Yeah, yeah, we all know why the chicken crossed the road. But figuring out how a chicken could cross the road—especially in the age of six-lane highways and railroad crossings—is a far more pressing question for conservation biologists. The answer to the riddle may be wildlife corridors, which provide a “bridge” between habitats that have been separated by human activity. From elephant underpasses to crab bridges, these animal-friendly pathways provide safe passage for all kinds of critters and score big points for communities interested in ecotourism.
What is a wildlife corridor?
Simply put, a wildlife corridor connects two or more habitats that have been interrupted by civilization, be it cities, dams, or highways. If that sounds like a broad definition, that’s because it is. Wildlife corridors aren’t always literal bridges crossing over freeways—corridors can be whole areas of land spanning hundreds of thousands of land acres (like the Yellowstone-to-Yukon corridor) or be as small as a meadow. In fact, a few aren’t even on land. Some corridors take the form of protected ocean areas, designated to serve as an underwater highway for marine-life migration.
Do wildlife corridors work?
It can be hard to quantify how successful a wildlife corridor is, but Dr. Nick Haddad has spent nearly 30 years dedicated to doing that. An ecologist and conservation biologist at Michigan State University, one of Haddad’s primary focuses is researching the effects of wildlife corridors. To him, one project that exemplified a wildlife corridor’s effectiveness was a study he conducted investigating butterflies and corridors. The results astonished him.
“What shocked me is the types of different organisms that use these corridors,” Haddad says. “It wasn’t just butterflies, but birds, small mammals, pollinators, plants that are dispersed by birds, plants that are dispersed by winds—all these things benefited from the corridors that were initially created with butterflies in mind.”
So, wildlife corridors are definitely good for animals. But are they any good for humans?
Turns out, these pathways are great for us, too. Haddad notes that sometimes wildlife corridors are constructed primarily for human benefit. Case in point: The Wyoming Department of Transportation installed wildlife corridors around its Trappers Point crossing and experienced an 80 percent reduction in wildlife-vehicle collisions in the first three years after they were built, saving lives and dollars in potential vehicle damage.
And there is, of course, the human desire to feel closer to nature. Take the popular Appalachian and Continental Divide trails, for example. Haddad notes wildlife corridors and corridors for humans sometimes intersect and make a richer experience for the people who hoof it down the trail.
“People who want to do environmental tourism, they might be birders or they might be looking for large animals. People want to be in natural areas,” Haddad says.
Where can you find wildlife corridors?
With wildlife corridors’ many benefits for tourism and conservation, it’s no wonder more governing bodies are leaning into this idea as a more environmentally conscious way of development. Just look at Florida’s nearly 18 million–acre wildlife corridor or the construction of a 200-foot bridge in Los Angeles meant to provide wildlife with a path to the Santa Monica Mountains. On a federal level, the Biden administration has also committed to protect 30 percent of U.S. land and water by 2030; constructing more wildlife corridors is an integral part of their plan.
But it’s not just the U.S.—the concept of wildlife corridors is gaining momentum all around the world. Here are some places that showcase the many different forms these wildlife corridors can take and how they’re shaping wildlife tourism.
What: Robert L.B. Tobin Land Bridge
Where: San Antonio, Texas
Notable animals: bobcats, deer, coyotes, squirrels
The Robert L.B. Tobin Land Bridge in San Antonio is a shining example of how both humans and animals can benefit from wildlife corridors. The 189-foot-long bridge connects two sides of the Phil Hardberger Park and is 150 feet wide at the top, giving animals and people more than enough room to travel side by side above six lanes of Texas traffic.
Since its opening in 2020, wildlife biologists have documented bobcats, possums, rabbits, deer, and coyotes using the structure. Although visitors aren’t allowed to feed any animals they come across, there are plenty of opportunities to admire wildlife from afar from the bridge’s trail or Skywalk.
What: Cocos-Galápagos Swimway
Where: Galápagos Islands, Ecuador, and surrounding waters
Notable animals: sharks, whales, manta rays, sea turtles
Humans don’t necessarily have to build man-made structures to facilitate a wildlife corridor. Take the Cocos-Galápagos Swimway, an underwater area connecting the Galápagos Islands to the waters of Costa Rica. In January 2022, Ecuadorian President Guillermo Lasso officially expanded protections of the Galápagos Marine Reserve to include 23,166 square miles of ocean. Half of the land in this expansion includes the “no-take” Cocos-Galápagos Swimway, which consists of ecosystem areas, migratory paths, and feeding areas. Underwater animals like humpback whales, sea turtles, sharks, and manta rays can freely move in the swimway without the threat of activities like fishing.
This swimway is a part of a larger goal of protecting 500,000 square kilometers of the Pacific. The effort, called Corredor Marino del Pacífico Este (the Eastern Tropical Pacific Marine Corridor), is a multinational effort to create a large, protected marine area between Costa Rica, Panama, Ecuador, and Colombia. Each president of the four countries signed the declaration agreeing to this plan during the COP26 conference in Glasgow, Scotland, in 2021.
What: Oslo’s bee highway
Where: Oslo, Norway
Notable animal: bees
Oslo’s “bee highway” shows how communities can band together to create change. In 2014, beekeeping group ByBi started a passage project to turn the city into a safe passageway for bees traveling from one nearby forest to another. This community-led movement encouraged locals to install pollinator-friendly structures on top of roofs, plant flowers on balconies, and create their own beehives–an effort that created a corridor stretching from Holmenkollen to Lake Nøkkelvann. These pollinator passageways are gaining popularity across the continent and have also popped up in Ireland and England.
What: Mount Kenya elephant corridor
Notable animal: elephants
In the heart of central Kenya, an underpass under the Meru-Nanyuki highway provides safe passage for elephants moving between the Mount Kenya National Park and Reserve and the Ngare Ndare Forest Reserve. Construction of the underpass was completed as part of a larger 8.7-mile corridor and is part of an effort to re-create the historic migration routes of elephants in northern Kenya. With hundreds of elephants spotted traversing the corridor since its creation in 2010, the project has been considered a success.
Notable animals: civets, pangolins, monkeys, bats, birds
Singapore’s Eco-Link@BKE is an approximately 200-foot-long ecological bridge that connects the Bukit Timah Nature Reserve and Central Catchment Nature Reserve, which used to be one continuous patch of rain forest before the Bukit Timah Expressway split it into two.
The bridge replicates the natural habitats of the preserves it links, providing wildlife with more than 3,000 native plants along with food and shelter. Tracking cameras have captured animals like the common palm civet, lesser mousedeer, macaque, and the critically endangered Sunda pangolin using the bridge. Humans, less so. To encourage animals to use the bridge, people aren’t allowed to walk on the bridge itself. However, visitors can visit the Bukit Timah Nature Reserve or Central Catchment Nature Reserve for wildlife sightings.
What: Crab bridges
Where: Christmas Island, Australia
Notable animal: red crabs
During the beginning of the wet season (which can be anytime from October to January), Christmas Island turns red during its biggest tourism event: the annual red crab migration. Visitors flock to the Australian territory during this time to see male and female crabs scuttle their way from the inland forest to sea to breed and to see their babies make the return trip a month later.
While these crabs have an inner sense of where to go, their instincts don’t account for roads and cars that could kill them in the process. The island’s government, taking this into account, has created a series of corridors to help them avoid the roadkill outcome. Visitors watching the annual phenomenon can see crabs using bridges and underpasses during their monumental journey.