10 Important Wildlife Corridors

Wildlife bridge on the Trans-Canada Highway in Banff

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Housing developments, major highways, expanding farmlands, and general urban sprawl have made it increasingly challenging for wildlife to move freely. These human-made barriers especially impact predators, which are naturally inclined to roam long distances in search of prey. Other large mammals, such as deer, might find themselves separated from water sources or grazing ground by highways or suburban neighborhoods. The solution? Wildlife corridors.

Wildlife corridors are bridges, tunnels, or just land off-limits to humans where animals can roam without interference. These "nature highways," benefitting animals both large and small, are now being established all around the world, from India to Canada to Australia. The idea behind wildlife corridors is to help entire ecosystems expand and thrive despite their close proximity to humans.

Here are 10 successful and important examples of wildlife corridors.

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Terai Arc Landscape (India and Nepal)

Elephants crossing a stream in the Terai Arc Landscape

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The Terai Arc Landscape is an international World Wildlife Fund project that spans 13 different protected areas in India and Nepal. The grasslands, forests, and river valleys here are important habitats for a number of species, including rare Indian rhinos, Asian elephants, and Bengal tigers. Alone, the parks and preserves, such as Chitwan National Park in Nepal and Rajaji National Park in India, are not big enough to sustain a healthy population of these large mammals. Linked, however, the 13 areas provide more than enough.

The Terai stretches from the Bagmati River in Nepal to India's Yamuna River. Since its inception in 2000, it has caused some problems with local, poverty-stricken communities that have long used natural resources within the corridor to make money. The government of India has undertaken several initiatives to combat these issues, including paying farmers in the area to grow flowers instead of resorting to poaching and other illegal activities.

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Banff Wildlife Bridges (Alberta)

Moose crossing a wildlife bridge in Banff National Park

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The arches built over the Trans-Canada Highway in Banff National Park, Alberta, act as bridges for animals crossing the highway. The project began in the '80s, when the Canadian government allotted $100 million to reducing car-wildlife collisions. That money was used to fence the entire highway, more than 100 miles, and build six overpasses and several dozen underpasses. Researcher Tony Clevenger has been studying the corridors for decades and observed 11 large mammalian species using the structures more than 200,000 times between 1996 and 2009.

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Lower Rio Grande Valley National Wildlife Refuge (Texas)

Bird by the water in the Lower Rio Grande Valley

Danielle Brigida / Flickr / CC BY 2.0

Southeastern Texas is among the fastest-growing regions in the U.S. housing developments, commercial buildings, farms, and roadways now crisscross the landscape, and the city of Houston continues to expand. In the middle of all this development is the Lower Rio Grande Valley, a socio-cultural region that stretches from the Falcon Dam to the Gulf of Mexico.

The Lower Rio Grande Valley National Wildlife Refuge has actually been working with conservation groups for more than four decades to create a wildlife corridor along the river valley. This often involves purchasing land from farmers and then replanting the fields with natural foliage. The wildlife along the Lower Rio that benefits from these efforts include migrating birds and rare mammals like the ocelot.

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Christmas Island Crab Crossing (Australia)

Crabs in front of tunnel on Christmas Island

David Stanley / Flickr / CC BY 2.0

On Australia's Christmas Island, an annual crab migration has inspired a series of "crab crossings." The crabs live deep in the island's forests but migrate en masse to the ocean to breed and lay their eggs each year. Population estimates vary from about 50 million to well over 100 million. The crustaceans literally carpet the island (and its roadways) as they move from forest to ocean, making it impossible for people to avoid them while driving.

Over the years, the island's human population has grown due to a new center that houses detained undocumented immigrants, and the influx of people poses an even greater risk to the migrating crabs. Christmas Island's solution was to build a bridge—the only "crab bridge" in the world—and tunnels over, under, and alongside the road.

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Sawantwadi-Dodamarg Wildlife Corridor (India)

Forest and mountains in the Sawantwadi-Dodamarg wildlife corridor

Sumaira Abdulali / Wikimedia Commons / CC BY-SA 3.0

The Sawantwadi-Dodamarg Wildlife Corridor links protected preserves and sanctuaries in Southwestern India. The Western Ghats, a wildlife-rich mountain range that towers over this region of the subcontinent, is home to Bengal tigers, bears, and elephants, not to mention many of the natural medicinal herbs used in traditional Ayurvedic medicine.

With the help of the Mumbai-based Awaaz Foundation, a charitable trust that focuses on environmental issues and conservation, the lands inside the Sawantwadi-Dodamarg Corridor have been designated as part of an "ecologically sensitive area." Because of this, the mining companies that have long dominated the Western Ghats cannot stake any claims here.

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Oslo's Bee Highway (Norway)

Bumblebee at work on a heather flower

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Although Norway's capital is a global leader in green-ness, it lacks the urban parklands and plants that pollinators need to survive and thrive. So, its "bee highway"—a route of flower beds, protected pollen stations, and green rooftops — gives the insects a network of plants on which to forage.

The bee-friendly venues include rooftop gardens and balconies with abundant, pollen-rich vegetation. The goal is to have habitats every 800 feet, so bees can enjoy a movable feast as they travel through the city.

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Highway 93 Wildlife Crossings (Montana)

Montana Highway 93 wildlife bridge on Salish-Kootenai Reservation

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U.S. Highway 93 is known as the Peoples Way, but the interstate highway caters to more than just people. Its Montana portion has been the site of one of the most extensive safe-crossing efforts in the country: A total of 41 crossing structures, both underpasses and overpasses, speckle a 56-mile stretch of road. Fencing was installed along portions of the highway to funnel the wildlife into these safe corridors. Cameras have caught grizzly bears, deer, elk, and cougars using these passageways and bridges.

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Burnham Wildlife Corridor (Illinois)

Trees and grass in the Burnham wildlife corridor, Chicago

David Wilson / Flickr / CC BY 2.0

Burnham Park sits on a prime piece of real estate along Chicago's Lakeshore area. Naturally, it sees about 4 million visitors per year, but with the Burnham Wildlife Corridor, a 100-acre protected portion of the park, animals and human parkgoers peacefully coexist.

The corridor runs right through the city and features both prairie and woodland ecosystems that are native to this part of the U.S. It is mainly used as a refuge for the more than 300 species of migratory birds that pass through the Windy City each year. Members of the public have been able to take part in the clearing and planting of these new habitats.

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European Green Belt (Central Europe)

Forest and meadow in the European Green Belt, Germany

Nickel van Duijvenboden / Wikimedia Commons / CC BY 3.0

The European Green Belt was conceptualized in Germany shortly after the fall of the Berlin Wall. Over the years, it has expanded through a series of agreements—it now runs from the Finnish-Russian border all the way through the Balkans. The corridor is located roughly where the Iron Curtain—a World War II-era political boundary—used to be. For this reason, the Green Belt also has cultural and historic significance.

That nature still thrives in these particular areas is one silver lining of the Cold War. With little economic activity along these borderlands, the landscape was able to develop uninhabited for decades. In Finland, for example, old-growth forests still dominate. In Germany and the rest of Central Europe, the Green Belt has given endangered species a lifeline.

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Ecoducts (Netherlands)

Wildlife overpass in Leusderheide, Netherlands

Joostik Pieter Joost Lemmens / Wikimedia Commons / CC BY-SA 3.0

When it comes to wildlife corridors, the Netherlands is second to none. Hundreds of crossings—both bridges and tunnels—allow deer, wild boar, endangered European badgers, and other animals to safely cross highways throughout the European country. The Dutch call these wildlife bridges "ecoducts." Some of these are quite modest, and some are enormous: The largest, Natuurbrug Zanderij Crailoo in Hilversum, stretches for almost half a mile.