**DANGEROUS DESERT DWELLERS?**

Gila Monsters and Rattlesnakes

Over the years, most of us have read books or seen movies and TV shows
about the \"real\" West. In many of these stories, the villains are not
men, but reptiles. Gila monsters attack innocent women and children;
rattlesnakes lurk behind rocks, waiting to sink their fangs into the
unsuspecting hero. Exciting as these tales are, the truth is much more
interesting.

**Gila Monsters**

The Gila monster is one of only two venomous lizards in the world. Its
Latin name, Heloderma suspectum, refers to the animal's textured skin
and suspicions that it might be poisonous. "Gila" may refer to the fact
that they are often seen around the Gila River, or it may be a
corruption of Heloderma.

Gila monsters primarily live in the Sonoran Desert, ranging from sea
level to about 5000\'. They come out of their burrows between March and
April, which coincides with the appearance of their preferred prey -
bird eggs and baby animals. They conserve precious energy by spending
more than 99% of their lives underground and, with their low metabolism,
may only need to eat the equivalent of three dozen quail eggs each year.

At an average length of 14 - 16\", and weighing about 1½ lbs, this is
the largest lizard in the US. Gila monsters have an elongated body,
heavy tail, large flat head, short neck and legs, and feet with five
toes and claws. The tail stores fat and its circumference indicates the
animal's condition. The teeth are grooved, and venom is produced in
large glands in the lower jaw. The venom is used for defensive purposes,
since the usual food sources cannot escape. The Gila monster is immune
to its own venom and appears to be resistant to that of rattlesnakes, as
well.

The skin is black to dark brown with orange, yellow, pink, or red
"beads" which are produced by skin covering particles of bone. There are
two subspecies -- the most common is the reticulate, which has irregular
blotches. The banded Gila monster has definite bands or rings. The
reticulate is found at Tonto National Monument.

As might be expected, Gila monsters are usually rather slow animals,
with an average speed of .15 mph; they only manage a top speed of about
.5 mph. Their vision and hearing are good, they are efficient diggers,
can climb well, and are adequate swimmers.

We think mating takes place in early summer, and a clutch of 2 - 12 eggs
is laid in July or August. The young appear approximately 10 months
later. They may hatch earlier and overwinter; we don't know much about
this part of the life cycle. Hatchlings are about 6\" long and weigh
approximately one ounce. They reach maturity at 4 - 5 years, and can
live to be 20 - 30. They do not have any definite predators; most
literature says they \"may\" be preyed upon by coyotes and birds of
prey.

The Gila monster\'s bite causes severe pain and a drop in blood
pressure; death may result from respiratory failure or cardiac arrest.
If unlucky enough to be bitten, get medical attention. The teeth are
very brittle and may break off in the wound, so a tetanus shot is also a
good idea. There are no documented cases of humans dying from a Gila
monster bite.

Harassment and/or possession of Gila monsters are prohibited under state
and federal law. Because of this, and the fact that they are venomous,
they should be left alone. The Gila monster is not yet an endangered
species, but protection of its desert home is essential to insure its
continued presence.

**Rattlesnakes**

As a group, venomous snakes are some of nature's most efficient hunters.
The use of venom to capture prey helps conserve energy that would
otherwise be needed to capture and subdue an animal.

Like other reptiles, rattlesnakes are not actually cold-blooded, but are
affected by outside temperatures. They are most active in the warmer
months, but may be seen out sunning on warm winter days. Generally, they
prefer temperatures between 70° - 90° F, regardless of the time of year.
Contrary to popular belief, they cannot tolerate extreme heat, and may
die if unable to find shade.

Rattlesnakes are members of a group of snakes called "pit vipers". The
pits are part of a sensory system that no other vertebrate has. They are
located between the eyes and nostrils, and can detect temperature
differences of perhaps fractions of a degree. This "heat vision" is
useful in locating prey even in total darkness. They also have
chemoreceptors on their tongue to help locate prey.

Rattlesnakes have long, curved fangs that fold back when not in use.
When the snake strikes, its fangs rotate forward. Since they are hollow,
this allows the snake to inject venom directly into the victim. The
venom is generally used to assist in capture and digestion of prey.
Adult rattlesnakes are able to control their venom flow, and usually
conserve it when biting for self-protection.

Rattlesnakes give birth to live young. Depending on the species, there
may be as many as two dozen babies, which average 6 -- 12" in length.
The young are born fully equipped with fangs and venom, and are capable
of inflicting painful bites. For years, it was assumed that rattlesnakes
did not care for their young after birth. Research is showing that this
may not be correct; most species appear to stay with their young for
several weeks.

The snake is born with a non-functional rattle, or \"prebutton\", which
will be lost at the first shedding, and replaced by a button. A new
segment is added with each shed skin, as many as four per year. Segments
vibrating at 60 or more times per second create the distinctive noise.
Since rattles are easily broken, it is impossible to age a snake by
counting the segments.

There may be four different species of rattlesnake at Tonto National
Monument:

Western Diamondback (Crotalus atrox) -- one of the most common snakes in
Arizona, it has diamond-shaped or hexagonal markings along the center of
the back and a light eye stripe from the eye to the upper lip. Because
of the distinctive black and white bands on the tail, it is often called
a "coontail".

Arizona Black (Crotalus viridis cerberus) -- a subspecies of the western
rattlesnake, they are normally found at higher elevations. At Tonto,
they prefer more wooded or moister habitats. Adults may be dark gray or
black to olive, with dark brown or black markings. Some individuals may
be almost solid black.

Black-tailed (Crotalus molossus) -- a large brightly patterned
rattlesnake with dark coloring above the rattles and on the snout. They
are often confused with Mojaves due to their green and yellowish
coloration.

Mojave (Crotalus scutulatus) -- often confused with western diamondbacks
or blacktail rattlesnakes, they generally have a greenish cast, and the
black tail bands are slightly narrower than the white. Herpetologists
also look for 2 - 3 large scales between the eyes. Although the Monument
is within this snake's range, it has not yet been confirmed here.
Generally, Mojaves prefer flat desert areas without rocks.

What should you do if you encounter a snake? Maintain a safe distance.
Rattlesnakes do not have to be coiled in order to strike. Never try to
handle one, even if it is dead. If you are bitten, get to a hospital as
quickly as possible. Most traditional first aid remedies are no longer
recommended.

Rather than fear and hatred, we should view these remarkable animals
with awe and appreciation for their amazing adaptability. Snakes were
around long before humans, and they will be here long after we are gone.