Safe crossing

The 600-pound elk hesitates in the dark meadow, pausing in the doorway of the small mesh enclosure, tantalized by the smell of a pile of alfalfa. Not far away, Arizona Game and Fish wildlife biologist Jeffrey Gagnon sits in a trailer and watches the elk through a night-vision camera, his finger poised above the switch that will drop the door on the cage should the elk take the bait. 

The elk and Gagnon will both be up all night, playing their small but crucial role in curtailing a lopsided, messy war that kills some 200 humans and more than 1.5 million elk and deer each year. With each crash costing an estimated $2,300 in property damage, these wildlife encounters cause $10 billion in damages annually. Moreover, cars kill perhaps 1 million other vertebrates every day while creating barriers that fragment habitat and threaten some species with extinction, including high-profile ones like the Florida panther. 

This explains the importance of Gagnon and the elk he's about to trap, wrestle to the ground, radio-collar and then track for the next two years. He's one of the lead researchers in an attempt to build a network of wildlife-friendly underpasses beneath the newly widened State Route 260, which runs along the base of Arizona's Mogollon Rim. Stung by lawsuits and the deaths of up to five drivers annually, the Arizona Department of Transportation called in wildlife biologists to determine whether wildlife crossings could make a difference. Five years later, a combination of underpasses and fencing has reduced collisions by a heartening 83 percent. As a result, this 18-mile stretch of busy highway has provided a national model, as both the federal government and key states work to protect wildlife and drivers by retrofitting highways and considering wildlife issues at the drawing-board stage. 

"I'm so proud of Arizona," says University of Utah researcher Patricia Cramer, a passionate advocate for wildlife-friendly highway design. Spurred by 12,000 crashes a year involving deer in Utah, Cramer and fellow University of Utah researcher John Bissonette recently compiled a list of 400 road crossings built to protect wildlife. 

At this point, Arizona's high-tech set of crossings on Highway 260 is the best-studied system in the country, perhaps reflecting the impact of a multimillion-dollar jury verdict that caught the attention of highway designers nationwide. 

In December 1998, the car Jerry Booth was driving along I-40 near Flagstaff crashed into the carcass of an elk that had been hit by another motorist and left on the highway. Booth, who suffered serious injuries in the crash, sued the state for not keeping the roadway clear. A jury in 2004 awarded him some $3 million, agreeing that the state should have gotten the dead elk off the highway faster. When an appeals court upheld the verdict, it sent a chill through state highway departments nationwide, and gave an extra boost to research into ways to reduce wildlife-related car crashes. 

Meanwhile, state and federal governments grapple with an aging and deteriorating interstate highway system. One recent survey revealed the need to replace 59,000 bridges along interstate highways in the next decade. Each of these could become an effective wildlife crossing - if planners think ahead. 

"The number-one priority is to consider wildlife and ecosystems in the transportation-planning process - at the very beginning of that 15- to 20-year pipeline," says Cramer. "Now, wildlife isn't considered until it's too late to change anything." 

When it came time to widen Arizona's Highway 260, however, transportation planners turned to Game and Fish researchers Norris Dodd, Gagnon and others. The biologists have spent the past five years capturing, radio-collaring and monitoring more than 100 elk to study how the animals react to a combination of fences and wildlife-friendly underpasses. In areas where no streams or gullies offer the opportunity to construct an underpass, the biologists and traffic engineers have installed military-grade motion detectors that trigger warning lights on the highway when a large animal approaches the road. 

The satellite-connected radio collars record an elk's position every two hours for two years, allowing the biologists to accumulate a treasure trove of information about elk behavior. The collars, along with cameras that watch the underpasses, enabled the researchers to study how elk reacted to the highway and to different underpass designs. This detailed tracking revealed that elk won't detour very far to use an underpass, a fact that makes both fencing and the spacing of the underpasses crucial. It also revealed a simple answer to the question, "Why did the elk cross the road?" It crossed to get to the meadow on the other side, where the grass provides the most energy per mouthful to animals that must feed constantly. Thus, the most popular elk crossings are near meadows. 

Moreover, the radio collars showed that a small percentage of the elk cross repeatedly - and they're the ones most likely to end up getting smacked by a car. Although most elk won't go far out of their way to use an undercrossing, once funneled by fencing to one, they cross readily. The year-round elk act as pioneers and may speed the acceptance of the underpasses by other elk migrating through the area. The elk much prefer underpasses with an open design lacking high concrete walls, presumably because the dark ledges at the top of the wall look like a great place for mountain lions to lurk.

• Wildlife