Highways, wildlife, and mitigation measures

HIGHWAYS, WILDLIFE, AND MITIGATION MEASURES

This page contains photos related to highways, wildlife and mitigation measures and other road ecology topics. The images are of animals alive on the road, animals killed by cars, and of mitigation measures that are designed to reduce the number of wildlife-vehicle collisions. These measures include the often used but probably largely ineffective wildlife warning signs and deer mirrors and reflectors. Wildlife crossing structures such as overpasses, bridges, ecoducts, pipes, culverts, and underpasses are much more effective in reducing wildlife-vehicle collisions, especially when used in combination with wildlife fencing and jump-outs that allow animals to escape from the fenced road corridor. These measures are typically targeted at large mammal species that pose the greatest threat to human safety (e.g. large ungulates such as deer, elk and moose). However, these measures can and have also been implemented because of conservation or ecosystem integrity concerns, or ethical reasons. Mitigation measures may then also target other species groups, including invertebrates, amphibians, reptiles, birds, small and medium-sized mammals, and large carnivores, particularly if they are threatened or endangered. Rope bridges, portals with planks or stand alone poles are a unique type of crossing structure. They are installed to encourage arboreal mammals such as martens, dormouse, squirrels, and some marsupial species to cross roads. The location, type, dimensions, and other features related to the structures (e.g. soil, cover, vegetation, litter, row of tree stumps, ponds, streams) should be based on the needs or preferences of the species concerned. This is critical as these factors influence the main purpose of the structures; to provide safe crossing opportunities for wildlife and to help ensure the long term population viability for the species concerned. Human presence in the landscape can make the implementation of fencing and crossing structures more challenging, but there are some solutions. For example, when access roads are present, gaps in the fence can be mitigated through wildlife guards or gates that discourage animals from accessing the main road. Animal detection systems are designed to detect large animals as they approach the road and then activate warning signs so that drivers can slow down and be more alert. They are a relatively new mitigation measure and, although there have been some encouraging results, they should still be considered experimental. While mitigation measures cost money they can also reduce costs associated with wildlife-vehicle collisions. Some mitigation measures are very effective and can generate a financial benefit to society; they save more money than they cost. In summary, mitigation measures do work; they improve human safety, are good for conservation, and they can also help society save money.

Please contact me if you would like to use any of the images. All content © Marcel Huijser