Except for small lizards, reptiles are not much in evidence in the
monument. Nevertheless, they are present and are important in the
various plant-and-animal communities in which they live. Almost all
lizards are insectivorous, and along with birds and other insect-eaters
help to keep the number of insects within bounds. A notable exception is
the GILA (HEE-lah) MONSTER, (See appendix for scientific names of
reptiles) largest of the lizards found in the United States. (It is one
of the world’s two poisonous lizards, and the only one found in this
country.) The gila monster is especially fond of bird eggs, and also
eats nestlings and small rodents, obtaining necessary moisture from
their body juices. These food habits are quite similar to those of the
several species of snakes found in the monument, the majority of which
are perfectly harmless to humans.
[Illustration: The short-horned lizard, more cold-tolerant than the
desert horned lizard, ranges from the foothills into the mountain
forests of Saguaro.]
Just as the lizards help to control the insect population, the snakes
are important in preventing the buildup of large numbers of rodents that
would result in widespread damage to vegetation. Visitors to the
monument rarely have the opportunity to observe snakes, since they are
in hibernation during winter and remain in the shade or in underground
burrows during the hot part of each summer day. Perhaps those most
frequently seen are the GOPHER SNAKE and the COACHWHIP. Many desert
snakes hunt only at night; others that are normally active during days
of moderate temperatures become night hunters during hot weather.
Although they are not abundant, there are several kinds of rattlesnakes
in the monument, the commonest desert species being the WESTERN
DIAMONDBACK and MOHAVE RATTLESNAKES. Except for the small, very rare,
and secretive ARIZONA CORAL SNAKE, rattlesnakes are the only poisonous
snakes in the monument. Snakes, like other living things in the national
monument, are protected by law.
Don’t be surprised while following a desert footpath to come upon a
plodding tortoise. This bona fide desert dweller, the DESERT TORTOISE,
is a vegetarian, feeding on cactus, grass, and other low-growing plants.