In the midst of the constant traffic of U.S. Highway 101 in Agoura Hills, northwest of Los Angeles, United States, rises a project that seeks to reconcile urban infrastructure with nature. This is the Wallis Annenberg Wildlife Crossing, the world’s largest wildlife crossing, which promises to become an icon of ecological engineering.
With dimensions of 64 meters long by 52 wide, this green bridge will span one of the busiest highways in California, allowing species such as mountain lions, deer, lynxes, monarch butterflies, and bats to safely cross between habitats separated by urban development. The structure will be covered with soil and over 5,000 native plants, replicating the local ecosystem and blending in with the landscape of the Santa Monica Mountains.
The project arises from an urgent need: to save the population of southern California mountain lions from extreme genetic isolation. Scientific research warned that, without a connection to the Simi Hills, the felines would be trapped in an “ecological island”, increasing inbreeding and endangering their survival. Documented cases of breeding between siblings or parents and offspring raised alarms.
In addition to protecting wildlife, the crossing also aims to reduce road accidents —an estimated 1 to 2 million collisions between vehicles and large animals occur in the U.S. each year— and create infrastructure that harmonizes with the natural environment.
Innovation at the Service of the Environment
The Wallis Annenberg Wildlife Crossing will be the first of its kind in an urban area of this scale. Its design includes multiple layers of materials that mimic a real ecosystem: from a waterproof base to layers of rock, vegetation, and soil, facilitating the transit of different species and contributing to ecological regeneration.
The project, initiated in 2022 with a planned completion for 2026, is a public-private effort led by the California Department of Transportation (Caltrans), with strong support from the Annenberg Foundation and the State. For Governor Gavin Newsom, it represents “the vision of a future where infrastructure and nature are not exclusive, but complementary.”
A Replicable Model
Beyond its local impact, this green bridge opens the door to a new way of thinking about cities: as spaces where development and conservation can coexist. Wildlife crossings are not simple technical solutions, but sustainability tools that help restore ecological connectivity, mitigate climate change, and reduce human pressure on biodiversity.
The Wallis Annenberg Wildlife Crossing will not only unite two hills separated by a highway, but will also mark a global milestone in building with environmental awareness. Because, as its proponents rightly point out, if humans created habitat fragmentation, they can also be part of its restoration.
Ingenious Solution: Hanging Bridges in the Amazon to Protect Primates
Deep in the Amazon, an innovative conservation project has managed to reduce the mortality of threatened primate species. The initiative, led by researcher Fernanda Abra, involves the installation of hanging bridges between the treetops, allowing monkeys to safely cross roads without risking their lives. Thanks to this strategy, vulnerable species like the Groves’ tamarin, the Guianan spider monkey, and the red-handed howler monkey were able to move safely through their fragmented habitat.
So far, the Reconecta project has installed 30 of these structures in the Brazilian state of Amazonas. These bridges were designed with the support of the Waimiri-Atroari indigenous community, who provided their knowledge about the habits and movements of local fauna. Additionally, each bridge is equipped with camera traps that allow monitoring of animal usage and collecting key information for planning future interventions.
The advancement of road infrastructure in the Amazon has posed a serious problem for local wildlife. Forest fragmentation forces animals to cross roads, exposing them to collisions and reducing their chances of finding food and mates to reproduce. This is the case of the Groves’ tamarin, one of the most threatened primate species in the world, whose situation inspired Fernanda Abra to develop this innovative solution.
Source: Ecoinventos.
