Nature

The Comeback Lizard

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Horned Toad

Photo by jamezevanz


Story By Kevin Holamon
Freelance Writer
[email protected]

The Comeback Lizard

About 30 years ago, the phrynosoma was a familiar sight in the Texas Hill Country. Most over the age of 35 can recall catching them to play with. The guys will remember stuffing them into their pockets and carrying them to school to pester the girls. Pretty much anytime one felt the need to go out and catch horned lizards, they could be found. Unfortunately, like the once prolific populations of quail in the region, the horned lizards faded away and many of our kids have never seen one in the wild. Fortunately, there is a small group of people who are working to find out if the horned lizard can make a comeback in the Texas Hill Country.

Devin Erxleben is the TPWD wildlife biologist at the McGillivray and Leona McKie Muse Wildlife Management Area, located in Brown County, near the town of Blanket. Comprising only 1,975 acres, smaller than the typical WMA, the Muse is a low-fence Area where Devin and others conduct surveys of wildlife, including game species, small mammals, birds, reptiles, and vegetation. The Area is also used for experimentation in habitat manipulation and as an educational tool for ranchers interested in implementing wildlife management practices on their own properties. The Muse WMA was given to the TPWD in 2006 and Devin came on board a couple of years later, when they began to do the surveys.

“I had an interest in horned lizards, because they should be here. We have plenty of ants and they should be here. But, we never found any, using several different methods,”he said on the day this writer was lucky enough to tag along.

Horned Toad

Photo by Kevin Holamon

“So, we decided maybe they were pushed out by grazing. We had red harvester ants, but not in huge numbers. We think overgrazing and possibly some pesticide use pushed the red harvester ants out of this area.” He noted it is estimated 60 percent of the horned lizard diet is the red harvester ant.

Devin attributes the demise of the horned lizard populations to a variety of factors: fire ants, the pet trade, climate, and pesticides used to kill the fire ants and inadvertently also killing the red ants.

“So, by losing that main food source, that could have pushed the horned lizards out of their native range.” Probably, according to Devin, the biggest known detriment to the demise of the horned lizards is just habitat change and habitat loss. This region has seen a lot of changes in land use over the last 30 years and that’s caused habitat loss, also affecting other species such as the quail. In this area of the state, in particular, many of the old large ranches have been subdivided repeatedly, as the elder generations have left their properties to their progeny. Devin acknowledged this was quite likely a contributing factor. “We’ve got all these small parcels and possibly each is being managed differently.”

Horned Toad

Photo by Kevin Holamon

“A lot of people have asked and we’ve wondered for some time, can we reintroduce them and bring them back. Due to the popularity of the Prop 11 Wildlife Tax Evaluation more and more ranchers are actually managing for wildlife these days and there’s profit to be made from managing for wildlife. We kind of feel like a lot of the habitat in our region is better now than it may have been 30 years ago and we think a lot of horned lizard habitat has possibly been improved so that it could support them.”

After five years of planning and preparation, Devin and fellow biologist Nathan Rains launched the experiment in reintroducing the horned lizard in Central Texas, in the spring of 2014. Livestock grazing had ceased in 2006, allowing native seed grasses and forbs needed by the red harvester ants to come back and thrive.

“It seems our ant numbers are increasing. So, we thought it was the right time. We did some habitat manipulation to try to open up some areas that had the right soil types (sandy loam soil that they can burrow into), because they like it open, kind of like quail. They need to be able to navigate. The area we chose for the horned lizards was because of the soil type and there is a high density of ant colonies per acre. Some of our neighbors also told us that this field in particular had lizards in it about 30 years ago.” The preparation included the construction of a 10’ x 10’ welded wire enclosure, placed over an ant colony, where the lizards spent the first couple of weeks on the property. Devin said that allowed them to acclimate to the soils, the weather conditions, and everything else that was different from what they were accustomed, protected from predators. Fourteen lizards were captured on private property, west of San Angelo, and released into the enclosure, in what Devin referred to as “a soft release.” After the initial couple of weeks, sections of the wire cage were opened and the lizards were allowed to disperse on their own. But, not before each was fitted with a radio transmitter to allow the staff to track them.

Horned Toad

Photo by Kevin Holamon

Tracking is done every day, seven days a week. Rowdy White, seasonal technician, and Dacia Griffin, summer intern, all take part in the daily task.

“We typically all go out on Mondays, when we actually handle each lizard, getting body weight, do an overall health assessment, and we check the transmitter. The rest of the week is pretty much just tracking, getting a visual location and logging the GPS coordinates.”

At the office, Devin inputs the GPS data into a GIS mapping program, enabling them to immediately start looking at habitat use and what they are doing.

“We really don’t know much about horned lizards. We don’t know much about their home range size, habitat use, foraging behavior, sources of mortality. All that is important to see if this could work and be successful.”

Horned Toad

Photo by Kevin Holamon

Tracking began in late May and Devin said they have already learned a lot about habitat use and dispersal. The lizards dispersed a lot further than what they thought they would, initially. He said the thought was that they had a home range of two to four acres. A few of the lizards immediately dispersed and moved out away from the enclosure, establishing a pretty large home range. As summer has gone on and it’s hotter and drier, their home range sizes have shrunk and they’re not moving as much, which was to be expected.

In the beginning, tracking was done several times a day. Rowdy, who lives on-site, would go out at 10 o’clock, or midnight, or 2 in the morning, just to see what they were doing. Everyone wondered, are they sleeping the whole night, are they burrowing into the ground or are they just hunkered down under the brush.

“On cooler evenings, they would kind of create a nest bowl and slightly burrow into the soil. On warmer evenings, they just lay up in real thick brush. As it’s gotten warmer, they’re really active in the morning. In late spring, they were pretty much asleep until 10:30 or 11, then they’d be active until 2 o’clock. Then they would just kind of loaf, until about 6:30 or 7, they’d get active again and feed, just before night. Now that it’s hotter, they’re active from about 8 until 10:30 or so, then they head for the shade. So, lately, more of our tracking has been in the morning hours, mainly because it’s easier on us.”

Of course, there were concerns from the start, such as loss to predators and whether or not sufficient food sources existed to allow the lizards to thrive.

Horned Toad

Photo by Kevin Holamon

“We did have some predation, early on. It looked like it was more small mammal predators, like mice and rats, were eating some of our lizards. It was unfortunate. As they quit moving as much and became a little more localized, the predation really dropped off. It’s been about two months since we’ve lost a lizard, so we’re pleased with that.” The data collected, however, alleviated the second concern. The lizards’ weight has consistently climbed, indicating those that remain are healthy and finding plenty to eat. In fact, another encouraging sign is the establishment of two nests.

“We’ve got eggs now in nests and we’ve got cages over them to protect them from predators. We’re monitoring those nests daily and we’re hoping we’re going to have some babies soon. So that’s pretty neat that reproduction has happened here again, after probably 30 years. It’s pretty exciting.”

Devin said the lizards are really social, in their natural environment. He said there is a high density of lizards, where these were caught, and they are pretty much communal. Here, after they initially scattered, some have come back and spent some time together. In fact, those identified as Lizard 10 and Lizard 14 have since remained pretty much side by side.

Horned Toad

Photo by Kevin Holamon

“We’ve had some males and females that came together for a few days and we think there was probably some breeding going on and we’ve had a couple of females that spent some time together. Lizard 12 and Lizard 13 spent about a month and a half together and all of a sudden, 13 has gone off north and she’s on her own now, a long way from the others. They’re all pretty spread out now. 7 and 11 are pretty close to each other and 10 and 14. Lizard 5, down in the south, she’s been pretty much isolated since day one. She actually went way west, out onto the neighbor’s property and spent about three weeks there and then came back to us.”

The initial experiment appears to be a tremendous success, with promising data and observational evidence suggesting the desired outcome is likely. So much so, the program is on target to expand next year, with plans to introduce and additional 30 lizards on the WMA. Along with the eight current residents and nest sizes ranges from 15 to 30, Devin and his staff could well be tracking 40 to 50 lizards, next summer. Although he is cautious about estimating numbers from a hatch, considering the success rate is only about 30 percent. It could get exponential, if
they start breeding and everything goes well. Devin said, if that happens, they will likely hire a graduate biology student to work the project on a full-time basis.

Horned Toad

Photo by Kevin Holamon

“We’re going to continue to do this for the next several years, to learn as much as we can from them and see if we can get a new colony established. If so, then we’ll be interested to move out onto other properties in the area and see if we can extend their range over this portion of the county. We’ve also considered looking at some other counties that used to have horned lizards, maybe going to some different regions and testing it there, maybe moving further south into the Edwards Plateau and in the Hill Country, where they had lizards at one time, but don’t now. We’ve had some folks in east Texas on the Wildlife Management Areas interested in participating, where they are know to have been in the Post Oak Savannah eco-region. We eventually may have some sister sites, where we’re doing the same thing and monitoring in different parts of the state and make comparisons so we can learn more about how they react in different parts of the state.”

Horned lizards are an icon of the southwest and they ought to be here. Devin pointed out a comment by Nathan Rains, in a video about the project posted to the TPWD Youtube channel, when he said good horned lizard habitat is typically good habitat for quail, turkeys, deer, and everything else, which encourages landowners to get on board.

The Eyes of Texas are upon Devin, Nathan, and the rest of the staff, as well as those eight horned lizards. Only time will tell, but this writer, for one, is cheering them on. With a little luck, our grandchildren may get the chance to witness what we once took for granted.

Horned Toad

Photo by fwweekly.com