Jennie Mook, a graduate research assistant with the Cooperative Wildlife Research Laboratory at Southern Illinois University Carbondale, holds at Texas horned lizard hatchling while conducting a study of the animal on the lands around Tinker Air Force Base in Oklahoma. (Photo provided)
July 11, 2016
Research focuses on demise of Texas horned lizard
CARBONDALE, Ill. – The horned lizard is well-loved part of culture in its range, which stretches from Kansas through Oklahoma and into Texas. But the once plentiful species has been harder to find in recent years.
A graduate student from Southern Illinois University Carbondale is the university’s most recent scholar to try and find out why that is, and hopefully help the species thrive once again.
Jennie Mook, a graduate research assistant with SIU’s Cooperative Wildlife Research Laboratory, is scouring the lands around Tinker Air Force Base in Oklahoma studying the Texas horned lizard.
Mook’s three-year study, funded by an annual $34,000 grant from the U.S. Air Force, is the latest incarnation of SIU’s connection to the work in the area, which stretches all the way back to 2003. At that time, then-Oklahoma State University researcher Eric Hellgren began the research before coming to SIU and bringing the project with him. Hellgren subsequently went to work for another university, leaving the project in the hands of Eric Schauber, associate professor of zoology at SIU, and Mook’s faculty adviser.
“Our role in the SIU Cooperative Wildlife Research Lab is to train the next generations of wildlife managers, researchers, and conservationists while generating the information that is needed now to best conserve the resource,” Schauber said. “This ongoing project is a great example of how well that model works.”
Mook, who is the third SIU graduate student to work on the project, said the long-term nature of the study makes for interesting work and deeper findings.
“Having a long-term data set provides the perspective to see trends that you won't necessarily know after just a year or two,” she said. “This has allowed me to ask some interesting questions based on the last decade of data.”
Mook started work on the project as a volunteer during the summer of 2013, officially becoming a graduate student in May 2014. Since then, she has returned each April, staying until nearly September, which coincides with the Texas horned lizards’ most active period.
The animals hibernate underground during the winter months, beginning about October. The small creatures, which can fit in the palm of one’s hand, typically emerge from hibernation in late March or April, making this the fourth summer Mook has examined the Texas horned lizard.
The animal is unique in several ways, from its fearsome “prehistoric” looking body to its ability to squirt blood from its eyes to deter predators. The lizard currently is listed as threatened in Texas and as a “species of concern” in Oklahoma, making research on management practices and conservation efforts critical, Mook said.
The research, therefore, is focused on finding out what is driving the popular animal’s downward trending numbers. It’s a question that has personal meaning to Mook, whose grandmother remembered them playing a role in her life as a young girl in Oklahoma.
“In fact, my grandmother's generation used to race ‘horny toads’ as a pastime,” she said. “But my generation and younger barely know what a horned lizard is.”
The Texas horned lizard’s possible demise is of great concern to local people in Oklahoma and Texas, where it is beloved enough to be the state reptile and the mascot for Texas Christian University’s “Horned Frogs.”
“Texas horned lizards are a perfect example of an imperiled species that people are literally seeing vanish during their lifetimes,” Mook said. “It's very sad and people take it very personally because these lizards were a part of their memories and childhood.”
It’s an alarming state of affairs for a creature that has roamed the planet for more than 20 million years. Mook said she feels an urgency to find answers.
“Horned lizards are a unique species both physiologically as well as behaviorally,” she said.
Of eight separate species in the United States, only the Texas horned lizards are suffering major declines. Being ant “specialists,” (more than 95 percent of their diet is composed of ants), they play an important role in the food web and the ecosystem.
Mook is studying the predatory threat to the lizards, and there are many. Snakes, raptors, raccoons, feral cats, coyotes and even rodents prey on them. To quantify the threat, she is conducting surveys including using camera traps for mesocarnivores, such as raccoons, coyotes, bobcats and skunks. She also conducts “point count surveys,” in which she looks for raptors within a 50-meter radius of a specific point, among other methods.
Mook also is studying the overall health of the lizards by checking the condition of the bodies of the ones she catches. Factors such as body fat content (the more fat the animal has, the healthier it is considered to be), as well as analyzing blood chemistry and other methods.
The most challenging aspect of this aspect of the study is catching the lizards … by hand.
“Horned lizards are caught during visual surveys and captured by hand, and the hardest part of catching a lizard is spotting it,” Mook said. “They are made to blend in with their environment very well! So, no we don’t use traps.”
Mook also is exploring a little-known area of the horned lizard life cycle: the hatchling to juvenile stage.
“The hatchling work, in particular, is important because there is little in the literature regarding this life stage,” Mook said. “This is mainly because hatchlings are so small – less than a gram in body weight – and are difficult to track.”
To counter that problem, Mook is using a novel tracking method known as “harmonic radar” to monitor the hatchlings. She said the new method has successfully helped her monitor nearly 70 hatchling and juvenile lizards, helping the researchers learn more about this largely unknown stage in their lives.
“Jennie's passion for understanding and conserving these amazing lizards shines through everything she does,” Schauber said. “We know from prior research that survival of hatchlings is a critical bottleneck in the life cycle, so if she can uncover ways to help hatchlings survive better that should pay dividends for the population as a whole.”
“I'm excited to get back to Illinois in the fall to begin to analyze the data,” she said. “The really amazing thing about this research is that it doesn't seem to take much convincing as to why people should care about the conservation of this species. People who grew up in Kansas, Oklahoma and Texas love horned lizards and affectionately call them their horny toads.
“My field site is a very urban area with lots of walking trails running through it. So there is a lot of opportunity for outreach with the public. As soon as I say that I work with the horned lizards, people's faces light up and the common phrase is ‘I used to see those all the time!’”
Mook said she hopes her work will make that a common occurrence once again.