The eastern collared lizard is a colorful, long-tailed lizard with a large head. The color is most conspicuous on males during the breeding season (May and June); the general ground color is tan, yellow, green, or blue green. There are usually a number of small light spots scattered over the upper body and limbs and dark bands across the entire back. Both males and females have two dark brown or black irregular lines across the neck, resembling a collar. Females are yellowish tan or light brown with faint light spots. Females also have black dots along each side of the cloaca (anal opening) that are absent in males. Females heavy with eggs have red spots or bars on the sides of the body and neck. Newly hatched young have dark bands and yellowish crossbars.
Adult total length: 8–14 inches.
Throughout most of the Missouri Ozarks and in glades of the St. Francois Mountains. Relict populations occur south of the Missouri River within the Kansas City area. Populations occurring north of the Missouri River appear to be introduced.
Habitat and Conservation
In Missouri these lizards live among rocks on dry, open, south-or southwest-facing limestone, sandstone, and granite glades. They can also be found in human-altered landscapes such as rock quarries and rocky riprap along reservoir dams. Adult males prefer to observe the world from a perched location on a large boulder.
As with all native lizards in Missouri, the eastern collared lizard is active by day, especially when the weather is sunny and warm. The preferred air temperature for this species is between 73° and 93°F. Seasonal activity usually lasts from April to September for adults, with a peak from May to late July, but young lizards may remain active through October.
These lizards spend a great deal of time basking in the sun on exposed rocks, but they quickly take shelter under large rocks or in rock crevices when approached. If caught in an open area, a collared lizard can run very fast to escape; it will often run on its hind limbs with the forward part of the body held upright.
Each lizard defends a home territory by chasing away other collared lizards when a territory is violated. The bright colors of males are used to ward off other males from invading an individual’s home range.
Population studies of the collared lizard in Shannon County documented that most glades can generally support 15–25 animals, but some population estimates for glades can exceed 50 animals with favorable conditions.
Collared lizards overwinter in burrows 8–12 inches under large rocks.
This species is a great example of the benefits of glade habitat conservation. Over many years, Missouri's native, desert-like glades had become overgrown with cedars due to the lack of periodic fires, and many populations of collared lizards were greatly reduced or disappeared because of unsuitable environmental conditions. When glade habitats are marginal (shadier or cooler than optimal), this lizard's growth and reproduction decreases, and their period of seasonal activity becomes shorter. Their foods become scarce, too. The lack of fire in glades permitted trees such as cedars to overgrow those desert-like areas. In the 1980s and 1990s, wildlife managers and foresters worked to improve collared lizards’ glade habitats throughout the Missouri Ozarks. These habitat improvements resulted in population increases in existing locations and the successful introduction of lizards throughout many other locations in Missouri. This lizard remains on Missouri's list of species of conservation concern because there is still some cause for long-term concern.
Collared lizards eat a variety of insects such as grasshoppers, beetles, and moths. They also eat spiders, small snakes, and other lizards.
This species of conservation concern was once quite rare in the state due to lack of management of glade habitat throughout Missouri. Today, thanks to improvement and protection of Missouri's glades, the eastern collared lizard appears to be quite common and secure in Missouri. Maintaining the open nature of glade habitat, minimizing human disturbance of rocks, and reducing the illegal collections of animals will help keep this species common in Missouri.
In Missouri, eastern collared lizards are active mainly from April to September. Courtship and mating occur from mid-May to early June, and the territorial males are often brightly colored at this time. An adult male will court a female by showing off his brightly colored throat and body as he prances around her.
Females usually lay eggs within 20 days after breeding. Some females may deposit two clutches in a single season. The eggs are creamy white and leathery, and a clutch can comprise 4–24 eggs (with an average of 7 or 8, and seldom more than 12). The female deposits these in a burrow she digs beneath a large rock. When the eggs are laid, the female plugs the nest's entrance with dirt to protect the eggs from predators. The eggs hatch 2–3 months later.
The young lizards grow rapidly and may be large enough to reproduce within their first or second year of life. The lifespan rarely exceeds 5 years.
These nifty lizards always generate interest because they are so colorful. Because they are an indicator species, when their numbers decline, we know that something is wrong with their habitat. In this case, it is human suppression of fires that allowed trees to overgrow their sunshiny glades.
A popular common name for this lizard is mountain boomer, implying this lizard makes a booming sound. This name probably originated in southwestern United States where settlers may have seen the lizard on rocks while hearing the barking call of a local frog species. In reality, the collared lizard is voiceless.
This species preys upon a variety of insects, spiders, and other small creatures, keeping their populations in check. These lizards are in turn preyed upon by snakes, hawks, and, in southwestern Missouri, roadrunners. They will escape predators by running fast, seeking shelter, and even swimming at the water’s surface.
The eastern collared lizard is a charismatic, colorful, and interesting species that can help people care about glade habitats. Glades are open, rocky areas usually located amid upland woodlands. Their high location, thin soils, exposed rocks, few trees, and south- or west-facing aspect make glades hot and dry, like little deserts. Several distinctive plants and animals live in Missouri's glades, including prickly pear cactus, glade coneflower, geocarpon, eastern narrow-mouthed toad, variable groundsnake, eastern coachwhip, roadrunner, painted bunting, prairie warbler, Texas and desert mice, striped bark scorpion, Texas brown tarantula, Ozark swallowtail, and lichen grasshopper.
The eastern collared lizard is Missouri's only species in the family Crotaphytidae. The family includes 12 recognized species consisting of two genera. This group is restricted to North America from eastern Missouri to the west coast and south into northern Mexico. Many species are native to the U.S. desert southwest and northern Mexico. These lizards have large heads, robust bodies, and the ability to run on their hind legs. They require a dry, open habitat. Other characteristics of this family include teeth located on the inner surface of the lower jaw and a form of communication employing head bobbing and body pushups. Males use these gestures to defend small territories or to court a female. Lizards in this family defend themselves by biting and scratching.