These Highways Save Crabs and Cougars

In April 2022, construction began in California on the world’s largest green bridge. Spanning the 10-lane Route 101 near Los Angeles, this bridge will aim to create a wildlife corridor in the Santa Monica mountains. Such a crossing will allow the movement of lizards, snakes, toads and mountain lions across the freeway without the threat of being killed by cars, unlike the mountain lion P-104 killed in March. The $87 million green bridge project will be part of the attempt to restore genetic diversity to the isolated populations of cougars trapped south of the freeway. As Beth Pratt, who helped raise the money for the construction, says, “we have the chance to give these mountain lions a shot at a future.”

The world’s first green bridges were built in France in the 1950s. But as journalist Sophie Pedder says, these “early versions were pretty basic.” She adds, though, that the versions now under construction in France “are quite deluxe models, 25-meter wide structures with a pond for frogs and amphibians.” Opaque wooden fences ]shield those creatures from the glare of headlights. While there is no official data to show how many animals are saved by these structures, a study by construction company Vinci, which has spent €177 million building more than 200 animal passages in the last decade, offers reasons for optimism. According to Vinci, each bridge sees an average of over 1,000 red deer crossings annually, along with fewer numbers of wild boar.

Each year on Australia’s 52-square-mile Christmas Island, an estimated 50 million crabs migrate from the sea to the forests, covering the island’s roads. To stop an annual road kill crab-pocalypse, rangers from Christmas Island National Park have set up miles of barriers that direct the crustaceans up a 16-foot high bridge over the main road. What looks like the world’s biggest folding table now woos “tourists from all over the globe,” says Linda Cash of the Christmas Island Tourism Association. Tourists flock to watch the crabs’ annual journey over a protective mesh extending from the sea back to the forests.

The Yellowstone to Yukon Conservation Initiative (Y2Y) is a not-for-profit organization which aims to create a network of interconnected wild lands and waters stretching about 2,100 miles, from the Greater Yellowstone Ecosystem to Canada’s Yukon Territory. Launched in 1993, this joint Canada-U.S. project has seen significant success. Recent research has shown that the Y2Y region grew by 45% between 1993 and 2018. During this period, the grizzly bear population doubled while over 100 wildlife crossings were built. According to this research “the Y2Y region has become a global model for green infrastructure to reduce fragmentation and foster connectivity.”

The BBC reported this March that some roads would be closed in order to allow toads to make it to their breeding ponds. The past 30 years have seen rapid decline in the U.K.'s toad population due to “habitat fragmentation.” This year, local volunteers calling themselves the “Ellesmere Toad Patrol” took to a street in Shropshire with buckets in hand to help toads cross the road. Last year, an estimated 81,761 toads were helped over roads by volunteers across the U.K. As George Orwell once wrote: “Love of such things as … toads … makes a peaceful and decent future a little more probable.”

According to National Geographic, one of the first attempts in the U.S. to create a wildlife crossing was made in 1995 in Davis, California. The good people of Davis built 6-inch wide tunnels, now called “ecoducts,” in order to help frogs cross under the Pole Line Road. The city spent $14,000 to build the toad access tunnels for toads journeying to and from the Davis Wetlands. The town’s postmaster at one end built a “toad village,” calling it Toad Hollow. The city’s efforts were unique enough to have drawn a young Stephen Colbert for The Daily Show.

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If animals struggle in the countryside with infrastructure, the development of Cape Town, South Africa, has created a very particular set of problems for wildlife. Few cities have a national park slap bang in their center. As O’Riain of the University of Cape Town explains, “roads run through Table Mountain National Park and exact a heavy toll on the many wildlife species that take refuge there.” Caracal, cape clawless otter, baboons and the endangered leopard toad are routinely killed crossing urban roads. In the case of baboons, the city has employed special field rangers who follow the baboon troops most of the day and deter them from crossing roads. “If the baboons do cross, the rangers use flags to slow traffic,” O’Riain says.

For the past seven years in the Norwegian capital of Oslo, local bee enthusiasts and schoolchildren have been planting flowers on top of apartment rooftops in order to help save the endangered bee population. They’re calling it a “bee highway.” And to this was added a huge futuristic-looking beehive on the 12th floor of a building. Agnes Lyche Melvaer, a landscape architect who led the project, said: “We are constantly reshaping our environment to meet our needs, forgetting that other species also live in it. To correct that we need to return places to them to live and feed.”

Interrupted migratory patterns affect not just land animals. Several species of sharks, whales and turtles use underwater highways — known as swimways — to migrate. These are often interrupted by unsustainable, illegal and unregulated fishing practices. The Cocos-Galapagos Swimway, home to nearly 3,000 marine species, is an underwater migration highway that connects the Galapagos Marine Reserve and the Cocos Island National Park. Recently, the president of Ecuador, Guillermo Lasso, signed a historic executive decree creating a new marine reserve called the “Reserva Marina de Hermandad.” The reserve will consist of a 23,000-square-mile ocean corridor or “swimway” connecting Ecuadorian and Costa Rican waters. The aim is to protect threatened migratory wildlife, such as humpback whales, sea turtles, giant manta rays and endangered hammerhead sharks.

Have you come across any other creative and unconventional ways to protect animals from human traffic or infrastructure? Tell us about it!

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