Last week construction crews began placing the very first layers of soil over the surface of the Wallis Annenberg Wildlife Crossing, launching what will become a nearly one-acre native wildlife habitat that will grow across 10 lanes of the 101 freeway in Agoura Hills. The so-named “fuzzy” overpass is designed to encourage wildlife to use the bridge to safely cross the freeway.
To commemorate the moment, key members of the #SaveLACougars campaign gathered on the surface of the bridge and participated in a ceremonial, ‘fist-throw’ of soil. Covering the entire surface of the bridge will require approximately 6,000 cubic yards of soil and the work will take several weeks to complete.
This construction milestone is the result of years of meticulous work envisioned by the project’s landscape architecture team with the goal to create a native soil that will help plant and wildlife flourish. The effort required close collaboration with soil scientists, biologists, engineers, and mycologists who identified, harvested, and cultivated native soil biology and beneficial fungi directly from the project site. Soil placement will be followed by the planting of about 5,000 native plants that will grow into a rich habitat that will support mountain lions, deer, bats, desert cottontails, bobcats, native bird species and monarch butterflies, just to name a few. Weather permitting, planting on the crossing is expected to begin in May.
The habitat on the bridge will be comprised exclusively of coastal sage scrub plant species native to the Santa Monica Mountains and, as part of the crossing’s restorative design approach – is part of a broader ecological restoration strategy that will revitalize an additional 12 acres of open space and require 50,000 native plants, including native trees, shrubs, and perennials.
A critical element of this restoration is the ongoing work happening at the wildlife crossing’s dedicated native plant nursery. Over the last three years, nursery staff have hand-collected well over 1.1 million hyper-local native seeds representing over 50 distinct native plant species in the Santa Monica Mountains. The native plants, soil biology and seeds that have been collected until now, were all sourced from within a 5-mile radius of the crossing.
In preparation for future planting efforts, staff have also started growing plant and tree species including coast live oak trees, valley oak, toyon, ceanothus, several sages, California buckwheat and the flowering penstemon, to name a few. The soil amendment that will be used to create a healthy ecosystem on top of the wildlife crossing – is also being applied to the plants and trees at the nursery. The restoration of native plants across the landscape also helps reduce fire risk—along with the full irrigation and sprinkler system that is part of the crossing structure.
The plant nursery is a critical part of the Wallis Annenberg Wildlife Crossing. Funding for the nursery has been made possible by the National Wildlife Federation’s #SaveLACougars campaign and is located on land donated by the Mountains Recreation and Conservation Authority. Overseen by the landscape architecture practice that leads every aspect of the crossing’s design: Rock Design Associates – work at the nursery is being advanced by experts from the Santa Monica Mountains Fund, the National Park Service, Caltrans, and the Mountains Recreation and Conservation Authority.
Work on the wildlife crossing began on Earth Day 2022 and is scheduled to be completed in 2026. Once finished, the Wallis Annenberg Wildlife Crossing will be the largest bridge of its kind in the world and a global model for urban wildlife conservation. The project is the result of a public-private partnership of unprecedented scope that has leveraged the world-renowned expertise and leadership of dozens of individuals, organizations, and institutions.
New diagrams of the innovative engineering and science behind the soil placement, renderings and drone footage over the construction site of the Wallis Annenberg Wildlife Crossing are available here.
Communities all over the world are also invited to follow construction on the bridge in real-time through its dedicated webcam and learn more about the Save LA Cougar’s #P22Legacy Campaign phase at savecougars.org and the Wildlife Crossing Fund at wildlifecrossingfund.org.
