Highway overpasses successful at curbing wildlife/vehicle collisions

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By Christie Greene

The sun was warm as we gathered on Vail Pass last July. Paige Singer, a biologist for Rocky Mountain Wild, and Lisi Lohre, Citizen Science intern for the Denver Zoo, handed out hardhats and bright orange vests to the three volunteers before we piled into an SUV. We drove to a spot between Copper Mountain and Vail Pass, and parked on the shoulder along westbound Interstate 70, near where a number of motion-triggered cameras had been placed in the spring.
Our first stop, a 20-minute walk just about straight uphill, led us to a camera mounted on a narrow pole. Singer and I unlocked the camera, recorded the data, replaced batteries and removed the memory card containing the photographs, inserting an empty one. In total, about 10 cameras were visited that day.
Singer later uploaded the photos to the website “Zooniverse.” This program allows organizations to download photographs that can be categorized by members of the public. Bears, coyotes, rabbits, a raccoon, a couple of elk and many deer had visited the cameras recently. Some animals were unconcernedly ambling by, while others appeared to be startled by the flash of the camera in the darkness. One deer appeared to be curiously sniffing the camera, mostly just the tip of her nose visible.
Through our data collection, we were taking part in the Colorado Corridors Project, a study of wildlife living in and traveling through a targeted area near Vail Pass. Rocky Mountain Wild, a nonprofit located in the Denver area, the Denver Zoo, Colorado Parks and Wildlife, and the Colorado Department of Transportation are collaborating on gathering data and conducting viability studies with the goal of building a wildlife overpass over I-70.
This proposed structure will accomplish two goals — the overpass will greatly reduce animal mortality from vehicle collisions, and the overpass will provide safe passage along strips of land that can be connected into a wildlife corridor. When combined with elk fencing, overpasses have been proven to be wildly successful at keeping animals off the road.
Wildlife corridors are an important part of wildlife protection strategies, forming an uninterrupted swath of wildlife habitat that might have been otherwise severed by development.
The first wildlife overpasses in Colorado were built in 2015 and 2016 along Highway 9 between Silverthorne and Kremmling. The chosen 11-mile section is a migration path from the Blue River to winter habitat on the east side of the highway.
The project added three underpasses, two overpasses, elk fencing and widening of the shoulder. According to Colorado Parks and Wildlife, the Highway 9 project has resulted in a 90 percent reduction in wildlife-vehicle collisions.
The effectiveness of this program has led CDOT to consider adding passes to existing highways, and the agency already examines opportunities to design wildlife crossings into new projects.
With Colorado population on the rise, building wildlife passes as well as protecting corridors of land to provide healthy and safe movement for animals makes sense from safety, economic and aesthetic perspectives. The expense of wildlife-vehicle collisions in terms of property damage, potential injury to occupants, emotional trauma and loss of animals, which are considered a state resource, can be greatly diminished by building over- and underpasses.   
To find out more about these corridor projects and to give your input, visit Rocky Mountain Wild, Colorado Parks and Wildlife, Denver Zoo and CDOT websites.
Evergreen resident Christie Teague Greene moved to Colorado temporarily almost 30 years ago — and never left. A Tennessee native, she was drawn to this area by its wildlife and natural beauty and has been committed to preserving both for many years. Send your column ideas and questions to christiegreene@comcast.net.