For most Arizona residents, traveling Interstate 11 (the to-be-constructed roadway linking Phoenix to Las Vegas) is a long way down the road.
That’s not the case for desert bighorn sheep and other wildlife needing safe passage over the Nevada stretch of I-11, three miles west of the Arizona-Nevada state line. It’s there where Arizona Game and Fish Department biologists teamed with Nevada and federal officials to design and build a wildlife overpass over the new 15-mile stretch of roadway, which opened last month.
“This has been a great project and example of interstate collaboration to assist in conserving and protecting desert bighorn sheep and wildlife,” said Jeff Gagnon, AZGFD statewide research biologist. “Barriers such as roadways can fragment wildlife habitat and impact their access to water. Through projects such as these, our collective goal is to do what we can to minimize such impacts by providing locations for wildlife to safely cross highways.”
When Nevada Department of Transpiration Committee of Southern Nevada and Nevada Department of Wildlife officials began planning the first 15-mile stretch of I-11 in 2014, engineers and wildlife officials turned to Arizona.
Prior to the project, bighorn sheep were outfitted with GPS collars to learn their distribution patterns near Boulder City, Nev. Data collected were then used by AZGFD and their Nevada partners to assist project engineers to design and identify the proper location for a new wildlife overpass. While this particular project has been completed, AZGFD will continue to assist NDOT with monitoring the project using GPS collared bighorn sheep and cameras to document how wildlife are using the new overpass.
Wildlife crossings aren’t a new concept to Nevada, but the state had limited experience with desert bighorn sheep and officials knew AZGFD, Arizona Department of Transportation and federal officials have had success on such projects to assist bighorn sheep and local wildlife.
Three overpasses and fencing to guide the animals to the structures were installed between 2007 and 2011 on U.S. 93 between Kingman and the Nevada state line. As a result, wildlife-vehicle collisions were virtually eliminated along the stretch of roadway and nearly 6,000 bighorn sheep crossings were documented in the first four years of monitoring.
AZGFD, ADOT and their Arizona partners’ record of successful wildlife-vehicle collision mitigation stretches to 2001, when wildlife crossings, fencing, and an animal detection system were installed on State Route 260 east of Payson. The projects helped to reduced elk-vehicle collisions by 97 percent.
In southern Arizona, the Oracle Road wildlife crossing opened in May 2016 on State Road 77 north of Tucson, allowing local wildlife to safely cross seven lanes of heavy traffic. Within days of its opening, trail cam video captured coyotes, mule deer, and javelina crossing the overpass, which was recently named after former Pima County Supervisor Ann Day.
“Whether it’s installing systems alerting motorists that elk are crossing the roadway in the high country or constructing underpasses or overpasses — these projects have truly had a positive impact on Arizona’s wildlife,” Gagnon said. “Each crossing has helped to save wildlife and motorists, all while limiting habitat fragmentation and potential barriers to adequate water resources.”
To learn more about project planning for wildlife, visit: