Click to Enlarge Collared lizards often live on open hillsides,where you can see them basking on rocks. During breeding season,male collared lizards (top right) are more brightly colored than females.   Rock Runners by Roxanna Watts, photos by Jim Rathert The feisty collared lizard holds its ground in Missouri's glades. At first I thought it was a scrap of blue plastic some careless hiker had dropped on the trail. As I stepped closer, the scrap swiveled and opened its small pink mouth. It wasn't litter - it was alive! It was a collared lizard. It stood like a small statue on a small outcrop. The yellow-orange hue of its head was framed by two black stripes. From its shoulders to its tail, faint bands of gold crossed its back, and small white spots mottled its scaly skin. A turquoise tail almost twice the length of the its body, draped over the rock. Nearby stood a female, a duller image of her mate. Like many reptiles, they were absorbing the heat of the noonday sun. As I moved closer, they made a quick dash to the safety of the rocks. Collared lizards are among Missouri's most fascinating reptiles. Members of the Iguanidae family, they are cousins to a variety of strange creatures, including a horned lizard with blood-squirting eyes, a green iguana that can grow to more than 5 feet long, and the Galapagos iguana, the only known marine lizard. Of course, the collared lizard also is a peculiar animal. Although they usually run from danger, male collared lizards are highly territorial and will aggressively confront invading rivals. To intimidate intruders, a male collared lizard opens his jaws and bobs his head as a warning. If the intruder comes nearer, the collared lizard may perform what looks like rapid push-ups, or he might expand his throat and compress his sides, arching his back to appear larger than he is. If this still does not discourage the interloper, the defender will attack. Though not venomous, collared lizards will bite. Collared lizards are carnivores. They eat insects, as well as small snakes and lizards. Where grasshoppers are plentiful, collared lizards help control their numbers. While some lizards rely on a darting tongue to capture a meal, the collared lizard has a small tongue that cannot be extended. They have to run down their prey. Collared lizards run on two legs. They are the only Missouri lizard with this ability. Their hind legs are much longer than their fore limbs and are very muscular. When speed is essential, a collared lizard may lift its body and race along on these powerful hind limbs, using its tail for balance. The length of its running stride may be three times longer than its body. They also need their speed to avoid being eaten. Hawks and snakes are the main predators of collared lizards. Because a collared lizard needs its tail for balance while running, its tail doesn't break away in the grip of a predator, the way other lizards' tails do. The head bobbing and swelling used by male collared lizards to intimidate intruders also help them attract mates. Breeding typically takes place from April to June, but collared lizards may mate more than once a year. After mating, pregnant females develop bright red or orange spots on their sides and necks that gradually intensify with color. The colors fade after the eggs are laid. The eggs are cream colored and have leathery shells. The female carries one to 13 eggs for up to three weeks before depositing them in loose, sandy soil or burying them in a burrow under rocks. The parents then abandon the nest and never return. Incubated by heat from the sun, the embryos grow. As they develop, a special "egg tooth" forms on the middle of their upper jaw. The hatchlings use this tooth to break their shells. After hatching, the young lizard sheds this tooth. When they hatch, young lizards are about 2 to 4 inches long and are tan with dark cross bands. The bands fade as the lizards age. By the age of three months, they reach a length of 8 to 10 inches. As adults, they may reach a foot long. Like all cold-blooded reptiles, collared lizards have no internal system to regulate their body heat. They rely instead on the surrounding environment to regulate body temperature. That's why you frequently see them basking on rocks. Ideal temperatures for collared lizards are between 73 and 93 during the day, and from 70 to 85 degrees at night. They seek rocky ledges and open forest glades to bask in the summer sun. As the days begin to cool, collared lizards burrow down into the soil or hide under protective rocks to wait out the winter months. Collared lizards do not make sounds. Because early settlers believed they made a booming call, probably mistaking them for the deep croaking of frogs, they called collared lizards "mountain boomers." That name is still popular today. Collared lizards can be found from eastern Missouri to Mexico. They are fairly numerous in some areas. The Missouri Department of Conservation is working to improve their habitat in the Ozarks by restoring glades, their preferred habitat.