Fort Worth Zoo to release thousandth captive-born Texas horned lizard into wild

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Since the Fort Worth Zoo first started breeding Texas horned lizards — also known as horned frogs — in 2001, the ectotherms, or cold-blooded animals, team has worked to address the species’ declining numbers.

On Thursday morning, Fort Worth Zoo ectotherms curator Diane Barber and her team will release the thousandth captive-born Texas horned lizard into the Mason Mountain Wildlife Management Area.

More urbanization throughout the state has caused habitat loss for the threatened lizards, said Nathan Rains, Texas Parks and Wildlife diversity biologist.

The program is part of a pilot conservation effort that attempts to address the lizards’ declining numbers in the Texas Panhandle, eastern and north-central Texas. The Fort Worth Zoo teams with the Texas Parks and Wildlife Department and TCU, whose mascot is the horned frog, to work on reintroduction methodologies.

In order to assess survival rate and conditions, the team uses harmonic radar tags to track the lizards.

A Texas horned lizard hatchling rests in a plastic container after being tagged on Wednesday, September 15, 2021, at the Fort Worth Zoo. The Fort Worth Zoo and Texas Parks and Wildlife Department will release 204 Texas horned lizards, including 100 hatched at the Fort Worth Zoo, into the wild on Thursday.
A Texas horned lizard hatchling rests in a plastic container after being tagged on Wednesday, September 15, 2021, at the Fort Worth Zoo. The Fort Worth Zoo and Texas Parks and Wildlife Department will release 204 Texas horned lizards, including 100 hatched at the Fort Worth Zoo, into the wild on Thursday.

The Fort Worth Zoo ectotherms team handles around 20-24 clutches, or groups of eggs, in a year, which averages about 20 individual lizards per clutch, assistant curator Vicky Poole said.

It takes 60 days for the horned lizards to hatch from their Tic Tac-sized eggs. After they reach 4-6 weeks old, Barber and her team tag them in preparation for release.

After cleaning the lizards’ backs with an alcohol wipe, the team uses a gel super glue to attach the harmonic radar tags on the back of the animals. The tags weigh less than 0.01 grams; the baby lizards weigh 0.09 grams and higher.

Attaching the tags on the tiny bodies is fairly simple; a horned lizard’s initial reaction when approached is to keep still and hunker down to blend in, Barber said.

The tags are longer than the lizards’ bodies, appearing like a tail trailing behind them. Barber said the tags have to be long in order to track them from a distance.

Once out in the wild, a field researcher observes the lizards, analyzing data based on how they fare out of their specific clutch. As the lizards grow and shed their skin, the tags fall off, so the researcher periodically replaces the tags.

Rains said the point of the project is to determine the feasibility of reintroducing the Texas horned lizard populations to where they once were.

“We’ll never be able to restore them to where they used to occur across the state, but if we can restore a few populations and put them in a vicinity where people can see them, I think that would be a pretty big deal,” he said.

Conservation projects are expensive and at the end of the day it takes money to make it happen, said Tom Harvey, Texas Parks and Wildlife communications deputy director. In order to move the needle on efforts like the Fort Worth Zoo’s pilot program, conservation funding is essential.

The Recovering America’s Wildlife Act is a bipartisan bill in Congress that, if passed, would provide $50 million, out of $1.3 billion, in funding for Texas conservation efforts. It would also benefit the nature tourism economy in Texas which brings in hundreds of millions of dollars yearly and tens of thousands of jobs, Harvey said.

The Recovering America’s Wildlife Act would not raise taxes, instead earmarking existing federal money for wildlife nationwide.

Harvey said the Texas horned lizard is a bellwether for what’s going on in the natural environment.

“If an animal like this is in trouble, many other animals that share its habitat are also in trouble,” he said.

A lot of species conservation is enacted when it’s the eleventh hour, Barber said. At that point there are few animals left and more legal limitations on how to work with the species.

“For us, that was one of the things we talked about, was ‘Let’s be proactive with the conservation of the species’,” Barber said. “‘Let’s figure out how we can bring them back and how we can assist them once we find out what’s going on.”

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