"Look closely at nature. Every species is a masterpiece, exquisitely adapted to the particular environment in which it has survived. Who are we to destroy or even diminish biodiversity?" — E.O. Wilson

The wealth of biodiversity of the Coachella Valley region is the result of a serendipitous happenstance of geography. We have our habitat islands, the sand dunes and high elevation sky islands that have provided for species found nowhere else on earth, but we are also at a biological crossroads sharing species otherwise only found in the Mojave Desert, the Colorado Desert, the Sierra Nevada Mountains (their biological southern extent ending through the Transverse Range into the San Bernardino Mountains), the southern California coastal plain, and Baja California via the Peninsular Mountain Range, whose biological northern extent reaches into the Santa Rosa and San Jacinto Mountains.

Check any map, there is nowhere else in North America that is situated at the juxtaposition of so many different biological influences.  Even in a dry year, wildflowers abound in Mission Creek and Whitewater Canyon, places that share their biological richness with the coastal plain and the Sierra Nevada, as well as the arid deserts. Take a hike in the Santa Rosa Mountains and you are treading in Baja California.

As you stroll through this northern limit of Baja California, notice the abundance of agaves. The desert agave, Agave deserti, is a Baja species. Imagine the good fortune of the Cahuilla, having this abundant and highly valued source of food and fiber, resources unavailable to the Chemehuevi and Serrano tribes immediately to the west and north (no agaves naturally occur on their lands). Higher in elevation, the Cahuilla had access to both single leaf pinyon, Pinus monophyla, (a more northern species) and Parry Pine, Pinus quadrifolia, (from Baja), two species of pinyons to collect pine nuts from; the Serrano and Chemehuevi had just access to the single leaf pinyon. As you continue your hike, notice the dominant cholla cactus, Gander’s cholla, Cylyndropuntia ganderi, and if you look closely you might see a fishhook cactus, Mammillaria dioica, you guessed it, both found there way here from Baja California. Apparently, the fishhook’s fruits were also enjoyed by the Cahuilla. Many years ago, I had the occasion to visit many of the islands in the Gulf of California; one was a tiny spec of an island about halfway down the gulf, Isla Ildefonso. The island is flat-topped, perhaps the size of a football field; on that flat mesa I found a “forest” of tens of thousands of these fishhook cacti growing so close together there was no room for any other plants to grow. 

Baja California’s influence is not limited to plants; the Baja lizards have also extended their ranges into the Santa Rosa and San Jacinto Mountains. Gaudy with their yellow feet and chocolate colored back, Baja California collared lizards sun themselves on rocks, hoping to catch a smaller lizard with its guard down. In canyons with perennial water, and then more broadly dispersed at middle and higher elevations are granite spiny lizards whose range extends south nearly to La Paz. Their closest relatives are restricted to Baja’s subtropical Cape Region. Here they occur on palm tree trunks as low as Andreas Canyon on the Cahuilla tribal lands, to above 7000’-8000’ (2000-2500 m) on granite boulders on the slopes of the San Jacinto mountains. When they have breeding on their minds, the male granites can be infused with cobalt and turquoise hues of blue. Granite spinys have a curious habit of forming communal aggregations to spend the winter under exfoliating sheets of granite, a behavior I have not heard of in any other lizard. These lizards are dispersed in their individual home ranges during the warmer months, but when it gets cold, they come together and as many as 37 individuals have been found under a single slab of granite. When I heard about this my mind filled with questions. Are those aggregations comprised of closely related individuals (fathers and mothers and their extended offspring) or can anyone join the commune? Then, since when its warm they are widely dispersed, what signal tells them where and when to aggregate? As far as I know, nobody knows the answers to these questions. The assumption is that the multiple lizard bodies huddling for warmth, or something particular about the sheet of granite they selected, offers added protection from freezing winter temperatures (or maybe predators). Otherwise why bother?

Other Baja lizards that reach the Santa Rosa and San Jacinto Mountains include the banded rock lizard, granite night lizard, and leaf-toed gecko. All are saxicolus (rock loving). This makes it all the more curious that, in just the past few years, a father and his young daughter found a population of leaf-toed geckos on the north side of the Coachella Valley in the foothills of the Little San Bernardino Mountains. How could these geckos have breached that sand dune barrier to get from the rocks in the northern extent of the Peninsular Mountain Range (Santa Rosa and San Jacinto Mountains) to the rocks of the southeastern edge of the Transverse Mountain Range (San Bernardino and Little San Bernardino Mountains)? Did it happen before the dunes developed? 

The banded rock lizards’ colors provide a near perfect match to the granite rocks where they live. Unless they move there is a good chance you will not see them at all. This sort of cryptic color matching is an adaptation for avoiding predation. Makes sense, but then their close relative, restricted to the Cape Region of Baja California is anything but cryptic, with bright blue and yellow bands. Good for attracting girls, but not so good for avoiding predators. Are there fewer lizard predators in southern Baja? Maybe, but if not, why not?

One of the aspects of natural history that is so compelling is that while we think we have many answers as to the how and whys of understanding the patterns of biodiversity across the earth, there are always more unanswered questions. There are always new questions to explore.

Nullius in verba

Go outside, tip your hat to a chuckwalla (and a cactus), and be safe.