Wildlife Connectivity

Sprawl Development Can Hurt Wildlife

Large urban and agricultural developments and their infrastructure can be major barriers to all kinds of wildlife, from fish and frogs to mountain lions and elk. Without proper planning, they can lead to fragmented habitats that constrain wildlife movement.

These limitations hurt wild animals and plants. Habitat fragmentation limits their movement, impairing some animals’ ability to find food, shelter and mates. Populations get isolated, sensitive species go locally extinct, and key ecological processes like plant pollination can be lost.

If populations are isolated for too long, inbreeding can increase birth defect risks, reproductive problems, and vulnerability to disease. This isolation can also reduce resilience to stress, lowering the population’s chances of survival.


In the 1990s Florida panthers had a population of fewer than 30 due to decades of hunting and habitat loss. Suffering from genetic defects, disease, and low reproductive success, they were expected to go extinct in 20 years. But after the introduction of eight female mountain lions from Texas, a gene pool historically connected with Florida panthers, the population has shown some recovery [1], with an estimated 230 panthers in 2017 [2]. The Center continues to fight to protect important habitat for these big cats.

Roads can fragment habitats and lead to vehicle-wildlife collisions that kill or injure animals and motorists. These accidents can result in property damages and high healthcare costs.

According to the UC Davis Road Ecology Center, from 2015 to 2018, more than 26,000 wildlife-vehicle collisions on state highways were reported to the California Highway Patrol (mostly involving deer, but also coyotes, bears, elks and mountain lions). This cost Californians over $1 billion in damages [3]. The actual figure is likely much higher since it does not include unreported incidents.

Habitat Connectivity Is Key

Wildlife corridors and crossings link two or more habitat areas, enabling migration, (re)colonization and breeding opportunities for flora and fauna.

These connections come in different shapes and sizes and can consist of existing and intact swaths of habitat, created crossings, restored linkages or a mix. They can be overpasses or underpasses, and their positive effects have been observed in many places, including  highways in Utah, culverts in California, and salamander tunnels in Vermont.

Preserving wildlife corridors and connecting habitats save wildlife and motorists from harmful accidents.

Current Projects Involving Wildlife Corridors and Connectivity:

Altair Development, Temecula, California

In 2018 the Center — along with the Sierra Club, Mountain Lion Foundation and Cougar Connection — sued the city of Temecula for approving a 270-acre development that would further isolate an already dwindling mountain lion population in the Santa Ana Mountains. The proposed development would destroy some of the last remaining lion habitat that connects the mountain population with a more diverse one in the

Eastern Peninsular Mountain Range. In 2020 the project was blocked because the development’s environmental review failed to properly account for impacts to imperiled Santa Ana mountain lions.

Northlake Development, Santa Clarita, California

In 2018 the Los Angeles County Planning Commission approved an isolated housing development that would destroy more than 1,300 acres of important wildlife habitat connecting the Angeles and Los Padres national forests and generate more traffic and air pollution. The Center challenged the approval, and in 2021 a judge blocked the Northlake development.

Wildlife Connectivity Ordinances, Ventura County, California

With the Center’s support, Ventura County adopted a first-of-its-kind ordinance to protect habitat connectivity and wildlife-movement corridors for mountain lions and other species. The ordinance was challenged in court by industry groups, and in 2020 the Center joined a coalition of conservation organizations to defend it.

Pacific Newt Crossings Campaign at Lexington Reservoir County Park, Santa Clara County, California

About 5,000 newts are killed every year by cars and bikes on Alma Bridge Road, the park’s only access road. The Center is working with community scientists to document newt roadkill in the park, raise awareness of the issue, and push public agencies to improve connectivity on the road. Seasonal road closures and amphibian under-crossings, such as elevated road sections and modified cattle guards, have been shown to allow amphibians and other small wildlife to safely cross deadly roads.

References:
1. UC Davis Road Ecology Center (2017). Impact of Wildlife-Vehicle Conflict on Drivers and Animals.

2. Johnson et al. (2010) Genetic Restoration of the Florida Panther. Science 329(5999):1641-1645. DOI 10.1126/science.1192891

3. Florida Fish and Wildlife Conservation Commission (2017) Florida panther population estimate updated. http://myfwc.com/news/news-releases/2017/february/22/panther-population/

 

Photo of desert tortoise crossing road (in Joshua Tree National Park) by Brad Sutton/National Park Service