Do California Highways Act as Barriers to Gene Flow for Ground-Dwelling Mammals?

The principle of sustainable transportation suggests that impacts to environmental processes and patterns will be limited as much as possible during construction and operation of the transportation system. Wildlife populations are affected by transportation in various ways, including individual animal deaths due to collisions with vehicles, animal aversion to roads due to light and noise, habitat fragmentation, and human access for recreation and hunting. If individual animals of a species have limited movement in part or all of their range, then divided populations can become genetically different from each other, which can jeopardize survival of populations and even whole species. This population subdivision can happen even in the relatively short time since California highways were constructed.

This policy brief summarizes findings from a research that examined the potential population division effect of highways on coyote populations in the Bay Area and Sierra Nevada foothills.