A group called Green Foothills wants to protect farmland and open space in San Mateo, San Benito, and Santa Clara counties. On August 21, they held a meeting to ask a simple question: How did the mountain lion cross the road? The speakers said that the answer is no, in many parts of California, unless it has some help.
Restoring California’s Wildlife Connectivity 2022, a report from the California Department of Fish and Wildlife, says that in 2020, 61 barriers to wildlife movement in California were found as high-priority sites for some kind of crossing. One of them is in the grove of eucalyptus trees near Rocks Road, which is south of San Juan Bautista on Highway 101.
“We know that animals move from one habitat to another for many reasons, like to breed or to follow the seasons,” said Morgan Robertson, Caltrans Environmental Program Manager. “But roads and highways that connect habitats can sometimes make it hard for animals to move.”
A field scientist for the California Department of Fish and Wildlife named Zach Mills says that the main things that cause animals to migrate are things that are inside them, like food and water, and things that are outside them, like fires and changes in the environment.
In this study, tri-axial accelerometers are used in tracking devices. These are precise enough to pick up when an animal, like a mountain lion, tilts its head to drink. Also, these gadgets show when an animal has died.
“Our programming is sent by a collar to a satellite, which dumps it on our computer,” he explained. It lets us keep an eye on everything that comes from it. When the accelerometer stops in a certain spot, we can quickly figure out what happened and why that animal died.
The data from the tags makes it clear that Mountain Lions in the Rocks Ranch area can’t move north because of Hwy 101.
Animals are kept from their normal migration or hunting grounds by things like highways. This can cause genetic defects and inbreeding that can wipe out a species. Mills said that explaining this idea to regular people would be hard because they might think that a species is genetically sound just because it seems to be common.
“That could be 500 animals,” he said. But it’s possible that all of the genetic material came from just two or three parents. Variation helps the species live through the next disease attack, fire, or whatever else comes up.
In the end, Mills said, freeway crosses make it easier for species to share genes, which is important for their survival. Without it, some species will probably go extinct in the next fifty years.
Robertson said that there were more accidents between cars and animals in the Rocks Road area, which a land bridge would stop.
Statistics from the National Wildlife Federation show that car accidents kill more than a million animals in the U.S. every day, which is the main reason many kinds of wildlife die. Their studies show that big animals are involved in more than 2 million accidents every year, which hurt or kill more than 26,000 people and cost $10.7 billion in medical bills and car repairs.
The Wildlife Conservation Board has given Caltrans a $6 million grant to study the Rocks Road crossing and get the necessary permits, says Mark Bibbo, Conservation Project Manager for the Land Trust of Santa Cruz County. The crossing will need money from both the business sector and the government. It is expected to cost $50 million and could be finished in 10 years.
“It was based on the Wallis Annenberg Wildlife Crossing in the Santa Monica Mountains,” he said. “It won’t be built for a while, but we’re moving quickly toward it.” So we’re just trying to keep going in the same direction.
The 85 concrete beams that make up the 210-foot-long verdant Annenberg Crossing will open in early 2026. The project, which is part of Gov. Gavin Newsom’s 30×30 Initiative to protect 30% of lands and marine waters by 2030, raised more than $92 million. This included $58 million in state funds and a $10 million grant from the Annenberg Foundation.