The Endemic Scrub-Jay of Santa Cruz Island

A world set apart.  The Galapagos of California.  Ancestral home of the Chumash people.  

Located some 25 miles off the coast of Southern California, the archipelago of eight islands that collectively make up the Channel Islands have been called many things throughout their ancient history.

But for birders across the globe, one of the islands in particular is known as the home of the world's only population of one very special inhabitant: the Island Scrub-Jay. 

Island Scrub-Jay

Santa Cruz Island, the largest and northernmost of the Channel Islands, measures approximately 24 miles long by 6 miles wide.  Yet this windswept rock, rising from the Pacific and riven by canyons and creeks, has given rise to a rich assemblage of plant communities, from grasslands to coastal sage scrub and chaparral.  Sheltered canyons hide stands of oak woodland and, perhaps surprisingly - owing to a long history of European settlement and ranching - groves of eucalyptus trees.  

Santa Cruz Island

In turn, the island's plant communities support a remarkable cobalt blue bird with an unmistakably strident call, the Island Scrub-Jay.  

Island Scrub-Jay

Noticeably larger than mainland California Scrub-Jays by about one-third, Island Scrub-Jays are also darker blue in color, and have a different call from their more familiar cousins.  DNA analysis suggests that Island Scrub-Jays diverged from their mainland counterparts around 150,000 years ago, when sea levels were lower and the landmass now known as the Channel Islands rose up from the sea as one large island, a mere two to five miles from the mainland.  

Though scrub-jays are reluctant to cross large expanses of water, as evidenced by the present-day lack of jays on neighboring Santa Rosa Island, the short distance of two miles was probably surmountable, and the ancestors of today's Island Scrub-Jays most likely flew across the span to take up residence on the large island.  As sea levels rose and the islands were further distanced from the mainland, and separated from each other as well, gene flow to the island population of scrub-jays was cut off, and speciation began.  

Island Scrub-Jay

It seems likely, from fossil as well as anecdotal evidence, that Island Scrub-Jays once inhabited neighboring Santa Rosa Island as well.  In 1892, an ornithologist visiting the island spoke with a rancher who claimed jays lived on the island, at least in recent memory.  But since by that point the islands had undergone extreme degradation due to sheep ranching, it's hard to know if the scrub-jays vanished from the island thousands of years ago, or only in the past 150 years.

Island Scrub-Jay

In any case, today their last and only stronghold remains Santa Cruz Island, which is now owned and protected by The Nature Conservancy and the National Park Service, and managed for wildlife as well as visitors as Channel Islands National Park.  Over the last several decades, The Nature Conservancy has restored much of the degraded island, which has not only saved the Island Scrub-Jay, but the incredibly adorable and diminutive Santa Cruz Island fox as well.  (Read more about their incredible work on the island here.)

Santa Cruz Island Fox

As North America's only avian island endemic (meaning, the only North American species of bird that is found solely on one island), the Island Scrub-Jay has the smallest range of any North American bird.  The entire population of somewhere around 2,300 individual birds is restricted entirely to this one island in the Pacific, which makes the species particularly vulnerable to the decimating effects of diseases, especially West Nile Virus (which closely related California Scrub-Jays are very susceptible to).  Currently, temperatures on the island are low enough to prevent mosquitos carrying the disease from becoming established, but as we all know, that may very well change in the future.

For now, the jays are thriving.  Like other members of the corvid family, scrub-jays are omnivorous and somewhat opportunistic, utilizing a wide range of food resources, from acorns and invertebrates, to small reptiles, mammals and even the eggs and nestlings of other birds.  In turn, their own nests are predated by snakes, skunks, foxes, ravens... and even other scrub-jays.  Pairs are highly territorial, and mate for life.  According to the National Park Service, average life expectancy of an Island Scrub-Jay is 4.8 years, but can be up to 20 years.  

Island Scrub-Jay

To see this striking bird for yourself, you'll need to hop on a boat: either a private vessel, or, more likely, a ferry operated by park service concessionaire Island Packers.  The trip from Ventura harbor to Santa Cruz takes about an hour, but once on the island, prepare to be self-sufficient, as there are no services or transportation of any kind available on the rugged rock.  Many trails are steep and primitive, so pack plenty of food and water, wear sturdy shoes and sunscreen, and don't miss the boat back (unless you plan to camp on the island, which is also an option)!

The jays and foxes aren't the only species of interest on the island: Santa Cruz island is home to a host of endemic plants as well.  The island, detached as it is from the hustle and bustle of the mainland, is an excellent place to peek back in time and experience a taste of what ancient southern California would have been like.  And it is absolutely gorgeous! 

The landing at Scorpion Anchorage