance.
AXIS DEER
KING RANCH BLUESTEM
Axis axis
Bothriochloa ischaemum
•
KR bluestem was introduced to California from
China in 1917, but it was not noticed until 1937
on the King Ranch in Texas.
Axis deer are native to the Indian subcontinent and
were introduced into Texas in the 1930s. They are
remarkably resistant to disease, and they are one of
the most adaptable and popular exotic species.
•
Ranchers began obtaining Axis and other exotic species
for personal interest, venison (food), antler production,
additional income from hunting, and as an attempt to
safeguard certain species from extinction.
•
Overpopulation of Axis coupled with native wildlife
populations results in over-utilization of the landscape
and plant communities. This overuse causes loss of
biodiversity and soil erosion in the Hill Country.
•
•
•
Axis can reproduce year-round. Native white-tailed
deer cannot. Axis gestation is approximately 7.5
months. In Texas, fawning peaks in January to April and
October to November.
The major concern with importation of exotic species
is transmittal of foreign diseases and/or parasites to
native animals and domestic livestock.
There is
no single,
surefire
method
for control
of KR
bluestem.
It was seen as a desirable species for erosion
control since it is drought resistant and establishes
quickly. It was grown as livestock forage and
included in seed mixes used to stabilize roadsides
by highway departments.
Feral pigs are
not related to
native javelinas.
Feral pigs are
true pigs;
javelinas are
collared
peccaries
Tayassu [Pecari]
tajacu –
a separate family
of mammals.
FERAL PIGS
Sus scrofa
• Feral pigs in Texas are primarily escaped or
released domestic pigs and their descendents.
With each generation, the pig’s domestic
characteristics diminish and they develop traits
needed for survival in the wild. Half the feral pig
population in the United States is in Texas.
• Spanish explorers brought domestic swine into
Texas in the mid-1500s. The first pigs to
establish a wild population probably originated
with East Texas colonists in the early 1800s.
• Feral pigs cause economic and environmental
damage. Depredation of native wildlife and
livestock, and destruction of habitat and
agricultural crops, cause hundreds of millions
in damages each year.
• Feral pig signs include tracks, rooting, wallows,
and scat (droppings). They are largely nocturnal,
and the visible signs they leave behind are
often all that indicates their presence.
Texas has more hoofed exotics than any other state,
probably due to its mild climate and the fact that most
land in the state is privately owned.
Axis deer outcompete native
white-tailed deer for available
forage. They both prefer browse
and forbs. Once this forage is
depleted, axis deer can utilize grass;
native white-tailed deer cannot.
They have relatively
poor eyesight but
have keen senses of
hearing and smell.
• Feral pigs are omnivores with a simple digestive
Vocalization is
important in axis
deer society and is
one of their most
noticeable
characteristics.
Axis males can
bugle like elk. Both
sexes sound sharp,
high-pitched,
barking alarm calls.
All Axis signal
each other with
barks and body
movements like
tail-switching.
tract. They are opportunistic feeders and can
eat pretty much anything, but primarily eat
vegetation.
KR bluestem is now considered an invasive species
and its presence threatens the abundance and
diversity of native species.
Sows have high
reproductive
rates, with a
114-day
gestation
and an
average
litter of six
piglets.