California Department of Fish & Wildlife’s Terrestrial Barrier Dataset

California is home to extraordinary biodiversity, as well as over 39 million people and a booming economy. Maintaining habitat connectivity across a matrix of developed areas is critical to conserving California’s biodiversity and ecosystem resilience now and into the future. Threats to habitat connectivity and wildlife movement across the landscape include habitat loss and fragmentation from development, as well as barriers created by linear infrastructure, such as roads, highways, dams, canals, and railroads. Not only do these impede wildlife movement, but they often result in mortality and affect population demographics, gene flow, resilience and ultimately persistence of California’s wildlife.
Wildlife must navigate thousands of miles of linear infrastructure that crisscross California’s landscape as they go about their daily and seasonal movements to secure the resources they need, such as food, mates, and shelter. The California State Highway System alone consists of more than 16,000 miles of paved roads of varying widths. Historically, identifying important wildlife movement locations has been piecemeal and based on local information and interest. However, increasing attention is being directed toward wildlife habitat connectivity as a mechanism of maintaining biodiversity in the face of population growth and climate change. Listing priority wildlife barrier locations helps focus limited resources where the greatest needs to improve wildlife movement have been identified.
The California Department of Fish and Wildlife (CDFW) conducted an assessment of priority barriers to wildlife movement throughout the state. CDFW scientists across the state identified numerous segments of linear infrastructure that currently present barriers to wildlife populations in their jurisdiction. In doing so, we used all available empirical information in our possession, including existing connectivity and road crossing studies, collared-animal movement data, roadkill observations, and professional expertise. Each identified linear segment was then evaluated using 10 criteria and each of the 6 CDFW Regions identified their top ten priorities for remediation. Nearly all of the barriers identified are associated with the State Highway System, but railroads, canals, high-speed rail alignments, and local roads are also represented. The barrier dataset is an important step toward identifying and remediating barriers throughout the state and a valuable tool for wildlife and transportation professionals engaged in on-the-ground efforts to maintain or restore connectivity at local, regional, and statewide scales. This dataset is complementary to CDFW’s fish passage barrier priorities identified for anadromous fish, and like the fish passage priorities, the wildlife barrier dataset will be periodically updated to reflect new information and barrier removal successes.