Wildlife Habitat Connectivity

Mission Statement

To improve wildlife connectivity and roadway safety across California using the best available science.

Overview

Photo of wildlife crossing — CDFW photo by Sara Holm

Connectivity is essential for wildlife, enabling animals to move, migrate, find mates, and access resources. Barriers do more than obstruct movement; they can alter natural behaviors and increase the risk of injury or death. Maintaining landscape connectivity supports natural dispersal, gene flow, and colonization of unoccupied habitat, enhancing long-term population viability and sustaining ecosystem services. Conserving and restoring corridors that link habitat patches helps alleviate pressures from anthropogenic change by facilitating safe movement and reducing mortality from vehicle collisions and fence entanglements. Connectivity is also increasingly important as species shift their distributions in response to climate change.

Over time, numerous partnerships with non-governmental organizations, local, State and federal agencies have been developed to address connectivity challenges, ranging from local efforts focused on specific barriers and crossings to statewide initiatives addressing policy and landscape-scale conservation. Staff across multiple regions and branches of the California Department of Fish and Wildlife (CDFW) have participated in these collaborations to foster coordination with external partners and implement on-the-ground conservation actions. In 2024, after the passing of AB 2344, a connectivity team was formed that included permanent staff working exclusively to improve wildlife connectivity across California. This team includes a senior scientist in each of the Department's six terrestrial regions and headquarters, and an engineer specializing in wildlife crossing infrastructure. This team is responsible for assisting Caltrans with the implementation of AB 2344, developing the Terrestrial Wildlife Connectivity Barriers Dataset, develop the California State Action plan under Secretarial Order 3362 and provide technical advice regarding wildlife connectivity to Caltrans and advance connectivity science in California.

Building on these efforts, habitat quality remains a critical component of effective connectivity. Even where corridors or crossing structures are present, degraded or low-quality habitat can limit their functionality by discouraging use or increasing energetic and predation risks. Restoration projects that enhance native vegetation, reduce invasive species, and improve forage and cover conditions can substantially increase the permeability of the landscape. By improving habitat within and surrounding movement corridors, these efforts encourage wildlife to use existing pathways and crossing structures, ultimately increasing the success of connectivity investments. In this way, habitat restoration complements barrier mitigation by not only reconnecting landscapes structurally, but also ensuring they function ecologically to support movement, gene flow, and population resilience.

Terrestrial Wildlife Connectivity Barriers

CDFW conducted an assessment of priority barriers to wildlife movement throughout the state. These barriers which are created by linear infrastructure such as roads, railways, and canals can influence wildlife movement, impede genetic exchange, cause mortality, and ultimately reduce population resilience. The assessment dataset currently includes 204 segments of linear infrastructure that have been identified as wildlife barriers, or locations where wildlife movement is known to be negatively impacted. These barrier segments comprise a total of 4914.7 kilometers of linear infrastructure. Many of the known barriers are associated with the State Highway System, but railroads, canals, dams, high-speed rail alignments, border walls, and local roads are also represented. This assessment helps direct research and funding, with the ultimate goal of improving the barrier to the point where it is removed from the dataset.

Laws & Policies

Streets and Highways Code Section 158 (AB 2344, Friedman 2022)

AB 2344 (Friedman 2022) added Section 158 to the California Streets and Highways Code (SHC), establishing a formal partnership between the California Department of Fish and Wildlife (CDFW) and the California Department of Transportation (Caltrans) to improve wildlife connectivity and reduce wildlife-vehicle collisions across the state highway system. The legislation directs CDFW and Caltrans to collaborate to identify locations where wildlife passage improvements are needed and to incorporate wildlife connectivity considerations into transportation planning, project design, and implementation. To support this effort, CDFW hired eight new staff, including a senior scientist in each of the Department's six terrestrial regions, an engineer specializing in wildlife crossing infrastructure, and a statewide spatial ecologist.

Under SHC Section 158, Caltrans must consult with CDFW for projects in designated connectivity areas to evaluate potential barriers to wildlife movement and identify design solutions that improve permeability across transportation corridors. The statute also establishes a Caltrans-led program, developed in collaboration with CDFW and with public input, to fund and implement wildlife crossing and connectivity projects. In addition, Caltrans must conduct Wildlife Connectivity Assessments for projects that add highway lanes or may significantly impair wildlife movement in designated connectivity areas. Through this framework, CDFW regional staff work with Caltrans districts to identify priority locations, review connectivity assessments, and recommend appropriate mitigation and design solutions. These coordinated efforts integrate wildlife connectivity considerations into statewide transportation planning and strengthen the ongoing partnership between the two agencies.

Secretarial Order No. 3362

Secretarial Order 3362 (SO 3362) directs appropriate agencies within the Department of the Interior [DOI; US Fish and Wildlife Service (USFWS), National Park Service (NPS), and Bureau of Land Management (BLM)] to work in close partnership with the CDFW to identify, enhance, and improve the quality of big-game winter range habitats and migration corridors for mule deer (Odocoileus hemionus; hereafter deer), pronghorn antelope (Antilocapra americana; hereafter pronghorn), and Rocky Mountain elk (Cervus canadensis), Roosevelt elk (C. c. roosevelti), and Tule elk (C. c. nannodes); collectively hereafter elk. There are five priority areas designated in the 2024 State Action Plan. These areas consist of deer populations within hunt zones X9a, X9b, and X12 (East Sierra Deer Conservation Unit) and hunt zones X6a, X6b, X7a, and X7b (Northeast Sierra Deer Conservation Unit), the Likely Tables priority area for pronghorn in hunt zone 3, and the elk populations in the Del Norte/Humboldt priority area and the San Luis Reservoir priority area. These priority areas are managed in a way that recognizes state authority for conserving and managing big-game species and respects private property rights.

Wildlife and Habitat Connectivity Conservation Element (AB 1889, Friedman 2024)

AB 1889 (Friedman 2024) requires every city and county in California to include a wildlife and habitat connectivity conservation element in any newly adopted or amended general plan. The purpose of this new element is to proactively maintain, restore, and improve wildlife movement and habitat connectivity within the jurisdiction's general plan boundaries. Under the law, local governments must consult with CDFW during the development of the element to ensure it reflects current scientific data, state conservation priorities, and best practices for protecting wildlife corridors and ecological connectivity. The element must identify key wildlife movement areas, barriers, and opportunities for conservation or restoration, and integrate these considerations into long‑term land‑use planning.