Wildlife Overpasses Around the World: A Green Way to Cope with Nature and Wilderness
Here are pictures of my preferate and most interesting wildlife overpasses in the world.
Wildlife overpasses, green bridges and ecoducts are structures that have been built over roads to allow wildlife to cross it safely.
Wildlife Overpass, Banff National Park, Alberta, Canada. In Banff National Park, there are currently 41 wildlife crossing structures (6 overpasses and 35 underpasses) that help wildlife safely cross the busy Trans-Canada Highway. Since monitoring began in 1996, 11 species of large mammals—including bears, elk and cougar—have used crossing structures more than 200,000 times. [ link1, link2]
The bridges are for animals: Animals walk over the road, and the vehicles go through the structure. Most of the structures are between 10 m (30 ft) and 60 m (180 ft) wide. They typically have soil, litter, and vegetation on top to provide suitable habitat for a range of different species and species groups.
Ecoduct De Woeste Hoeve over the highway A50, The Netherlands; The Netherlands contains an impressive display of over 600 wildlife crossings (including underpasses and ecoducts) that have been used to protect populations of wild boar, red deer, roe deer, and the endangered European badger. [link1, link2]
The larger structures are typically intended for large mammals ranging from ungulates (e.g. deer, elk, moose) to large carnivores (e.g. black bear, grizzly bear, Canada lynx, wolverine, wolf).
Ecoduct in Netherlands; The Netherlands was one of the first countries to deploy a network of wildlife crossings across the landscape [ link].
Others are made for fishes.
Wildlife crossing structures take many forms around the world; there are global solutions to providing safe passage. This example from the Netherlands incorporates a canal. [link]
Sometimes ponds are created on one or both sides of the structure to increase the attractiveness to wildlife and to stimulate the use of the overpass. It is also possible to pump water to the top of an overpass and create small streams that flow to the sides. This is particularly beneficial to amphibians.
Green bridge over the A20 near Grevesmühlen, Germany [link]
Cover, for example through a row of tree stumps, is important for invertebrates, amphibians, reptiles, and small mammals. Fences, screens, or berms on the sides of the overpasses not only keep animals from jumping of the structure. They also reduce light and noise disturbance, and block out the fast moving vehicles below.
Wildlife overpass near Keechelus Lake, Washington, USA [link]
Combined with wildlife fencing and underpasses, wildlife overpasses can reduce collisions with large mammals by 80 to almost 100%. Numerous studies have also found that a wide range of wildlife species uses wildlife overpasses, often in high numbers.
Ecoduct (wildlife bridge) on highway A1 through nature area the Veluwe, the Netherlands. [link]
Wildlife bridges are important as animals may need to reach the other side of the road for food or water. Crossings by certain individuals maybe almost daily as they have their home range on either side of the road.
Ecoduct in France [link]
Migration over long distances is important as animals may need to reach habitat patches that are small and isolated so that they can strengthen their population viability in the region.
Ecoduct The Borkeld, Netherlands [link]
Other individuals may use crossing structures for seasonal migration or long distance dispersal.
Unusual overpass for crabs, Christmas Island National Park, Australia: Red crabs climb over an overpass to cross a road on Christmas Island during their migration. [link]