Research overview: the Wallis Annenberg Wildlife Crossing over a Los Angeles freeway

The Wallis Annenberg Wildlife Crossing is among the largest wildlife overpasses in the world, built to span a major multi-lane freeway northwest of Los Angeles and reconnect puma and other wildlife populations isolated in the Santa Monica Mountains. This overview synthesises the science that justified it: genetic evidence of inbreeding, population-viability models projecting extinction risk, and telemetry showing freeways as near-total barriers to big-cat gene flow. It covers crossing design principles such as width, vegetated cover, sound and light shielding, and approach habitat, and frames the structure as a landscape-scale experiment in restoring connectivity for an urban apex predator, with monitoring to test whether animals adopt the span.