Nearly extinct, rare kangaroo rat found in Santa Clara County
For decades, an imperiled rodent was thought to exist only in a tiny pocket of sandhills in Henry Cowell State Park in Santa Cruz County – and nowhere else on Earth.
But scientists have spotted new populations of the rare Santa Cruz kangaroo rat about 25 miles away in the rugged and arid mountains of Santa Clara County, raising hopes for the long-term survival of a unique creature that seemed destined for extinction.
The discovery shows that the furry and nocturnal pipsqueaks, who are more closely related to chipmunks than rats, are still hanging on — and are benefiting from habitat conservation.
“I was shocked when I found these animals. It was unbelievable,” said Ken Hickman, who detected the elusive subspecies in Sierra Azul Midpeninsula Open Space Preserve, above Los Gatos, using trail cameras. “People have been looking for them for years,”
His 2019 discovery, confirmed in April when a team of Midpeninsula Regional Open Space District biologists trapped four live animals, is now being followed up by a much larger state-funded survey and genomic analysis.
With super long tails, bulging eyes and big hind feet, kangaroo rats are accomplished jumpers, leaping like the much larger kangaroo. The animal has adapted so beautifully to dry landscapes that it rarely needs a sip of water; instead, it gets moisture from food.
Why does this little creature matter? Kangaroo rats are considered a “keystone species,” integral to maintaining a balanced and thriving ecosystem. Their caches of buried seeds help give rise to a new generation of manzanita plants. Their burrows provide shelter for toads, snakes, and other wildlife.
Santa Cruz kangaroo rats, a subspecies of the diverse family of kangaroo rats found in western North America from southern Canada to southern Mexico, were once far more abundant, living in patches of steep and sandy chaparral throughout Santa Cruz, Santa Clara, and San Mateo counties.
They’re lousy diggers, so they need loose and porous soil. They also depend on the seeds of the manzanita plant for food.
Since 1900, their range has severely shrunk. Much of the animal’s original habitat has been destroyed or degraded by sand mining operations and residential and commercial development, according to David Lee of San Jose State University and Jodi M. McGraw of The Land Trust of Santa Cruz County. Once contiguous, the Bay Area’s many sandhills have been cut into fragments.
Despite extensive and repeated searches, the Santa Cruz kangaroo rat could only be found in one place: the remains of an ancient seabed in the protected hills of Henry Cowell State Park. The California Department of Fish and Wildlife labeled it a critically imperiled subspecies, meaning that it is at risk of extinction.
“It was thought to be down to that one pocket,” said Hickman.
With a background in engineering and a permit from Midpen, Hickman in 2016 designed and built customized wildlife cameras.
He placed them strategically at about 100 sites in Sierra Azul Preserve, famed for its steep sandstone ridges and abundant manzanita.
A kangaroo rat hadn’t been seen in that area since 1940. But the Sierra Azul Preserve is the most massive of Midpen’s open space lands, protecting more than 19,000 acres of wilderness — so Hickman sensed it could be potential habitat.
In 2019, during a routine review of his cameras, Hickman made a stunning discovery.
“I loaded up my photos and saw all these kangaroo rats,” he said. “I had tears running down my face. It was basically a lightning strike.”
The images were thrilling to Midpen, which has made great efforts to protect and restore Sierra Azul. Its prominent 3,486-foot peak, Mount Umunhum, was once the site of an old military radar base, with deteriorating buildings and hazardous waste.
“It wasn’t an instant success story,” said Midpen wildlife biologist Matt Sharp Chaney. “It took a lot of work, a lot of diligence. But when we saw those photos, we were awestruck.”
This April, Chaney and his team hiked through the preserve to set “Sherman traps,” metal box-style animal traps designed for the safe capture and release of small mammals. After three days of trapping, they only found four individuals, a reminder of just how rare Santa Cruz kangaroo rats are.
Traps were set at sunset and then checked at sunrise, so animals wouldn’t overheat. Each individual was carefully measured and then sent on its way.
The next step is to conduct additional kangaroo rat surveys and inventory plants within the animal’s habitat to better understand where it lives.
In addition, a team of geneticists from UC Davis, UC Santa Cruz, and Cal Poly San Luis Obispo is collaborating on genomic research. Although the animals’ Santa Cruz and Santa Clara populations belong to the same subspecies, it’s not yet known how closely related they are.
Scientists also plan to compare the genetics of today’s animals to historic specimens stored in museums, to see if the species diversity has changed over time.
The project, to be completed in 2025, will eventually lead to a formal “Habitat and Population Monitoring Plan” to ensure that the animals’ habitats are well managed.
The effort could also spur efforts to list the animal under the California Endangered Species Act.
Now found, they should never again be lost, said Hickman. “With populations this small, they can ‘wink out’ really quickly.”