You Haven't Heard of a California Scrub Jay? Evolution Explains That, Sort Of

There's a maxim among field geologists...one can go through an entire field season and end up never collecting a sample of the single most common rock in their study region. We geologists know why; we arrive, note that say, granite, is everywhere, and tell ourselves we'll pick samples of that later, and then we never do. We concentrate on the exotic stuff. I've found that it is the same way with my newer hobby of bird photography. I look for the new and exotic, and end up more or less ignoring some of the most common and yet most beautiful species found in our area. I got these pictures of a California Scrub Jay (Aphelocoma californica) while I was looking for the rather more exotic Sandhill Cranes the other day at the San Joaquin River National Wildlife Refuge.

Scrub Jays are common in our area. They are in my yard constantly, sometimes to the point of obnoxiousness. We awaken some mornings because they are on our roof pounding open acorns and pecans. They feel so common that we sometimes become jaded and forget what a beautiful bird they are. This becomes all the more odd because most people in North America never get to see them, as they are only found in the western states, and when we consider the species level of things, they become even more special. Until just a few years ago, the California Scrub Jay didn't even "exist".

It's not that they weren't here. They've always been here. But we've come to recognize that there are significant differences between the familiar blue corvids that range widely across the western states. Those differences provide a marvelous example of how evolution works. Ornithologists now recognize five distinct species of Aphelocoma scrub jays in the United States with another two species in Mexico. The U.S. species include the California Scrub Jay, the Woodhouse's Scrub Jay, the Florida Scrub Jay, the Mexican Jay, and the Island Scrub Jay. Prior to 2016, the Woodhouse's and California Scrub Jays were considered to be the same species, the Western Scrub Jay, but there are significant differences between them, including the shape of the beak and the intensity of the color of their plumage. They are found in different environments as well.

It's the different environment that provides the example of how evolution works. The California species lives only on the coastal strip of California and the other western states, while the Woodhouse's lives in the interior, east of the Sierra Nevada and Peninsular ranges. The isolation into different ecosystems has meant that the birds utilize slightly different food sources. The California jays consume large amounts of acorn, contained in a seed cover that must be defeated before the bird can eat. The Woodhouse's jays often consume pinon nuts, which are must be dug from cones. Over the millennia the young of each species would be born with the slightest of variations in beak shape, and sometimes those variations gave an individual a slight edge in the success at getting enough of their favored food source. Those individuals were the ones that tended to survive at a higher rate, and thus they passed on their genes to future generations. In other words, the isolation of populations in different habitats gave rise to the variations that made the birds separate species.

The other species display the evolutionary process as well. The Florida Scrub Jays are descendants of Woodhouse's Scrub Jays that somehow ended up in the swamps of the Florida peninsula more than two million years ago. With the isolation and different food sources, the Florida population has diverged into a new species.

Likewise, the Island Scrub Jay is also isolated. The jays won't willingly fly over large bodies of water, and thus California Scrub Jays are never found on the Channel Islands off the coast of the state. But somehow a few got to Santa Cruz Island, perhaps 150,000 years ago, and in their isolation, they became larger and bluer.

There are other more distantly related species of jay as well. The only one I have seen is the Pinon Jay that like the Woodhouse's lives east of the Sierra Nevada. I got this picture of one in Lava Beds National Monument a few years ago.

One doesn't need to travel all the way to the Galapagos or Hawaiian Islands to see the evidence of evolutionary change. The evidence might just be in your own back yard, making a lot of noise and harassing your cats.

A California Scrub Jay Like You've Never Seen Before, at the Stanislaus Wildlife Care Center

For reasonably logical reasons, albino animals don't survive well in the wild. They might as well have a target painted on their bodies, for without camouflage they are easily detected by predators. The lack of melanin in their feathers is another problem: without it, the feathers are weaker and easily damaged. The birds can't fly as well, and lose insulation.

This particular bird, a California Scrub Jay (Aphelocoma californica), is a permanent resident and wildlife ambassador at the Stanislaus Wildlife Care Center, which rehabilitates injured animals and birds, and when possible tries to release them back into the wild. They do good work, and depend on donations from the public. We were attending an open house the other day.

American Kestrel and California Scrub Jay on the Tuolumne River

Lots of travels lately, so I haven't had many chances to explore the river in my own backyard, much less post pictures of birds in general. But this morning I got the chance and almost immediately noticed an American Kestrel (Falco sparverius) in the top of one of the dead oak trees. That wasn't unusual, but it was being mobbed a bit by two or three California Scrub Jays (Aphelocoma californica). I don't know what they were arguing about, but they all flew away when I walked under the tree.

You haven't heard of a California Scrub Jay before? That might be because it has only been a species for less than a year. Those in charge of such things decided in 2016 that two races or subspecies of the Western Scrub Jay were actually distinct species. The California Scrub Jay ranges across the coastal mountains of Baja, California, Oregon and Washington, while the Woodhouse's Scrub Jay ranges across the interior states of Nevada, Utah, Colorado, Arizona, and New Mexico. The California Jays have a slightly hooked beak that allows for attacking acorns while the Woodhouse's beak is straighter, allowing them to dig out pine nuts from cones.

It's Jay Day! But Don't Call Us "Blue": The Jays of California

Western Scrub Jay on the Tuolumne River Parkway

Blogging doesn't evoke much in the way of mysticism and supernatural signs and that sort of rubbish, but I had signs that I was finally supposed to post pictures of two of the most common kinds of birds in my region, the jays. I was exploring the upper reaches of the Stanislaus River near Sonora Pass when smoke from the Kings Canyon fire chased us back down the hill. In consolation, I took a walk along the Tuolumne River Parkway at sunset. In the whole day I saw only jays. I haven't mentioned them before on this blog, so this must be the day.

Western Scrub Jay on the Tuolumne River Parkway

The birds were the Steller's Jay (Cyanocitta stelleri) up in the mountains, and the Western Scrub Jay (Aphelocoma californica) down in the valley. Notice in these pictures that they are blue in color, but they are not "blue". The actual Blue Jay (Cyanocitta cristata) is mainly an eastern species found mostly beyond the Rocky Mountains, although they are occasionally found in the Pacific Northwest and northernmost California. But not around here.

Western Scrub Jay on the Tuolumne River Parkway

There are two other species of jay in California. One is really special: the Island Scrub Jay (Aphelocoma insularis) is a rare species found on Santa Cruz Island off the California coast and nowhere else in the world. There are perhaps 2,500 of them in existence. Isolated from its relatives on the mainland, it has evolved into a unique species that is bigger, with a larger bill, blacker cheeks, longer legs and deeper blue color.

Western Scrub Jay on the Tuolumne River Parkway

The other jay is the Pinyon Jay (Gymnorhinus cyanocephalus). It lives mostly in the Basin and Range province east of the Sierra Nevada. I haven't had the pleasure of seeing them yet, although they have been seen in the Central Valley on very rare occasions.

Western Scrub Jay on the Tuolumne River Parkway

The Western Scrub Jay is a common bird in my neighborhood, and one of those birds that don't really care what humans think. They'll go about their business in my backyard or by the river, not caring whether I'm watching them or not. On many mornings I can be awakened by their pounding of acorns or pecans on the roof. I'm constantly digging up tree sprouts that came from seeds they have inadvertently left lying on the ground in our yard.

Sunset view of the Tuolumne River from the new parkway trail

The Steller's Jay (Cyanocitta stelleri) lives primarily in the conifer woods above the valley floor, but they will venture onto the valley floor during the winter at times. They are another "in your face" species, inhabiting campgrounds and picnic areas loudly and in large numbers. The one I saw today was being sneaky, though, because I was nibbling on a sandwich looking one way while it was sneaking about in the tree behind me waiting for some crumbs to fall.

Steller's Jay in the upper headwaters of the Stanislaus River north of Yosemite

I have surprisingly few good pictures of Steller's Jays. As common as they are, they've never remained still enough for me to get sharp pictures. The picture above is from this afternoon, but I had to go back to a trip in Big Sur in 2008 for some adequate shots of the species. That's like two cameras ago!

Steller's Jay at Big Sur

So...two jays down, and two to go, unless I go far afield. I'll have the best chance on our Cascades Volcanoes trip in a few weeks when we go into northeastern California and the pinyon country. I'll be looking for Pinyon Jays. I don't know when I'll have a chance to reach Santa Cruz Island to see the Island Scrub Jay, but I'm really looking forward to the day when that can happen.

Steller's Jay at Big Sur