Viatouch Teacher Articles
Science

The Mountain Boomer
by Damian Fagan

When early settlers heard a booming sound in the valleys of Oklahoma, they thought an animal made the sound, but they were not sure which one. They mistakenly believed that a colorful lizard sitting on some rocks made the sound, so they called this lizard the "mountain boomer." Today, the mountain boomer is Oklahoma's Official State Reptile, but herpetologists (people who study lizards, snakes, and amphibians) now call the mountain boomer the "collared lizard" because the boomer does not boom.

Size and color of collared lizards
Collared lizards are good-sized with large, stout heads. Their body length is about 10-12 inches long, from the nose to the tip of the tail. They have two black neck bands that are like collars, hence their common name. Depending upon where they live, some are brighter green and with deeper yellow heads than others. Though males are more colorful than the females, both have white spots on their bodies. Another way to tell the sexes apart is when the females are pregnant, called gravid. Then, the females develop reddish-orange spots on their sides and necks.

Where are collared lizards found?
Collared lizards live throughout the western United States, from Missouri and Texas to California and into the drier parts of Idaho and Washington, and northern Mexico. They prefer dry, open areas with rocks where they can hide or sit. Usually they are active in the warm months, from April through October, and hibernate during the winter in underground burrows.

So why the bright coloration?
Collared lizards live in mostly rocky areas with scattered plants. Their bright colors and body movements are for communicating long distance to other collared lizards. Remember that these lizards do not sing like birds or howl like coyotes to communicate with other members of their species.

When defending their territory, a male collared lizard sits on a rock or high point for a good view. When another lizard enters his turf, he may bob his head or do "pushups" to warn the other lizard. His bright color, black markings around his legs and neck, and physical displays tell other collared lizards to stay away. If the other lizard gets too close, the male scampers off his perch and chases the intruder. Sometimes these lizards will stand upright (more like a 45° angle) and run on just their hind legs while using their tails for balance! This is called bipedal motion. When they scamper like this, they resemble a miniature Tyrannosaurus rex dinosaur.

Daily life
Collared lizards like warm weather and may not leave their underground burrows until mid-morning. When they are warm, these cold-blooded reptiles hunt for grasshoppers, beetles, or spiders. They even prey upon smaller lizards.

Mating takes place in early summer. Females lay up to a dozen (usually 4-6) white eggs in an underground burrow in the middle of summer. Birds incubate their eggs, but not collared lizards. The female deposits her eggs, covers them with some soil, and then goes away. About ten weeks later, the eggs hatch. The young eat a lot to gain weight before they have to survive their seven-month hibernation. Though adults may enter into hibernation in August or September, the hatchlings remain above ground as long as possible.

When bright is too bright
Being colorful has some drawbacks. Predators like hawks or roadrunners may easily spot these lizards sunning on a boulder. Bull snakes and rattlesnakes also prey upon these lizards. But wary lizards may dash underground into a protective burrow or find safety in a pile of rocks. Too bad they can't "boom" to scare away their enemies!

Check out the nature film produced by ABC Kane Productions called The Living Eden: Canyonlands to see these lizards in action.

Bibliography
Behler, John L. and F. Wayne King. National Audubon Society Field Guide to North American Reptiles and Amphibians. New York: Alfred A. Knopf, Inc., 1998.

Degenhardt, William G., Charles W. Painter, and Andrew H. Price. Reptiles and Amphibians of New Mexico. Albuquerque: University of New Mexico Press, 1996.

Stebbins, Robert C. Peterson Field Guide to Western Reptiles and Amphibians. Boston: Houghton Mifflin, Co., 1985.

Williams, David B. A Naturalist's Guide to Canyon Country. Helena, MT: Falcon Press Publishing, 2000.

Internet Resources
http://animaldiversity.ummz.umich.edu.
http://www.desertmuseum.org.
http://www.geocities.com.
http://www.wildlifedepartment.com.

Damian Fagan is a biologist, writer, and photographer living in Bend, Oregon. He was a researcher, location scout, soundman, and occasional lizard wrangler on the set for "The Living Eden: Canyonlands" film.