From Photos to DNA: Citizen scientists focus on Gila monsters at Saguaro National Park

Emma steps out often but stays close to home.

After almost drowning, Ward kept a low profile for 12 years.

King Tut likes to strut and has been spotted many times over the past several years.

This trio, along with another 180 Gila monsters (Heloderma suspectum), have been identified through a citizen science project conducted in the Rincon Mountain District of Saguaro National Park, east of Tucson, Arizona. Funded by Western National Parks Association, this study supports conservation efforts for the Gila monster through natural history and genetic studies. The project’s researchers also see citizen involvement as a key factor, since it fosters appreciation for science and protection of the park.

These iconic Sonoran Desert lizards can provide a thrilling, and potentially bucket list, sight for park visitors. The only venomous lizards found in the United States, Gila monsters spend about 90 percent of their time underground and live about 20 years. The distinctive patterns on the beaded skin of adults are akin to human fingerprints, providing a method for unique identification.

The researchers capitalized on visitor interest in Gila monsters by requesting photographs. Using an app, citizen scientists upload their photos, along with the time and location of each sighting. Alternatively, they email or snail-mail them to the researchers. Trained volunteers pore over the photos, using the beaded patterns to identify individual animals.

Citizen scientists have contributed over 350 photographs. With the addition of staff and archived photos, researchers have reviewed more than 500 photos to identify 183 individual Gila monsters.

Photos help the researchers collect data about the lizards’ home range. The homebody Emma, for example, was spotted seven times during 2013 and 2014, but all her photo shoots occurred within 100 yards of each other.

The reclusive Gila monster Ward was photographed in 2001 but not again until 2013 —12 years after his rescue. In 2001 Mike Ward, a park biotechnician, saved his namesake from death in one of the park’s natural pools or tinajas. These rock depressions store water but can trap an animal when the water level recedes.

King Tut, on the other hand, seeks the limelight. Several photos of him adorn an office bulletin board at Saguaro National Park headquarters.

The scientists leading this study—Don E. Swann, a biologist at Saguaro National Park, and Kevin E. Bonine, a faculty member at the University of Arizona—have been collaborating on Gila monster research since 2008. Both strive to engage the public in science. “Ideally, science in a national park runs that whole spectrum from participation to peer-reviewed published results,” Swann said.

Swann has engaged volunteers, including citizen scientists, in park activities and research for years. He pairs people with positions that are rewarding for both the volunteer and the science. Students match Gila monster photos, hikers measure the height of saguaros and a retired physicist runs laboratory tests to assess water quality.

“Science is very important for protecting the resources in our national parks in the long run,” Swann said. “But I also think the greatest value of science in national parks is the fact that it answers the questions of visitors and that it instills an appreciation for the park by having a deeper knowledge of the resources.”

When people become more engaged with their surroundings, they are more likely to support measures to protect an area, Bonine said. “Part of my goal for the increased awareness and understanding has to do with mitigating the effects of urbanization.” With houses and roads expanding into the homeland of Gila monsters in the Rincon Mountains, the lizards may face threats to their survival.

To support conservation efforts for Gila monsters, the researchers collected and analyzed DNA from 100 animals. They concluded that the Gila monster population at Saguaro National Park is genetically robust, according to a paper published in Amphibia-Reptilia. With a sufficiently large breeding population, the lizards maintain a crucial diversity in their genetic makeup. These results showed the benefit of protection by both the park and state laws.

While Gila monsters are seldom seen, they are not rare, Bonine said. Their reclusive nature makes them an exciting find during a hike. So when Emma, Ward or King Tut venture out next for a stroll, citizen scientists may be on the alert, enjoying the rare sight and advancing science.

For more information on the Gila monster project at Saguaro National Park or to send in your Gila monster photographs, go to

By Chris Stidley

Kevin Bonine, one of the lead researchers on the project and a faculty member at the University of Arizona, displays a Gila monster. Courtesy of the National Park Servic, Tom Uhlman.