page_title: Wildlife corridor
section_title: Types
hierarchical_section_title: Wildlife corridor / Types
caption_attribution_description: English: Wildlife overpasses are used as a mitigation measure worldwide to reduce the mortality of wildlife on roads, and to a certain extent, to facilitate the genetic exchange of both flora and fauna species in forest fragments. This photo depicts a newly constructed wildlife overpass in highly urbanized Singapore, which connects two rainforest nature reserves that was separated by an eight-laned highway for close to 30 years. Rainforest afforestation on the overpass with the appropriate plant species will be crucial in forming a functional wildlife corridor between the two fragments. The success of such a mitigation technique can only be shown with the careful planning of monitoring programs (using camera traps and passive ultrasonic recordings) and genetic studies of target animal groups.
context_page_description: A wildlife corridor, habitat corridor, or green corridor is an area of habitat connecting wildlife populations separated by human activities or structures. This allows an exchange of individuals between populations, which may help prevent the negative effects of inbreeding and reduced genetic diversity 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.
  This may potentially moderate some of the worst effects of habitat fragmentation, wherein urbanization can split up habitat areas, causing animals to lose both their natural habitat and the ability to move between regions to use all of the resources they need to survive. Habitat fragmentation due to human development is an ever-increasing threat to biodiversity, and habitat corridors are a possible mitigation.
context_section_description: Habitat corridors can be categorized according to their width. Typically the wider the corridor, the more use it will get from species. However, the width-length ratio, as well as design and quality play just as important of a role in creating the perfect corridor (Fleury 1997). The strip of land will suffer less from edge effects such as weeds, predators, and chemicals if it is constructed properly.  The following are three divisions in corridor widths: 
  Regional – (>500m wide); connect major ecological gradients such as migratory pathways.
  Sub-regional – (>300m wide); connect larger vegetated landscape features such as ridgelines and valley floors.
  Local – (some <50m); connect remnant patches of gullies, wetlands, ridgelines, etc.
  Habitat corridors can also be divided according to their continuity. Continuous corridors are strips that are not broken up, while “stepping stone” corridors are small patches of suitable habitat. When stepping stones are arranged in a line, they form a strip of land connecting two areas, just like a continuous corridor.
  Some kinds provide linkages between protected core areas and stimulate or allow species to migrate.
  Corridors can also come in the form of underpasses or overpasses, which can be very safe for both animals and humans. Many busy highways cross through natural habitats that native species occupy, as well. Large animals such as deer become a hazard when they cross in front of traffic and get hit. An overpass or an underpass serves as a bridge to facilitate the movement of animals across a busy road. Observations have shown that underpasses are actually more successful than overpasses because many times animals are too timid to cross over a bridge in front of traffic and would prefer to be more hidden (Dole et al. 2003).
caption: Wildlife overpass in Singapore
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