Roads can have unintended effects on wildlife populations, such as causing direct mortality through animal collisions with cars, changing animal behaviors or distributions from traffic disturbance (e.g., noise, lighting), and fragmenting habitat. Roads may also act as barriers to wildlife movements, which prevents populations on either side from exchanging genes. Over time, wildlife populations isolated by barriers will lose genetic diversity, a process associated with an increased risk of extinction.
To better understand this dynamic in Northern California, a studywas completed examining whether State Route 49 (SR 49), a road initially constructed during the Gold Rush era, acts as a barrier to movements of two similar species with different tolerances to human activity, the coyote and gray fox. This policy brief summarizes findings from that study and discusses the policy implications.