The Islands of Interior California: The Pygmy Mammoths and the Doomed Sky Islands

An 80,000-year-old pygmy mammoth tusk discovered on Santa Rosa Island. (Image credit: Daniel Muhs, USGS.)

The waves crash against the cliff, tearing at the rock on Santa Rosa Island off of Southern California. The face of the cliff is in constant retreat, changing yearly, and sometimes daily as more of the rock disappears into the surf. In one brief moment, a visitor notices a strange object exposed in the cliff. Is it a tree trunk? No, that white stuff is ivory...it's a tusk! There were elephants on the island! How in the world did that happen?

The presence of fossils of elephantine species on the island has been known since the late 1800s, and a survey in the late 1990s discovered at least 150 sites with remains of the creatures, now called the Pygmy Mammoth (Mammuthus exilis). There is little doubt that these creatures were descended from the mainland's Columbian Mammoth, but as their name suggests, they were small. A full-sized Columbian Mammoth stood 14 feet high, but the Pygmy Mammoth was only half as high at most, and perhaps a quarter the weight. A nearly complete skeleton discovered and excavated in 1994, and the adult was only 5.5 feet tall (below).

Pygmy mammoth skeleton found on Santa Rosa Island in 1994. It was 5.5 feet tall (Image: © Bill Faulkner, NPS)

It seems impossible that mammoths could have made it out to the islands, and under current conditions it probably would be. The nearest island is more than 20 miles away from the mainland. But things were much different 150,000 years ago. A phase of the ice ages was ongoing, and when a vast ice sheet covered Canada and 30% of the United States, sea level was around 300-400 feet lower than today. The four main Channel Islands (San Miguel, Santa Rosa, Santa Cruz, and Anacapa) would have been a single large island, which has been given the name Santarosae. The open water gap between the island and the mainland was only about 4.5 miles.

Elephants actually are excellent swimmers, what with having a natural snorkel and all. Present-day elephants have been documented as have swam more than 20 miles. So it is not hard to imagine mammoths on the mainland, perhaps suffering food shortages because of drought or wildfires, catching the scent of fresh vegetation on the islands and swimming out to investigate. A population was established, but then things began to change. The ice age was ending and the globe was warming up. The ice melted and sea rose to near today's level. The single large island was inundated, forming the four islands of today, and the total area was reduced by 76%. For the mammoths, this was a crisis. The islands were no longer big enough to support the mammoth population.

Outline of Santarosae and the present-day Channel Islands (Image credit: U. S. Geological Survey)

The outcome might come as a surprise because the cliché about evolution is sometimes misstated as "survival of the strongest". It is actually the survival of the best adapted. Although the biggest mammoths may have been able to consume much of the decreasing food supply, their dietary needs were also much higher. The evolutionary lottery favors those individuals who have the best adaptations for the specific environment, and it was the runts of the litter who could survive on less food. Over time the size of the adults decreased until they constituted a new species, the Mammuthus exilis. They survived on the islands for tens of thousands of years (from at least 80,000 years before present).

In the end, the Pygmy Mammoths also succumbed to extinction sometime around 12,000 years ago. Their disappearance coincided with the extinction of numerous other large mammals in North America, the "megafauna". Many reasons have been offered as hypotheses, but the cause (or causes) remain elusive. It needs to be noted that humans arrived on the islands around 11,000 years ago, and the small mammoths would have had few defenses against armed human beings.

As we can see, islands are places of refuge, but they can also be a prison of no escape. Which brings us to the doomed sky islands of the Mojave Desert.

The New York Mountains in the Mojave National Preserve (image credit: Garry Hayes)

People may envision a number of stereotypes of what constitutes a desert. Many people see vast seas of sand dunes, while others may see mesas and spires inspired by childhood memories of Roadrunner and Coyote cartoons. Others might see a landscape of huge saguaro cacti. These kinds of deserts exist of course, but except for several dune fields here and there, they don't exist in California. The deserts of eastern California (along with parts of Arizona and Utah, and all of Nevada) are within the Basin and Range Province, a region of the Earth's crust that has been stretched and broken into hundreds of high mountain ranges and deep faulted basins.

The Clark Mountains as seen from Kokoweef (image credit Garry Hayes)

Because the relief (the difference between the highest and lowest points) can range up to two miles, these mountain ranges encompass numerous life zones or ecosystems, from the hottest barren salt flat to alpine peaks. These mountains constitute rich biologic islands that are analogous to the Channel Islands off the coast of California. And like the Channel Islands, some of the inhabitants are ultimately doomed.

Because the mountain peaks are so isolated, one might not expect much diversity, but these environments are not static nor were they always isolated. They were influenced by the ice ages, even though the ice fields never reached the arid region. The climate was cooler and wetter so trees more characteristic of the Rocky Mountains or the Sierra Nevada were able to migrate into the region, including the Rocky Mountain White Fir. But as the ice age waned, the rising temperatures and growing aridity caused the trees to retreat higher and higher into the mountains. If the mountains weren't high enough, the trees were extinguished. In the present day, only three islands remain that possess the Rocky Mountain White Fir: the New York Mountains, Clark Mountain, and Kingston Peak.

Scene from the Kingston Peak area (Image credit: Bureau of Land Management)

None of these relict forests are easy to get to, and I have never had the privilege. And unfortunately I may never have the chance because these trees are ultimately doomed. They are at the very edge of survival, clinging to the cooler north-facing slopes in a micro-climate that is just wet enough to allow the trees to cling to life. As the world continues to warm up, the dry desert will continue creep up the mountain slopes, ultimately "flooding" the last trees in hot dry air.

Image credit: https://www.amargosaconservancy.org/native-plants-wildlife/

We will never fully comprehend the full effects the changes on our planet brought about by global warming and climate change. In the mountains of the Mojave Desert, the "islands" are not occupied just by fir trees. There are dozens of species that shelter within these small forests and they will disappear too. It's a small corner of the world rarely visited by humans, but climate change is global, and there are literally millions of micro-environments like these that will disappear without ever being studied or appreciated. It's a crying shame and all the more tragic considering we've lost three decades of time that we could have acted on behalf of our planet.

Image credit: https://www.amargosaconservancy.org/native-plants-wildlife/

An Important Island in Southern California Gains Permanent Protection

San Gorgonio and the San Bernardino Mountains from the vicinity of Idyllwild

There's an island in Southern California. There are lots of islands, actually, and some, like Catalina and the Channel Islands, are famous. They are also surrounded by water. This island is a bit different. Instead of water, the island is surrounded  by lowlands and urban development. The island is the San Bernardino Mountains, one of several mountain ranges that form a ring around the Los Angeles Basin and Inland Empire.

 The range includes the tallest mountain in Southern California, San Gorgonio Peak (11,499 feet), and a high alpine ridge that has a dozen or so peaks exceeding 10,000 in height. It has the southernmost aspen grove in North America, and evidence of the southernmost glaciers (even a few small glacial lakes). The ruggedness of the range has precluded the kinds of developments and "improvements" that have spoiled many other beautiful places. The Whitewater River, with its headwaters near San Gorgonio Peak, flows a vertical distance of two miles to the desert floor, unimpeded by dams or other developments. Few such rivers are left in the state (it's probably fair to say that a dam would have been foolhardy, as the river crosses the San Andreas fault, and engineering would be very...iffy).

Photo by Mrs. Geotripper

The mountain range is a treasure. In my youth, I honed my hiking and camping skills in these mountains, and from them I learned to love topographic maps. It pains me that I don't have digital images of the sights I saw in these peaks forty years ago when I regularly backpacked in and out of the canyons and across the mountaintops. One of my most vivid teenage memories is a hike I took into the headwaters of the North Fork of the Whitewater River. The camp was on a terrace above the creek, and there was an expansive view eastward into the desert around Palm Springs. As the sun set, we could see thunderheads rising in the far distance, and the nighttime was punctuated with flashes of lightning. I had never felt so isolated in my life, and that is not a common feeling for the people of SoCal. It was exhilarating, and I loved every moment.

Source: National Park Service

I want to tell a story. The Channel Islands off the coast of Southern California were once much larger. This was because of the lowering of sea level by the glacial ice ages at various times during the last two million years (so much water was locked up in ice on land worldwide that sea level dropped several hundred feet). The islands were never actually connected to the mainland, but the distance between them was much less than it is today. Somewhere in that stretch of time, a herd of Columbia Mammoths (or a pregnant one) was panicked into the ocean surf (or perhaps they smelled food on the islands), and they (or it) swam the 5 or 6 miles to the island. Elephants come equipped with a snorkel; they're good swimmers. They thrived on the island, but the ice age ended. Sea level rose, first shrinking the size of the island, and then dividing it into four much smaller islands. Food became scarce. The mammoths continued to produce offspring, but it was only the smaller animals that could survive in the restricted environment. They could get by on less. Because the runts survived, they were the most successful at passing on their genes. The Columbian Mammoths, some of whom stood as tall as 14 feet at the shoulder, got smaller.

Source: U.S. Geological Survey, via http://www.livescience.com/48393-pygmy-mammoths-channel-islands.htmls

And smaller. Eventually, a race of pygmy mammoths (Mammuthus exilis) evolved. Some of the adults stood no higher than 7 feet at the shoulder, and weighed one ton, instead as much as ten. Eventually though, even small size wasn't enough. They became extinct about 12,000 years ago.

There is a lesson here, of course. All good stories have them. The environment that supported the mammoths became smaller and more limited, inexorably, until it was strained beyond recovery. The animals disappeared, and we are today deprived of what must have been a fascinating creature. Think about what has happened to Southern California in the last century. The population has expanded to tens of millions of people, and the wild lands that surround the urban valleys have become smaller and more isolated. The ecosystem is breaking down, as animals are no longer able to cross urban corridors to find others of their kind. They retreat farther into their shrinking habitats, and populations plummet. If there is no intervention, they will simply disappear. The bighorn sheep, mountain lions, bears, foxes, and condors will all be gone.

But this post is not pessimistic. Far from it. This is about a piece of tremendously good news that came to pass this week. For years, California Senator Feinstein has been promoting the idea of several national monuments or parks in Southern California. The political gridlock in Congress has prevented anything from being done, but President Obama has used his authority under the National Antiquities Act to declare three new national monuments. Two of them are in the Mojave Desert, in the Castle Mountains, and in the landscape between Joshua Tree National Park and the Mojave National Preserve. The third, Snow to Sand National Monument, brings protection to the highest ridges of the San Bernardino Mountains to the desert floor at Morongo, and even more importantly, linking the mountains to Joshua Tree National Park. This has the effect of bringing permanent protection to a very scenic wilderness area, but even more importantly, producing an intact ecosystem that will give declining wildlife populations a fighting chance to survive, especially as our global climate warms up.

By preserving an unbroken habitat from just above sea level to 11,499 feet, there were be room for upward migration of animal and plant species as the lower levels become hotter and drier. Few places in the world offer such a range of available habitats. There is so little left, so I'm glad to see these efforts to protect such a fascinating region. The mountains of my youth!