This GIS map traces the movement of a single male mountain lion from California to Mexico and back.
“Protecting a buffer of open space on both sides of the border could help make the border easier to secure and provide important wildlife habitat.”
Dr. Scott Morrison, director of science for the Conservancy’s California Program
When it comes to figuring out what animals need, sometimes it’s best to let the animals themselves show us.
That’s been the case with mountain lions in southern California. There, Conservancy scientists have been working with researchers from the University of California Davis’s Wildlife Health Center to monitor mountain lions as they navigate a landscape increasingly fragmented by roads, housing developments and an international border.
“We know that lions need large areas of habitat,” says Dr. Scott Morrison, the Conservancy’s science director in California. “So studying them can help us identify the places where we should focus our conservation efforts.”
Researchers have captured and affixed tracking collars to more than 50 mountain lions since the study began in 2001. As the project enters its second decade, new data from those collars are revealing the challenges facing wildlife in the hills of southern California, a region where intensive and rapid development is having a profound impact on native species.
Consider the recent travels of M53, a young male lion captured in the backcountry of San Diego County by the study’s field team, led by veterinarian Dr. Winston Vickers.
M53 ventured 40 miles south from where he was collared until he reached the U.S.–Mexico border—and then he kept going.
¡Bienvenidos a México!
He continued south for another 50 miles, traversing the Sierra Juarez mountain range, before circling back north to California. Over the course of eight months, M53’s international jaunt took him across a 200-square-mile area.
Along the way, he roamed across numerous public and private conservation lands, including Bureau of Land Management holdings in California and a national park in Mexico. Many of the lands he traveled through are managed by partners in the study, including California State Parks and the California Department of Fish and Game.
M53 also journeyed through a number of properties threatened by development and made several dangerous highway crossings. And that creates a key conservation challenge: making sure that human land use doesn’t sever the habitat connections needed by wildlife.
“A main strategy of the Conservancy is to stitch conservation lands together into a connected network for wildlife,” Morrison says. He notes that M53 walked across a number of properties the Conservancy recently protected near San Diego.
Two Countries, One Ecosystem
“Conservation lands north of the border depend in many ways upon connections to the south,” Vickers says. “Especially in light of a changing climate, we know species need to move around. So we need to figure out how to keep the corridors they use open.”
Development near the border, however, threatens to cut the connections used by M53. And, in addition to cutting off wildlife corridors, such development can make the border more difficult to secure.
“Protecting a buffer of open space on both sides of the border could help make the border easier to secure and provide important wildlife habitat,” Morrison says.
Parque to Palomar: A Critical Link
The Conservancy and partners on both sides of the border are working to ensure that California’s habitats stay ecologically connected to those of Baja California. A key priority is to link the Parque Nacional Constitución de 1857 with Palomar Mountain State Park.
The northwest corner of Mexico is recognized as a global hotspot of biodiversity. Although many of its habitat types are currently under-represented in the region’s network of protected areas, Morrison is optimistic that greater protection is possible.
“The Sierra Juarez range is a rare expanse of wilderness in this part of the world,” Morrison says. “There’s a growing recognition of its importance to the livelihoods of people who live there and the watersheds of the coastal cities and agricultural valleys. So there is an opportunity to link protecting biodiversity with safeguarding important ecosystem services.”
The habitat needs of wide-ranging species underscore the importance of large-scale conservation. Understanding how a lion like M53 moves around southern California is helping conservationists prioritize places to protect so wildlife will have more room to roam in the future.