Where Mountains Float in the Air
From a distance the Chisos Mountains don’t look wooded. They seem to be sculpted from naked rock. Even as you begin the drive up Green Gulch you expect to see only buffy grass, century plants, and sotol. But as you pull abreast of Lost Mine Peak the grass is gone from the road’s edge and the shoulders are covered more and more thickly with green, leafy shrubs. Soon you see taller bushes on the open slopes, the evergreen sumac, Texas madrone, cat claw, and common bee-balm, crowned with beautiful deciduous and evergreen leaves.
The Chisos Mountains fascinate for so many reasons: their great beauty, their wooded coolness and greenness, the exceptional variety—and rarity—of plant and animal life. Lying close to the border, they encompass an interesting blend of U.S. and Mexican species. But because they stand alone and apart, they support species found nowhere else. And their height creates a temperate environment, a grassed and timbered island in a sea of rock and sand.
In the Chisos as elsewhere in desert country, what lives where depends on highly local conditions of soil and climate. While daytime temperatures in the mountains average significantly cooler than the desert flats, and while rainfall in the Basin is twice as heavy as at Rio Grande Village, just as crucial are the land’s shape and the sun’s angle. You might expect that trees grow as a woodland belt around the mountains, with treeline determined by altitude. Not so. Many trees prefer canyons to exposed slopes because soils are deeper there and drainages offer more water. Even in the same canyon, more trees may grow on cooler north-facing slopes, while grasses predominate on sunny south-facing slopes. Or pinyons, junipers, and oaks may flourish at lower elevations, while most other forest species occupy the canyon’s heights.
At about 1,400 meters (4,500 feet) of elevation as the mountains begin to close, a surprise delights the eye: The first of what you might call trees beside the road. Suddenly, masses of trees—junipers, little oak trees, and pinyon pines—higher up in the drainages that crease the mountainside. And multitudes of woodland birds dart in and out of the trees and bushes along the roadway. You understand now why they call this valley Green Gulch. As you approach the first water tank you are in actual woodland. Grasses still grow on the open slopes along with bushes and pricklypear and sotol, but here are the first easily distinguished little pinyons beside the road. At 1,600 meters (1 mile) of elevation they are fairly respectable pines. Tree cover increases and, after the second water barrels, the woodland comes right down to the road. The grass is less obvious now, but it covers the ground between the trees and is especially thick on south-facing slopes. Flocks of little birds fly up from the road ahead of you. At the switchbacks in Panther Pass you peer up the steep slopes at solid stands of deciduous green trees set off against darker evergreens. Way up at the top leap scarlet flames of frost-touched Grave’s oak and fragrant sumac.
These pinyon-juniper-oak woodlands are pretty typical of the dry Southwest. Chisos woodlands include only one pine, three junipers, and many varieties of oak. You can easily identify pinyon and juniper trees, but the oaks are often hard to tell apart because they tend to hybridize. The different tree species have different soil and water requirements and where moisture is harder to come by they grow smaller and more widely spaced. You’ll find redberry juniper at drier, lower elevations, such as Green Gulch. This is a rather scraggly shrub or small tree whose lower branches often touch the ground. It has scale-like yellow-green leaves, and red berry-like cones. It will often invade abused grasslands. The gray oak, an evergreen with small olive-green leaves and dark gray bark, also prefers drier soils. On exposed slopes it too takes on shrub-like proportions but grows to 20 meters (65 feet) in protected canyons. Birds, peccaries, and deer feed on gray oak acorns. The Indians preferred the acorns of the Emory oak.
Startling plant combinations comprise this forest floor on the South Rim of the Chisos. Such biotic richness and surprise led to the park’s designation as an International Biosphere Reserve.
Volcanic spires remind us that change has not always come slowly in the Big Bend. Molten rock under intense pressure created these spires as plugs inside softer rock, which has long since eroded away.
The other narrowleaf evergreens prefer intermediate to moister soils and the Chisos Basin is a good place to see both drooping and alligator junipers, the latter named for the square scales that make its bark look like alligator hide. This slow-growing, long-lived tree has bluish-green needles, and gray fox and rock squirrel relish its berry-like cones. Drooping juniper all but cries out for recognition. Its wilted leaves and drooping branches seem to be dying of thirst, but in fact are perfectly healthy, as is the bark that shreds in long, fibrous strips. You’ll find plenty of drooping juniper in Mexico, but the only place you can see it in the United States is right here in the Chisos Mountains.
The Chisos Basin has been hollowed out of volcanic rock by stream erosion. The peaks that ring the Basin all came into being when molten rock squeezed up under enormous pressure from deep within the Earth. Some of the red hot stuff poured out over the land surface in lava flows which cooled so quickly that they cracked in long vertical fissures. Then as the ages passed, joints toppled and square-faced peaks, buttresses, and free-standing spires emerged. So the Basin wall took shape from Casa Grande southward through Emory Peak. Later on, more molten rock pushed up from below, bulging the surface rocks upward without breaking through. Again the eons passed and the softer surface rocks wore away, exposing the dome-shaped peaks which now rim the Basin to the north and west. Today, loose rocks and clays still inch downhill toward the Window. All Basin runoff heads for this chute, and when it storms in the heights, the dry waterfall turns into a torrent, with boulders bouncing along like so many corks. Growling and grumbling, the big rocks plunge over the pouroff in a 67-meter (220-foot) free fall, coming to Earth in a great rubble pile below.
Pinyon pines grow abundantly across both Mexico and the American Southwest. In the Chisos you’ll find them almost anywhere above 1,500 meters (4,800 feet) of elevation, and at lower elevations they will be the only pines. Short of trunk, with spreading lower branches, egg-sized cones, and short, slender, bluish-green needles, pinyons range from dwarf size to a tree 15 meters (50 feet) tall. Many birds and mammals eat its delicious nuts.
As elevation increases you may find fewer junipers, while more pinyons appear on the open slopes and more oaks along drainages. The deciduous Graves oak requires more moisture than other oaks, so you find it putting forth its shiny, dark green leaves in high moist canyons. The Emory oak also prefers high drainages but it grows at slightly lower elevations. It has small lance-shaped leaves. The Chisos oak, a small, graceful tree with narrow, leathery leaves, requires a high water table. In all the world it grows only in the Chisos Mountains’ Blue Creek Canyon.
Mule deer frequent the park’s lower, drier elevations.
The Sierra del Carmen whitetail haunts the Chisos Mountains. It has much smaller ears than the mule deer and bears the characteristic flag tail. Isolation allowed this sub-species of whitetail to develop. These deer live only in the Chisos and across the river in the Sierra del Carmen.
Many of these interesting woodland features can be studied at leisure in Upper Green Gulch, reached by the Lost Mine Trail from the trailhead in Panther Pass, following the well-kept path at least as far as Juniper Canyon Overlook. Here you find yourself among the very pines and oaks that you viewed from the switchbacks far below. On location it appears much as it did from far below. There are few grasses and a host of flowering bushes. Shaggy mountain-mahogany and fragrant sumac make excellent feed for whitetail deer. Fragrant ash puts out long clusters of cream-colored flowers in springtime. Mountain sage, a beautiful shrub that grows nowhere else in the world, bursts into crimson flower each fall. As a hummingbird feeder it even outranks the golden platters of the century plant. Probably most surprising at this elevation is the persistence of desert and grassland plants, for here among the pinyon pines and oak trees grow clumps of ocotillo, lechuguilla, pricklypear, and the great gray-green blades and towering bloomstalks of the Big Bend agave.
Dryness is a fact of life in these woodlands. The north-facing slope is densely covered with trees, while the opposite south-facing slope exhibits mostly ocotillo and lechuguilla. The same holds true on the narrow ridge extending from Casa Grande. Pine woodlands face north and lechuguilla flourishes on the south-facing slope. It’s a question of solar exposure and resulting temperature and moisture variations.
Oddly enough, you will likely see more wildlife in the populated Basin than along the whole Lost Mine Trail, for animals find the Basin as attractive as man does. The del Carmen whitetails find it a good place to feed off and on throughout the day. These deer are found only in the Big Bend and across the river in the Sierra del Carmen. To the rock squirrels the Basin offers acorns, pine nuts, and plenty of rocky lodgings. The busy cactus wren can indulge its habit of year-round nest building, because there is abundant tall grass, and introduced yucca, a favorite avian building site. Sounding like a child’s squeeze toy, the brown towhee takes to his human habitat as freely as a house sparrow, and the crestless Mexican jay scolds ferociously, as jays will.
The Jackrabbit Economy
Should the jackrabbit reflect on its situation it might think life is a conspiracy. This prolific breeder might feel it exists solely to keep the local web of life functioning. Many predators include this big-eared, nimble-footed creature in their diets.
Big ears, big feet, and protective coloration are the jackrabbit’s major survival mechanisms. It will listen for danger, sit motionless until perceiving a threat, and then burst into speedy flight. The ears may also represent an adaptation through which the jackrabbit can emit excess body heat to the environment, a useful ploy in deserts.
Birds, snakes, and numerous mammals prey on the jackrabbit, which is really a hare, and on the park’s desert cottontail and eastern cottontail rabbits. The coyote can sustain bursts of speed sufficient to run them down. An arch opportunist, the coyote eats almost anything, including an occasional tennis shoe. The bobcat and mountain lion (photo [page 103]) are the park’s two felines. The bobcat hunts by stealth. It will sit by a game trail for hours and then pounce on passing prey. Threats to the jackrabbit come from above, too, where the golden eagle soars.
Coyote
Bobcat
Golden eagle
Toward twilight the whitetail deer put in another appearance. These dainty little animals are highly territorial, so you are likely to see the same band of bucks in the upper Basin, and the same doe and twin fawns near the campground turnoff. The eastern cottontails, larger than the desert cottontails, also come out at dusk, after spending the day in the very same thickets that the deer come to browse. A little later, skunks may appear. These spotted, striped, or hognosed nighttime foragers are cyclic in their populations, and like the raccoon they have a decided fondness for campgrounds.
In the Basin as elsewhere, many residents are heard rather than seen, especially the tree crickets and katydids that sing their songs at night. The Chisos Mountains even boast their own katydid, known nowhere else in the world, the Big Bend quonker. Scraping its wings together it produces a squeak much like that of a cork being pulled from a wine bottle.
The woods that rim the Basin to the south have a softer, more life-supporting look than the slopes above Panther Pass. They feature the same junipers and pinyon pines and the same pricklypear and century plant, but the difference is the grass. Tall and short, gold and blue, tasseled, tufted and feathered, it grows so thickly under the trees and between the shrubs that it all but covers the ground. You find basketgrass, too, with leaf edges like fine sawteeth and their tips frayed into curls of twine. With such abundant cover animals should thrive, and judging from the scat they do. In the fall the pricklypear is still in fruit, and it appears that everyone is eating brick-red tunas. At lower elevations where the tunas have already gone by, many animals are eating black persimmons.
But strong as the signs of life are, the evidence of death and dying cannot be ignored. You hear the shrieks of some creature on the edge of a little meadow, watch a hawk come to circle the tree tops, wonder who has won that contest as the cries cease and the hawk flies off. You smell the pungent odor of pine resin and follow it to its source, a pinyon oozing crystal drops from dozens of holes. As the sticky stuff ages it turns yellow, and there, mired in the gum, is a small black beetle exactly as some fossil bee in amber. And here is a redberry juniper so strangled by pink tree-thief that the greenest thing on it is the mistletoe cluster.
The mountain lion’s mystique explains the many park place names that bear its alias, panther. Most park sightings of these regal cats occur at Panther Pass, usually in May or June.
Quicksilver Mining
Quicksilver, or mercury, the only metal that remains liquid at ordinary temperatures, was mined as cinnabar in the Big Bend country from about 1884 until after World War II.
Cinnabar, red mercuric sulphide, was used as a pigment and medicine as early as the first century. Indians used it as pigment for war paints and pictographs. Today mercury is used in electrical apparatus, control instruments, thermometers, and medical and dental preparations. The United States once produced about one-third of all quicksilver. From 1910 to 1920 Texas mines produced about one-third the U.S. production. Locally, quicksilver mining began in 1884, but real production began after 1896. The park’s Mariscal Mine was opened as Lindsey Mine by D.E. Lindsey, an immigration inspector, about 1900. Production increased greatly about 1916, under the ownership of W.K. Ellis, as World War I pushed up quicksilver prices. The mine floundered again with postwar price declines and was not profitable anew until World War II. In the Mariscal Mine’s heyday between 1919 and 1923, from 20 to 40 men worked it. All were Mexicans except the manager, foreman, and a brick-kiln specialist. Wood for the furnaces came from as far as 80 kilometers (50 miles) away, by burro. These photographs show quicksilver operations at the Waldron Mine, just outside today’s park, in 1916. Laborers toiled 12-hour shifts for $1.00 then.
Aplomado falcons once ranged this far north and east, but no longer. Now that the national park offers a large protected area, we hope these birds of prey will return.
The death of trees is actually part of the continuing cycle of life because it returns much needed nutrients to the soil. Termites play an important role in converting dead wood into substances useful to plants although they cannot digest the wood themselves. Tiny protozoans living in their intestines secrete digestive juices that do the job for them. Dead trees also provide nesting and resting places for various birds and mammals: Screech owls and mice may make their homes in hollow trees and logs, and so may the ringtail, gray fox, and bobcat. These four mammals are adept tree climbers. The brush mouse climbs to garner pine nuts, acorns and juniper berries, while the ringtail and gray fox add berries to supplement their largely meat diet. The bobcat, as sure-footed aloft as other cats, will take to the trees when pursued but prefers to hunt on the ground.
The bobcat, so-called because of its short tail, limits his diet to mammals, birds, and insects. This smallest and most common of the wild cats prefers rocky canyons and outcrops in pine-oak woodlands. Hunting mostly at night and on the ground, he prowls on padded feet, hides for hours beside a game trail, and springs on his prey in one lethal pounce. The ringtail is the busiest of small predators. Strictly nocturnal, he covers a wide territory several times each night. He has much the same tastes as the raccoon, but without the latter’s fondness for water. The ringtail especially likes to prowl rocky ledges and canyon cliffs on the lookout for insects and small rodents. He climbs easily and hunts in trees for roosting and nesting birds.
Water, those rare spots where it occurs permanently, can do astonishing things to a woodland. In a secluded canyon you’ll find a grotto no bigger than a room, with countless seeps trickling down the face of a high, nearly dry waterfall. At the foot of the fall, maidenhair ferns and stream orchids crowd beside a deep pool, while redbud, oaks, and maples canopy a burbling brook. The sun rarely reaches this rock garden, so that at midmorning it is significantly cooler than the grassy slopes nearby. The water in the main pool is even cooler. So many big boulders lie heaped across the canyon that few animals can reach the water, yet all sorts of creatures live here. You’ll find leeches in the pool, and, looking like a shelled peapod, a dead katydid’s exoskeleton gutted by water insects. You’ll hear a canyon wren echoing its own song, and spy tiny canyon tree frogs clinging to trees and rocks with sticky little suction-cup mounted toes. Tiniest are the mites living in parasitic comfort on the tree frogs. Such microenvironments stand in surprising contrast to the grandiose environment of the mountain masses surrounding you here in the Chisos, and elsewhere.
People call one particular spot high in the Chisos the top of the world. If you sit there at sunset you can watch the turkey vultures describing long, lazy figure eights from the top of the world down to the Window and back. At that time of day those vultures, not looking for food, simply seem to be enjoying their world and being alive. In those sunset cruises they’re living to the limit of their unique life form—and are glorifying Big Bend!
Big Bend’s future, as its past, will be ruled in the long run by triumphant nature. The vulture’s self-celebration almost portends this. If we are entering another Ice Age, what a new lease on life this will be for the high mountain forests of Douglas-fir, ponderosa pines, Arizona cypress, and quaking aspen. What vindication for the staying power of these many beleaguered species. If on the other hand the desert pushes on, the summer rains don’t come, and the springs dry up for good, then Big Bend’s big trees will vanish like the dinosaurs.
Such events are beyond our power to influence or foretell. Indeed, change may be so imperceptible, so slow, that people, supposing there are people left in Big Bend, may find it perfectly natural. Or change may be catastrophic, and those last Big Benders disappear without a trace, as though snatched off the Earth. And those, if any, who come after may then marvel over ruins and artifacts and ask what drove these Ancients from their homes.
The peregrine falcon’s easy soaring belies its diving speeds of up to 320 kph (200 mph). Peregrines nest in the river canyons and high Chisos.