Roads are everywhere. That may seem obvious, but the full extent of their pervasiveness is difficult to conceptualize. According to a recent Smithsonian Magazine article: “[i]n the contiguous United States, [it is] impossible to get farther than 22 miles from the nearest road.” The United States has the largest network of roads in the world, so it is no surprise how car-dependent American society has become. The vast majority of Americans, 83 percent, drive regularly, logging more than 3.17 trillion miles traveled in 2022. Most Americans drive a motor vehicle despite well-documented poor health outcomes, detrimental environmental impacts, and immense harm to wildlife.
Car accidents involving wildlife are relatively common, especially in rural areas. Though the exact number of animals injured or killed by vehicles in the United States is difficult to determine, available data suggest a number somewhere in the millions. A 2008 Department of Transportation study estimated that there are one to two million vehicle collisions involving “large” wildlife annually. However, some experts—like Ben Goldfarb, author of Crossings: How Road Ecology Is Shaping the Future of Our Planet—believe historical estimates are far too low. Recent data indicate that each year 89 to 350 million birds are killed by vehicular collisions on American roads alone. Statistics measuring car accidents involving wildlife are difficult to ascertain because they are underreported and often fail to consider collisions involving “smaller-bodied” and “less mobile” animal species, which face an even greater risk of mortality than other species. Regardless of the exact number of animals killed per year, roads pose a significant threat to biodiversity: road mortality is a major threat to the survival of at least 21 federally listed threatened or endangered species.
In addition to the serious hazard that cars pose, animals near roads are affected by vehicular sounds and lights, vulnerable to road-based pollution, experience habitat loss and fragmentation, suffer from the effects of non-native invasive plant and animal species, and sometimes become unable to travel to areas necessary for their reproductive or migratory needs.
The National Forest System (NFS) is of vital importance for wildlife because forests provide habitat for 80 percent of land-dwelling species on Earth. The U.S. Forest Service manages 193 million acres of land within the National Forest and National Grasslands systems, including the largest transportation network of all federal land management agencies. With more than 372,000 miles of roads, it is responsible for approximately 208,000 more miles than the U.S. Federal Highway Administration.
Historically, NFS roads were primarily built for timber harvest, which can cause additional harm to animals by removing wildlife habitat, food sources, and protection. Today, NFS roads serve a wider variety of purposes—including logging, mining, grazing, hunting, fishing, skiing, hiking, and camping. On one hand, the Forest Service argues that roads increase access to private lands, make public lands easier to traverse for outdoor recreation and research, and can aid in fire and vegetation management efforts. On the other hand, the Forest Service states that forest roads can introduce non-native invasive species, create barriers for aquatic organisms, and increase the number of non-motorized recreation areas. Further, it states that forest roads can pose risks to historic sites and cultural resources; “sensitive” wildlife and plants; and “sensitive” soils, erosion, and water quality. Ultimately, forest roads present risks to wildlife regardless of their intended purpose.
The Forest Service’s 2005 Travel Management Rule requires each National Forest to identify and designate a system of roads, trails, and areas where motorized vehicle use is permitted. If a road, trail, or area is not designated for motorized vehicle use, it is considered “closed” to such uses by default. Roughly 23 percent of Forest Service Roads are closed to the public at any given time, but wildlife advocates argue that the Forest Service has failed to account for—and adequately prevent—illegal driving on “closed” roads, causing harm to grizzly bears and other species. To address this harm to animals, the Forest Service should strictly enforce its road closures by closely monitoring barriers, repairing damaged or breached barriers, and patrolling for illegal use.
The Forest Service states that public demand for NFS roads has increased over the last two decades, while funding has decreased. This dynamic has caused many forest roads to fall into disrepair, creating an 8.6 billion dollar backlog of unmaintained roads. Some advocates argue that the Forest Service should stop building new roads and instead decommission and remove old forest roads. They point out that the Forest Service already has support for decommissioning old forest roads via the recently reestablished Legacy Roads and Trails Remediation Program (LRT). However, less than 10 percent of nationally funded LRT projects included road decommissioning in 2022.
WildEarth Guardians, a nonprofit organization, believes that the lack of road decommissioning is due to insufficient public involvement in the program. They have submitted Freedom of Information Act (FOIA) requests for access to Forest Service documents and are urging others to help them demand increased transparency and public involvement in the LRT project selection process. As for halting future road construction, Guardians asked the Forest Service to prioritize protecting and expanding roadless areas by following the goals of the 1999 Roadless Area Conservation Rule.
Other sources indicate that the biggest hurdles to implementing and enforcing closures include lack of agency funding, inadequate staffing, political interests, and undesirable economic impacts of reduced access. To overcome these hurdles, the Forest Service can focus its energy on planning and implementing seasonal (during key migration and breeding periods) and temporal (during certain times of day) road closures. Temporal road closures could be a useful place to start because they are less economically intrusive than seasonal closures, but still have been shown to improve habitat quality for wildlife. These changes should be planned with an emphasis on the needs and habits of local wildlife.
Wildlife corridors—including crossings, tunnels, and refuge networks—are another increasingly popular options for addressing harm to wildlife from motorized vehicles. The essential purpose of wildlife corridors is to connect segmented habitats, allowing animals to travel safely between them. Sometimes these corridors expand existing habitat. Other times they are used, alone or in a series, as “stepping stones” between habitats. Both methods promote biodiversity by allowing animals to follow their migration paths, find genetically diverse mates, better locate food and water, utilize “escape routes” during times of disaster and shortage, and avoid interactions with cars and humans.
Crossings over roadways in particular decrease the number of vehicular accidents involving wildlife. While some groups argue that wildlife crossings are not the best solution for wildlife because they can be costly and difficult to fund, there are a variety of funding options available. One example is the Wildlife Crossings Pilot Program, which issues federal grants from the U.S. Department of Transportation. Another critique of wildlife crossings is that not all species will use them. However, studies taking place at existing wildlife corridors—including highway crossings—show measured drops in animal-related accidents overall.
With increased familiarity, more animals might utilize dedicated corridors; and simultaneously implementing other protection strategies could aid in that transition. For example, according to the National Agroforestry Center, buffer zones are “…designated areas used to protect sensitive landscape patches…from negative external pressures.” On top of further protecting the landscape, buffer zones protect the wildlife that live in them. Buffers can be employed around existing habitats and connective corridors to further insulate animals from the effects of roads, leading to greater utilization of corridors.
The most effective ways for Americans to reduce their impacts on wildlife—besides abandoning motorized vehicles altogether—are to drive slower and less often. The next best options include limiting the construction of new roads, challenging existing transportation projects, placing temporal and seasonal limits on the use of roads, decommissioning and rewilding old roads, protecting existing habitats, and creating more wildlife corridors to connect existing habitats. None of these options are perfect on their own, but if used together they have the potential to make measurable improvements for wildlife. Ultimately, it is up to humans to advocate for and make these changes because there is no other way for animals to escape the harmful effects of roads.
