Individual behaviors dominate the dynamics of an urban mountain lion population isolated by roads

Riley and colleagues used GPS telemetry and genetics to show that the small puma population in the Santa Monica Mountains was severely isolated by surrounding freeways, with the 101 in particular nearly halting movement and gene flow. They documented genetic signs of inbreeding and found that the population's dynamics were dominated by the behaviors of a few individuals, including rare crossings and bouts of intraspecific killing exacerbated by confinement. The study quantified how roads trap pumas in a habitat island too small to maintain genetic diversity, projecting a real risk of inbreeding depression. It provided the scientific case for the wildlife crossing later built over the 101 and became a defining example of how urban infrastructure imperils a big-cat population through isolation.