As the human population has grown and spread to all corners of the world, we have constructed endless miles of roads and highways. While these roadways help us travel to almost anywhere on the planet, sometimes they also pass through delicate ecosystems and can have a negative impact on the native wildlife populations that pass through them. In a conscious effort to fix this problem, creative engineers have designed bridges, overpasses, and tunnels that provide safe passages for various species. From crab bridges on Christmas Island to toad tunnels in California, here are seven clever wildlife crossings around the world.
A556 Green Bridge (Cheshire, United Kingdom)
Throughout the United Kingdom are a number of wildlife crossings known as green bridges. A particularly notable one opened in 2018 on a stretch of the Knutsford-Bowdon Bypass, a heavily trafficked link between two busy highways in Cheshire, Northwest England. Part farm track and part wildlife crossing, the bridge is planted with various species of grasses, shrubs, and trees. It provides a safe haven for badgers and voles in addition to being a natural habitat for birds and insects. The green bridge was just one of a series of eco-conscious features of the larger bypass — others include human-made badger setts, newt habitats, and ponds.
Banff Wildlife Crossings (Banff National Park, Canada)
When the Trans-Canada Highway was laid out in the 1950s, planners didn’t anticipate how busy the stretch through Banff National Park would become. As the traffic increased, so did the amount of wildlife incidents. Since 1996, the Banff Wildlife Crossings Project has fought to improve the situation for the park’s wildlife with the construction of overpasses and underpasses. When viewed from the roadway below, the bridges don’t look much different to standard concrete highway structures, but the major difference is the forest that spans the surface — inviting bears, coyotes, elk, and wolves, among other species to cross uninterrupted. To date, the project has been responsible for installing 38 underpasses and six overpasses, which have helped to reduce animal-vehicle collisions by an impressive 80%.
Crab Bridges (Christmas Island, Australia)
At the beginning of the wet season on Christmas Island (usually between October and December), around 50 million red crabs scuttle from their forest homes to the Indian Ocean to spawn their eggs. It’s a truly magical sight — British naturalist and broadcaster Sir David Attenborough once described it as one of his greatest TV moments. One obstacle that can hinder the migration, however, is human infrastructure and car traffic. To guarantee a trouble-free crossing across the busier island roads, the crabs can utilize specially designed metal bridges. They can also make use of 31 underpasses and several miles of barriers in order to reach their destination — which come in handy, as the crabs literally take over the island during the migration. One local has even invented a car attachment to brush the crabs out of harm’s way.
Davis Toad Tunnel (Davis, California)
Set on a patch of grass outside the main post office of Davis, California, are a couple of miniature buildings that might seem like whimsical dollhouses at first glance. But they are actually part of a wildlife underpass called the Davis Toad Tunnel, created after a six-lane highway replaced a city dirt road. The new highway cut the native amphibian population off from its wetland habitat and forced it into a real-life game of Frogger to cross the road. In 1995, outraged residents convinced city officials to approve a $14,000 project to install tunnels to and from the wetlands. Toad Hollow, as the miniature buildings are affectionately known, are painted to mimic a hotel for frogs and toads. The story of the tunnels is told through the eyes of the toads in the illustrated book The Toads of Davis: A Saga of a Small Town.
Highway 93 North Wildlife Passages (Flathead Reservation, Montana)
According to a 2020 study, Montana ranked as one of the worst states in the country for animal collisions. One of the most notorious spots for these unfortunate incidents is a 56-mile stretch of U.S. Route 93, which cuts through the vast wilderness of Flathead Reservation. This area of western Montana is rife with animal species such as bear, bison, elk, fish, and moose. In the mid-2000s, the U.S. 93 North Wildlife Passages were built to provide secure passage across the highway, and enhance the safety of motorists and animals alike. Among them are 60 jump-outs, 41 fish and wildlife crossings (including one that replicates a natural stream), and two livestock underpasses. The most visible of these is the Animal’s Trail, a 197-foot-wide vegetated bridge that serves as a link between forested areas on either side of the highway and allows the animals to continue their historical migration routes.
Natuurbrug Zanderij Crailoo (Hilversum, Netherlands)
The Netherlands boasts 30 wildlife bridges, with 20 more in the planning stages. The creatures that call the Goois Nature Reserve outside Amsterdam home have the privilege of using the 2,625-foot-long Natuurbrug Zanderij Crailoo, which spans across a busy highway, railway lines, business park, and sports complex. It links the Brunssummerheide wetlands with the Spanderswoud woodland, two areas of the reserve that were connected prior to the introduction of the railway in 1874. Construction of the bridge took over three years and was completed in 2006. Today, it’s a popular passageway for the reserve’s resident deer population and is also accessible to cyclists and walkers. However, human visitors are encouraged to respect and maintain a safe distance from any animals that they encounter.
Nutty Narrows Squirrel Bridges (Longview, Washington)
Squirrels in Longview, Washington, have a construction contractor to thank for providing them with an ingenious route between the garden of the city’s public library and a nearby park. Amos Peters came up with the idea of the Nutty Narrows Squirrel Bridges in the early 1960s, when he became frustrated watching from his office window as the animals attempted to dodge the traffic of a city thoroughfare. Peters designed a 60-foot-long bridge made from aluminum and fire hose and ordered it to be strung out between two trees above the road. Four similar bridges have since been erected around the city, offering safe travel (and perhaps an element of fun) for the nut-eating animals. Peters passed away in 1984, but his contributions have been immortalized with a wooden statue of a gray squirrel that gazes satisfyingly at the bridge.