Protecting one of Arizona's wildest attractions

Agencies work together to reverse dwindling sheep population

JC AMBERLYN/Miner<br /><br /><!-- 1upcrlf2 -->Rob Nelson (right) and Clint Luedke of the Arizona Game and Fish Department release “# 59” after attaching a radio collar and ear tag during recent operations to protect the animals.

JC AMBERLYN/Miner<br /><br /><!-- 1upcrlf2 -->Rob Nelson (right) and Clint Luedke of the Arizona Game and Fish Department release “# 59” after attaching a radio collar and ear tag during recent operations to protect the animals.

The crew is after three of them right now and our spotter found another bunch near milepost 5.1," I heard the speaker inform us over the radio inside the Arizona Game and Fish Department truck.

Game and Fish Public Information Officer Zen Mocarski was driving me and two other journalists down U.S. 93 near the Hoover Dam in the northwest corner of Arizona. Our quarry was a charismatic but elusive target that should have been hard to find in the remote, rugged mountain terrain.

But we had technology on our side - a scout plane was out scanning the countryside for any sign of life, and eagle-eyed "spotters" with spotting scopes and binoculars aided the effort on ground. A helicopter holding biologists and a net gunman lurked nearby, ready to swoop down when the target was spotted.

What animal was this that brought a whole team of biologists, pilots, volunteers and three journalists to work together in the stark desert on a windy, overcast November day?

It was the Ovis Canadensis Nelsoni, better known as desert bighorn sheep.

• • •

Desert bighorns are similar to their cousins, the Rocky Mountain Bighorn, but they've adapted to life in the desert. The area near the Hoover Dam holds the largest single population of desert bighorns in not only Arizona but in the entire United States. This area, consisting of the Black Mountains, winds north to south along the eastern side of the Colorado River and holds about one-third of Arizona's bighorn population.

Historically, bighorns numbered as high as 1,800 here. However, bighorns have experienced some problems and populations have been on the decline as of late, reaching a low of 600-800 sheep in 2007.

The herds have been hit by several things, including disease, drought and predators. They were also vulnerable to vehicle traffic when trying to cross Highway 93 near the Hoover Dam. The highway has fragmented sheep habitat and isolated herds, making the transfer of genetic diversity difficult and increasing the effects of drought, disease and predation.

When the Mike O'Callaghan-Pat Tillman Memorial Bridge, also known as the Hoover Dam Bypass, was scheduled to be built, the sheep's future seemed to darken even more. The highway would go from two lanes to four, and traffic speeds through the area would increase. The sheep seemed doomed.

• • •

Biologist Kevin Morgan and other G&F employees were determined not to let that happen. With some calls and presentations, G&F, the Arizona Department of Transportation and the Federal Highway Administration began to work together on a three-part study to determine how the highway impacts the sheep. The original plan for the Bypass Bridge included building several underpasses (tunnels that wildlife can safely cross under the highway) to prevent motorist-wildlife collisions.

However, recent local research on State Route 68 had shown that bighorn sheep hesitate to use underpasses. They appear insecure entering a dark tunnel where a predator might wait to ambush from above. So, something else needed to be done.

The idea that emerged was the nation's first wildlife overpass, which provides road crossing above, instead of below, the highway. It has been successful in Canada, and the time to try it here had come.

It would be about a $5 million project to build three overpasses, one at each of the mile-marker locations that sheep had been trying to cross at. Each overpass consists of a bridge spanning over the highway, lined with fences on the side and dirt on the floor. Fences are also being built along the highway to "funnel" the sheep toward the overpasses.

• • •

Part One of the bighorn sheep study consisted of capturing several sheep in the Black Mountains and tracking their movements with radio collars. It was determined that sheep were most often trying to cross the highway at mile markers 3.3, 5.1 and 12.2, but they usually turned back. Part Two of the study looked at how the sheep were responding to the construction in the area. Now, Part Three of the operation has begun.

Part Three consists of capturing the sheep and determining their movements now, including whether they are using the new overpasses. To do this, G&F rents a helicopter and pilot and employs its own biologists and a gunman. Once sheep are spotted, the helicopter chases after them and the gunman shoots a net, which captures a single sheep.

Biologists then quickly work to get to the animal, put a hood over its eyes to reduce stress and take blood samples for research. Finally, a radio collar with a GPS is put on its neck and an ear tag attached. The hood is removed, the sheep runs off, and the team searches for their next subject. This study is slated for two years, then the collars are programmed to drop off the sheep automatically.

The plan for this weekend had included a goal of capturing 35 sheep, but high winds eventually grounded the aircraft and the total was half of that. However, another capture effort is planned for January. Biologists expect the sheep to start using the overpasses soon. If for some reason they do not, G&F may use bait or water to entice animals onto the overpasses. Once sheep learn to use them, they will teach their offspring.

• • •

Some ask, why save the sheep? The cost of the overpasses alone is in the millions. Mocarski would point out that the underpasses were already factored into the cost of redoing the highway. He also had this to say: "If some people don't value wildlife that much, we're probably not going to change their mind. But many of us do. And this was a rare opportunity to make something better. You can't go back years from now and tear down the roads (because of a bighorn population decline due to the new four-lane highway). This time was a chance to do it right."

Celina Tuason and Christine Haverkamp were the two other journalists along for the ride last Friday. They are students at the University of Nevada-Las Vegas and are making a video about the sheep project. To see it, visit starting on Dec. 3.