Riff Ram Bah Zoo: TCU joins fight to save horned lizards

Saving the mascot, part one

By Camilla Price

The bronze Horned Frog Statue greets students between Sadler and Reed Halls. TCU adopted the horned lizard as its mascot in 1893. (Jeffrey McWhorter/TCU Marketing and Communication)

In Fort Worth, the mythical Texas horned lizard is thriving.

Statues, billboards and t-shirts tout the “Horned Frog.” TCU students toss up hand signs and cheer on SuperFrog, the only lizard mascot in the NCAA.

"It’s a very unique mascot," said Sara Ruelas, a junior finance major with a concentration in real estate. "When people hear of the Horned Frogs, they kind of know it’s us."

But in reality, the future of the palm-sized lizard is in doubt.

As urbanization swept across the Southwest in the last half of the 20th century, horned lizards lost their habitats. Pesticides also reduced their main food source: ants.

The reptiles once blanketed football fields, ranchland and shortgrass prairie all over the state and as far as Kansas, New Mexico, Colorado and parts of Mexico. But horned lizards haven’t been seen in the wild in Dallas-Fort Worth since the early 1970s. In fact, they’re no longer found in the eastern third of Texas.

Now, researchers worry climate change could also have a negative impact on the reptiles as increased temperatures push them to the limits of what they can survive.

“It’s probably kind of death from a hundred pinpricks,” said Dean Williams, the professor of biology who heads TCU’s horned lizard research team.

A TCU student flashes the "Frogs" hand sign at a football game on Dec. 9, 2014. The curled-over peace sign is meant to resemble the horns of TCU's lizard mascot. (Sharon Ellman/TCU Photo Library)
A TCU student flashes the "Frogs" hand sign at a football game on Dec. 9, 2014. The curled-over peace sign is meant to resemble the horns of TCU's lizard mascot. (Sharon Ellman/TCU Photo Library)

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In the early 2010s, the Fort Worth Zoo and the Texas Parks and Wildlife Department wanted to reintroduce horned lizards to the wild, but they predicted the lizards differed genetically based on where they were from, said Diane Barber, herpetologist with the Fort Worth Zoo.

They needed to find out how many populations there were, so they looked “up the hill” and asked for help from Williams, whose specialty is analyzing the genetics of endangered and invasive species.

Williams divided Texas horned lizards into three groups: those native to the arid West Texas region, those found south of San Antonio and the northern clade that canvassed the rest of the state.

“We kind of divvied up the conservation efforts,” said Nathan Rains, wildlife diversity biologist and Texas horned lizard project lead for Texas Parks and Wildlife.

Conservationists in Dallas-Fort Worth focus on the northern population, while the San Antonio Zoo concentrates on the South Texas lizards.

Williams didn’t stop once he worked out the genetics - he’s worked on getting a baseline for the lizards’ diets and habitat preferences as well as testing different reintroduction sites to help save the species.

Bringing horned lizards back

Reintroducing horned lizards into the wild takes more than letting them go with a "Good luck."

The process is arduous.

“They always just seemed to disappear and nobody was really sure exactly why or how,” said Williams. “We’re trying to take a much more kind of research-oriented method.”

TCU, the Fort Worth Zoo and Parks and Wildlife spent several years tinkering with the process behind releasing the lizards.

“We did all kinds of studies involving telemetry and what happens with lizards when we let them go,” said Rains. “Do they stress out, do they gain weight, do they grow and reproduce?”

They also experimented with different release methods.

“Is it going to be a soft release where you put them in an enclosure, let them establish and get used to the environment... or can you do a hard release with captive born horned lizards and just plunk them out there and let them go on their own?” said Barber.

During the first two reintroduction efforts, conservationists breathed a sigh of relief when adult lizards responded well to the ‘soft release.’ But predators ate them before the population stabilized.

The “bite-sized” lizards make good snacks for coyotes, bobcats, raccoons, roadrunners, hawks, snakes and even cats.

So researchers switched gears.

“We all kind of stepped back and said, ‘Okay, this isn’t working in terms of releasing adult animals, so now we need to look at age classes,’” said Barber.

^{Photos: Hatchlings are ready for tagging and release at Mason Mountain Wildlife Management Area in Mason, Texas; Conservationists release a horned lizard hatchling into the wild on Sept. 16, 2021. (Photos courtesy Dean Williams)}

The team found releasing captive-bred hatchlings increased the lizards’ survival.

But a new worry arose: fire ants.

In horned lizard lore, fire ants have long been a villain. The invasive ants are often blamed for killing off horned lizards across parts of Texas.

Invasive fire ants will attack horned lizards and drive out the local ants they depend on for food. (National Park Service/Public Domain)
Invasive fire ants will attack horned lizards and drive out the local ants they depend on for food. (National Park Service/Public Domain)

However, conservationists said the fire ant problem is somewhat overblown - agriculture and urbanization have played a bigger role in horned lizards’ retreat.

Adult lizards can coexist with fire ants, but hatchlings are still vulnerable.

“Baby horned lizards do not seem to have any natural defenses in terms of getting away from the ants, and it’s probably just because evolutionarily they have not been exposed to carnivorous ants like fire ants,” said Williams.

Not only do they attack the lizards, but they drive out the native ants that horned lizard hatchlings eat.

At the private release site, fire ants wiped out the hatchlings before they could reproduce. So the conservationists packed their bags and moved to Mason Mountain Wildlife Management Area in Central Texas. The protected site is owned and managed by Texas Parks and Wildlife.

“It’s one of those places, like a lot of areas, where they used to have horned lizards and now they don’t,” said Rains.

Native predators - roadrunners, foxes and coachwhip snakes - abound. But Texas horned lizards naturally evolved to lay many eggs at a time. By breeding hatchlings in captivity and releasing them en masse, wildlife biologists give the lizards a better chance at survival.

Barber and Rains described the releases as “a numbers game.”

“We have to just keep putting a large number of hatchlings out there for them to survive to adulthood,” said Barber.

A hatchling Texas horned lizard at the Fort Worth Zoo. Babies may weigh less than a paperclip when they are released. (Andrew Emery/TCU Marketing and Communication)
A hatchling Texas horned lizard at the Fort Worth Zoo. Babies may weigh less than a paperclip when they are released. (Andrew Emery/TCU Marketing and Communication)

Last summer, researchers saw a promising sign.

For the first time, reintroduced Texas horned lizards bred in the wild.

Williams said the team discovered at least three - likely four - clutches of eggs laid by hatchlings that were released two and three years ago.

Barber said the finding as “really encouraging,” adding reintroduction programs sometimes take 10 years before conservationists know they are working.

“It’s exciting that we’re seeing those results so quickly,” she said.

“That’s the first measure of success is can they breed in that habitat, and the next measure of success will be can they be a self-sustaining population,” said Williams.

Memories sweet

When Texas horned lizards began vanishing from backyards, ranches and towns, the outpouring of public support for the reptile sparked efforts to save the species, Rains said.

“Landowners, they’d always ask what happened to horny toads, and the second question is ‘Can you ever bring them back?’ ” said Rains.

Mary Rachel “M.R.” Tucker studied the thermal habits of Texas horned lizards in South Texas for her master’s thesis in biology at TCU, which she successfully defended in October 2021.

She said the people who lived in the nearby towns were invested in the project.

“We get to kind of know the residents and they’ll bring us out like Diet Cokes and stuff while we’re looking for lizards and they’re like, ‘How are they doing this year?’ she said.

Residents told stories about collecting lizards in shoeboxes or carrying them in their pockets.

While most reptiles would try to bite or escape, the horned lizard’s placid personality was “very appealing for a lot of people because they could have firsthand experience with it,” said Williams.

For Tucker, an Alabama native, the nostalgia for Texas horned lizards is personal: They featured in the stories her father and his siblings told about their childhood in Abilene, Texas.

“They always talked about horned lizards and keeping them in their like pockets, and I remember my aunt would have an entire dresser drawer - apparently she would fill them with it and have like a heat lamp and stuff and one time my grandmother went in there and opened the drawer and just screamed,” said Tucker, laughing.

"[The horned lizard] just has a cultural attachment to people that kind of defies explanation," said Rains.

Cacti and other native flora make up the prairie ecosystem Texas horned lizards call home. Horned lizard conservation protects habitat for many other species. (Andrew Emery/TCU Marketing and Communication)
Cacti and other native flora make up the prairie ecosystem Texas horned lizards call home. Horned lizard conservation protects habitat for many other species. (Andrew Emery/TCU Marketing and Communication)

Unlike elephants or bees that act as “keystone species,” Texas horned lizards are thought to have little influence on the shortgrass prairie habitat they call home.

But Barber considers the horned lizard an ambassador animal that can help protect habitat for dozens of other species.

“If you bring back or if you take care of the ecosystems and the habitat, you’re going to have more diverse wildlife,” she said.

Barber worries the iconic role of the horned lizard in the public imagination is fading fast - and with it, conservationists’ ability to raise funds and attention for the species.

“I’ve already started to see like with the younger generation in Texas, they didn’t grow up with the horned lizard in there and so they’re not as attached as a lot of the people my age are that grew up with horned lizards and played with them as a child,” she said. “So I think that our role is really important in terms of keeping that momentum alive and that connection with the Texans and their horned lizards so that they care about them and take care of them in the future.”