Emerald predators: Ohlone tiger beetles find their way home with the help of local scientists
Adult Ohlone tiger beetles have a striking iridescent green coloring and are known to be ferocious predators.

By Ashley McConnell

Santa Cruz, California – Their metallic emerald bodies appear iridescent in the sunlight as they scurry across bare earth following winter rains at a preserve near Soquel in Santa Cruz County.

For the first time in over a decade, endangered Ohlone tiger beetles roam the preserve and await their chance to pounce on unsuspecting prey.

U.S. Fish and Wildlife Service biologist Chad Mitcham spearheaded the first-of-its-kind adult translocation of Ohlone tiger beetles in Santa Cruz County this March.

“The excitement in the air is palpable,” says Chad Mitcham, fish and wildlife biologist with the U.S. Fish and Wildlife Service, after releasing 43 Ohlone tiger beetles to their new home in Santa Cruz County.

Service biologists Mitcham and Mark Ogonowski spearheaded the first-ever translocation of adult tiger beetles in the world, with the help of local land managers and tiger beetle experts from across the country. The goal: a self-sustaining population of the rare beetles in an area of Santa Cruz County where they’ve been absent for more than a decade.

“The danger with any rare species is that any of the populations could be wiped out for any number of reasons in a given year,” Mitcham explains. “Its overall range would significantly decline with the loss of any one cluster.” For a species whose remaining suitable habitat is estimated at 200-300 acres, the threat of extinction is real.

Mating Ohlone tiger beetles collected in a vial from a University of California, Santa Cruz reserve property.

Entomologist Dick Arnold may have been the last person to see an Ohlone tiger beetle at the preserve near Soquel more than a decade ago.

“Unfortunately, the habitat conditions changed over time as more and more of the areas nearby got developed,” he said. As someone who’s studied rare insects for more than 40 years, Arnold says he’s delighted at the possibility of re-establishing a population where they’ve been extinct for more than 10 years.

A re-established population in this location - if it becomes self-sustaining - is critical for the tiger beetle’s long-term survival, explains Tara Cornelisse, a senior scientist with the Center for Biological Diversity. She has studied Ohlone tiger beetles for more than a decade and helped train local resources managers to assist with the unprecedented translocation.

“It provides an insurance population for the species,” she says.

Tara Cornelisse and Matt Timmer carefully transfer an Ohlone tiger beetle from a net into a vial at the Glenwood Preserve in Santa Cruz County.

Ohlone tiger beetles likely inhabited a larger area before development around Santa Cruz reduced the extent and connectivity of their habitat. Populations lost from isolated sites may not be recolonized naturally, increasing the species’ overall risk of extinction. The translocation project aims to give the beetle some help.

“The idea started back in 2016 as a conversation with Grey Hayes, a rangeland ecologist active in Ohlone tiger beetle conservation,” explains Ogonowski. “Grey thought translocating beetles to properly managed sites where they used to occur could be successful and put us in touch with the experts who have made this project possible.”

Local Santa Cruz land managers and species experts join forces to collect 43 male and female Ohlone tiger beetles for the first-ever adult translocation of this species.

Sixteen males and 27 females were hand-collected one-by-one using nets and vials from three locations in the county where tiger beetle populations are known to be stable. The animals were placed in ice chests and transported to the preserve, where land managers from the Center for Natural Lands Management have been working since last fall to prepare the area for its new inhabitants. The litter layer of dead grass and leaves was removed by raking, weeding, and hand-pulling vegetation to create the bare ground habitat Ohlone tiger beetles need to survive.

They require open, bare areas to stalk their prey, and they lay their eggs in tiny burrows in the ground.

“Tiger beetles evolved during the Pleistocene era with megafauna that grazed the landscape from mammoths and mastodons to giant ground sloths and bison - the same lands that were later burned by Native Americans and then grazed by dairy ranchers in the early pioneer era,” says Tim Hyland, who manages state parks in Santa Cruz County, where some Ohlone tiger beetles find safe haven. “All of these historical activities allowed the tiger beetle to flourish. The tiger beetle is an embodiment of coastal prairies that rely on disturbance.”

An adult Ohlone tiger beetle seeking refuge.

Aptly named for the Native American tribe with which they co-existed for millennia, Ohlone tiger beetles have ferocious predatory instincts. With excellent vision, they lie still on the bare ground and stealthily pounce on ants and flies that enter their line of sight.

“They’re like green jewels with jaws like the fangs of a saber tooth tiger,” Cornelisse says. “People are delighted when they see them.”

They’re also an important part of the food chain, and are prey for a variety of animals from birds and toads to lizards and dragonflies, Arnold explains. “Anytime you start to lose species in a food chain, it weakens the whole system,” he says. “You don’t know how many can be lost before the whole food chain collapses.”

In 2001, due to habitat loss, invasive grasses, and lack of natural disturbance, the Ohlone tiger beetle was designated as endangered by the U.S. Fish and Wildlife Service. While the designation secured protections for the beetle, proactive management and recovery efforts would be required to bring the species back from the brink.

“A lot of rare species like the Ohlone tiger beetle have plans to help them recover, but it takes a proponent and community involvement to move the recovery forward and put the plan into action,” says Kelli Camara, technical program director for the Resource Conservation District of Santa Cruz County. “Without Chad and Mark at the helm, we wouldn’t be doing any of this.”

An Ohlone tiger beetle pair are observed mating at their new home at a preserve near Soquel, California, in the hours following their translocation. This is a promising sign for the long-term success of the translocation project.

The beetles were transferred to the site near Soquel from Glenwood and Moore Creek Preserves and natural reserve lands on the University of California, Santa Cruz campus.

Today, rotational livestock grazing, prescribed burns, non-native vegetation removal, and even mountain biking trails all play key roles in the survival of the Ohlone tiger beetle.

Matt Timmer, natural resource manager with the Land Trust of Santa Cruz County, manages the 200-acre Glenwood Preserve in Scotts Valley. Glenwood Preserve was established more than two decades ago to protect habitat for Ohlone tiger beetles and other rare plants and animals as mitigation from impacts of a housing development.

At Glenwood Preserve, Ohlone tiger beetles thrive in pastures grazed by cattle. The cattle form paths that create bare ground where the tiger beetles spend most of their time as adults.

“Historically, these grasslands would have consisted of perennial bunch grasses and forbs with patches of bare ground. With the arrival of European settlers, livestock, and non-native grasses, that system has changed over time,” says Timmer. “Today, we’re using grazing to try to mimic historical conditions, like the large herds of ungulates that once roamed the area, to create more suitable habitat for the beetle.”

The University of California, Santa Cruz created two preserves on campus through a habitat conservation plan put in place to mitigate impacts to Ohlone tiger beetles and other federally protected wildlife from a faculty and staff housing development. Some of the now-preserved lands are used for academic research, grazing, and recreation, and provide much-needed habitat for Ohlone tiger beetles to carry out their life cycle.

“Santa Cruz County has a lot of open space that people use and appreciate – people are already in love with this area,” says Alex Jones, who manages the University’s reserve lands. “We should celebrate the tiger beetle and Endangered Species Act as one of the reasons we have so much open space here in Santa Cruz. Conservation of tiger beetles has allowed for some of this open space to exist.” Jones recruits university students to conduct Ohlone tiger beetle surveys, a source of key data to further conservation of the species.

Wilder Ranch State Park boasts one of the more stable Ohlone tiger beetle populations in the county, a testament to successful ongoing management activities, from prescribed burns to the creation and management of mountain biking trails.

“There’s an inherent conflict between mountain bikers and beetles. They both come out in the spring, and one is generally faster than the other,” says Hyland. California State Parks, however, has found an approach that seems to benefit both bikers and beetles. By re-routing bikers from known breeding areas, beetles are given the space to mate without threat of disturbance and mountain bikers in turn help create new bare ground trails used by the beetles to hunt their prey. “Now, when I run into mountain bikers on the trail, they are usually excited to hear about how the beetles are doing,” says Hyland.

If this initial translocation proves successful, additional beetles may be translocated from Wilder State Park to the preserve near Soquel to further augment the new population.

Ohlone tiger beetles lay their eggs in tiny burrows in the ground.

More than 100 species of tiger beetles are known in the U.S. and Canada alone; five species of these mythical-looking micro-fauna are listed as threatened or endangered under the Endangered Species Act (ESA). Barry Knisley has been studying tiger beetles for more than 40 years, and says, “Like so many organisms, there is clearly a decline. We’re losing habitat as development and urbanization and human activity progress. As we lose natural areas, we’re losing tiger beetles.”

Tara Cornelisse (kneeling) releases an endangered Ohlone tiger beetle at a preserve near Soquel while Matt Timmer and Mark Allaback observe.

Knisley played a role in securing ESA protections for several species of tiger beetle across the United States and perfected larval translocation to boost dwindling populations. One of his most fruitful recovery successes was developing the methodology to translocate more than 100 northeastern beach tiger beetle larvae from Martha’s Vineyard to Monomoy National Wildlife Refuge in Massachusetts, which, as a result of the larval translocation, now boasts an estimated population of more than 4,000 adults.

“There’s good evidence that larval translocation works, and now we’d like to see if adult translocation can also be successful,” says Knisley, who consults on the Ohlone tiger beetle adult translocation project in Santa Cruz. “We do know, unlike vertebrate animals, that tiger beetles can rebound genetically and biologically if the habitat is suitable. If we double the number of sites, we have a chance.”

Camara and others involved in the project say they are hopeful and optimistic for the future of Ohlone tiger beetles. “The first step is raising awareness. Then, we want to maintain or increase existing populations. Then, we can begin to move them to other extirpated sites,” she says. “Setting small, short-term goals helps us move closer to recovery.”

The team continues to monitor the new arrivals at their new home, and early observations appear promising. In the hours and days following release, the beetles were observed hunting and mating.

Local natural resource managers and species experts joined forces to implement the translocation project.

“No one knew what to expect, but we knew what we wanted to see happen. Hunting and mating are exactly that.” Mitcham says. “It’s a very good sign.”

Mitcham and the rest of the team remain hopeful that this first-ever translocation will be the first of more to come, steps that will bring this enigmatic species one step closer to recovery. “They’re ambassadors for insect conservation and the health of the prairies, and they’re worth saving,” he said.

Partners include Dr. Richard Arnold and Dr. Barry Knisley, California State Parks, the Land Trust of Santa Cruz County, the Resource Conservation District of Santa Cruz County, the U.S. Fish and Wildlife Service, Center for Biological Diversity, City of Santa Cruz, Center for Natural Lands Management, and the University of California, Santa Cruz.

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Endangered and/or Threatened species