AASHTO Journal

Arizona Agencies Move Chuckwalla Lizards for South Mountain Freeway Project

Officials from the Arizona Department of Transportation and other agencies captured and relocated about 120 foot-long chuckwalla desert lizards as part of its 22-mile South Mountain Freeway project in southwest Phoenix.

The freeway is expected to open by late 2019, when it will provide drivers with an alternative to Interstate 10 through downtown Phoenix, and a long-planned direct link between the East Valley and West Valley. It is the largest highway project in state history.

The department said its biologists – working in partnership with the Arizona Game and Fish Department, the Gila River Indian Community's Department of Environmental Quality and South Mountain Park/Preserve – recently spent several hot summer mornings dressed in hiking gear and searching crannies along ridges in the southwest corner of the preserve.

dollarpump.jpg"While most animals flee when threatened, chuckwallas wedge themselves deep in cracks between rocks," ADOT said. The large lizards are common in the U.S. Southwest and northern Mexico, and include orange-tailed males that are unique to the South Mountain Park/Preserve.

So ADOT "is working to relocate chuckwallas in the small portion of the preserve where the Loop 202 South Mountain Freeway will pass." Construction in that part of the freeway corridor is scheduled to begin in mid-2018.

"With the work that we are doing in collaboration with our partners, we believe the chuckwalla population will continue to thrive in the area surrounding the South Mountain Freeway," said ADOT biologist Kris Gade.

But capturing the lizards, which can measure up to 15 inches long, was no easy task, ADOT said.

"Groups of four to eight biologists made multiple passes, looking deep into crevices in the rocks with flashlights. If a lizard was spotted, the biologists would first attempt to grab it with their gloved hands before the chuckwalla could dive deeper into a crack.

"If the chuckwalla wiggled too deeply into a narrow crack, it sometimes required multiple biologists to move the rock with a pry bar while another made the capture."

The teams released the animals several hundred feet away, after first weighing and measuring them, tagging their feet with white paint and inserting a tiny transponder tag beneath the skin of each one to help biologists identify them during future surveys.

Crews also fitted 15 chuckwallas with radio telemetry harnesses so that biologists can track their movements.

Daniel Leavitt, a Game and Fish Department herpetologist who led that agency's chuckwalla efforts, said his department routinely works with ADOT to minimize the impact highway construction projects have on wildlife.

"That is why it is key to learn what we can about chuckwallas that may impacted by this project and safely relocate them to a new area nearby," he said. "Data collected during this partnership will be used to assist in decisions to help conserve and protect chuckwallas and other wildlife near the Loop 202 extension in the future."

ADOT said that as with any of its projects, this one began with a biological evaluation to determine what effect the work would have on plants and animals.

It said that "project biologists are also tracking movements of desert tortoises in the segment where the freeway will pass through the preserve, and working with wildlife rehabilitators as needed to relocate burrowing owls and other wildlife that may be disturbed by construction."

The completed freeway will have several multi-use crossings in the center segment, at points chosen in consultation with the Game and Fish Department, to allow wildlife to pass along with hikers and people riding on horseback.

Questions regarding this article may be directed to editor@aashtojournal.org.

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