A wildlife corridor or green corridor[1] is an area of habitat connecting wildlife populations separated by human activities (such as roads, development, or logging). This allows an exchange of individuals between populations, which may help prevent the negative effects of inbreeding and reduced genetic diversity (via genetic drift) that often occur within isolated populations. Corridors may also help facilitate the re-establishment of populations that have been reduced or eliminated due to random events (such as fires or disease). This may potentially moderate some of the worst effects of habitat fragmentation.[2]
Wildlife corridors are susceptible to edge effects; habitat quality along the edge of a habitat fragment is often much lower than in areas further from the habitat edge. Wildlife corridors are important for large species requiring significant sized ranges; however, they are also vital as connection corridors for smaller animals and plants as well as ecological connectors to provide a rescue effect.
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In 2001, a wildlife corridor was restored through a golf course in Jasper National Park, Alberta, which enabled wolves to pass through the course. After this restoration, wolves passed through the corridor frequently.[3] This is one of the first demonstrations that corridors are used by wildlife, and can be effective in decreasing fragmentation. Earlier studies had been criticised for failing to demonstrate that corridor restoration leads to a change in wildlife behaviour.[4]
One common example of bird species' ranges are land mass areas bordering water bodies, for example oceans, rivers, or lakes, and called a coastal strip. A second example, some species of bird depend on water, usually a river, swamp, etc., or water related forest and live in a river corridor. A separate example of a river corridor would be a river corridor that includes the entire drainage, having the edge of the range delimited by mountains, or higher elevations; the river itself would be a smaller percentage of this entire wildlife corridor, but the corridor is created because of the river.
A further example of a bird wildlife corridor would be a mountain range corridor. In the U.S. of North America, the Sierra Nevada range in the west, and the Appalachian Mountains in the east are two examples of this habitat, used in summer, and winter, by separate species, for different reasons.
Bird species in these corridors are either connected to a main range for the species, (be contiguous), or in an isolated geographic range and be a disjunct range. Birds leaving the area, if they migrate would either leave connected to the main range, or have to fly over land not connected to the wildlife corridor, and thus be passage migrants over land that they stop on for an intermittent, hit or miss, visit.
Elephant corridors are narrow strips of land that allow elephants to move from one habitat patch to another. There are 88 identified elephant corridors in India.
According to new research, wildlife corridors are best built with a certain degree of randomness or asymmetry, rather than built symmetrically. The research was conducted at UC Davis.[5]
Several artificial wildlife corridors have been created, these include: