Researchers at Saguaro National Park are going where few scientists have been brave enough to go before - into the mouths of Gila monsters.
A project has been tracking the venomous creatures at the park since 2009, but Gila monsters remain some of the Sonoran Desert's most elusive and little known residents. To change that, researchers are - very carefully - taking mouth swabs of the stocky, pink-and-black lizards, which are known for their painful, venomous bite.
The resulting DNA analysis, started this month, will give the Gila Monster Project - a collaboration between the park and a team led by researchers from the University of Arizona - another way to draw conclusions about an enigmatic population, said Kevin Bonine, an adjunct assistant professor in the UA Department of Ecology and Evolutionary Biology.
"The genetics part is neat - it gives us the ability to answer a whole range of questions," said Bonine, the study's principal investigator.
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Field biologists are already tracking the movement of five lizards equipped with radio transmitters and hundreds of others with microchip identification.
The creatures are handled carefully by hand or with long, tonglike hemostats - and no one has been bitten yet, Bonine said.
lives underground
Gila monsters have rarely been the subject of long-term studies, Bonine said. They spend much of their lives underground and little is known about the size and status of the population around Tucson or the threats posed by urbanization.
The project has collected data about the number and movement of these creatures in and around the Rincon Mountain District of the park for three years.
Adding DNA analysis will help determine genetic diversity, including whether the subpopulation of Gila monsters in Saguaro National Park differs within the Rincon Mountains or from populations elsewhere.
Researchers could draw conclusions about whether the population has become fragmented by construction of highways, houses or other infrastructure, Bonine said. Fragmentation can cause inbreeding and have other negative effects on the population.
"This is kind of a rare thing for these animals," said Victoria Farrar, a UA undergraduate working in the lab. "Getting to understand them genetically better helps us protect them and coexist with them."
8 to 9 hours to find
Meanwhile, the team is continuing to track Gila monsters in the field and find new animals. Field biologists drive and hike around the park looking for Gila monsters that don't already have microchip identification.
It takes an average of eight to nine hours to find a new Gila monster, Bonine said. Fifty new lizards were tagged with microchips in 2011 while 60 new animals were added to the study this year.
Five lizards received radio transmitters through surgical operations. The transmitters are about the size of an AA battery with an attached antenna.
Darren Anderson, a UA graduate and field biologist intern with the project, tracks the lizards at least once a week with a receiver tuned to the radio frequency of the Gila monster's transmitter.
The Gila monsters tend to stay near the same spots, Anderson said. He tracked one to a rock outside the visitor center on a recent Thursday afternoon, then hiked through a wash looking for others.
"They can get into some rough terrain," Anderson said. "Sometimes we can't even see them."
For each Gila monster Anderson tracks, he takes a photo and records the GPS coordinates, habitat, temperature and humidity of its location. He spends the rest of his shift driving the roads of the park to look for new subjects.
New animals are measured for characteristics including body mass, tail volume and body condition.
The Gila monsters are then injected with a chip about the size of a grain of rice.
"Sometimes it's difficult," Anderson said. "They squirm if they don't want it. They can be pretty feisty."
unique creature
The study - combined with the presentations researchers give throughout Tucson - helps educate people about the importance of conserving these animals, said Don Swann, a biologist for the park. The park's unique wildlife is a main draw for visitors, he said.
"The Gila monster definitely fits into that," Swann said. "We're trying to understand the animals as well as we can so we can protect them."
On StarNet: Search the database to find facts and photos of more Southern Arizona native creatures: azstarnet.com/critters
Did you know?
Park visitors can help researchers learn more about Gila monsters by submitting their own sightings.
Post details of encounters at www.herpcount.org or pick up written forms from park rangers.
A cellphone application in development will allow hikers to take a picture of a Gila monster and submit it with GPS coordinates.
Brenna Goth is a NASA Space Grant intern. Contact her at bgoth@azstarnet.com
