National Center for Sustainable Transportation

As roads and other developed land uses proliferate, the resulting habitat fragmentation and loss of wildlife connectivity hinder animals’ ability to forage, establish new territories, and maintain genetic diversity. Wildlife crossing structures such as culverts and bridges theoretically can reduce these impacts by allowing species to effectively cross highways. However, previous research has shown that traffic presence and density can disrupt wildlife use of highway crossing structures, and that noise and light from human activities can affect animal behavior. Researchers at the University of California, Davis, Road Ecology Center measured traffic noise and light levels and placed motion- and heat-triggered cameras at 26 bridges and culverts along four interstate highways, 11 state highways and one major county road across California. The presence and behavior of animals at these highway crossing structures were compared to those detected at sites unaffected by roads to understand the effects of noise and light from a highway on wildlife behavior. This policy brief summarizes findings from that research and provides policy implications.

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