In the effort to save the beloved Texas horned lizard

This story originally ran

There were once Texas horned lizards in much of the state: crouching reptiles the color of rusty red and gray gravel, heads crowned with a fan of sharp little horns. Known as “horny toads,” the 5-inch lizards have been immortalized in magnets, murals, and even as TCU’s mascot. They were commonplace, easy to catch, and easy—in their grumpy, frowning way—to fall in love with.

“It has this cultural attachment in Texas,” said Nathan Rains, a biologist with the Texas Parks and Wildlife Department. “Everyone has an affinity for horny toads.”

The largest and most common of the North American horned lizards, Texas horned lizards thrive in arid landscapes as far east as Austin, largely on a diet of red harvest ants. Slow and relatively docile, horned lizards rely on camouflage to stay out of trouble, but if cornered, they can spray blood from their eyes to startle predators.


At first glance, the Texas horned lizard looks prehistoric, timeless and tough. But starting in the 1950s, horned lizards disappeared from much of their historic territory. Older Texans “probably have fond memories of the abundant horned lizards that are no longer around,” said Andy Gluesenkamp, ​​director of conservation at San Antonio Zoo’s Center for Conservation and Research.

Now, Gluesenkamp and San Antonio Zoo are part of a coalition of zoos, government agencies, and private landowners working on a tricky project: to restore the state’s most famous and finicky reptile to the places it once roamed — and ensure that those habitats are ready for their arrival.

Adult lizards feed on red harvest ants. (© Seth Patterson/Texas Highways)

The San Antonio Zoo’s Horned Lizard Reintroduction Project is housed in a tin warehouse, far from the zoo’s public exhibits. The “lizard factory,” as Gluesenkamp calls it, contains racks of terrariums populated by horned lizards basking under heat lamps, some of which are still small enough to sit on a nickel. “Most of our animals were plucked off the tarmac, where the next car might have been the one that put them in,” Gluesenkamp says. “We’re really trying to minimize the impact on wild populations, even if we’re only collecting a negligible amount in any given year.”


The lizard’s vulnerability has been recognized since at least 1977, when the state officially classified horny toads as endangered. The growing sprawl of cities in Texas has wiped out large areas of habitat. Rangeland also changed when non-native grasses such as Bermuda grass, intended to feed livestock, created impenetrable thickets for the lizards, which live their lives an inch above the ground. The widespread use of pesticides and invasive fire ants meanwhile devastated the red harvest ant colonies on which horned lizards depended. By the 21st century, horny toads had all but disappeared from East and Central Texas.

In 2007, TCU researchers began studying the diet and genetics of the species. They found that the populations of horned lizards in North Texas and South Texas are genetically different. To preserve genetic diversity, Rains says, conservationists tried to match adults from their specific groups for breeding. In doing so, they found that 70-90% of adults normally die each year in the wild.


“That’s a real challenge when you’re trying to reintroduce a species,” Rains says. “There just weren’t enough existing adults to make up for the losses.”

In other words, if the horned lizard had to be returned to its old stomping grounds, conservationists needed a ready supply of new lizards. The Fort Worth Zoo had begun a breeding program for the northern genetic population as early as 2000. After years of trial release programs in the Mason Mountain Wildlife Management Area – 53 miles west of Llano – several dozen cubs released in 2019 were the first to breed and reproduce. Last September, the zoo released another 204 cubs.

When Gluesenkamp left his position as a Texas Parks and Wildlife herpetologist in 2016 to join the San Antonio Zoo, he immediately began work on a reintroduction program for the Southern genetic population. “Texans love horned lizards as much as all other reptiles put together,” he jokes. “That makes it a lot easier to get people involved in what we’re doing: restoring this truly iconic species to our native landscape by managing biodiversity.”


However, breeding Texas horned lizards is difficult. To survive, the lizards need precise temperature and light regimes and regular misting. A single lizard can eat as many as 100 harvest ants a day, and they are easily stressed. Females are capable of laying 30-40 eggs at a time, or have multiple nests in a season, but results in San Antonio have been mixed so far, said Arianna Duffey, a conservation engineer at the zoo. One lizard laid 46 eggs, possibly a world record. Another left her eggs scattered haphazardly in the terrarium. Another dug down to the glass bottom and piled them up there.

Senior conservation technician Kamryn Richard weighs a horny toad in the horned lizard breeding facility at the Texas San Antonio Zoo. (© Seth Patterson/Texas Highways)

“We’ve all seen it,” says Duffey. “It’s hard to say why they do what they do — whether it’s a matter of captivity versus in the wild, or being a first-time mother versus an experienced mother.”

The goal is to produce enough fry to ground 100 babies per year in a given location for three years, with another 25 per year indefinitely. For that strategy to work, the team also needs to raise the tiny, extremely snackable babies — Gluesenkamp calls them “nature’s popcorn” — to a size where they have a better chance of survival. Since the start of the program, the San Antonio Zoo has managed to hatch more than 100 lizards. “There is no user manual for it,” says Gluesenkamp.


The project in San Antonio works primarily with private landowners. The boy’s first release was 84 lizards on Matthew Winkler’s 2,000-acre ranch in Blanco County in October 2020. Last year, the zoo released an additional 23 lizards on the same land. “As a biologist and ranch owner, I think it’s a good idea to bring the ranch environment back to the way it was 300 years ago,” Winkler says. “My goal is for other ranchers to go, ‘Wow, this is interesting, maybe we can get involved.'”

Gluesenkamp and Rains say they’re hearing from plenty of landowners eager to participate in horned lizard recovery efforts. But it will be years before the zoos can produce enough babies to dent demand. In the meantime, Gluesenkamp says, landowners can encourage lizard habitat by restoring native grasses, establishing controlled grazing and burning regimes, and promoting existing red harvest ant mounds.

Some ranches still have native populations of horned lizards. At the White Ranch near Mason, ranch manager Brian Wright raves about the wild boy running across the red soil. The babies come here often enough that scientists visit them to study them.


When he arrived at the White Ranch in 2015, Wright was working with a landowner who focused solely on managing livestock. Now Wright also manages for wildlife, including horned lizards. “The other ranchers think I’m a tree hugger,” he says, beaming through his white beard. “But I’m looking at ecotourism, which I think has the potential to be really marketable. And horned lizards are a big part of that.”

From the January 2022 issue of: Texas Highways magazine.

Copyright 2022 by KSAT – All rights reserved.

Leave a Comment

%d bloggers like this: