In the past few centuries, humans have built sprawling communities all over the world. An unintended consequence of this has been that animals are no longer able to roam free, and animal safety has become an issue. Animal bridges, sometimes called wildlife crossings or wildlife overpasses, are structures that help animals to cross man-made barriers. These barriers - such as roads, railroads, canals, power lines, pipelines, and dams - create a problem known as habitat fragmentation that can have a hugely negative impact on the quality of life, health, and population size of animal species in any given ecosystem.
These crossings take many forms, but all of these animal bridges around the world allow a diverse array of species to move freely without having cross the huge, and often incredibly dangerous, man-made barriers. Habitat corridors not only keep animals safe, but keep humans out of harms way as well. Find out more about these incredible life-saving animal bridges that have helped countless animals in the wild.
Habitat fragmentation doesn't just affect primarily-land animals. Animals known to climb and fly often are affected by roadways that make passages difficult to cross. To help these animals, special rope bridges were constructed over highways and other man-made structures in many parts of the world. These bridges are much like the rope bridges you see on a child's playground, except a lot smaller.
In Victoria, Australia, researchers at the Australian Research Centre for Urban Ecology constructed a rope bridge for gliding squirrels, but found lots of other creatures - including birds - were using it. In Washington state, squirrels have their own bridge called the Nutty Narrows Bridge. Squirrels are so beloved in this town they have their own festival.
The first known proof of animal bridges come from 17th century France. Fisheries would build channels out of tree branches over dams and other river obstructions to give fish a safe passage. Often called fish ladders, they were likely not for the benefit of the fish themselves - as the conservation movement was not popularized until the late 18th century - but for the benefit of the many citizens who fished the rivers for their food.
The first known wildlife crossings were built in France in the 1950s. These were used to protect indigenous amphibians, badgers, ungulates, invertebrates, and other small mammals. Soon the concept of animal bridges spread throughout Europe, popping up primarily in the Netherlands. It didn't take long for the bridges to become popular in the US. In the past 30 years alone, thousands of animal corridors were built in Canada and the US spanning from Florida and Southern California to Maine and Alaska.
Roadways have the most widespread and damaging effect on wildlife land area. In the United States, scientists estimated that roadways are the primary threat to the survival of wildlife. About one-fifth of US land area is fragmented by roads and railways. While these passages help humans, they negatively impact wildlife in four major ways: they decrease the size and quality of animal habitats, increase mortality from collisions, prevent access to resources animals need, and divide populations, making reproduction and other necessary interaction far more difficult.