Environmental Technical Assistance Program Newsletter

The Minnesota Department of Transportation is helping test ultrasonic bat “deterrence devices” at two bridges to help keep the mammals away from such structures when they undergo maintenance and/or repair activity.

[Above photo by the Minnesota DOT]

The agency noted in a blog post that bats like to roost in bridge expansion joints and temporarily preventing such roosting during bridge maintenance repair activity typically requires installing physical barriers that are often difficult to establish effectively, due to the design characteristics of many structures.

More importantly, the Minnesota DOT does not necessarily want to keep bats away permanently from its bridges because bat populations throughout North America are in serious decline. For example, the agency said white-nose syndrome – a fungal disease – has killed more than 5.7 million bats in eastern North America since 2005. On top of that, wind turbines kill hundreds of thousands of bats in North America annually, according to a study by the U.S. Geological Survey.

The Minnesota DOT has worked with the Minnesota Department of Natural Resources and the U.S. Fish and Wildlife Service for the last two years testing battery-operated ultrasonic deterrence devices that reduce bat activity at bridge site when activated, but ensure a quick return of bat roosting activity when deactivated.

“This project was innovative. We worked with a technology that wasn’t really on the market yet for real-world applications in anticipation of its availability,” noted Christopher Smith, wildlife ecologist with the Minnesota DOT’s Office of Environmental Stewardship.

He added that current regulations require shorter maintenance period options during the construction season in order to protect bats – mandating that crews must avoid having bats present during their work, which impacts cleaning, painting, and other maintenance timelines.

“The presence of bats disrupts bridge work timelines and budgets, and work upsets habitation for species struggling to survive,” Smith said.

The Minnesota DOT noted that it hopes to develop a procedure for deploying this ultrasonic bat deterrence technology when needed and determine associated expenses from this two-year research effort.

Further study could consider the technology in different configurations and environments, test the devices at many bridges around the country, and conduct a cost-benefit analysis, the agency added – while also comparing the “relative impact” of acoustic deterrents on specific bat species.

A state government report is calling for increased funding for transportation projects that protect big game habitats and corridors and prevent thousands of vehicle-wildlife crashes each year on Colorado’s roads.

[Above photo by the Colorado DOT]

The Colorado Department of Transportation and the Colorado Department of Natural Resources authored the Big Game Policy Report, subsequently released by Governor Jared Polis (D) on September 29.

A statement from the governor’s office said the report seeks to “prioritize state policy, coordination and investment to support our wildlife and ecosystems.”

The report notes that the effects of climate change, increased industrial, residential construction, plus ongoing infrastructure development increase the number of situations putting wildlife in conflict with people. The most glaring examples of such conflicts are the estimated 4,000 vehicle crashes with wildlife that cost an estimated $80 million each year in Colorado.

The Big Game Policy Report served as a follow-up to an executive order Gov. Polis issued in 2019 directing Colorado DOT to incorporate wildlife protection measures into “all levels of its planning process, to the greatest extent possible.”

The Colorado DOT already planned to make road improvements to U.S. 160 between Pagosa Springs and Durango when it decided to incorporate wildlife protection elements. The busy stretch of highway has been the scene of more than 350 big game-vehicle collisions in the last 10 years as drivers make their way to the Chimney Rock National Monuments.

The project, expected to wrap up this winter, now includes a wildlife overpass and underpass, high-deer fencing, and “jump out” ramps within the two-mile project area. The fencing helps “funnel” the moving herds toward the overpass or underpass, where they can safely cross the busy highway. The earthen ramps are inside the fencing and allow the animals to safely escape traffic.

By including wildlife elements into planned projects, “it gives us a bigger bang for our buck,” said Lisa Ann Schwantes, a Colorado DOT regional communications manager.

“We look at the projects already identified that need to be done, and we overlap them with wildlife projects and marry them together,” she said.

Though incorporating wildlife protection elements into existing planned projects can be cost-effective, the costs still add up. The U.S. 160 project has a total price tag of $12 million, $5.4 million of which include just the construction costs for the wildlife protection features.

The report points out that, while Colorado DOT continues to look for ways to protect big game and drivers from each other, the agency has no dedicated funding source for such wildlife projects – one reason why the new report calls on the state legislature to find new money to support such projects.

“While progress has been made, the General Assembly should prioritize new funding for transportation projects identified by CPW (Colorado Parks and Wildlife) and Colorado DOT that provide a clear benefit to wildlife populations and human health,” the report states.