These Wildlife Bridges Are Saving Animals All Over the World
How far would you be willing to go to protect the wildlife around you? Are you someone who has had the misfortune of crossing the path an animal out for a stroll while you’re behind the wheel of your SUV? There might be an answer to this issue with animal bridges and underpasses designed to keep both creaturea and humans safe.
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Animals Versus Vehicles: A Billion-Dollar Problem
In the United States alone, it’s estimated that vehicle-animal collisions cost $8 billion a year. Over one-fifth of the country’s ecology is affected by road systems. There are lots of opportunities for collisions with an animal, or accidents caused by swerving to avoid an animal.
People have crosswalks to let them get across roads safely, so why not animals? If you’re thinking it might be hard to train the wildlife to obey traffic signals, you may be right.
The solution is clear: let them cross any time, safely, in a place where there is no human traffic.
A Simple Plan
And since they can’t go through it, they need to go over or under the road. It seems like a pretty simple idea — obvious, even — but passages to allow animals to travel safely over and under busy roadways are revolutionizing the interaction between humans and wildlife along roadways.
After installing them in Banff National Park in Canada, the number of incidents involving cars and creatures dropped over 80 percent. Other areas have reported up to a 90% decrease in roadkill collisions.
Animal bridges originated in France in the 1950s, and have now spread around the world. However, the idea of building something to help animals get around an obstruction had been around even before that.
A Woman Needs a Man Like a Fish Needs a... Ladder?
Dams and other obstructions in rivers were blocking fish from their natural migrations. That’s what gave some in the field the idea for a fish ladder. As the name implies, it creates a series of ladder-like steps that allow fish to move up and down from one step to another and bypass whatever is blocking their way.
And that is the essence of a wildlife bridge: to allow animals to naturally get around the obstacles we create. Roads are the most common obstacle, but even our cities themselves greatly impact the ability of some creatures to move around.
Depending upon the types of animals that need to use them, the shape and style of the bridge can vary widely.
The Many Means of Keeping Wildlife Living Wildly
In addition to the many different styles of fish ladder, there are overpasses and viaducts, underpasses and amphibian tunnels. There are also canopy bridges suited for monkeys and squirrels, culverts for small mammals and green roofs to give butterflies and birds respite when flying over urban areas.
A recent documentary called “Cascade Crossroads” follows the building of a series of animal crossings in Washington, USA, along a main interstate highway. It focuses on a small area near Seattle which sees a lot of daily traffic, both human and animal.
The busy road slices through dense natural habitats a wide array of creatures both big and small call their home.
Why Do We Need Animal Crossings?
These animals naturally move through the forests as they hunt for food and mates, and generally live their lives. It’s really kind of shocking how many roads lead to exactly the same thing.
After all, we tend to build busy highways through areas where we don’t have to move people’s houses out of the way. Which doesn’t mean that the areas aren’t inhabited, they’re just not inhabited by humans.
Each year in the US, millions of animals are killed by cars. Over 200 people lose their lives in collisions with wildlife.
How Diverse Groups Had to Collaborate to Help the Animals
That’s in addition to the estimated $8 billion in property damage. It’s a problem worth solving. The documentary shows how diverse groups had to collaborate to help the animals with a variety of different crossings.
Some are culverts designed to help fish, amphibians and other animals to pass, while the main structures built are highway over-and-underpasses for larger mammals. As part of the initiative, shrubs and other plants are strategically placed alongside fencing to help encourage animal traffic towards the safe passages.
The work in Washington builds upon previous examples all over the world. The example that likely helped them the most in their plans is found not far away, just a bit to the north across the border to Canada in Banff, Alberta.
What's Being Done?
The National Park in Banff has the densest concentration of wildlife bridges in the world. The Trans-Canada Highway — a main thoroughfare running east-west across the entire vast country — runs through the park, and the four-lane divided highway creates a real problem for the copious local wildlife.
Since 1996, a total of 44 crossing structures have been built to bypass 82 km (51 miles) of the highway, six overpasses and 38 underpasses, with another 10 underpasses in nearby parks.
At first, people thought they didn’t work, because animals weren’t using them. But as the animals got comfortable with the idea, the traffic over and under the human roads along the animal paths became busier and busier.
Even the Shy Animals Are Using Them
Parks Canada set up motion-activated cameras to records activity on all the wildlife bridges and tallied over 2000,000 crossings by large animals in the first 15 years. The kinds of critters using them in Banff include deer, moose, elk, caribou, wolves, coyotes and cougars, as well as black bears and grizzly bears, lynxes and even the elusive wolverine.
Wolverines are rare these days, having been trapped and driven out into endangered status. They are also very hard to see.
One of the few ecologists who specialize in these animals spent years studying them without ever seeing one in the wild.
But after 15 years, a Parks Canada camera recorded a wolverine using one of the bridges in Banff.
Nature Advocates Love the Bridge Idea
Nature lovers hail this as a major success, since if a wolverine is using the bridge it shows how accepted it has become among the local wildlife.
Wolverines may be the world’s toughest creature, right up there with its cousin the honey badger. They are smart and fearless. According to the Globe and Mail’s Bruce Kirby in his article Have you seen Canada’s most elusive creature?:
“They are blessed with the endurance of a marathoner, the speed of sprinter and the mountain-climbing ability of a goat. Chasing a wolverine through the wilderness is like pursuing the Terminator.”
Why the Terminator reference? They pretty much never stop moving, with a metabolic rate that’s off the chart.
Wolverines Have Adopted the Bridge Concept
One wolverine was tracked moving 800 km (500 miles) in 10 days, while another climbed a near-vertical 1500 metre (5000 foot) rock face in just an hour and a half. They’ll eat anything, and if they want what you’re eating, you’d best give it to them.
Even if you happen to be a grizzly bear. They are so strong, they’re known to crush bones grizzlies have given up on, and tear apart solid logs in search of grubs.
Studying the Behaviour of Animals at Crossing Structures Provides Valuable Insight
Consider a wolverine’s use the gold seal of approval. The wildlife bridges offer an added bonus to researchers because they know exactly where animals will be. Not only can cameras capture images, but barbed wire can also collect fur samples for DNA analysis.
Studying the behavior of animals at crossing structures provides valuable insight for how to improve future bridges. For example, different animals prefer different types of crossings.
In Banff, they learned that grizzly bears, wolves and moose prefer wide and open crossings, whereas cougars and black bears like to move under the shelter of an overpass.
It takes a while for any animal to get used to the idea. Grizzly bears took seven years to get used to the bridges at Banff, and the wolverine took fifteen.
That’s despite the fact that the wildlife bridges are covered in native vegetation and other habitat elements designed to either make the creature feel at home or facilitate its passage along the bridge.
These Critter Bridges Are Global
While Banff may have the most in one area, the Netherlands seems to have a lock on the most in a country. It has 66 big ones, including the world’s longest wildlife overpass, but a network of over 600 small tunnels have also helped the endangered European badger’s fight to survive.
The Natuurbrug Zanderij Crailoo is a half-mile long, crossing a variety of landscapes including a railway and a golf course. Other endangered species have been the direct focus of animal crossing structures as well.
The Florida panther is in dire danger of extinction and is particularly vulnerable to vehicular collisions. There may be less than 100 of these animals left, and Florida has built 24 underpasses and 12 bridges to help them travel safely.
Bridges Designed for One Species Are Usually Used by Many
In California, the desert tortoise fares poorly along highways. The simple addition of fences and culverts under the road has reduced tortoise death on the highways by 93%. Other species are getting in on the action, too.
In Florida, the panther crossings are also used by bobcats, deer and raccoons, while in California the culverts benefit bobcats, coyotes, gray fox, mule deer and long-tail weasels as well. Turtles are particularly vulnerable to being smooshed by cars, and not just because they move so slowly.
Sometimes they don’t move at all. As cold-blooded animals, they often come onto the road and stay there to warm up.
Natural Instincts Can Put Animals in Danger
Drivers may not even notice them. The same is true for snakes, who are also hard to see because they’re long and skinny. For turtles, roads are a double hazard because they often have sandy shoulders.
Turtles lay their eggs on beaches, and sometimes can’t tell the difference between a sandy beach and the sandy edge of a road. If they do choose to lay in a roadside nest, they could be stuck there for 2-3 months while the embryos develop.
That is, if they live long enough. Roads aren’t the only problem, turtles also have troubles with train tracks.
Look Up. Look Waaaay Up
Japanese railway engineers were finding a lot of turtles killed while trying to cross the railway tracks, so they installed some shallow tunnels under the tracks that allowed the little amphibians to slowly make their way to the other side of the tracks safely.
The tunnels look like small drainage canals running perpendicular to the tracks, but they’re just deep and wide enough for turtles to make their way through without getting caught up in track switches or being run over by trains.
Lion-tailed macaques, an endangered primate with a mane of hair and long tail like a lion, have a hard time crossing the road in Valparai, India.
The Christmas Island Crab Movement
They like to climb, and are much better at doing that than at dodging cars, so canopy bridges spanning between trees on either side of the road were built, and have helped them greatly.
Christmas Island National Park in Australia is home to the unique migration of 50 million red crabs, who every year make a journey overland from their burrows in the rainforest to their spawning grounds in the sea.
Unfortunately, several busy roads lies in the way. More than 20 km (12.5 miles) of plastic barriers were erected to funnel the crabs away from the roads and into a series of 31 crab underpasses as well as a scalable overpass specially designed for crabs to climb up and over the busiest road.
Any Bridge for Squirrels Has to Have Nutty in the Name
Nutty Narrows is the name of a special rope bridge in Longview, Washington, built to guide squirrels above busy streets instead of across it. Built in 1963, its 18 meter (60 foot) span crosses over busy Olympic Way.
Made of aluminum and an old fire hose, it cost $1,000 to make and has saved thousands of squirrels from a squishy fate over its over fifty-year history. A similar structure — or at least a structure with a similar purpose — was built in the Netherlands to help dutch squirrels across a road.
This futuristic bridge cost over $200,000 and was intended to help squirrel populations from either side of the road inter-breed to prevent inbreeding among the isolated groups.
Not Every Crossing Has a Happy Ending
Unfortunately, the squirrels aren’t keen on it, and in two years only five squirrels were ever seen using it. The Dutch squirrel bridge is an important reminder that our effort to help animals cross roads are not always effective.
In fact, there are many who question whether or not designed animal crossings do more harm than good. However, studies on the overall effectiveness of animal corridors indicate that they are generally successful, and mostly getting better.
Every time we build a new one, our knowledge about what does and does not work increases, so we get better and better at it. Like most things in life, it’s not always a 100% win.
Sometimes Animals Will Just Do What They Want to Do
It’s not always 100% necessary, either. In southern England, three bridges were built in 2010 to help dormice cross over a bypass. Dormice live in trees, and the road creates a break in the canopy they normally move through, so the bridges were made to reduce the ecological impact of the road.
Made from wire mesh tubes suspended between trees and poles, the bridges cost about $100,000 each. A storm destroyed them in 2016, and they were not rebuilt. The reason? Officially, the ecological needs shifted and they were no longer required.
Reading between the lines, however, a cynical individual might suspect that either the dormice bridges didn’t work as well as they’d hoped, or perhaps people just don’t love dormice enough to justify spending another three hundred grand to help them over a road.
Animal Safety Isn't All About Bridges and Underpasses
Some initiatives weren’t begun specifically to help animals, the assistance to our animal friends is a happy by-product of something else. Green roofs, for example – an urban rooftop covered in grass, trees and other plants – might not seem like the same thing as a wildlife bridge spanning a busy road.
However, for birds and butterflies trying to move across a city, they perform much the same function.
Not originally designed for the purpose of helping animals, they not only provide a happy green space where human beings can escape the urban mash or concrete and steel, but they also offer a place for flying creatures to take a rest, and perhaps even roost for an extended period, among natural plant growth.
More and more of these types of initiatives are being introduced all over the world. People are recognizing that roadkill is not a necessary side-effect of our transportation addiction, and our impact on nature can be greatly mitigated by a little effort and ingenuity.
Efforts That Save Time, Money and Lives
Some people balk at the expense of such projects, but it’s not only animal lives that are being saved, it’s human lives as well. Not to mention the monetary cost of damage to vehicles and other things as a result of human-animal collisions, and the time lost to resulting traffic jams as well.
Plus, it just makes us feel good. And, as an important footnote to answer the question that we just know you are burning to ask: no, to the best of our knowledge, nobody has yet built a crossing to assist chickens in crossing any roads.
Sources and Video
Sources and Video
- Green roof – a potential new habitat for plants and animals in urban areas
- Nutty Narrows – Squirrel Bridges
- Church Village Bypass: £126k mouse bridges not replaced
- Crabs get their own bridge to cross busy road on Christmas Island
- Was a Dutch city nuts to spend $220,000 on a bridge for squirrels?
- Life in the Crossroads: A New Age for Highway Wildlife Crossings
- Do Habitat Corridors Provide Connectivity?
- Have you seen Canada’s most elusive creature?