This piece was written by AAMN Barbara Merrill (Class 49)
Today I’m going to write about an extraordinary species, the Texas Horned Lizard (Phrynosoma cornutum) or THL. This lizard is special in many ways. First, the THL is an indicator species. When they are present, it indicates a healthy, functional ecosystem. Second, they regulate the number of harvester ants in their habitat. This keeps the ants from disrupting the local flora. Third, THLs are a food source for predators.
Now that I’m older, I have a tendency to look back on life. I used to live in the Bulverde City area back in the 1980’s. I loved exploring outside back then as much as I do today. One activity that I really enjoyed was catching and observing the Texas horned lizard. Back then they were easy to find. Not so today.
How can a person distinguish the THL from the other horned lizards?
Why do I love this species? One of the reasons is that I’m absolutely fascinated by these lizards; they look like little dinosaurs. Just like the other horned lizards, they have many horns on their heads, flatten bodies, and camouflaging colors. They have specialized skin that allows them to access water from moist sand and dew. Rough scales along their heads collect and transport water to their mouths.
There are several ways to differentiate the THL from the other two horned lizards native to Texas. The other two are the round-tailed horned lizard (Phrynosoma modestum) and the greater short-tailed horned lizard (Phrynosoma hernandes). THL distinguishing features are….
- The two central horns on their heads are longer than the other horns.
- Their facial markings are unique, having dark stripes extending from their eyes down the sides of the head.
- They have two distinct rows of fringe scales along the sides of their flat abdomens.
- They have a light-colored line running down the center of their backs along the spine.
THLs possess unique behavioral characteristics. Despite their fearsome appearance, they are actually quite timid, relying on camouflage as their primary line of defense. When spotted by a predator, they puff up their bodies to appear larger and more intimidating. If this doesn’t work, they will shoot a stream of blood mixed with an obnoxious, foul-tasting, fluid out of their eye socket. The lizard aims this stream at the predator’s face and can reach distances of up to 5 feet. Even though this can be a costly defense, they can lose up to 6% of their body weight when performing it; it is effective.
When I was 22 years old, I met and married a military man. I left Texas for more than 25 years. I came back about 10 years ago. I still love being outside. I’m out hiking and camping all the time. Unfortunately, I haven’t seen any of these special little creatures since I’ve been back. Being upset by this, I decided to find out where the THL went. What I found out broke my heart.
What challenges do THLs face today?
Their numbers have been decreasing for about 50 years now. They are not on the threatened list yet, however. Even though they are well adapted to survive Texas’ harsh environments, they are not well adapted to survive what people do to their environment. We humans tend to cause ecological crises everywhere we go. Urbanization has caused deterioration, fragmentation, and loss of habitat for THLs, as well as many other wildlife species. Urbanization of rural areas reduces the amount of suitable grassland and savanna habitats.
As we build homes, roads, and other buildings in an area, we remove homes for the local wildlife. Even when the builder leaves a small space for wildlife, it’s still not enough. Being locked in by roads leads to inbreeding and health problems. Plus, many animals are killed on our roads. As we all know, roads are dangerous. This fact is especially true for Texas’ cold-blooded animals. Roads hold and radiate a lot of heat; therefore, cold-blooded animals tend to bask on them to warm up. Leading to THL being run over.
Another problem THLs are facing is the introduction, by humans, of non-native species. These invasive species include exotic grasses, such as KR Bluestem. Bluestem grows in dense patches that restrict the lizard’s movement.
Red fire ants (Solenopsis invicta) are another invasive species causing the decline of the THL. Red fire ants directly and indirectly affect THL. THL are dietary specialists, meaning they feed mostly on harvester ants (ogonomyrmex barbatos). Around 70% of their diet is comprised of harvester ants. THLs do not eat red fire ants. The invasive red fire ants out compete with the harvester ants. Therefore, taking habitat and food sources that harvester ants once retained. Red fire ants have been known to attack and eat THL’s eggs and hatchlings. People have added to the problem of fire ants being in Texas by using pesticides to kill the fire ants. Thereby poising many other wildlife species to include the harvester ants.
Why it’s not all bad news
People are working hard to save this beloved species, as they should—it is the Texas state reptile, after all. Texas wildlife conservation focuses on preserving animal species and their habitats to ensure their long-term survival. Here in Texas, conservation is vital; our state is home to 126 vertebrate species that exist nowhere else in the world.
Texas Parks and Wildlife and the San Antonio Zoo are currently collaborating on the Texas Horned Lizard Reintroduction Project. This initiative focuses on captive breeding and reintroduction, and researchers work closely with private landowners on land management. They teach landowners about the specific needs of this species and how they can help through undertakings such as brush control and creating a healthy mix of bare ground, native grasses, and shrubs. To date, over 1,000 hatchlings have already been released on private lands and sites like the Mason Mountain Wildlife Management Area.
You might be wondering what you can do to help.
Public education is vital, so consider telling people about Texas Horned Lizards (THLs) and the challenges they face. You can also donate to established reintroduction projects or the Horned Lizard Conservation Society. At home, try to ditch the pesticides when treating fire ant mounds and keep your cats indoors. Lastly, you can landscape your yard using native plants. If you join these efforts, you can help many Texas wildlife species, not just the THLs.
We all need to work together so that generations to come can enjoy the Texas Horned Lizard like I did.