Spot-tailed Earless Lizard
Download larger photo (121 KB)
Distribution Map of the Spot-tailed Earless Lizard
Download larger map (PDF)
Spot-Tailed Earless Lizard
Mike Duran, zoologist for The Nature Conservancy of Texas, talks about the vanishing spot-tail lizard and his efforts to determine where it still exists in Texas. Duran notes that the disappearance of the species from several places in Texas raises concerns about what might be happening in the environment to cause its demise.
Scientists at The Nature Conservancy of Texas and several universities are looking throughout the state for the increasingly rare spot-tailed earless lizard, scientific name Holbrookia lacerata, to find evidence of how many of these lizards still remain in the wild. They’re hoping herpetologists, amateur naturalists and others who enjoy spending time outdoors will also keep an eye out for the lizard.
Mike Duran, a vertebrate zoologist with The Nature Conservancy of Texas, said that while the spot-tailed earless lizard is not officially listed as threatened or endangered, there has been concern among scientists for the status of the reptile for some time, and its demise could underscore important environmental changes. Once thought to reside widely in Texas within a rough circle outlined by Pecos, San Angelo, Austin, Corpus Christi and Laredo, the lizard today is very rarely seen.
“On surveys that we have conducted for The Nature Conservancy within the range of the species, we have never seen it,” Duran said.
He noted that Ralph Axtell, a professor at Southern Illinois University-Edwardsville who is considered the leading expert on the spot-tailed earless lizard, believes it may now be gone from many of the places where it used to reside.
“When you have a species disappearing from its historic range, it’s indicative of something going on with the environment,” Duran said. “In this case, we’re guessing that it’s pesticide use. If pesticide use is so devastating that it’s wiping out an entire species, that’s something we need to take a closer look at.”
He points to another species that was almost driven into extinction by the use of pesticides – the bald eagle. “We saw a tremendous decline in bald eagles,” he said. “They almost became extinct. But studies revealed that the reason for the decline with bald eagles, which may be the case with the spot-tailed earless lizard, was pesticides. We were able to do something about that, and bald eagles are no longer endangered. Raising awareness of the species is a key step toward conserving it.”
Now, Duran is working to determine where in Texas the spot-tailed earless lizard still remains, along with a team of herpetologists that includes Axtell, Toby Hibbitts at Texas A&M University, Travis LaDuc at the University of Texas-Austin, Kelly McCoy at Angelo State University and Michael Forstner at Texas State University – with help from a cadre of volunteers. They plan to survey 207 sites within the lizard’s historic range.
The spot-tailed earless lizard is about 6 inches long and is covered with spots on its back and tail. It is so named because, unlike similar lizards, it also has spots underneath its tail. It is called “earless” because it has no external ear openings. Except in the northernmost part of its range in Texas, where close relatives of the spot-tailed earless lizard are found, there are few similar lizards likely to be confused with it.
The lizard is most active, Duran said, from March to June, and that’s when his team plans an intensive effort to search for it. The scientists are seeking volunteers willing to go to specific locations to search for the lizard, and would be happy to hear from anyone who thinks they have seen one either alive or dead. Photos are encouraged when possible.
Habitat for the lizard within its historic range is believed to be areas that are sparsely vegetated with some bare ground. It is found on a variety of soil types, though never on pure sand. Its environs include upland savannas, plowed fields in places that originally were grasslands, thinly vegetated mesquite shrublands, semi-xeric mesquite and prickly pear brushlands, and coastal prairie.
Anyone who believes he or she has seen a spot-tailed earless lizard is asked to contact Mike Duran at (361) 249-1712, (361) 882-3584, ext. 105, or email@example.com; or Ralph Axtell at firstname.lastname@example.org. More information on the lizard is available online at nature.org/texas, including a form for lizard-spotters that may be downloaded, a map of historic locations, photos, video and a poster.
Duran also makes the point that he would be happy to hear from those who specifically went looking for the lizard in one of its historic habitats and did not see it.
As the scientists search for the lizard in places where it previously has been found, they also will collect data on the current condition of the habitat and create a predictive habitat model. Even if they don’t find the lizard, they hope to be able to make an educated guess about whether it’s still likely to be found at a particular site.
“It all starts with gaining more knowledge, the basic building blocks of science,” Duran said. “Right now, we just don’t know where the spot-tailed earless lizard is and where it has probably been extirpated. That’s what we have to start with."
The project is being funded through a grant from Texas Parks and Wildlife Department's Texas Horned Lizard License Plate Fund.
The Nature Conservancy is a leading conservation organization working around the world to protect ecologically important lands and waters for nature and people. The Conservancy and its more than 1 million members have protected nearly 120 million acres worldwide. Visit The Nature Conservancy on the Web at www.nature.org.