Experts say the Texas horned lizard has mostly disappeared from its range east of Interstate 35.
Experts say the Texas horned lizard has mostly disappeared from its range east of Interstate 35. Credit: Brendan Gibbons / San Antonio Report

When Andy Gluesenkamp worked for the Texas Parks and Wildlife Department, it seemed like everyone in Texas wanted to ask him about horny toads.

“It was one of the most common requests that I got from the public,” Gluesenkamp, formerly the TPWD’s top reptile and amphibian expert, said about the squat, spiky lizards that many call horny toads or horned frogs.

The questions ranged from where to find them to how to best manage their habitat. But of all the questions, the most common was, “What happened to the horned lizards?”

San Antonio Zoo Conservation Director Andy Gluesenkamp leads visitors on a tour of the laboratory where zoo staff house Texas horned lizards.
San Antonio Zoo Conservation Director Andy Gluesenkamp leads visitors on a tour of the laboratory where zoo staff house Texas horned lizards. Credit: Brendan Gibbons / San Antonio Report

Long a symbol of the Lone Star State, the Texas horned lizard has suffered a decline throughout the central and eastern part of the landscape starting in the 1950s through the 1970s. Experts say the lizard has disappeared from a third to half of its former territory.

Of the more than 20 horned lizard species found only in North America, the Texas horned lizard has the largest range and is most well-known. Biologists at the San Antonio Zoo and others around the state are working to reintroduce it to places where it’s disappeared.

Gluesenkamp, now the director of conservation at the zoo, is heading up efforts south of Texas’ Colorado River.

Next spring, he and colleagues will introduce dozens of horned lizard babies hatched at the zoo to a 2,000-acre ranch in Blanco County. The plan is to find more suitable properties and put as many lizards out there as possible until they can establish populations that can thrive on their own.

“The ultimate goal is to put horned lizards back on the landscape where they once occurred so that everybody can enjoy them,” Gluesenkamp said.

That will be welcome news for many Texans, especially older generations who remember when there seemed to be horned lizards everywhere. Gluesenkamp’s had enough people ask him about them that he often can guess how old questioners are and where they come from.

“It’s typically they grew up somewhere between Houston and Dallas, which is where we’ve lost lizards for the most part,” Gluesenkamp said. “[They] were likely a child in the ’70s or maybe the ’80s, and the last time they saw a horned lizard was when Ronald Reagan was president.”

Ahead of this article’s publication, the Rivard Report and San Antonio Zoo asked people to share their horned lizard stories on social media. More than 250 people responded.

In social media comments, they told stories of catching lizards in empty lots, playgrounds, and alleyways. Many mentioned flipping the lizards over on their backs and stroking their soft white bellies until they seemed to fall asleep. Others described their shrieks of childhood terror when the lizards squirt blood from their eyes, a unique defense mechanism.

“I really don’t know if there’s a bottom to the depth of affection people have for these lizards,” Gluesenkamp said. “It’s not just lizard nerds; it’s not just outdoorsy people. People just love these things.”

A Rebirth

Behind the main exhibits housing elephants, giraffes, and hippos, the San Antonio Zoo’s conservation and research department works out of a set of buildings and shipping containers converted to house a different set of critters.

On a tour of the facility last month, Gluesenkamp led the way into a laboratory that’s been serving as what he calls the zoo’s “lizard factory.” Inside were adult lizards and babies the size of a penny.

The babies are a stroke of luck, Gluesenkamp explained. A female horned lizard caught last year turned out to be pregnant and laid a clutch of 28 eggs, Gluesenkamp said.

Zoo conservation manager Bekky Muscher-Hodges pulled one of the babies from its tank and laid it on the table next to its adult mother, an eggshell, and a penny, for scale.

“The adorability factor is huge,” Gluesenkamp said.

The zoo still has less than half of the horned lizard population it would like, Gluesenkamp said. The goal is to make the program one where lizards caught in the wild can be bred at the zoo, with their offspring then released elsewhere to help repopulate places where the lizards no longer exist.

The lizards don’t need much, Muscher-Hodges said, not even a water dish. The lizard’s horns help collect morning dew, and grooves in its head channel water toward its mouth like a built-in beer guzzler hat.

“Generally, we come in in the morning, mist them, and make sure they’re well hydrated,” she said. They’re fed twice a day with a mixture of harvester ants and crickets dusted with a light coating of vitamins and supplements.

San Antonio Zoo Conservation and Research Manager Bekky Muscher-Hodges holds an adult Texas horned lizard.
San Antonio Zoo Conservation and Research Manager Bekky Muscher-Hodges holds an adult Texas horned lizard. Credit: Brendan Gibbons / San Antonio Report

As the visitors watched, some lizards warmed themselves under bright light. In other tanks with the lights shut off, they lay quiet, buried in sand with only their heads poking out.

“If you look in these tanks, you don’t see a lot of lizards,” Gluesenkamp said. “It just kind of seems like sleepy time.”

At the time, zoo staff was starting the cycle that begets the next generation of lizards. Slowly, they were lowering the temperature and reducing light in the environment, sending the horned lizards into a state of topor known as brumation.

Going into brumation sets in motion the hormonal changes that lead to successful lizard mating, Gluesenkamp said. They’re not too fussy about it, he said.

“Once they’re up and active and starting their spring, you put a male in with a female, and it’s on,” he said.

Females can lay up to two clutches per year with up to 30 eggs each. But with so many new lizard hatchlings entering the world each year, why have they become so much harder to find?

A Native Icon Now Rarely Seen

There’s no one villain responsible for the vanishing lizard. Biologists have tied the contraction of the species mostly to a loss of habitat and a decline in harvester ants, their preferred food source.

“It’s probably death by a thousand pinpricks in a lot of cases,” said Dean Williams, a biology professor who has studied the lizards and their genetics at Texas Christian University, whose mascot is the horned frog.

Most Texans use the phrase “horny toads.” Their squat bodies, bumpy skin, and the ease with which even a child can catch one make them seem more like toads than lizards.

As lizards, they’re adapted for the kind of dry, brushy environment that once existed across Central Texas. Across the farm fields and ranches that once blanketed the region, horned lizards could maneuver their way through native grasses, hide from predators beneath clumps of brush and small trees, and feast on the juicy red ants.

When all of these things started disappearing, so did the horned lizards, biologists say.

From Houston to Dallas-Fort Worth to San Antonio, houses, malls, offices, golf courses, and parks replaced farms and ranches. Native grasses and brush are becoming less common than manicured lawns of carpet grass. Harvester ants also have declined as a result of pesticide use and invasive species like fire ants and crazy ants.

An adult Texas horned lizard basks under a light at the San Antonio Zoo.
An adult Texas horned lizard basks under a light at the San Antonio Zoo. Credit: Brendan Gibbons / San Antonio Report

Other native species also depend on this mix of native grass, bare ground, and brush, Williams said. These include bobwhite quail, whose decline in population has correlated with that of the horned lizards, biologists said.

“Quail habitat and horned lizard habitat are almost identical,” Williams said.

Williams said Texas horned lizards are still fairly common in parts of the Panhandle and South and West Texas. He’s worked with them in Karnes County, south of San Antonio, and knows of places in the town of Kenedy where they’re still “ridiculously abundant.”

Far West Texas also is home to two other species of horned lizard: the greater short-horned lizard and the round-tailed horned lizard.

Of all the horned lizards, the Texas horned lizard has the widest range in the state. Starting in the mid-20th century, they’ve mostly declined east of the Interstate 35 corridor, Williams said.

In North Texas, people from Texas Parks and Wildlife started meeting with biologists working at zoos to discuss restoring horned lizards about 10 years ago, TPWD wildlife biologist Nathan Rains said.

Since roughly six years ago, they’ve been releasing adult lizards on several properties, including Mason Mountain Wildlife Management Area in the Hill Country, Rains said.

The work has been challenging. No matter how many adult lizards they’ve released, not enough have survived to start a new, self-sustaining population, Rains said. In the wild, only 8 percent to 30 percent of lizards survive, while most of the rest get gobbled up by predators.

“The downside is there’s really high mortality rates, and it’s all predation,” he said.

Since last year, they’ve started releasing hatchlings raised in zoos in the hope that by putting as many lizards out there as possible, enough will survive to go on to have lizard babies of their own.

“To be honest, it’s just a numbers game,” Rains said. “We could either catch 50 adults or we could hopefully hatch 500 babies.”

The Bumpy Road Ahead

Rains is hopeful that the horned lizard can make a comeback, but after 10 years, he tries to temper expectations. He doesn’t think they’ll ever be as abundant as they once were.

“We won’t be able to establish them to their former glory and range,” Rains said. “But if you can go see them and interact with them, it’s a success.”

Gluesenkamp acknowledged it might take a long time, but he believes it’s worth the effort.

“This is a great example that I can share with the public about what zoos do in terms of real boots-on-the-ground conservation,” he said. “Fortunately, this example’s really close to home. It’s really close to the hearts of the public. So I’m in.”

The biggest challenge they face is funding, Gluesenkamp said. After an initial startup grant by Texas Parks and Wildlife, all of the money for the horned lizard reintroduction program has come from private donations.

The expenses are considerable. At full build-out, Gluesenkamp thinks the program could cost $75,000 per year, though that should taper off once they have much of the equipment they need.

At that level, the bill for harvester ants alone would be $1,000 per month. Zoo staff has been ordering the ants from a supplier in Utah to feed the lizards.

To save costs, they’re starting to build their own ant colonies at the zoo. Next to the horned lizard tanks are huge black plastic containers full of sand. Fat red ants scurry around the top and disappear underground.

A harvester ant farm set up at the San Antonio Zoo to provide food for Texas horned lizards.
A harvester ant farm set up at the San Antonio Zoo to provide food for Texas horned lizards. Credit: Brendan Gibbons / San Antonio Report

They’ll also be experimenting with a new way of tracking the lizards they’ve released. Instead of radio trackers, they’ll be using trained dogs, Gluesenkamp said.

Paul Bunker, owner of Chiron K9 in San Antonio, has decades of experience training dogs for military and security jobs. More recently, he’s trained dogs to sniff out oil and gas spills and leaks.

Now he’s interested in training dogs to use in conservation work. When he met Gluesenkamp, the horned lizard project seemed like a perfect fit.

He’ll start by exposing the dogs to scent from gauze wiped over live lizards, along with scat, urine, and eggshells, then pairing those odors with food and toys so the dogs form a positive association with them. He’ll also train the dog to avoid “distraction odors” like snakes and other types of lizards.

“Basically, that’s how the dog will learn what it’s got to look for,” Bunker said. “That’s not anywhere outside the realm of capability for a dog.”

Bunker hopes to eventually start training rescue dogs for the job and pairing them with conservation volunteers who can give the dogs permanent homes. He thinks the idea could become more widespread in tracking other at-risk species, such as the endangered dunes sagebrush lizard in West Texas.

“We can help rescue dogs, we can help the community, we can help endangered species,” Bunker said. “It’s the right people in the right place doing good for Texas.”

Here’s what Texans had to say on social media about horned lizards

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Brendan Gibbons

Brendan Gibbons is a former senior reporter at the San Antonio Report. He serves as the assistant manager of the Greater Edwards Aquifer Alliance.