Mountain Boomers Boom Back

The eastern collared lizard, often called the mountain boomer, is just one of several desert-adapted species living in Missouri's Ozarks.

Though typically associated with the more arid regions of the southwestern U.S. and northern Mexico, this lizard has managed to survive for thousands of years on small, fragmented habitats that we call glades. Glades are open, rocky areas where thin soils, high landscape position and maximum exposure to sunlight create a near desert environment. Native grasses and forbs are the dominant vegetation, and few trees are present. With plenty of exposed rocks for cover, a dry climate and abundant insects, glades provide excellent habitat for collared lizards.

In Missouri, glades are usually small, isolated islands in an otherwise wooded environment. Therefore, collared lizards must be able to freely move about to take advantage of all the glades that exist in an area. This requires the presence of travel corridors connecting these areas.

Fires, often ignited by aboriginal Americans, periodically burned across the Ozarks, reducing underbrush and promoting the growth of grasses and wildflowers in the understory of these woodlands. The structure created by fire on these sites was critical to maintaining the open conditions that allowed collared lizards to circulate.

Early explorers, such as Henry Rowe Schoolcraft, remarked on the openness of the wooded areas in the Ozarks and the abundance of grasses and wildflowers growing under the oak canopy. Other accounts often described how aboriginal Americans frequently burned the woods to make travel easier and to attract bison, elk and other large herbivores. For thousands of years, the use of fire by these early inhabitants shaped the habitats of the Ozarks, creating conditions favorable to many wildlife species.

Collared lizards thrived under these conditions until widespread European settlement began to change the landscape. Although early settlers continued the practice of burning the land, increases in the frequency and pattern of fires, along with open-range grazing of livestock, led to further declines in the once diverse and widespread natural communities of the area.

By the early 1900s, the native flora and fauna of the Ozarks were in jeopardy. Fifty years of relentless burning, heavy grazing and uncontrolled logging had left little evidence of the plants and animals that formerly inhabited the region.

In the 1940s, federal and state resource management agencies began advocating reforestation programs which included the widespread control of all wildfires. This change in policies began, quite possibly, the longest fire-free period in the recent history of the Ozarks.

Fire suppression in the Ozarks allowed areas to reforest, but the diverse glade and woodland communities that once dominated the area were replaced by dense, second-growth forests with few similarities to the rich habitats to which most of our native plants and animals had adapted.

As collared lizards and many other native wildlife populations continued to decline, biologists with state and federal agencies began searching for solutions. While on the surface it appeared that conditions were improving for wildlife, most gains were coming from generalist species like white-tailed deer. Collared lizards, however, could not cope with the dense growth of underbrush that was now taking over their glade and woodland habitat in the absence of fire.

It became clear that if these species were to survive, their habitat would have to be restored. In the early 1980s, managers at Peck Ranch Conservation Area in Carter County were among the first to take steps toward restoring glade and woodland habitats.

Located in the eastern Ozarks, 23,000-acre Peck Ranch is owned and managed by the Missouri Department of Conservation. Historically, the area in and around Peck Ranch supported vast acreages of oak and pine woodland, along with numerous dolomite and igneous glade communities.

Like many other places in the region, Peck Ranch was subject to extensive clearing, livestock grazing, and other abuses before its purchase by the Conservation Department. Following acquisition, a strict fire suppression policy was instituted to help protect wild turkeys, which nested on the ground. Although turkeys flourished, the collared lizard did not fare so well. By the 1980s, surveys found no collared lizards remained on Peck Ranch.

As the glades and woodlands continued to be overgrown by invading brush, the future of these natural communities and the collared lizard on the area looked grim.

When staff at Peck Ranch first began working on restoring glades and woodlands, the idea was relatively new, and little information existed. Initial efforts were targeted at removing woody vegetation from individual glades and localized burning to encourage the growth of grasses and wildflowers. While this work successfully re-established open conditions and promoted native plants, the small size of these areas and lack of disturbance in the surrounding woodlands did little to create habitat conditions that would support healthy populations of wildlife dependent upon these habitats.

In 1983, the Conservation Department began a collared lizard re-introduction project in cooperation with Washington University in St. Louis. The initial releases were made in glades at Stegall Mountain Natural Area on Peck Ranch. From 1984 to 1989, three populations of collared lizards were relocated to Stegall Mountain from Taum Sauk Mountain, where construction on a pump-back reservoir for power generation threatened to destroy their habitat. The relocation was successful, and all lizards survived.

As collared lizards were released onto Stegall Mountain, researchers with Washington University marked each lizard and gathered DNA information that would be critical in tracking their progress and survival. After completing the release program, they set up a long-term study to monitor the effects of habitat changes on the lizards.

For the first several years, annual surveys of the lizard populations showed that they were surviving and reproducing at Stegall Mountain. However, further studies indicated that no new glade sites had been colonized and that no breeding was taking place between the different populations.

This information concerned researchers who feared that individual glades would soon become overpopulated and that a lack of gene flow between populations would ultimately lead to local extinctions. Local managers devised a plan to address these issues.

In 1993, managers developed a proposal to use prescribed fire on a landscape scale that would incorporate not only the glades, but also the surrounding woodlands. This concept was almost unheard of in the region at that time, and many were skeptical of its merits. By applying carefully controlled fire to the area, managers hoped they could eliminate woody underbrush on the glades, as well as in the woodland areas, allowing collared lizards to colonize new sites.

The following year they conducted the first of these prescribed burns, treating almost 400 acres of Stegall Mountain. After only one burn, surveys of the lizard populations showed that 13 glades that previously had no lizard populations became colonized. Studies of the vegetation in the burn area revealed that the fire had reduced woody undergrowth to the point that lizards could move from glade to glade.

Pleased and excited with the results of their work, managers decided to increase the size of the area being treated. To do this, Department of Conservation personnel enlisted the help of the National Park Service and The Nature Conservancy, both of which owned and managed the remaining portions of Stegall Mountain Natural Area. With this partnership firmly in place, the fire management program on Stegall Mountain increased to nearly 5,000 acres.

With the aid of DNA information, researchers continued to track the lizard population and were amazed at how quickly the population increased with the availability of new habitat. As new glade and woodland complexes came under similar management near Stegall Mountain, they too were colonized. Each time, DNA linked the new populations back to one of the original populations that were relocated to Stegall Mountain.

The studies on collared lizards at Stegall Mountain provide some of the best documentation to date on the recovery of a native Missouri species as a direct result of landscape management using prescribed burning. Hopefully, the knowledge gained through this successful project will encourage other attempts to recover the native plant and animal communities that make the Ozarks unique.

Today, restoration work continues on Stegall Mountain Natural Area. The destruction of our native habitats certainly did not take place overnight, and we can not expect to repair them quickly. Nevertheless, it is a good sign for future restoration efforts that the mountain boomers are once again booming on Stegall Mountain.