Wildlife Corridors: What are they & why are they important for biodiversity?

What are Wildlife Corridors?

A ‘wildlife corridor’ is an area in the environment that functions as a passageway for the purpose of providing connectivity between wild species by means of dispersal and migration of individuals. These corridors are often vegetation-based habitats that facilitate movement, while offering less risk of predation compared to when travelling through open lands. Wildlife corridors vary in size, shape, length and composition ^[1].

Why are Wildlife Corridors important?

Wildlife Corridors allow for the increase in gene flow between small and fragmented wild populations ^[1]. This is important for maintaining biodiversity through the conservation of potentially at-risk local populations in the wild and has proven to greatly improve species richness ^[2]. Small wild populations that are isolated from all other populations of the same species face a large risk of inbreeding depression and local extinction. This is due to a lack of variety in the gene pool of that population ^[1]. The use of wildlife corridors allows for the opportunity of connectivity between small isolated populations in the wild. This can result in the increase of genetic variation within these small populations and lower inbreeding depression risks.

Types of Wildlife Corridors

Habitat fragmentation is thought to be the number one biggest threat to global biodiversity. Habitat fragmentation can be caused by human activity such as urbanisation, agriculture and human influenced climate change, as well as natural disasters like earthquakes volcanoes flash floods etc [^3]. There are many different types of wildlife corridors including naturally occurring corridors and man-made corridors. In areas where human populations are dense, there are often physical barriers for migration and dispersal of wild populations ^[4]. For this reason, man-made corridors are often built to create a safe passageway that facilitates migration of wild species, while reducing the potential human-wildlife conflicts that can arise in areas where the natural environment meets urbanised areas.

Natural Corridors

Wildlife Corridors can naturally occur by means of already existing geographic features such as mountain ranges. An example of a mountain range that functions as a corridor would be the Terai Arc Landscape. This natural corridor stretches over 900 km in length and an area of over 51,000 km from Nepal’s Bagmati River right across the country to the Yamuna River in India. 

Riparian zones within the environment are also a great example of a naturally occurring corridor for wildlife. Riparian zones create a sufficient amount of vegetation and land cover to allow for a more protected passageway for animals that journey from one population in the wild to another, compared to open plains.

Man-Made Corridors

Corridors that have been purposefully created by humans to support biodiversity are often overpasses or underpasses for roads and large motorways that have created habitat fragmentation upon their construction. Other man-made corridors are often hedgerows found in rural farmland environments and domestic gardens, acting as land boundaries.  

The main purpose of man-made corridors is to facilitate movement of wild populations that have experienced habitat fragmentation due to human activities such as urbanisation and infrastructure. A good example of a man-made corridor would be the overpass created in Banff National Park located in Alberta, Canada. This overpass allows for the migration of wildlife within the park as the construction of large motorways has divided natural habitats and wild populations.

The success of these man-made corridors can be monitored by the use of camera traps. These will determine how often, if at all, these passageways are being used by the local migrating wildlife.

References

1. Burkart, S., Gugerli, F., Senn, J., Kuehn, R. & Bolliger, J. (2016). Evaluating the functionality of expert-assessed wildlife corridors with genetic data from roe deer. Basic and Applied Ecology, 17(1): 52-60.
2. Kiffner, C., Nagar, S., Kollmar, C. & Kioko, J. (2016). Wildlife species richness and densities in wildlife corridors of Northern Tanzania. Journal for Nature Conservation, 31: 29-37.
3. Wilcove, D., Rothstein, D., Dubow, J., Philips, A. & Losos, E. (1998). Quantifying threats to imperiled species in the United States. BioScience, 48(8): 607-615.
4. Dondina, O., Kataoka, L., Orioli, V. & Bani, L. (2016). How to manage hedgerows as effective ecological corridors for mammals: A two-species approach. Agriculture, Ecosystems & Environment, 231: 283-290.