The main purpose of implementing fauna crossings is to increase biodiversity. When land areas are broken up by human interference, population numbers become unstable, and many animal and plant species become endangered.
By re-connecting the fragments, the population fluctuations can decrease dramatically. Fauna crossings can contribute to three factors that stabilize a population:
animals can move and occupy new areas when food sources or other natural resources are lacking in their core habitat;
species that relocate seasonally can do so more safely and effectively when it does not interfere with human development barriers; and
animals can find new mates in neighbouring regions so that genetic diversity can increase and thus have a positive impact on the overall population
Development such as roads, buildings, and farms can interrupt plants and animals in the region from being destroyed along with natural disasters such as fires and floods. Animals have no choice but to evacuate their habitat. Unfortunately, if the habitat is not connected to a safer one, death usually occurs. Any remaining portion of the natural habitat is called a “remnant”, and it is these portions that need to be connected to ensure migration can occur; otherwise, if this does not happen, extinction increases.