Wildlife use of Highway Underpasses in Southern California Active

As a result of growing human populations, many areas have become urbanized and highly developed, leaving natural native habitats fragmented across the landscape. In southern California many of the remaining patches on native habitat are bisected by major, multi-lane highway systems.  Threats to the long-term sustainability of native wildlife populations include genetic isolation, where inbreeding can occur due to a lack of dispersal of offspring.  Ensuring habitat connectivity for wide ranging species, migratory species, and dispersing individuals has been identified as an important conservation strategy for many species of wildlife.  Highways and roads can be a major source of wildlife and human injury and mortality due to vehicular collisions and can also pose a barrier to wildlife movement.  Highway underpasses, culverts, and drainage structures may potentially pose a means to connect landscapes bisected by highways, but research is needed to assess whether or not wildlife use these structures and under what conditions.