Ecosystems, native plants, and wildlife populations depend on habitat connectivity to survive. Habitat connectivity is necessary for natural movement, including foraging, reproduction, and migration.
Roads and highways create a barrier effect for wildlife movement, resulting in habitat fragmentation and habitat loss, the two leading causes of species decline. Habitat fragmentation occurs when development bars natural ecological processes and movement. Urban areas are far more likely than rural areas to suffer from habitat fragmentation, but continued growth pressures in rural areas threaten habitat connectivity.
Habitat loss occurs when people build infrastructure on land previously used by wildlife. As roads and highways are built, land development around the transportation corridors diminish natural resources and ecosystems. The International Union for Conservation of Nature (IUCN) estimates 40 percent of the world’s mammals are affected by habitat loss.
Habitat fragmentation affects humans as well as wildlife. Every year up to 1.5 million animal-vehicle collisions are reported in the United States, killing more than 200 people and injuring nearly 30,000. In 2006, there were 104 animal-vehicle collisions in the SACOG region, 65 percent of which occurred in rural areas.
Wildlife crossings are counter-measures that can link natural habitats and prevent animal-vehicle collisions. According to Dr. Fraser Shilling, Co-Director of the UC Davis Road Ecology Center, roads should be thought of as “continuous obstacles to habitat connectivity,” and need solutions that fit the problem. For example, removing barriers for large mammals may require infrastructure investment, whereas removing obstacles for birds may require something as simple as planting trees along the highway to force birds to fly above vehicles.
For more information contact Christine Scherman at (916) 340-6262 or cscherman@sacog.org.