Innovative approach to help the Black Mountains bighorn sheep herd
Kingman, Arizona — A historic collaboration between state and federal agencies has led to an innovative approach to protect the Black Mountains bighorn sheep herd in northwestern Arizona, the largest contiguous desert bighorn sheep herd in the nation.
The first desert bighorn sheep overpasses, not only in Arizona, but in the entire lower 48 states, will soon be built on Highway 93, south of Hoover Dam. The project is the final result of a combined effort between the Arizona Game and Fish Department, Federal Highway Administration (FHWA), and the Arizona Department of Transportation (ADOT).
Construction could begin as soon as next fall.
When the Hoover Dam bypass effort on Highway 93 began several years ago, concerns were raised about potential impacts to the Black Mountains desert bighorn sheep herd.
With the bighorns already suffering from fragmentation - which splits the herd apart and diminishes overall genetic viability - and numerous vehicle collisions each year, biologists were concerned about the increased traffic on Highway 93 and the speed at which vehicles would be traveling.
“This project had the potential to affect the long-term sustainability of bighorn sheep in the Blacks,” said Kevin Morgan, former habitat program manager at the Game and Fish Kingman office and one of the key players in developing the project. “It was clear we had a problem.”
Past roadway efforts to allow safe passage for wildlife primarily focused on underpasses, but research has shown that bighorn sheep are reluctant to use underpasses.
“We had to think scientifically,” Morgan stated. “We have technology available to us now that didn’t exist in the past. We have the tools that allow the animals to provide us with the information we need to help them.”
In 2004, Game and Fish and ADOT took the next step in wildlife conservation. With funding from ADOT and the FHWA, Game and Fish began research efforts to study the movements of bighorn sheep near the bypass.
“This really was a collaborative effort,” said Mike Kondelis, district engineer for the ADOT Kingman district. “We formed a separate technical advisory committee that focused specifically on the wildlife crossings.”
Steve Thomas, environmental program manager for the Arizona Division of the FHWA, concurred. ”I think this is one of the finer collaborations I’ve ever worked on,” he said. “To recognize the need to get something done and then have the cooperation between state and federal agencies to complete the effort, is an outstanding result.”
“I give credit to ADOT for stepping to the plate and to Kevin Morgan for his passionate plea. We’re dealing with a species not protected by the Endangered Species Act, and ADOT really stepped up and did the right thing. This is going to be great for sheep and for research on a nation-wide scale.”
Using telemetry collars to track sheep movements over the past three years, it became clear bighorn sheep wanted to cross near ridgelines along the highway between mile markers 0 (Hoover Dam) and 17.
“Bighorns feel safe when they’re up high,” Morgan said. “They feel vulnerable to predators in an underpass. The research made it clear these animals want to cross from a high vantage point.”
At the conclusion of the study, Morgan presented the results to members of ADOT and FHWA. The results included 80,000 location points obtained from the telemetry collars.
The sheep location points told researchers they want to cross at mile markers 3.3, 5.1, and 12.2. However, when the sheep approach the highway at these points, they simply turn around. The road serves as a substantial barrier, and the sheep that do venture across are at risk.
With a four-lane highway planned for construction, that barrier was about to double in size and become a nearly impassable obstacle for the sheep - increasing concerns about diminished genetic viability and long-term sustainability of the herd.
“When news of this bypass first came out, my thoughts were of doom and gloom,” Morgan said. “This ended up being a unique case. It’s not often you get an opportunity to improve upon a situation like we have near the Hoover Dam. When roadways are in place, you generally don’t get a second chance to fix problems.”
The result? Three wildlife overpasses slated for groundbreaking in 2008.
The goal, Kondelis explained, is to wrap up design for the road widening and wildlife crossing, and advertise (bidding process) the project for construction in June 2008. If all goes according to plan, construction will begin in October or November.
“For the motorists and animals, this is a good thing,” Kondelis said. “It will allow this herd (of bighorns) to cross to areas that in the past they may not have been able to access.”
