The Javelina: working the roadsides
by Clay Green
Division of Range Animal Science
Sul Ross State University
Alpine, Texas
Driving Highway 118 between Alpine and Fort Davis, groups
of “pig-like” animals foraging alongside the highway are often
encountered. These mammals, although “pig-like” in appearance,
are really Collared Peccaries, or Javelinas, Tayassu tajacu. Javelinas
are members of the Peccary family, native only to North and South America.
Historically, the Javelina has one of the largest geographical distributions
of any American ungulate (hoofed-mammal). The geographic range of the Javelina
extends from South America northward into the southwestern United States.
The Javelina evolved as a Central and South American rainforest inhabitant,
and has over time extended its range northward to include the much drier
regions of the Chihuahuan and Sonoran deserts.
Javelinas are mostly herbivorous
(vegetarian), although occasional animal matter is sometimes ingested. Because
Javelina sows are not restricted to a particular breeding season (rut),
they are unique in that they can produce litters year-round. Litter sizes
vary from 1-4, but generally average two. They can live up to seven years
of age, although they have been known to survive in captivity as long as
16.
While early explorers and settlers thought them to be ferocious,
Javelinas are generally timid and fearful of humans, unless cornered. When
these animals are scared or threatened, a “clicking” sound is
often heard. The rapid opening and closing of the mouth creates this sound.
Javelinas have four canine teeth (two upper/two lower) that fit together
like the blades of a scissors. This rapid opening and closing of the mouth
makes the canine teeth create this “clicking” or popping sound.
This sound heard upclose can be quite discomforting and even unnerving!
Research on any animal is critical to gaining knowledge
about behavior, habitat and food requirements, life history, and human/Javelina
interactions. Research activities pertaining to Javelina biology has been
quite extensive in Arizona and in southern Texas, but has not received as
much attention in West Texas. Several studies have been conducted in Big
Bend National Park. Prior to 1997, specific information on the life history
of these animals in the Davis Mountains was sparse.
Recently, I conducted a one-year study of Javelina herds
on the O6 Ranch, in the Davis Mountains. The goal of my investigation was
to determine herd size, home range (territory), and specific habitats that
the herds preferred or avoided. Fifteen Javelinas from three herds were
captured using box traps baited with corn. Once captured, the Javelinas
were tranquilized and fitted with radio collars. Each collar emits a specific
frequency that is picked up by a receiver. This signal allows the researcher
to “home in” on the collared individual
Radio tracking allowed me to locate each individual and
plot the location on a topographic map. It also allowed visual observation
resulting in a record of the physical activities of the animals (sleeping,
eating, and walking) and the number of Javelinas accompanying each individual.
The home range of an animal is the area it occupies in its daily activities
and movement. Since Javelinas live in herds, home range and territory are
used interchangeably. Habitat selection (whether an animal demonstrated
preference or avoidance to a particular habitat) was also determined. The
area occupied by the three study herds was subdivided into 10 habitats defined
by plant species present, topography, and geologic boundaries.
The study herds were tracked for one year from October
1997 to October 1998. The average herd size ranged from 3-11 individuals.
One herd often numbered as many as 17. Occasionally, a solitary individual
was observed. Several of the radio-collared boars were frequently by themselves.
One individual boar spent greater than 80% of the time by himself. Generally,
these individuals were older boars, although this was not always the case.
Prior to giving birth, sows will frequently separate from
the herd and remain isolated. Following the birth of her offspring, she
will rejoin the herd. In the course of my study, several sows were seen
by themselves prior to and immediately after giving birth.
The home range of the study herds ranged from 142-198 ha
(1.4–2.0 km2). Various types of habitats comprise the home range of
each herd. The igneous rock formations, or outcrops, that are common throughout
the Davis Mountains, played a significant role in daily life. Two herds
favored these rock outcrops for bedding sites (dens). These rock outcrop
habitats are dominated by oak and juniper, and provide excellent protective
cover from the hot sun as well as cold winter winds. Within these habitats,
Javelinas frequently utilized caves and rock ledges for dens. Areas of dense
brush comprised of Whitebrush, Texas Honey Mesquite, and Catclaw Mimosa,
are frequently used by herds as travel corridors. These corridors offer
protection from the elements and from predators including the Mountain Lion,
Bobcat, or Coyote. Although considered an inhabitant of desert scrub, Javelinas
are also seen at some of the highest elevations in the Davis Mountains.
The next time you are driving down a West Texas highway,
be on the lookout for these “pig-like” creatures. If you should
spot Javelinas, pull over and watch. You might be surprised at what you
see.
Links to other Javelina sites:
Other Discovery articles: