Buzz
As cities continue to grow, humans are taking over vast portions of wildlife habitats, putting animals at risk. Sadly, many creatures face injury or death while attempting to navigate human-made roads. This leads to a decline in animal populations, a loss of biodiversity, and a fragmentation of ecosystems. Fortunately, we have recognized the danger our roads pose to wildlife and have taken action to build safe routes, reconnect habitats, and create wildlife crossings.
Wildlife crossings offer animals safe paths by providing alternative routes that are safe and accessible. These crossings come in various forms, including bridges, tunnels, and dams. Initially, there were concerns about whether animals would use these man-made structures, but nature proved its intelligence. Animals quickly adapted and embraced these crossings in all their forms and designs. Wildlife crossings have become life-saving solutions for a diverse range of species, from crabs to cougars.
While we may still be puzzled about why the chicken crossed the road, we now know exactly how it’s done. Below are some fascinating facts about wildlife bridges and crossings across the globe.
10. Eco-Ducts
European nations such as the Netherlands, Switzerland, Germany, and France have been constructing various types of structures to reduce roadkill for many years. In the Netherlands, these wildlife crossings are known as eco-ducts. The country currently has around 600 of these eco-ducts in place, located on protected lands where mining, drilling, or hunting is prohibited. Plans are already in place to build even more eco-ducts across the country.
Other nations are also coming up with creative ways to build these essential structures. For example, South Korea held a design competition for the Yangjaegogae Eco-bridge, which resulted in a design that mirrors the sloping mountains it connects. This design allows various local species to safely cross a busy eight-lane highway beneath it.
9. Not a Recent Innovation
In the 17th century, the French created fish ladders using bundles of branches, which functioned as steps in fast-moving water. This innovation allowed fish to bypass obstacles in their path and continue migrating upstream. Fish ladders today are typically made from rocks, logs, or timber, helping fish find food, mates, and other essential resources.
Richard McFarland, a Canadian lumber mill owner, invented an ingenious solution to help marine animals bypass his dam. His patented fishway structure, developed in 1837, was the first of its kind to be officially patented. Fish ladders are now a common solution, particularly in turbulent waters where fish struggle to swim upstream.
8. Biodiversity
Wildlife crossings have made a significant impact on the conservation of wildlife. The result has been a growth in animal populations within these protected areas and a boost in biodiversity. Biodiversity refers to the variety of life forms on Earth. Within an ecosystem, biodiversity provides the necessary biological and natural resources for its residents. A decline in biodiversity can lead to a shortage of resources and even the extinction of species.
In Japan, engineers have built 'Turtle Tunnels' beneath railway tracks to protect turtle populations and prevent trains from harming these creatures. Similarly, a turtle tunnel was created in Massachusetts under Route 44 to connect two isolated groups of spotted turtles. Without this connection, the turtles' ability to adapt to environmental changes would be hindered, as fewer turtles from diverse genetic backgrounds meant less adaptability. The turtles require 'new blood' to thrive.
7. From Mice to Grizzlies
In Canada’s Banff National Park, 44 wildlife passages have been established: 6 overpasses and 38 underpasses. These crossings were initially constructed as part of a road upgrade in 1978, allowing animals to safely cross the Trans-Canada Highway, which sees nearly 18,000 vehicles daily. Various species, including deer, lynx, coyotes, wolves, wolverines, and bears, have successfully used these passages.
Wildlife camera monitoring reveals that different species have distinct preferences when it comes to navigating around traffic. Grizzly bears, deer, and moose are drawn to the open air of overpasses, while cougars prefer the dark and secluded shelter of tunnels with thick coverings. Black and brown bears may opt for either an overpass or a tunnel, depending on their encounters during their travels through urban areas. Smaller culverts are especially beneficial to mice, voles, and other tiny creatures that inhabit the park.
6. Christmas Crabs
Across the globe, numerous wildlife crossings exist, including a unique crab bridge on Christmas Island in Australia. Christmas Island, situated in the Indian Ocean, is home to roughly 45 million bright red crabs. The island is just 52 square miles in size and has a small human population of around 2,000.
To assist the crabs during their breeding and spawning seasons, local residents constructed a bridge over the main road, allowing the crabs to cross safely from the forest to the ocean. This crab bridge has become a popular tourist destination, attracting visitors from all around the world. Watching the vivid red crabs crawl across the 16-foot man-made bridge is an extraordinary sight. While additional underpasses also help the crabs, the bridge remains the most captivating spectacle.
5. Avoiding A Cat-astrophe
Florida has built over twenty wildlife crossings to protect the endangered Florida panther. This elusive species, nearly driven to extinction in the 1970s due to hunting, faces another major threat: vehicular collisions. Thanks to decades of human intervention, the panther population has grown from just 20 individuals to an estimated ten times the number it would have reached without our efforts.
Despite these advancements, the Florida panther remains critically endangered. The underpasses built for their use have helped, but panthers need uninterrupted habitats to roam and hunt. The wildlife corridors, lush with local plants and flowers, provide the crucial habitat connections that the panthers require for survival and population growth. (Unfortunately, these crossings won't help the Carolina Panthers this season!)
4. No Monkeying Around
In Costa Rica, Monkey Bridges are designed to prevent primates from using electrical wires to travel, thus reducing the risk of electrocution. Since their installation, monkeys have adapted to using these safer bridges made of rope, allowing them to cross from place to place with ease.
The bridges have not only been used by monkeys but also by other animals such as sloths, anteaters, and even porcupines. Clearly, the animals recognize a great opportunity, as many have been observed crossing the bridges with their young on their backs. Watching a monkey traverse a bridge high above while journeying through the Costa Rican rainforest is a remarkable sight. I’m not monkeying around—wildlife bridges are a fantastic idea!
3. Going Bigger
The world's largest wildlife crossing is currently under construction in California, just northwest of Los Angeles. This massive project is intended to serve as a model for similar initiatives around the globe. Situated at the base of the Santa Monica Mountains, the crossing will offer safe passage over the 101 Freeway for a variety of species, including pumas, deer, coyotes, rabbits, squirrels, and lizards. Additionally, it will feature a pedestrian and bike path.
Named the Wallis Annenberg Wildlife Crossing, this overpass-style bridge will span ten lanes of the Ventura Freeway. Expected to be completed by the end of 2025, this crossing is a direct response to the declining population of mountain lions in the area. The freeway has created a genetic barrier, isolating the lions and significantly reducing their numbers due to the dangers of crossing it.
An earlier underpass constructed near the site was intended to allow mountain lions to cross under the freeway. Unfortunately, several lions lost their lives trying to use the underpass. Once the Wallis Annenberg Wildlife Crossing is finished, it will allow mountain lions in the Santa Monica Mountains to travel safely to the Simi Valley Mountains and beyond. Conservationists and animal enthusiasts alike are hopeful that this project will boost the population and genetic diversity of the mountain lions. As a Southern California resident, I am eagerly awaiting the completion of this remarkable wildlife bridge.
2. Keeping It Natural
Since the 1990s, the United States has seen the construction of thousands of wildlife crossings, including underground tunnels and overpasses, designed to ensure animals like elk and moose can safely traverse busy highways. These wildlife corridors not only prevent road collisions but also reconnect animals to their natural habitats. The newer crossings are designed with added care, ensuring not just cars but also pedestrians can safely cross highways when necessary.
Wildlife crossings are gaining popularity as a way to improve connectivity between different land areas. Engineers design these corridors using the natural vegetation from the surrounding environment. The wildlife bridges are often adorned with native plants and trees, making them blend seamlessly into the landscape while encouraging animal passage. These crossings work most effectively when paired with strategically placed highway fencing on one or both sides, guiding wildlife toward the green bridges.
1. Over the Down Under Bridge
In Australia, wildlife bridges and tunnels have been successfully used by koalas, an animal previously thought incapable of navigating such structures. Ecologist Darryl Jones from Griffith University had to admit he was wrong when, just three weeks after the construction of these passages in 2016, koalas were already using them regularly. It’s fortunate they did, as koalas are, without question, one of the cutest animals on the planet.
The passageways in Australia are often covered with lush vegetation, making it difficult for animals to realize they are crossing a man-made structure, which encourages more species to embrace these corridors. In one case, a bridge originally built for squirrel gliders has also been used by wrens, finches, and other bird species.
