PICTURED: While its overall population numbers are just around 2,000, the island scrub jay’s impact on the world around it is enormous. By caching thousands of acorns every year, it has helped to restore Santa Cruz Island’s precious oak woodlands. Photo by Chuck Graham
California’s Channel Islands have proven to be a safe haven for a wide array of flora and fauna ever since the chain became a national park in 1980. Over the years, cooperative efforts by the National Park Service, The Nature Conservancy, the Institute for Wildlife Studies and other agencies have managed to bring Channel Islands National Park toward a natural balance.
This is seen in the return of several significant avian species, including the peregrine falcon, California brown pelican and bald eagle. All three species were decimated by DDT pesticides but have made remarkable comebacks.
Bald eagles, for example, were extinct on the islands for 50 years, leading up to 2002 when the first eaglets were returned to Santa Cruz Island. More eaglets followed through 2006, and after years of intensive efforts there are now roughly 70 bald eagles that have reestablished historic habitat across the national park. In 2019, America’s national bird experienced something of a baby boom: This year there were 19 breeding bald eagle pairs on the islands, producing a total of 24 chicks, with 10 chicks on Santa Cruz Island, nine on Santa Catalina Island, two each on Anacapa and San Clemente Islands, and one on Santa Rosa Island.
Isolation has its advantages on the Channel Islands and with protections in place, it’s easy to see conservation at work. Once ranch animals were removed from the volcanic archipelago, much of the islands healed themselves, thus giving island endemics a chance to thrive. Still, more challenges lie ahead.
One species of significant ecological importance is the endemic island scrub jay. Santa Cruz Island, the largest, most biodiverse isle off the California coast, is the only place in the world this passerine species exists. The island scrub jay evolved from its mainland cousin, the western scrub jay, thousands of years ago while surrounded by open ocean — first when the northern chain was just one island (named by scientists Santarosae), and ever since, beginning 20,000 years ago at the end of the last Ice Age. From there, sea levels rose 400 feet and the Northern Channel Islands were created. It wasn’t until 1994, however, that the jay became its own separate species, Aphelocoma insularis.
Birders from all over the globe flock to Santa Cruz Island just to get a mere glimpse of the jay, a streak of brilliant blue amongst the island oaks, Bishop pines, manzanita, toyon, lemonade berry and eucalyptus trees. It is typically heard before being seen, with its rattling, guttural, raspy calls filling the rocky canyons, but there is no denying its bright Dodger-blue wings, smoky gray back and creamy white breast.
Biologists from The Nature Conservancy, Cornell Lab of Ornithology and the Smithsonian Institute are currently in the middle of lengthy research projects involving the island scrub jay, which began in earnest in 2007. Although they’ve made several amazing discoveries about the species and its diversified habitats on Santa Cruz Island, biologists are also finding that there’s still much to learn about one of the rarest birds on the planet.
“A fascinating, interesting and ecologically really important bird,” said Scott Sillet, a wildlife biologist for the Smithsonian Institute and its Migratory Bird Center. “There are a lot of unknowns surrounding this bird.”
The Isolation Game
If you spend enough time on any of the islands, it can feel isolated out there, even though the Ventura County mainland is less than 20 miles away, with Los Angeles a mere 60 miles southeast. Yet, Channel Islands National Park is also known as “the Galapagos Islands of the North.” With over 60 endemic species, Santa Cruz Island possesses the greatest number of plant and animal species of all the islands in the park.
Thousands of years of isolation on the Channel Islands forced endemic flora and fauna to evolve, with island species becoming larger or smaller (based on competition, diversity of habitats and available food sources) than their mainland counterparts. In the case of the island scrub jay, a natural phenomenon called “gigantism” has allowed it to grow larger by a third, with a beefier beak and a deeper blue color than its mainland counterpart and distant cousin.
But it’s not just the isolation of the mountainous, 96-square-mile and 22-mile-long isle. Gigantism is also associated with a lack of predators. Sure, the island scrub jay contends with tree-climbing island foxes (another island endemic) and burly, ruthless ravens, but compared to what the western scrub jay endures on the mainland, the island variety looks over its shoulder far less.
Competitively, the island scrub jay has no peers among other songbirds. Island scrub jays are mostly omnivorous, feasting within 10 different plant communities on a healthy variety of insects such as crickets and earwigs, reptiles such as side-blotched and western fence lizards, and even deer mice and other birds’ eggs.
Channeling the Bird Flu
There’s a flipside to this isolation game. Even though Santa Cruz Island is the largest isle off the coast, the range of the island scrub jay is described as tiny. Its small population size of roughly 2,000-plus jays makes it vulnerable to natural disasters such as wildfires (most recently the 258-acre blaze in the island’s central valley in April 2018). Even more worrisome is disease, such as the West Nile Virus. The mosquito-carrying virus has been well-documented on the mainland, but as far as anyone knows, it has never touched down on the Northern Channel Islands.
Due to these factors, the island scrub jay is listed as “vulnerable” by the International Union for Conservation of Nature (ICUN). Over the last seven years, a number of jays have been trapped and vaccinated, but the practice is labor intensive.
“It harkens back to Wile E. Coyote and the Roadrunner,” said Sillet, referring to the classic Looney Tunes cartoons. “A peanut, string, stick and a box. If you like to fish, you’ll like to catch jays.”
“They’re hard to catch, really smart and they don’t want to get poked twice,” said Scott Morrison, director of The Nature Conservancy (TNC) of California Conservation and Science Programs. “So there’s limitations on vaccinations. There’s a lot of field work involved. We could prepare to bring them into captivity.”
Trapping occurs a few times annually. Blood and measurements are taken, as are swabs from beaks extracted to check for disease. It’s about a 15- minute checkup. Some jays are fitted with GPS and radio tags.
On neighboring Santa Rosa Island, several miles to the west of Santa Cruz Island, there is evidence of island scrub jays dating back to the late 1800s. Any effort to reestablish a population on Santa Rosa, the second largest isle off the California coast, would require a thorough study of the current population, its role in the food chain and how much food is available for them to thrive. The last population survey took place in 2008.
“At the moment we’re pretty confident that West Nile has not yet established itself on the island with residents and migrants,” continued Morrison. “Some birds have been tested. Some mosquitoes tested, but it’s a matter of when and not if.”
I couldn’t make out what the jay was searching for. The cavity of an old, downed, bleached-out eucalyptus tree was captivating an island scrub jay. It was too busy thoroughly probing the cavity, so it didn’t mind me observing from just a few feet away.
After much probing, it finally emerged with its prize: an empty, nondescript snail shell. Then it proceeded to pin it down on the trunk of the tree and pummeled it open with its beak, extracting anything remotely nourishing from the vacant shell.
“They’ll cache anything,” said Sillet. “They don’t become satiated during caching mode. They put as much food away as they can to get through a winter.”
That includes island cherries and, more importantly, acorns from island oak trees. Santa Cruz Island possesses extensive island oak groves because island scrub jays are responsible for enhancing those groves on the craggy isle.
Contrast this with Santa Rosa Island, where the extent of oak groves is reduced, due to a combination of island scrub jays going extinct during the late 1800s and, possibly, cattle grazing up until the late 1980s. On this windswept isle, topsoil has been blown away by perpetual northwest winds.
Sillet said that the soil of island oak groves on Soledad Peak at 1,574 feet, the location of a cloud forest restoration site located in the middle of Santa Rosa Island, is so badly eroded that the exposed root systems of the oak groves resemble those of mangrove trees in the tropics.
It’s estimated that a single, mature island scrub jay caches somewhere between 3,500 to 6,500 acorns per year on Santa Cruz Island. The birds have the innate ability to immediately cache the ballistic-shaped acorns with their points down to generate growth in a dark, shady place. The embryo of the acorn is near the point. All that caching of acorns on Santa Cruz has reestablished its oak groves, especially following the eradication of thousands of ranch animals (sheep, pigs, cattle and horses) that ran amuck across the island’s rolling marine terraces, tranquil Central Valley and steep, rocky canyons.
Volunteers have tried to replicate on Soledad at Santa Rosa Island how jays disperse acorns on Santa Cruz. During one restoration project, 3,000 acorns were planted. It took 600 volunteer hours to perform the equivalent work of just one island scrub jay.
“I like to think their role is restoring oak woodlands,” said Morrison of the jays. “They’re ecosystem engineers and they have prolific memories. Pretty phenomenal recovery of vegetation on Santa Cruz Island and the jays have had a hand in it.”
The jay’s manner is scattering seeds virtually everywhere, efficiently distributing acorns across the island, and in particular moving seeds upslope. The number one water input on the islands is fog, so when acorns are planted upslope, the fog sweeps over the islands and the moisture catches in the leaves of the island oaks. From there it trickles into the ground and eventually the creeks. This is a much-needed remedy at places like Soledad Peak.
“This all gives communities a head-start on climate change,” continued Morrison. “I’m a big believer in a whole bunch of species benefit on the island.”
Channel Islands National Park
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