Most Utahns think of iguanas as exotic, tropical creatures, but there’s one tiny spot near St. George where scientists can find them.
What they discovered has inspired the launch of a four-day marathon of community science when researchers, students and volunteers survey the area for desert iguanas and gather data that’s vital to helping them thrive here.
“We live in an amazing place, and it has a lot of species that you might not expect,” Utah Tech University assistant professor Geoff Smith said. “A lot of people wouldn't think, ‘Yeah, there's iguanas out here.’ But we have them.”
Just two years ago, however, he wasn’t so sure Utah had them. In fact, the state was preparing to declare the native lizards locally extinct.
Then Smith’s colleague Megen Kepas noticed a photo of an iguana on a wildlife app southwest of St. George. In 2023, they went to that spot with a small group of students to confirm the sighting. They’ve kept coming back each spring since.
IguanaThon was born.
“It's all because of people who just like to go outside with their phones and take pictures of animals,” said Kepas, who worked for the state of Utah in 2023 but is now a herpetologist on the faculty at Utah Tech. “So, it's a really good example of how people who are recreating and exploring can contribute really meaningful data.”
Now in its third year, IguanaThon even has its own t-shirts designed by a local artist. They’re sold to raise money to power future lizard surveys.
Unlike their colorful tropical cousins, desert iguanas don’t have crests on their heads and are mostly grey-ish tan, except for a few accents.
“They kind of look like they're wearing eyeshadow, or a cat eye eyeliner,” Kepas said.
Desert iguanas are smaller than most other iguanas, too, typically just 10-16 inches long. The species’ closest relative is an iguana native to the Fiji Islands, Smith said, which illustrates how long ago the ones in Utah split from the rest of their family tree.
On this May morning, around a dozen IguanaThon participants fanned out across a sandy dry stream bed. They listened to scientists’ tips for the best places to look. The iguanas like to hang out under creosote bushes, which they eat, or near the openings of their burrows. If someone spots one, the next step is to capture it using a long fishing rod fitted with a tiny lasso.
“This is basically like a miniature version of a dog catcher's pole,” Kepas said as she held up the small loop. “They don’t weigh very much, so when we lift them up, it doesn't hurt them.”
Scientists then take the animal’s measurements and check its health before releasing it back into the wild. Finding a rare, foot-long camouflaged reptile in this vast, sparse landscape isn’t easy, though.
“You gotta really like walking around outside to do this,” Kepas said. “For every four hours that you walk, you see one lizard. So, it's a lot of nothing.”
The daunting task didn’t dampen the group’s enthusiasm, though. Utah Tech student Kerina Jauregui, an aspiring reptile veterinarian, came with high hopes of seeing her first desert iguana.
“I'm gonna be really excited, I'm gonna be honest,” she said. “But also, like, really shocked — not the fact that we found one, but that I'm seeing it.”
Desert iguanas are common in other parts of the southwest, but in Utah, they only live in a tiny sliver of the lowest elevation part of the state. There’s not much baseline data about the iguanas that live within our borders, said Alyssa Hoekstra, the native herpetology coordinator with the Utah Division of Wildlife Resources.
So, the information people gather during IguanaThon can help answer foundational questions, like how many there are, where their range is and if their numbers are growing or shrinking.
“This is filling a data gap for them, which is really important for the state,” Hoekstra said.
Without this type of research, the state won’t know what action plans or conservation efforts might be needed to help the species thrive here. That matters because biodiversity is a fragile thing in the desert, and every plant and animal that scratches out a life here is connected.
“They all fill a little niche in the ecosystem,” Hoekstra said, “so it's important to keep them here, if we can.”
Within a couple of hours, the group had come across several other reptiles, including horned lizards, zebra-tailed lizards and long-nosed leopard lizards. But no iguanas.
One reason may be that it’s still morning, Utah Tech junior Edwin Gutierrez said. Even at a sunny 86 degrees, it’s still a bit brisk for the heat-loving iguana. But this — hours of hard work, walking around the desert to find nothing — is also just what it takes.
“First day out here, we caught nothing,” Gutierrez said. “Then the next day, we caught our all-time record of four iguanas. So, it's all up in the air.”
After a few false alarms — spotting other lizards or seeing something hide too quickly to identify — the group called it a day without its quarry.
Across four days of IguanaThon surveys, however, the teams cataloged nine iguanas, more than twice as many as last year. Even better, one of the iguanas was a juvenile and another was producing eggs. Both are indications that Utah has a sustainable, reproducing population.
That’s a promising sign, Smith said, but desert lizards still face plenty of challenges.
Drought can shrivel their food sources. Cattle may stomp their burrows or compete with them for scarce water. As land development reshapes the fast-growing St. George area, there’s always a risk of losing a small slice of habitat like this one.
So, he said it’s important to keep reminding Utahns about their reptile neighbors.
“People protect what they love, and they can't love what they don't know,” Smith said. “I think just knowing that they're there is cool. And we were able to verify that they're here for a third year in a row.”
That gives him hope that these enigmatic lizards will be around for many more IguanaThons to come.
