Big Bend National Park

Big Bend National Park

Natural World

Park resources and wildlife

Below are commonly asked questions about park resources and wildlife in the Big Bend. Please contact us, use the site index, or look elsewhere on the website if your question is not answered here.

Didn’t you recently get a new addition to the park?
The Harte Ranch (North Rosillos) became part of the park in 1989. The Fay Ranch, a 10,000 acre inholding near Persimmon Gap, was purchased in 1994.

Big Bend Ranch State Park, to the west of Big Bend National Park, was purchased by the State of Texas and is now part of the system of state parks. It was opened to the public in January of 1991. The new state park is a little under 250,000 acres. Information is available at the Barton Warnock Environmental Education Center in Lajitas (tel. 432-424-3327) or at Fort Leaton State Historical Park, near Presidio (tel. 432-229-3613).
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When do the wildflowers bloom?
Generally, desert plants bloom in the spring, while plants in the Chisos Mountains bloom in the late summer, during the rainy season. March and April are probably the best time to see the park in bloom, but flowers can be seen almost throughout the year. Every year is different, depending on rainfall levels. Big Bend does not always look like the pictures on postcards. It is very difficult to predict when the best weeks will be.
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Are there many snakes in Big Bend?
Big Bend has 30 species of snakes, only 7 of which are poisonous. They include 4 types of rattlesnakes (Rock, Mojave, Western Diamondback, and Black-Tailed) as well as the Trans-Pecos Copperhead and 2 species of rear-fanged snakes. Most of the snakes that people see here are not poisonous, such as patchnose snakes, garter snakes, and bull snakes. Snakes, like all other animals in the park, are protected. Please do not harass or harm them.
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Do I have to worry about mountain lions?
Lions are most active at night, and few people see them during the daytime. Most sightings occur in the Green Gulch area (the road into the Basin), but sightings can occur anywhere in the park. A lion sighting is a rare event. Report any sightings to the nearest visitor center, and follow the safety rules concerning mountain lions if you should encounter one on a trail.
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Where can I go to see the Colima Warbler?
This bird is often sought after by birdwatchers, as Big Bend is the only place it can be seen in the United States. It is usually in the park from mid-April through August. Since it is only found in high elevations of the Chisos Mountains, plan to hike several hours to look for it. The best places are Boot Canyon, the Colima Trail, Laguna Meadows, and the upper section of the Pinnacles Trail. Sometimes people report Colima Warblers along the Lost Mine Trail, too.
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How deep is the river?

The depth of the Rio Grande is variable with the seasons; highest water is in the summer and early fall, lowest in the winter. It can range from only a couple of feet deep to 20 feet or more when flooding.

After Dark

As the setting sun slips below the western horizon a parade of colors dances across the mountains and sky. Another day has come to a close in the Chihuahuan Desert. This spectacular ending takes with it the scorching temperatures that keep much of the wildlife out of sight. As the temperatures slowly fall, things begin to fly, slither, creep, and crawl in the cool darkness of the desert night. Now is the time to experience a different side of Big Bend National Park, the night life.

You can begin your night time adventure by watching a breathtaking sunset. The clouds above the desert floor turn a crimson red followed by a rich, golden yellow, and finally an ashen gray. Watching this drama unfold can take away the build-up of everyday frustrations. So, where is the best spot to catch this nightly event? There is really no best place to view a Big Bend sunset, but some favorite spots are the Window View Trail in the Chisos Basin, Sotol Vista along the Ross Maxwell Scenic Drive, Maverick Junction, and the Rio Grande Village Nature Trail. From any of these places you'll get a wonderful panoramic view of the park's scenery and a sunset you'll never forget.

Dusk descends upon the land and many animals leave their hiding places to forage in the night. For these animals the cloak of darkness helps protect them from some predators and they avoid competing with diurnal animals for food. It's a perfect time for you to see more than the tracks or scat they leave behind. Dusk and dawn are the prime viewing times for wildlife in the park. Often, these animals are just off the road's edge enjoying the soft grass. Be sure to take it slowly as you enjoy your drive, because the jackrabbits, mule deer, and javelina are notorious for jumping in front of your car. Rattlesnakes are attracted to the warmth of asphalt and the abundance of rodents and other prey along the roadside.

On those occasions when a full moon graces the sky you may have the feeling that you're being followed because of your shadow. The high pitched howl of the coyote singing to the moon pierces the night air and you strain to determine which direction the sound is coming from. About that time an owl passes by on silent wings. This is also the time that bats take flight to navigate the night sky in search of food.

With the fading of sunlight, the sky begins to reveal a most impressive display. One by one stars begin to twinkle with the brilliance of diamonds in the night sky. Many visitors are amazed by the infinite number of stars overhead. The remoteness of Big Bend National Park makes it a stargazer's paradise. There is no light pollution from city streets and shopping centers. It's as if you can see the entire universe. Do astronauts get this same feeling while in space? Here, it's easy to see how the Milky Way got its name as it spills across the sky from horizon to horizon. A delightful way to take in this celestial celebration is while enjoying the warm waters of the old bath at Hot Springs, near Rio Grande Village. While soothing sore muscles after a long day's hike, tilt your head back and enjoy the drama unfolding overhead. What better way to end a perfect day in Big Bend National Park?

Exploring Big Bend National Park is fun and challenging, especially at night. Always think safety first: carry a flashlight, drive a little slower, and follow park rules. No matter how you choose to spend your night—enjoying a sunset, looking for wildlife, soaking in the hot springs, or counting shooting stars—there's a whole other world in Big Bend at night. Who could even think about sleep with all this going on?


The Stars at Night are Big and Bright...
What are the boundaries of Big Bend National Park? Most of us would reply in lateral terms, defining the "ground level" boundaries of the park. Yet what about the park's vertical boundary? We cannot define an upper limit to Big Bend National Park. Panoramic views of the horizon extend for almost 250 miles on a clear day, but on a clear night we can see as far as 2 million light years away to the Andromeda galaxy! (Converted to miles, that's 13.2 x 10 to the 17th power or 13,200,000,000,000,000,000 miles.) At night we look back in time as well as across space. For instance, when we see the reddish star Antares in the constellation of Scorpio, we're looking at light that takes 500 years to reach us.

Several factors make Big Bend an excellent place for night sky-watching. Our remote location, far from any large towns, provides naturally dark night skies. Big Bend's infrequent cloud cover and low humidity, especially in winter, allow for sharp visual acuity.

Casual observation and detailed study show that winter skies in Big Bend are the cleanest, compared to air quality at other times of the year. A great deal of air pollution blows into the park from sources in Mexico and other parts of the U.S. in the summer, but northerly winter winds bring much less debris. One more attribute to winter sky-gazing in Big Bend: the nights are longer than the days, so take advantage of them!

For city-dwellers accustomed to seeing only a handful of stars, Big Bend's star-laden skies can be dazzling and a little intimidating. On the clearest nights, around 2,000 stars are visible to the naked eye. Add a few planets and some "shooting stars", or meteorites, and you've got a nocturnal display that's well worth the cold weather! You don't need a telescope to observe the night sky, although some people use binoculars.

As it becomes increasingly difficult to find places free of air pollution and light interference, places with dark, clear night skies become that much more valuable. The noted Englishman Havelock Ellis said, "The moon and stars would have disappeared long ago had they been within the reach of human hands." Though they still remain far from our reach, we are indeed losing sight of the stars through the work of our own hands.

The Rio Grande

The Desert's Lifeblood
"At the heart of the desert there is no drought, there is only an occasional mitigation of dryness," so stated western historian Walter Prescott Webb. Big Bend National Park marks the northern extension of the Chihuahuan Desert, the largest of North America’s four deserts. Although water sources dot the landscape and flash floods occur after heavy rains, the Rio Grande provides the park’s most prominent source of water.

The Rio Grande begins its journey to the Gulf of Mexico from springs and snow melt high in the southern Rocky Mountains of Colorado. Along its way to the sea, the Rio Grande travels almost 2,000 miles. As it flows southward, its waters are diverted for flood control, irrigation, power generation, municipal uses, and recreation.

By the time the Rio Grande leaves El Paso, so much water has been diverted that the riverbed between El Paso and Presidio often lies dry. Depending upon annual rainfall patterns, 69 to 86 percent of the water in the Rio Grande downstream from Presidio flows from the Mexican Rio Conchos, which originates in the Sierra Madre of western Chihuahua. The Rio Conchos joins the Rio Grande near Ojinaga, Chihuahua and Presidio, Texas.

For more than 1,000 miles the Rio Grande serves as the international boundary between Mexico and the United States; Big Bend National Park administers approximately one-quarter of that boundary. The Rio Grande also defines the park's southern boundary for 118 twisting miles. It is within this stretch that the Rio Grande's southeasterly flow changes abruptly to the northeast and forms the "big bend" of the Rio Grande.

In 1978, Congress designated a 196-mile portion of the Rio Grande as part of the National Wild and Scenic Rivers System. Only the upper 69 miles of the Wild and Scenic River lie within the park's boundary; the remaining 127 miles lie downstream of the park's boundary. The Wild and Scenic Rivers Act directs that designated rivers " preserved in free-flowing condition, and that protected for the benefit and enjoyment of present and future generations."

Because the Rio Grande serves as an international boundary, the park's jurisdiction extends only to the middle of the deepest river channel; the rest of the river lies within the Republic of Mexico. On the Rio Grande Wild and Scenic River section downstream from the park's boundary, the park administers only from the gradient boundary at the river's edge on the United States' side to the middle of the deepest channel.

The Rio Grande corridor and its associated natural systems, cultural resources, and recreational opportunities comprise prime visitor attractions. River flow quantities and water quality, however, threaten those natural systems and recreational opportunities.


Big Bend is famous for its natural resources and spectacular geology. The park is home to more than 1,200 species of plants (including approximately 60 cacti species), 11 species of amphibians, 56 species of reptiles, 40 species of fish, 75 species of mammals, 450 species of birds, and about 3,600 species of insects. The park boasts more types of birds, bats, and cacti than any other national park in the United States.

Big Bend National Park also marks the northernmost range of many plants and animals, such as the Mexican long-nosed bat. Ranges of typically eastern and typically western species of plants and animals come together or overlap here. Here many species are at the extreme limits of their ranges. Latin American species, many from the tropics, range this far north, while northern-nesting species often travel this far south in winter. Contrasting elevations create additional, varied micro-climates that further enhance the diversity of plant and animal life and the park's wealth of natural boundaries.

Big Bend Blooms

Watching Cactus and Wildflowers
Feel free to observe, describe, and photograph flowers and inform park staff if you think something is noteworthy. But remember to help preserve our flowers. Do not pick or trample plants. Take only pictures and memories, and leave only footprints. Happy botanizing!

Elevation and weather play important roles in each season's blooming period; the higher elevations of the park generally bloom later, and the first blooms usually appear along the Rio Grande, in the lowest portions of the park.

Common Plants

Agaves are a low growing evergreen plant with succulent leaves that form a bowl shape or basal rosette. Colonies are often formed from the underground sprouts. The leaves are tipped in a hard spine and the leaf margins may also have spines. Agaves bloom once in their lifetime and then die. The rapidly growing flower stalk seems to exhaust all of its resources to survive. The fruit is a brown capsule with three cells and two rows of black seeds. There are eleven species of agave in Texas. 

There are three agaves in Big Bend National Park. Agave lechuguilla, commonly called lechuguilla, is the indicator plant of the Chihuahuan Desert. This means it is only found in the Chihuahuan Desert and nowhere else in the world! Lechuguilla was a very important source of fiber for Native Americans and is still used today to make rope in Mexico. The roots of the plant are high in saponins, so they taste bitter but are a good source of soap. The lechuguilla blooms once after growing three to twenty years. 

Agave havardiana or the century plant is the largest agave in the park. It blooms once in its life after growing 20-50 years. Mexican long-nosed bats pollinate the bright yellow flowers. The leaves of the century plant have a blue-gray color. The century plant also provides an excellent source of fiber for ropes, mats, sandals, etc. The hearts of the plants were harvested by the Native Americans and then baked in a stone lined pit for two to three days. Once baked, the plant provided a source of food that could be dried and stored to help them to survive the long winter. The dried flower stalks served as building material. Century plants in Mexico provide the alcoholic beverages of pulque, mescal, and tequila. 

The third agave in Big Bend National Park is actually a hybrid. Agave gracilipes is the plant that occurs when the century plant and lechuguilla cross breed. It looks like a large lechuguilla or a small century plant. It also provided fiber for the Native Americans.

Sotol (Dasylirion liophyllum) is composed of a cluster of numerous linear, flattened leaves that have hooked teeth along the margins of the leaf. The leaf bases are spoon-like. A tall flower stalk is produced each spring that has light colored, nondescript flowers clustered together. The fruit is three-winged and triangular. Twenty species occur in southwestern U.S. and Northern Mexico. 

Sotol was an important source of materials for basket making. The young flower stalks were eaten, as were the seeds. The heart of the plant was cooked along with agave hearts in a stone-lined pit for several days and then eaten. The stalks were used to make temporary shelters, porches, roofs, corrals and walking sticks. When the sap is fermented it produces the alcoholic beverage also called sotol.

Nolina species have linear leaves that are long, numerous, and clustered. Margins of the leaves are finely toothed. The flower is short stemmed, with cream-colored flowers. The leaves were an important source of material for mats, sandals, and basket making. However, the plant was not eaten since it is poisonous and could cause liver and kidney damage. There are five species in the Trans-Pecos area and 30 species in the U.S. and Mexico.

There are 45 species of oaks (Quercus sp.) in Texas and nine in Big Bend National Park. These trees or shrubs have simple alternate leaves with margins that are smooth, lobed, or toothed. The fruit or acorn is one celled, one seeded, and sits in a cup that partially envelops the seed. Hybridization is common among oaks. The oaks of Big Bend National Park are relic species—left behind on the mountaintops from a cooler time. The acorns on most species are edible. They need to be soaked in water before eating to remove some of the bitter taste. The early settlers of this area commonly made a flour or meal from the leached acorns. Oaks produce a hard wood important for firewood, tools, and furniture making.


Big Bend National Park is home to over 1300 plant taxa (about 1200 species). Hundreds of these species and varieties are showy, fragrant, or unique-looking enough to be generally categorized as "wildflowers". In the Big Bend, we usually have two major flowering periods per year - spring and late summer. The spring flower season, because it depends largely on the amount and timing of winter precipitation, is less predictable than the summer season, which is fueled by the dependable summer monsoon.

Many annual plants like bluebonnets and some mustards will only bloom in early spring. The majority of the 46 cactus species in the park bloom in mid to late spring. Many of these cactus species produce very large, showy flowers in varying shades of yellow, red, pink, and purple. The yuccas, including the impressive giant dagger, usually flower February-April. Many shrubs and small trees, such as the fragrant yellow huisache in the southeast part of the park, and the bright purple fruity-smelling Texas mountain laurel also bloom in March and April. In March and April, bright red bunches of flowers emerge at the ends of the spiny whip-like branches of ocotillo and provide nectar and pollen for hummingbirds, bees, and butterflies. The spring flowering season frequently starts in late February along the Rio Grande and proceeds upslope to the foothills of the Chisos Mountains by late April.

The late summer flowering season is dominated by members of the sunflower family. These plants are sometimes called composites because the "flower" is actually a tightly clustered group of very small individual flowers. Most summer-flowering composites are yellow or white, with yellows being abundant in the Chisos Mountains. The summer season also brings red, blue, and purple true sage flowers to the Chisos. These fantastic shows can last well into the fall, before the first freezes hit the mountains. Another group of plants commonly called "desert sage" or ceniza grows in the mid- and lower elevations of the park and produces magenta and purple flowers quickly after significant summer rain storms. These are not sages (genus Salvia) at all, but are members of the figwort family.

Many plants are opportunistic flowerers and will bloom whenever it is warm and wet enough, from February through November, and even sometimes in the middle of winter. Several yellow composites, like the forbs yerba raton, dogweed, paperflower, and the shrubby skeleton-leaf goldeneye bloom almost continuously in wet years. Many thorny acacia species will produce white to yellow blooms opportunistically throughout the warm months. The most common perennial mustard in the park, the wonderfully fragrant bi-colored mustard, can bloom extensively in the spring and then again, though less spectacularly, in late summer.

Angiosperms (flowering plants) like those mentioned above are the most numerous and diverse group of plants is the park, but dozens of gymnosperms (cone-bearing plants like pine and juniper) and non-seed producing plants (ferns) also grow here, especially in the cooler, wetter Chisos Mountains. Not all "flowering" plants produce stereotypical colorful petal-bearing flowers. In fact, one of the most important and diverse families of flowering plants in the Big Bend (and the world) is the grass family. Grasses produce numerous small, reduced flowers in a wide array of flower arrangement, all well-adapted to wind pollination. Viewed up close with a hand lens or macro camera lens, these diminutive flowers can be quite beautiful when they produce flowering tillers in the rainy season.

Wherever you are in Big Bend, no matter what time of year, you are likely to find something in bloom. In the spring and late summer you may be astounded at the abundance and variety of wildflowers. But remember that this is a desert, and long dry periods are not uncommon here, so there are times when flowers are few and far between. "Drought" is a natural part of this environment, and these plants have adapted to survive the dry periods. Remember also not to pick or trample our wildflowers so that they can live, grow, and flower another day.


Big Bend National Park is a great place to learn about plants! Many of the plants here in the Chihuahuan desert have spines or barbs that might catch on your cloths as you walk by them. These spines are to protect the plant from animals that might be after thier water or fruits. Those that do not have spines, will catch your eyes with thier flowers or general appearance. Over 1,000 species of plants are found within Big Bend National Park. In recent years park botanists, technicians and volunteers have found many new species and rediscovered some that haven't been seen in years. One of those plants, Hidalgo ladies tresses hasn't been seen in over 60 years!

Sixty years of botanical exploration

The Chisos Mountains, with their high diversity and sky-island habitat, have historically attracted many amateur and professional naturalists. Despite the remote location and difficult access of this rugged mountain range, the majority of the plant species in the Chisos were well-documented by the founding of the National Park sixty years ago. As far back as 1885, pioneering botanist V. Havard recognized the unique character of the Big Bend flora and described many species previously unknown and endemic to the region. In fact, the efforts of these early naturalists, including Omer Sperry, C.H. Mueller, and E.G. Marsh, helped clarify the importance of protecting the diversity of the region by creating Big Bend National Park.

In the past sixty years, the park staff and cooperating scientists have built upon this knowledge base. In the 1950s and 60s, Barton Warnock, the longtime botanist at Sul Ross State University in Alpine, Texas, was instrumental in documenting plant species occurrence and habitat requirements and establishing long-term ecological monitoring plots in the park. Park staff use these data to design and implement restoration and conservation projects to maintain the fantastic diversity of life in the Big Bend.

Current projects include grassland restoration in the Harte Ranch area, fostering riparian recovery at upland springs, weed control and re-establishment of native plant communities in disturbed areas, and the cautious re-introduction of fire as an ecosystem process in grasslands and woodlands.

Park Biologists are currently mapping rare, endemic, and threatened plants parkwide. We use these data to protect existing known populations and to define habitat conditions of rare plants. In 2004, we are focusing on orchids. At least nine species of orchid occur in the park, with seven species being considered rare or very rare. Several species of saprophytic coralroot occur only in a few mountain ranges in Trans-Pecos Texas and adjacent Mexico. Big Bend National Park is one of the only protected areas in the Chihuahuan Desert that supports such orchid diversity. Recently, the rare plant mapping project uncovered a rare gem that had not been seen in the U.S. since 1931 -the Hidalgo ladies-tresses. Knowledge of the location and habitat of this and other rare plants allows us to prevent accidental disturbance of populations and to make decisions about the appropriate use of wildland fire in these systems.

Knowledge is power. Big Bend National Park is committed to using the ecological knowledge, and associated decision-making power, accumulated by dedicated staff and scientists, to protect these fragile ecosystems for the next sixty years and onward.

More Common Plants

Prosopis glandulosa, or honey mesquite and Prosopis pubescens, screwbean mesquite, are both found in Big Bend National Park. These shrubby trees are armed with straight, stout spines that are solitary or paired, and have deep, drought-defying roots. The fruit is a tough pod where the seeds are partitioned and embedded. The fruits were an important food source for the Native Americans. The developing pods are sweet raw or cooked. The seeds are also edible and could be ground into flour or meal. The meal could be mixed with water to make a lemony drink. The drink was also fermented. The sap or pitch, was used to waterproof baskets, make candy, and produce a black dye. The sap was mixed with mud and plastered on the head. Once dry, it was removed leaving the hair shiny, black, and lice-free. The inner bark and roots were a source of fiber for baskets. The hard wood was an important source of tools and weapons. Today mesquite is used in posts, carvings, tool handles, gunstocks, and for barbecues.

Piñon Pine
Pinus cembroides, or the Mexican piñon pine, is a small evergreen tree with needles in clusters of two to five. They produce a woody cone that matures in two years and produces an edible nut. Although the nut has a hard shell, it is very tasty and was prized by the Native Americans. The nut stored well for winter and was high in protein and calories. This tree was once more widespread in cooler times and is now considered a relic species. It provided pitch or sap for waterproofing baskets, chewing gum, and also was used medicinally to treat sore throats and remove splinters. A tea made from the needles is high in vitamin C.

Rose-fruited juniper, Juniperus erythrocarpa, is the shrubby juniper of the park. Typically growing no taller that five feet, the alligator juniper, Juniperus deppeana, has checkered or scaly bark and is taller and more tree-like than other junipers in the area. Drooping juniper, or Juniperus flaccida, is common in Mexico but only found in the U.S. in the Chisos Mountains of Big Bend National Park. Its needles droop causing this small tree to appear like it always needs a drink of water. The bark of all three juniper species provided a source of fiber for sandals, mats, and baskets for early Native Americans. The cones are small and berry-like, and were used in seasoning meats and for beads in necklaces.

Yuccas are members of the lily family and bloom every year if there has been enough rainfall. The four yuccas of Big Bend National Park, Faxon yucca or giant dagger (Yucca faxoniana), beaked yucca (Yucca rostrata), soaptree yucca (Yucca elata) and Spanish dagger or torrey yucca (Yucca treculean), all have trunks that elevate the leaves above the ground. The trunk is often covered with dry, dead leaves. The leaves are long, fibrous, and spine-tipped. The cream-white flowers appear in late spring and produce a fleshy or dry fruit with black seeds. The flowers are pollinated primarily by the yucca moth. Native Americans ate the flower buds, petals, and young stalks. The fruits and seeds were also eaten. The fibrous leaves were used to make cloth, rope, mats, sandals, and baskets. The root provided soap and was used as a laxative.

Prickly Pear
There are sixteen species of Opuntia in the Trans-Pecos area of Texas. These species tend to hybridize, so it is often difficult to determine which prickly pear is which. There are two general varieties. The chollas that have cylindrical stems and the prickly pears that have flattened stems. The cacti have spines instead of leaves to conserve water and carry out all food production through the stems of the plants. The spines are numerous and can be yellow, brown, pink, red, or black in color depending on the species. The flowers appear in April and are usually yellow (prickly pears) or pink (chollas). Fruits are usually maroon (prickly pears) or yellow (chollas) and some varieties are very juicy and sweet. The Native Americans ate these fruits, called tunas, and today we use them to make jellies and syrups. The young cactus pads or nopals were used as a potherb (like greens) or pickled. Their taste is typically described as a cross between green pepper and okra. The seeds were eaten in soups or ground up for flour. The pads were sometimes split and soaked in water and could be used to bind wounds with the sticky side down. The insides are similar to aloe vera and softened the skin and lessened pain. The bitter juice from the pads could be used as an emergency source of water. In Mexico, fields of prickly pear are grown for a scale insect, the cochineal, which grows on the pads. This insect is used to produce a beautiful natural purple dye.

In terms of geographic distribution and the number of individual plants, the grass family is the most successful flowering plant family in the world! Over 8,000 species exist worldwide, covering one-third of the planet. They are found in the tropics, marshes, forests, tundra, and desert environments. Native Americans harvested over fifty kinds of grass seeds. No one type was considered an important food source, but when combined the seeds had many uses. The seeds could be boiled for a mush, made into bread, ground into flour or meal, and used to thicken gravy. The seeds could be eaten raw, but tasted better dried, roasted, or ground. The leaves of many species were used to make baskets, mats, or flutes. Today two-thirds of the crops cultivated on earth are cereal grasses such as wheat, rice, corn, oats, barley, rye, millet, sugar cane, and hay.


The coyote, Canis latrans, is a native of the grasslands, but is now found coast to coast in the United States. It lives in the grasslands, deserts, temperate forests, woodlands, swamps, sub-alpine areas, and even in major cities. Despite the billions of dollars spent on predator control projects throughout the U.S., the coyote is more abundant than ever. The coyote has filled the void left by the disappearance of the wolf.

The reputation of the coyote as a predator of big game and livestock is exaggerated. Over half of a coyote's diet are rodents like gophers, squirrels, and mice. They also eat rabbits, hares, grasshoppers, and other insects, frogs, salamanders, snakes, fish, birds, and eggs. Road kill, carrion, and injured animals are also eaten. Berries, nuts, and grasses are sometimes consumed. A coyote will cache or store food. Most of the time a coyote is a lone hunter. Using its keen senses of hearing, sight, and smell, the coyote locates its prey. The coyote will immobilize its prey, with its sharp teeth, grasping it by the throat and suffocating it by tooth punctures around the throat. A coyote may combine hunting efforts with one or two others, running in relays to tire the prey or waiting in ambush while the other chase the quarry towards it.

The coyote or song dog is known in the west for its howls and high pitched yipping. Coyotes don't bay at the moon just to enjoy themselves. The barks, yaps, yips, growls, and howls are a means of communication to help keep the band together. Coyotes mate for life. Mating usually occurs between January and March. After a gestation period of about two months, a litter of two to twelve pups are born. Five or six pups are average. A typical den is five to thirty feet long with a nesting chamber. It can be dugout in a hillside, in a cave, under a log, in a culvert, or be an old fox den. Regardless of where the den is, it will be well hidden and underground. If the den is discovered or disturbed, the coyote will change dens. The male helps raise the pups by hunting for their food. Young from a previous litter may help raise the new litter. This helps increase the new litter's survival rate and teaches the helpers about raising pups. The pups will leave the den at about one-month old to play, learn, and grow. One adult will be with the pups at all times. They are weaned by the summer's end. Parents will then carry food in their stomach and disgorge a partially digested meal for the pups outside the den. They begin to teach the pups how to hunt and by late fall they can survive on their own. Coyotes survive in the wild an average of six to eight years.

Coyotes tend to travel well-established paths. Their home range is 40 to 100 square miles. Scat is left at intersections as a sign of their territory. Tracks show four toes per foot with claws. The hind foot is slightly smaller than the front. Coyotes can leap up to 14 feet. They easily run up to 30 mph and can reach 40 mph in a sprint. Coyotes run with their tails down (wolves run with their tails horizontal and domestic dogs with their tails up). Coyotes are half the size of wolves, standing two feet high at the shoulder and four to five feet long from the nose to the tip of the tail. They weigh 30 to 70 pounds, and the female is smaller than the male. Their fur is gray to red gray with light under parts. The long legs show a dark vertical line on the lower forelegs. The bushy tail has a black tip and the ears are prominent. The snout is slender and pointed.

No matter what name Canis latrans is called - coyote, song dog, God's dog, prairie wolf, brush wolf, trickster- it is a symbol of the wild and free, a symbol of adaptability. It has survived where other carnivores have not and provides vital population control of rodents and other small mammals. It serves as "the garbage man" cleaning up carrion and road kill. The mournful howls and excited yips are a sound many treasure when heard in the Big Bend.

"Vulture Culture"

With its greater powers of flight, the turkey vulture has a much larger range than the black; found from southern Canada to the southern tip of South America. Populations in the north and west of North America are migratory, including the turkey vulture of Big Bend. They arrive in early March, some members of the population nest, then they all depart to Central and South America in the autumn. Black vultures range from the eastern and south central U.S., down through Mexico and South America. They are mostly non-migratory across their range and here are resident year-round, but never common. In Big Bend, turkey vultures are found from the mountains, through the desert, and down to the Rio Grande. Black vultures are seldom found away from the river.

Seen up close, neither the turkey nor the black vulture inspire words of praise. Both have un-feathered heads, the adult turkey vulture displaying the characteristic red-skinned head, while the black vulture has a wrinkled, black-skinned head. Both have long bare legs, often discolored by their habit of defecating on themselves for cooling. The talons are weak and the hind toe small and nonfunctional. Because the talons are almost useless for defense, both will, if threatened while nesting or roosting, either fall over and play dead, or vomit. Anyone who has had the misfortune to hit a vulture while driving can attest to the extremely foul odor of the vomit that is rendered in a final act of defiance.

Fortunately this is rare, and most people see vultures on the wing or in their large social roosts. A common behavior at the roost is the spread wing posture in the early morning. In the case of the turkey vulture, this activity serves to aid thermoregulation. In the evening a turkey vulture's body temperature drops to conserve energy. In the morning, spreading the wings to the sun's heat brings the body temperature back up quickly and allows the bird to prepare for flight. On rainy or cloudy, cool days, vultures seldom take to the air.

Both vultures are predominately carrion eaters. The family name for the New World vultures (Cathartidae) is from the Greek word meaning "cleanser," alluding to the tremendous service vultures and their kin provide. They patrol the air, finding and ridding the land of carcasses that, if left on the ground, could become harbors of disease. At one time in Texas and other areas where ranching occurs, vultures were killed because of the belief that they carried and transmitted anthrax and hog cholera. Recent studies have shown that these disease organisms do not survive passage through a vulture's digestive system and it has also been shown that vultures are immune to botulism. Vultures will on occasion eat rotting fruit and other plant material and are known to take small live prey, most often young, defenseless animals.

Because of similarities to true birds of prey, New World vultures were long classified as close relatives of hawks and eagles. Recent genetics studies however, strongly suggest that vultures are actually more related to storks.

One adaptation that sets the turkey vulture apart from most other members of the family is its well developed sense of smell. It was thought that all vultures found their food strictly by keen eyesight. In experiments using hidden carcasses, turkey vultures successfully found the carrion every time, always approaching into the wind on the scent of the food. In areas where turkey and black vultures coexist, usually the turkey vultures will locate carrion first by scent and sight. Black vultures, lacking a sense of smell, watch their cousins converge on a carcass, then descend and drive off the turkey vultures to take over the meal. It may not seem fair, but the end result is the same; a potential harbor of disease is removed and recycled once again.

Call them buzzards, carrion crows, zopilotes, auras, buitres, whatever name you choose. But always enjoy their amazing feats of flight, and be thankful for the service they render in cleansing the land.


Halfway between Laredo and El Paso, the Rio Grande swings southward to form a huge bend that is also the southern boundary of America's finest desert preserve - Big Bend National Park. Established in 1944 to preserve 1,200 square miles of Chihuahuan Desert and mountain grandeur, it contains & wide variety of Southwestern scenery. From the three great canyons of the Rio Grande to the rolling slopes and jagged peaks of the Chisos Mountains, the birder is offered exciting discoveries all months of the year.

It is this diversity that creates the great variety of plant zones, where more than 450 kinds of birds have been recorded. Yet Big Bend is best known for its specialties that occur nowhere else in the United States except within the Chisos Mountains or just within the border country of Texas to Arizona. Such unique birds as the Mexican duck, the Lucifer hummingbird, the Mexican jay, the black-capped and gray vireos, the Colima warbler, and the varied bunting do occur here at different times of the year.


Deserts aren't usually considered rich in amphibians, and yet twelve species are found in Big Bend National Park. Along the banks of the Rio Grande, Leopard Frogs grunt and chuckle and the high trill of the spotted toad may be heard on warm summer nights near springs and moist areas.

Big Bend's most intruiging amphibian is the Spadefoot Toad. Named after the hard "spade" on each hind foot, the spadefoot lives in the hot deserts of the park. The majority of its life, this toad is deep underground sealed in a gelatinous slime coat to hold in body moisture. When they hear summer rainstorms on the surface above, spadefoots frantically dig out to find tiny pools of collected rainwater. They quickly sing to attract others. Mating takes place, eggs are laid, and tadpoles develop to adults within two weeks-hopefully before the pools dry up.

Lubber Grasshoppers

Lubber grasshoppers are about three inches in length. Their wide, heavy bodies are shiny black with yellow pinstripes, and you'll see the flash of their rose-red wings when they fly. Like all other grasshoppers, they have strong mandibles for chewing. They are often seen in great numbers in the foliage of desert plants like mesquites and acacias,where they devour enormous amounts of leaves. They also eat their own dead, which leads to the piles of dead grasshoppers on the roads: when these slow-moving grasshoppers are killed by traffic, other grasshoppers come out to eat them and are often hit, and then even more cannibals come out to feed on them.

As in other animals, the bright coloration on the lubber grasshoppers indicates that they are toxic. Small mammals have vomited violently and even died after eating them. Birds, too, have died after eating them. Lubber grasshoppers sometimes secrete a foamy spray containing irritating compounds from their thoracic, or mid-body, region.

In addition to being virtually inedible, lubber grasshoppers appear to be highly heat tolerant, perhaps more than most other insects. They are often seen walking on roads in the heat of summer afternoons, when the surface temperature on the asphalt measures over 135 degrees.

Pick up a lubber, and you'll hear loud hissing as it forces air out of its spiracles, or breathing holes. It may also spit "tobacco juice" when handled. This brown liquid consists of partially-digested food material along with semi-toxic compounds, and it stains skin and clothing.

Durable, inedible, heat tolerant, and fearsome—the only enemies that lubber grasshoppers seem to have are moving vehicles. Once they learn that asphalt is meant to be crossed, not loitered upon, they'll be ready to take over the world.


A Birder’s paradise
Big Bend’s location, near the 100th meridian in the middle of the continent and along a migration route, is ideal for bird diversity at all times of the year.  While northern species migrate here to enjoy warm winters, birds from the tropics range this far north to breed in the spring.  One of Big Bend’s highlights, the Colima warbler, is only found in the United States exclusively in the Chisos Mountains of Big Bend National Park from April to September.

Remember, birds can be unpredictable and they do not read guide books. Stated simply, any advice provided herein should be taken as a general guide not a rule book or itinerary. We highly encourage visitors to find their own special birding places in the park. During any visit to the park, you should speak with other bird watchers to find out what is being seen and where.


Unfortunately, park staff are unable to observe birds regularly, though we are always interested in knowing what is out there. Park visitors are often our eyes and ears to rare or unique bird sightings.  If you have seen something that should be recorded (something listed as rare, sporadic, or otherwise not listed on the park’s checklist), please stop in to visitor center to fill out an observation report  Only the most detailed reports will be taken at face value, so be sure to report all necessary information such as a overall description of the bird, activity or behavioral comments, habitat, time of day, and possibly the most important: the exact location of where the bird was seen.


Owls are incredible birds. They live all over the world in the tundra, forests, grasslands, and deserts. There are 150 species of owls in the world, 19 in North America, and 12 of these have been seen in Big Bend National Park. Great horned owl, burrowing owl, elf owl, flammulated owl, eastern and western screech owl nest in the park. The barn owl, northern pygmy owl, northern saw-whet owl, short-eared owl and long-eared owl are rare or accidental visitors.

Owls are amazing creatures and well adapted predators. Owls eat mice, voles, shrews, rats, squirrels, lemmings, grasshoppers, fish, snakes, birds, skunks, rabbits, insects, spiders, scorpions, reptiles and even other owls. Some scientists estimate that one owl will eat 2,000 rodents a year, that's 5-6 per night!

All owls have a facial disk, an area of very short feathers arranged in a rounded pattern on the front of their heads. The facial disk helps collect sounds by funneling them to ears hidden beneath the feathers in the disk. Many owls have ear tufts - soft feathers that stick up and look like ears. But in reality, you can't see the ears since feathers hide them. Owl's ears are asymmetrical in shape, size, and placement. One ear is higher than the other so it can hear noises from above. One ear is lower to hear noises from below. This placement allows the owl to pinpoint the direction and location of sounds. Their hearing is so good, they can hear a mouse squeak up to a1/2 mile away! Owls can hunt by sound alone- locating a mouse under leaf litter or snow is easy with their excellent hearing!

Owls have large, fixed eyes at the front of their head. If our eyes were the same proportions as an owl, our eyes would be the size of grapefruits! Because their eyes are fixed and can't move, they must turn their heads to see an object to the side. Owls have very flexible necks with 14 cervical vertebrae and can turn their heads up to 270 degrees in either direction. This allows them to see more than a full circle of vision. They have binocular vision and can focus both eyes at once on an object for accurate depth perception. They can see during the day, but hunt at night when their prey is out. To adjust to the bright daylight, owls can close their pupils to a pinhole and lower their top eyelid. Scientists believe owls are color blind, seeing only shades of black, white, and gray. Their eyes have very few cones for color detection, but they have lots of rods for light reception. Their eyes are 100 times more sensitive to light than human eyes.

The owl's excellent hearing and eyesight make them effective predators, but they can also fly silently through the sky when hunting. Their wings are very wide and have soft comb-like edges to their flight feathers. This decreases the amount of disturbance from the airflow around the wings. The velvety surfaces and fringes on the back edge of their flight feathers muffles more noise. The owl molts yearly, but only one feather at a time, so it can always fly silently. Owls use their beaks and claws to smooth and tidy their feathers. The feathers are waterproofed with oil from a special gland. Owls even have short bristly feathers around their beaks that act like cat whiskers to help them sense objects around them.

Owls have sharp, curved, vice-like talons. They are made of keratin, which surrounds a living core. As their talons wear down, they continue to grow and get sharper. They are designed for catching and killing their prey. The talons clamp tight around a perch so the owl will not fall off a tree branch when sleeping. Owls have eight talons, one per toe, four per leg. Their hooked beaks are also made of keratin and are used for tearing food when they catch larger prey.

Owls are best known for their hooting calls, but they also shriek, bark, hiss, whine, and whistle. Owls call to attract a mate and defend their territory. Young owlets will call to beg for food from the adults. Owls will hiss or clack their beaks and tongues in self-defense and as a warning. Listening for owl calls is one way to locate them.

Owls are highly territorial and often live in the same area for many years. Unfortunately, their populations are decreasing due to loss of habitat and nesting sites. Poisons in their food also affect them. Owls will eat rodents that have fed on poisons or plants that were sprayed with pesticides. These poisons then concentrate in the owl's body cause illness or even death. Owls in Big Bend National Park are protected from habitat loss and contamination problems.

There are several ways to locate owls in the wild. Look for whitewash on trees and cliffs. Watch known holes in trees, they maybe the home of an owl. If you see small birds chasing and dive bombing a larger bird, check to see if the large bird is an owl. At night shine a flashlight around the area where you are watching. It may pick up eye shine or reflected light from the eyes of owls.

Another way to look for owls is to locate their pellets. The pile of pellets under a tree indicates an owl roost site. Pellets are small hard, rounded objects containing the fur, bones, and feathers that the owl can not digest. Eight to twelve hours after a meal, an owl will regurgitate or cough up the pellet and drop it to the ground below. Pellets are clean of all flesh and are virtually odorless. Scientists have used owl pellets to do small mammal studies. By breaking up the pellet and identifying the bones inside they can determine what mammals live in an area. Not all the bones will be in the pellets. Many of the tiny bones are actually digested by the owl and provide a source of calcium.


Leapin Lizards! Big Bend National Park is a great place to discover the diversity of many creatures like birds, snakes, and lizards. Big Bend is home to an amazing array of lizards! Twenty-two species to be exact.

Why are lizards important? What is their role in this ecosystem? Most of the lizards here, are found in the diet of many other creatures. Lizards are the main prey item for roadrunners, one of Big Bend's most popular birds. They help regulate the populations of other animals here, particularly insects, by feeding upon them.

Did you know that lizards in Big Bend are active most the year-round? Lizards are ectotherms, or cold-blooded creatures, because of this they need to regulate their body temperatures. Any extreme (too hot or too cold) could mean certain death for these animals. During the heat of the summer they are often hiding in burrows, while in the cold of the winter they are often burried below the ground surface (sometimes in burrows).

Visitors to Big Bend NP most frequently see the whiptails, earless, and spiny lizards. Often, lizards will be heard and not seen as they scurry through the vegetation off the side of a trail, though ones that are sighted are often fast and hide easily. The largest lizards in the park are the Collared (Crotaphytus) and Leopard (Gambelia) lizards which can measure over a foot! Both make their living off eating other lizards, insects, spiders, and small snakes.

There are other big lizards here though they are small compared to the monitors or komodo dragons. The largest Texas horned lizard (Phrynosoma cornutum) ever recorded was found here in Big Bend NP. Texas horned lizards are not very abundant in Big Bend NP, in the few places where they are located they are not in very big numbers. However, there is no evidence yet, that would suggest that this is abnormal. It is more likely that Big Bend NP may not have the proper type of habitat necessary for these lizards. The main and often only, food item for the Texas horned lizard is the harvester ant (Pogonomyrmex) which feeds mostly on grass seed. It is possible, if at one time there were larger grasslands in Big Bend, there may have been a larger harvester ant population and thus a greater number of Texas horned lizards.

"Interview with a Bat"

Ranger Mary Kay Interviews a Non-Vampire Bat
While hiking a trail recently, I met a friendly bat who was willing to answer some questions I had about him and his friends.

Ranger: Before we start, I have to ask you this. You aren't a vampire bat, are you?

Bat: Oh, no! I'm a Mexican free-tailed bat. During the winter I sometimes hang out with some vampire bats way down in southern Mexico, but they don't like to be cold, so they won't visit me here.

Ranger: So you won't bite me during this interview?

Bat: I might if you try to touch me! We bats don't like to be touched. It's probably hard for you humans to resist, because we're so soft and cute.

Ranger: You do look really soft and fuzzy, but I promise not to pet you. So if you don't eat blood, what do you eat?

Bat: My friends and I eat insects. We especially like moths and beetles—those are our favorites—but we also eat mosquitoes, termites, flying ants, and pretty much anything else that flies in front of us. Some of my friends, the pallid bats, also eat scorpions and centipedes.

Ranger: That sounds dangerous!

Bat: Well, for a human it would be. But the pallid bats are immune to the scorpions' sting, so it doesn't bother them.

Ranger: That's amazing. But it doesn't look like there's a lot of meat on a moth or a mosquito. On average, how many insects does it take to make a meal?

Bat: I try to eat about one-third of my body weight in insects every night. Now, some of the female bats who are nursing babies will eat about half their body weight or more in insects every night. Some of my bat friends, the cave myotises, can eat about 600 mosquitoes per hour, and up to 3,000 mosquitoes per night.

Ranger: Three thousand mosquitoes per night? That's incredible! But you don't look overweight; how can you eat so much and stay so slim?

Bat: Aerobics. Try flying over a fifty-square-mile area every night, and you'll stay pretty slim, too. Plus I've just returned from southern Mexico for the winter. Migration will sure burn off the calories!

Ranger: So that's why we don't see you bats around here much in the winter. Do you ever hibernate?

Bat: No, I fly south to warmer areas instead. But some of the other bats here do. They'll spend the winter in caves, rock crevices, mines, or under tree bark. They sleep all winter to avoid the cold. Personally, I prefer sunny Mexico.

Ranger: Let's go back to what bats eat. In other parts of the world, bats eat fruit. Do you or any of your friends here in Big Bend eat fruits or berries?

Bat: No, most of us stick with pure protein. None of that sugary stuff. But there are some bats here that eat nectar. Look around the blooming century plants this summer in the Chisos Mountains and you might see some of the nectar-eating bats—they're called Mexican long-nosed bats because they spend most of the year in Mexico, and their noses are long and pointy. I only see them here in June and July.

Ranger: At least nectar and fruit sit still while you eat them. How do you catch insects? I've heard that you bats use sonar.

Bat: That's right! We make really high-pitched noises like this...

Ranger: I don't hear anything.

Bat: Because most of our bat sounds are too high-pitched for you humans to hear. Anyway, we make this noise and then listen for the echo. By listening to the echo, I can tell you a lot about whatever the sound bounced off of. I can tell you how far away the insect is, how fast it's moving, how big it is, all kinds of things. In fact, I can find objects as fine as a human hair just by using my echolocation system!

Ranger: Maybe that's why lots of people think bats are blind, since you can fly around in the dark so well.

Bat: We bats can still see. We just don't rely on our eyes the way that you humans do.

Ranger: I see that you're hanging inside a dead tree branch today. Don't you bats normally live in caves?

Bat: Your national park doesn't have many caves, so we bats have to make do with rock shelters and crevices, dead trees, and mine shafts. Mine shafts are neat because they're so much like caves! Sometimes we live in buildings with you humans, or even in the expansion joints in bridges.

Ranger: You guys are really adaptable! You've mentioned some of your friends, other types of bats who also live in Big Bend. How many different types of bats are there here in the park?

Bat: At last count, 20 species of us bats were found here in your park. This is a great place for bats to live because it's warm most of the year; there are lots of insects; and there's a lot of different habitat, so we can pick and choose where we want to live. For instance, some of my friends like to live in the high canyon walls above the river, while the long-nosed bats like to live up high in the mountains. Lots of us like to live in caves and deep rock crevices, but others prefer dead trees. So lots of us can live here without crowding each other.

Ranger: Do you ever have to worry about predators?

Bat: Yeah—those snakes are devious! Snakes can crawl up trees and rock walls; you have to hang way out away from rock walls if you want to stay away from snakes. Skunks and foxes can sometimes climb up to where we bats live, too. And owls and hawks try to catch us in the air. People are our main problem, though.

Ranger: People? Why do people try to hurt you?

Bat: I think because you're afraid of us. You guys have all kinds of wild stories about how bats suck your blood, or how we all have rabies, or how we get stuck in your hair, and none of those things are true! People sometimes find caves where my friends are hibernating or just sleeping for the day and they'll blast the cave shut, or set fires in there to suffocate and burn them.

Ranger: I'm really, really sorry that happens. If people knew more about you and your friends, they wouldn't do things to hurt you.

Bat: Sometimes they don't mean to hurt us. Sometimes it's accidental - they cut down the trees we live in, or spray pesticides that poison our food, or close off the caves and mines that we like to hang out in. You people really know how to mess up good habitat.

Ranger: Unfortunately, that's one thing we humans do really well. What can I do to get people to help you and protect your habitat?

Bat: Tell them about all the good things we do! Like the tons and tons of bad insects that we eat every year, and all the plants we pollinate. And how little things they do can drastically affect millions of us. And don't forget to tell them how cute we are, too.

Ranger: I'll do that. Thanks for taking the time to talk to me. This has been really educational, and I think people will learn a lot about you and your friends.

Bat: You're welcome. And I promise to stay out of their hair if they stay out of mine.


With over 160 species of butterfly and innumerable species of moths, Big Bend is a great place for lepidopterists.

Whether your interests are research or fun this is a great place to discover butterflies. In fact, there are seven species that are known to occur in the U.S. in one place, Big Bend National Park. Those seven are: the Chisos banded-skipper; the Chisos metalmark; Chisos skipperling; the Chisos giant skipper; the bromeliad scrub-hairstreak; the Mexican dartwhite; and the Lajitas giant skipper.

What are the most common butterflies seen in the park? Most of the year around at all elevations you might find the Gulf fritillary, pipevine swallowtail, American snout, red admiral, checkered white, southern dogface, orange skipperling, Texan crescent, and Reakirt's blue.

Each year towards the end of the summer and through the fall, we begin to see a migration of Monarch Butterflies, at this time of year it is common to see certain flowering bushes teeming with twenty or more.


Studying and managing wildlife is seldom an easy task, but wildlife management along the border presents special challenges. Observing wildlife in the U.S. may tell only half the story, since many migratory birds, bats, and insects spend their winters deep in Mexico. Remoteness, inaccessible terrain, and a sometimes unstable political climate can make it difficult for wildlife researchers to gain information on wildlife along the border or far into the interior of Mexico. Problems can also arise when different countries have differing attitudes toward the same animal; one country may protect a certain species while another may want to eradicate it. Laws may protect wildlife and their habitat on this side of the Rio Grande while leaving them unprotected on the other side of the river


The black-tailed jackrabbit (Lepus californicus) is found throughout the western United States in the desert, open plains, and foothills. The jackrabbit is actually not a rabbit, but a hare. Hares live in open areas and rely on running in a zigzag pattern to escape their predators. Hares are also precocial, meaning they are born with hair and with their eyes open. They can run and hop shortly after birth. Rabbits, on the other hand, move slower, dig burrows, and scamper into their homes when threatened. Rabbits are altricial, or born hairless, blind, and helpless. The desert cottontail (Sylvilagus audubonii) is the common rabbit of Big Bend.

The black-tailed jackrabbit weighs between four and eight pounds. The female doe is larger than the male buck. Their total length is between 18 and 26 inches. The tail has a black stripe that runs along the top onto the rump (hence the name) and is 2" to 4 1/2" long. The characteristic large ears are 4-7" long and are whitish inside and out except for the black tips. There is a light colored ring around the eye. The iris of their eyes is yellow ochre with black pupils. The eyes are on the sides of the head, which enables jackrabbits to see in front, to the side, and behind them. Their eyes are used more to pick up motion than to focus on an object. The jackrabbit has excellent hearing and sense of smell. Their ears and nose are in constant motion to analyze their environment for sounds and smells.

Hares and rabbits are perhaps nature's ideal prey. Coyotes, mountain lions, bobcats, foxes, hawks, eagles, owls, and snakes will all eat them. The hare's and rabbit's sharp senses, effective camouflage, and fast running speeds are their only protection. The jackrabbit can hop 5'-10' at a time, and up to 20' when panicked. They can achieve speeds of up to 40 mph. When at a moderate run, every four to five leaps are exceptionally high to see their surroundings or predators. The jackrabbit runs with its ears flat and tail between its haunches. It will leap over objects rather than run around them. The fast, erratic leaps, bounds, and sprints are effective against predators, but they have poor endurance and often end up as some animal's dinner.

The amazing reproductive rate of hares and rabbits is an adaptation to being preyed upon by so many carnivores. Black-tailed jackrabbits will have up to six litters each year with as many as eight young in each litter, although two to four is more common. After a gestation period of 41-47 days, the female will give birth in a grassy hollow or shallow depression scratched into the ground. There is no nest. Within two weeks the young can forage for themselves, and after one month they are living on their own. By eight months of age they are having their own young.

The black-tailed jackrabbit is a herbivore, eating only vegetation like grasses, mesquite and cacti. To help digest this tough vegetation, the jackrabbit's appendix serves as a pre-digesting chamber to start breaking down these food sources before they reach the stomach. When feeding, the jackrabbit leaves neatly clipped diagonal cuts on plant stalks. They have a double row of upper incisors with small, secondary teeth located directly behind the main incisors. These teeth never stop growing, so the hare must constantly gnaw on vegetation to wear them down. Jackrabbits forage for food early in the mornings and late in the evenings, dozing in the shade during the day in shallow depressions. They deposit their scat wherever they happen to be. Two types of droppings are produced. The first is a soft, moist, mucous-coated sphere. The jackrabbit eats these droppings, as they are high in protein and certain B vitamins that are formed by bacteria in the intestines. After passing through the digestive system again, the waste products are deposited onto the ground as a dry dropping. The scat is composed of fibrous, compacted plant material.

Black-tailed jackrabbits are found throughout Big Bend National Park and are most common below 5000'. They are often nocturnal and can commonly be seen along the roadsides on summer nights. Use caution at all times when driving park roads because the jackrabbits seem to have kamikaze tendencies!

The Montezuma quail

In the spring of 2005, sightings of the Montezuma quail were documented in the Chisos Mountains for the first time since a reintroduction attempt over thirty years ago. This was the first confirmed sighting in the park since a release in Pine Canyon in the early 1970's. A Texas Parks and Wildlife biologist who has studied them in different parts of the U.S. was the first to sight a specimen within the park. Research is ongoing to learn more about the extent of this population.

Native to the Chisos Mountains, the Montezuma quail were extirpated from their mountain habitat in the 1930s.


There are only a few wet places in the park where turtles are found.  Though through the rainy season, it could be possible to find one out in the desert wandering between wet spots.  In the Rio Grande, the most common species would be the Big Bend slider.  This is a subspecies of the well-known Red-eared slider.  Also found along the river is the spiny softshell turtle, the yellow mud turtle, and in very small numbers, a new species found in 2005, the Rio Grande river cooter.  Though the Texas tortoise is on the park's checklist they are not found regularly enough in Big Bend to be considered resident.  One species that we hope to learn more about in Big Bend is the ornate box turtle once they were not considered resident though a few recent sightings have suggested the opposite.

Where to Bird

The best birding locations usually have close proxity to water, habitat and food. Within Big Bend, the traditional Birding hot spots are Rio Grande Village, the Chisos Mountains, and the Cottonwood campground. The information on the following pages serves as a guide to where to go in these places, and what you might see there.

Other Possible Birding Spots
Hot Springs—Where Tornillo Creek meets the Rio Grande, good for wading, shore, and desert birds.
Dugout Wells—This is a great place for desert resident or migratory birds passing through. The wells often create a year-round wet spot and are surrounded by desert.
Sam Nail Ranch—Similar to Dugout Wells. Here you will find an isolated island where migratory and desert birds will be found.
Blue Creek—This is one of the better bird watching places in the foothills of the Chisos Mountains. Often spring sightings of gray and black-capped vireos along with Lucifer hummingbirds make this one must stop for many.
Santa Elena Canyon—During warmer times of the day the canyon walls create a cool place to poke around looking for more birds along the river.
Terlingua Abajo—A beautiful and large spring along Terlingua Creek has been home to numerous unique birds and stands out as one of the wettest spots in the park, with the exception of the Rio Grande.


Big Bend's desert environment is a perfect place for reptiles! Thirty-one species of snakes, twenty-two species of lizards, and seven species of turtles have been found in Big Bend National Park. Remember that these animals, like all wildlife, are protected from harassment, killing, or collecting within the park.

Christmas Bird Count

The Christmas Bird Count is a long-standing program of the National Audubon Society. It is an early-winter bird census, where volunteers follow specified routes through a designated 15-mile (24-km) diameter circle, counting every bird they see or hear all day. It's not just a species tally—all birds are counted all day, giving an indication of the total number of birds in the circle that day. All individual CBC's are conducted in the period from 14 December to 5 January (inclusive dates) each season, and each count is conducted in one calendar day.

Big Bend National Park holds two bird counts annually in the week between Christmas and New Years day. One focuses on a circle in the Chisos Basin, the other in the Rio Grande Village area.

Big Bend Bugs

What's the most common form of wildlife you're likely to see in Big Bend National Park?
Ask many people that question, and you'll probably hear answers like "javelinas" or "turkey vultures." But while 75 species of mammals and 450 species of birds have been seen in the park, over 3,600 species of insects have been found here! The identification of a new species of beetle just a few years ago in the Chisos Mountains tells us that countless more unknown insects may still await discovery.

Insects make up more than half of all living things on Earth, comprising over one million species. They outnumber humans by 200 million to one: for every human, there are 200 million insects. This figure does not include non-insect arthropods, such as spiders and scorpions.

Observing insects, in the park or at home, will open up a whole new world of dimensions, color, form, activity, and beauty. You'll find insects living in flowers, wood, earth, fabric, hair, blood, flesh, water, and dung. You'll find them eating these same things, as well as grain, fungi, microbes, glue, spiders, and each other.

So where do you begin in your search to discover the insect world? Like most living things, insects are attracted to water, especially the still water of ponds. Sit quietly near a pond and watch for dragonflies and damselflies. These large, brightly-colored insects are voracious predators, and their legs form a "basket" that enables them to catch other insects in flight.

With its huge compound eyes, the dragonfly can detect prey up to 40 feet away. You might see clusters of small black beetles swimming and spinning at random around the water surface, resembling a group of bumper cars. These aptly-named whirligig beetles have two pairs of compound eyes; one pair looks for prey above the water surface, while the other pair looks for prey below the water. Beneath the surface, you might see water boatmen sculling through the water, powered by legs that are shaped like oars.

The arid desert also provides habitat for insects. Perhaps one of the most famous desert insects is the yucca moth. Observe a blooming yucca at night, and you may witness an example of insect pollination as these tiny white moths dart among the large white yucca flowers. The female yucca moth collects a ball of pollen from one or more yucca flowers. She deposits her eggs in the ovary of a flower, then puts the ball of pollen on the flower stigma, where it will fertilize the flower eggs. The moth larvae then feed on the developing seeds. A single yucca seedpod contains well over 100 seeds, and the moth larvae, which usually number only 1 or 2 per pod, eat relatively few seeds, sometimes fewer than a dozen each. While the yucca moth certainly benefits from this arrangement, the yucca itself also benefits, as most yuccas would remain un-pollinated and would not bear fruit if it were not for the pollination done by the moth.

Easier to witness is the pollinating activity of several types of bees found in the park. Most common are bumblebees, especially in beebrush plants in the Chisos Mountains. These large, heavy-bodied, fuzzy bees have black and yellow stripes on their abdomens. Although not native here, two types of honey bees are also found in Big Bend. European, or domestic, honey bees were brought to the United States from Europe several centuries ago and are now vital pollinators and honey producers; they provide 80% of the pollination required by agricultural crops in the United States, and one-third of our diet comes from crops pollinated by honey bees. These small bees appear virtually identical to their recently-immigrated cousins, the Africanized honey bees.

Only experts with powerful microscopes can distinguish the two types of honey bees. Behaviorally, though, these two honey bees are different. European honey bees are generally not very aggressive when threatened. Only a few bees defend the hive, and they not easily disturbed. When they are, they will usually only chase the attacker a short distance. Africanized honey bees, on the other hand, can be very aggressive. When they are threatened, many bees defend the hive. They are easily disturbed, especially by vibrations such as those from lawnmowers. Africanized honey bees will chase an attacker up to a quarter mile. We think of these as two distinct species of honey bees. However, they sometimes hybridize, producing crossbreeds with variable temperaments.

When entomologists analyze honey bees for identity, they study a number of anatomical characteristics and identify the degree of hybridization exhibited by a particular bee or colony of bees. For instance, a honey bee might be 25% European and 75% Africanized, or 50% Africanized and 50% European. Africanized honey bees have not attacked anyone in the park, but if bees chase you, you should:
• RUN as fast as you can! It helps to run in a zigzag pattern.
• Seek shelter in a building, car, or tent. As a last resort, seek heavy brush.

Many hikers return from the summit of Emory Peak reporting hundreds, perhaps thousands, of ladybugs gathered on the peak, forming a bright red and black cover on every rock and tree trunk. These beetles appear to cluster at high elevations all over the southwestern United States for reasons that are not clearly understood. Many scientists believe that ladybugs fly to high elevations to escape temperature extremes; others believe that this gathering has to do with mating.

Spring and fall are good times to see monarch butterflies in Big Bend National Park. The park lies just west of one of the monarchs' primary migration routes and receives many monarch visitors as they fly through here in April en route to summering grounds in the northern U.S. and Canada. In September they fly south to wintering grounds in central Mexico. These black and orange butterflies travel over 1,000 miles on their migratory journey, covering up to 80 miles per day. No one monarch makes the entire round-trip migration; since they stop to breed along the way, the butterflies that we see flying north in the spring may be five generations removed from those that originally migrated south in the fall. Monarchs are only one of many species of moths and butterflies that inhabit the park. Look for red admirals, mourning cloaks, sisters, dog-faced sulphurs, and various types of swallowtails; brilliantly colored tiger swallowtails stand out the most, but the duller pipevine swallowtails are more common. At night look for the black witch moth, one of the largest moths in North America.

In the late spring and early summer, people often see tarantula hawks flying low over the ground, searching for tarantulas. These large black wasps with golden wings, also known as pepsis wasps, will sting people if annoyed but seldom do, so intent are they upon finding arachnid prey. The female tarantula hawk stings the spider only to paralyze it, but not kill it. She drags the inert body into her tunnel, lays her eggs on it, and then seals the tunnel shut with pebbles and dirt. The wasp larvae hatch and eat the tarantula's body for a week or two. If the female wasp had killed the tarantula instead of paralyzing it, it would decay before the larvae could eat all of it. When the larvae finish eating the spider, they are old enough to move onto their next developmental phase.

While there are many types of grasshoppers in the park, two types are most commonly seen. The desert lubber grasshopper is large, chunky, and sports a vivid black and yellow body; when it flies, it flashes bright red wings. The smaller red-winged grasshopper is slim and black-bodied and may be hard to see at rest, as it hides in vegetation. Its large, bright red wings clearly stand out when it flies. With active curiosity and careful observation you will see many more types of insects during your visit to Big Bend National Park. An amazing display of beauty and diversity surrounds us, if we are willing to put aside our prejudices and explore the lives of the insects around us.

Bird Specialties

Each of these species is evocative of Big Bend National Park. Each is a Southwestern U.S. species that spends much, if not all of the year in the park (doesn't just migrate through). With some effort, each is observable within the park and is part of a classic group of Big Bend birds.

  • Gray Hawk
  • Zone-tailed Hawk
  • Common Black Hawk
  • Scaled Quail
  • White-winged Dove
  • Inca Dove
  • Greater Roadrunner
  • Elf Owl
  • Lesser Nighthawk
  • Lucifer Hummingbird
  • Blue-throated Hummingbird
  • Magnificent Hummingbird
  • Golden-fronted Woodpecker
  • Ladder-backed Woodpecker
  • Ash-throated Flycatcher
  • Black Phoebe
  • Vermillion Flycatcher
  • Mexican Jay

  • Verdin

  • Cactus Wren

  • Black-tailed Gnatcatcher
  • Black-capped Vireo
  • Curve-billed Thrasher
  • Crissal Thrasher
  • Phainopepla
  • Gray Vireo
  • Colima Warbler
  • Pyrrhuloxia
  • Varied Bunting
  • Canyon Towhee
  • Black-throated Sparrow
  • Cassin’s Sparrow
  • Black-chinned Sparrow
  • Rufous-crowned Sparrow
  • Scott’s Oriole
  • Hepatic Tanager

Black Bears

Black Bears Return!
One day in the 1980s, a black bear from the Sierra del Carmen in Northern Mexico started a journey. She descended from the mountains, walked through miles of desert, swam across the Rio Grande, and traversed more desert to reach the forested slopes of the Chisos Mountains in Big Bend National Park. She may have led offspring to the Chisos, and probably encountered a wandering male already using the park's mountain range. How they came and why they came, we may never know. But the return of bears to the park is a remarkable event. It is a success story, and a story of hope for the future.

The Past
In the early 1900s, black bears (Ursus americanus) were common in the Chisos Mountains in Big Bend National Park. Naturalist Vernon Bailey in 1901 described bears as being "... common in the upper canyons of the Chisos Mountains, where fresh tracks of old and young were frequently seen and where there was an abundance of old 'sign' and turned over stones." Bears continued to be common in the Chisos Mountains through the 1930s.

By the time the park was established in 1944, however, there were virtually no resident bears in the park. Shooting and trapping by ranchers, federal predator control agents, and recreational hunters, and loss of habitat due to settlement and development contributed to their decline. Individual bears occasionally wandered in and out of the park from Mexico, but only scattered sightings were reported from the 1940s through the 1980s. In 1969, and again in 1978, female bears with cubs were seen in the Chisos Mountains. Still, bears were extremely rare in the park.

The Reappearance
The late 1980s brought an amazing turn of events. Visitors began seeing bears in increasing numbers. In 1988, a visitor photographed a female with three young cubs in the Chisos Mountains. On 27 occasions, visitors reported seeing bears that year, more evidence of a resident black bear population. Observations increased in the early 1990s. In 1996, 572 observations were recorded. In 1999 there were 343 sightings of black bears in the park. Once a large animal is eliminated from its natural range, it is rare for it to return on its own. Often, only human intervention can bring back what humans caused to disappear.

The recolonization of black bears in Big Bend is a remarkable natural event. Researchers do not know exactly why the bears returned, but it is due in part to the preservation and restoration of habitat in the park.


Many visitors would be surprised to find out that 75 species of mammals inhabit the deserts and mountains of Big Bend National Park. Living in an area with high temperatures and low rainfall forces many animals to live extremely cautious lifestyles. Many leave their burrows only under cover of night. Others may forage during the cool of early the early morning. Larger mammals include whitetail and mule deer, coyote, mountain lion, and black bear. The snuffling you hear around your campsite at night may be a gray fox or a band of hungry javelina. Bats make up the largest portion of the park's mammal species. 20 different species have been observed here, including the endangered Mexican Long-nosed Bat, which has been found nowhere else in the entire United States.

Insects, Spiders, Centipedes, Millipedes

Big Bend National Park is home to a very large diversity in forms of invertebrates. A typical trip to the park will offer many sightings of tiny creatures like the Velvet Mite (Trombidium spp.) to the large Tarantulas (Aphonopelma chalcodes). The many forms of hard-bodied invertebrates have been numbered near 3,600 species and counting. Given the remoteness and the lack of research, the parks invertebrate checklist is still growing.

Some of the most easily sighted invertebrates in the park include Millipedes (Diplopoda), Butterflies (Lepidoptera), Dragonflies (Odonata), and Grasshoppers (Orthoptera).

Peregrine Falcons

"The peregrine is without dispute the most nearly perfect flying machine in existence"
—Phillip Callahan, The Magnificent Birds of Prey

Peregrine Falcons in Big Bend National Park
On a cool summer morning I make my way up a steep-sided canyon in the Chisos Mountains. Overhead, white-throated swifts wheel and spin, their clicking calls alternately growing and receding as they dart across the sky. I pause to catch my breath, and happen to look up. In that instant, a dark shape plummets from high in the clear sky, gathering speed so rapidly it causes me to stop breathing. The dark shape rapidly takes form; a Peregrine falcon, wings folded, dives into the midst of the swifts. In a maneuver that happens so quickly I'm not sure I see it, the falcon strikes a solitary swift in an explosion of feathers, then circles gracefully to snatch the broken body before it can fall to the ground. Witness to a drama that has played out daily for centuries in the Big Bend, I stand in awe.

Visitors and researchers have come to the Big Bend for years to witness similar spectacles, especially since 1970, when the Peregrine falcon was placed on the federal Endangered Species list. By that time the falcons had all but disappeared from the eastern seaboard and were barely hanging on in isolated sites in the west. Persistent organochlorine toxins unleashed into the environment from widespread pesticide use, particularly DDT, caused eggshell thinning. The falcons failed to reproduce as their eggs crushed beneath them in the nest. In the Big Bend region Peregrine falcons have been recorded nesting since the beginning of the 1900's. Through the 1970's their reproductive success rivaled or surpassed the rate of populations in other western sites. The high and inaccessible cliffs of the Chisos Mountains and deep canyons of the Rio Grande provide safe haven for falcon eyries and bountiful hunting grounds. In recent years the National Park Service has annually closed areas to visitor use during the breeding season. This ensures solitude for the falcons in that critical time. In cooperation with the U.S. Fish and Wildlife Service, park staff has monitored the falcons yearly, compiling data on the reproductive success of this small and persistent population.

Elsewhere within the Peregrine's vast range, similar monitoring revealed that the falcon has staged a remarkable comeback since that bleak day in 1970. The banning of the pesticide DDT in 1972, and successful captive breeding and release projects have returned the Peregrine to many former breeding sites and introduced it to new environments among skyscrapers. Today an estimated 1,650 breeding pairs range across Canada and the United States. On August 25, 1999, the Peregrine falcon was officially removed from the Endangered Species list. This was a success story that thrilled all who have followed the plight of this magnificent bird. Here in the Big Bend however, there remains a lingering doubt.

Beginning in the late 1980's and accelerating between 1992 and 1996, productivity (the number of young/successful eyrie) of Big Bend Peregrines fell to alarmingly low levels. This period coincided with extended drought conditions in the area. A link to the low productivity was suspected. In 1997, 17 falcon young fledged, the highest number since monitoring began in 1971, and note was made that '97 was a good rainfall year. Distressingly, drought conditions returned during the following two seasons and low fledgling success was observed. The impact of drought on wildlife populations is well documented, but concern remained that something else was playing a hidden, more sinister role in the falcon reproductive failure. The historical presence of mining in the region and continued agricultural practices upstream of the park provides sufficient reason to suspect that contaminants still affect Peregrines in the Big Bend. To address this concern, the U.S. Geological Survey, the National Park Service, and the Texas Parks and Wildlife Department conducted research to determine the levels of contaminants in potential prey species and their potential impact on Peregrine falcon reproduction.

During the summer of 1997, researchers began collecting samples from various prey species of peregrines. These included rough-winged swallows, black and Say's phoebes, cliff swallows, and bats. All of these creatures are insectivorous and employ different methods of capturing their insect prey, mainly along the river. They are all exposed to varying amounts of possible contamination. Tissue samples were analyzed and tests were conducted to detect concentrations of organochlorines, including DDE (a breakdown product of DDT), and several heavy metals, including selenium and mercury. The analysis revealed several disturbing trends.

Organochlorine compounds were not detected at levels that could affect survival or reproduction of Peregrine falcons, except DDE. Of the five species sampled, only the northern rough-winged swallow contained levels of DDE that could cause eggshell thinning and reduced reproductivity in falcons. Significantly, the level of DDE in the swallows was five times above the threshold, the level above which serious physiological effects begin. Higher DDE levels in northern rough-winged swallows may be accounted for by differences in diet and foraging. Northern rough-winged swallows are more likely to feed over water and skim insects from the surface than the other species sampled.

The heavy metals selenium and mercury were also detected at levels of concern. Selenium levels at five micrograms per gram of sample weight could result in embryo deformities. Selenium concentrations were at threshold in rough-winged swallows and approached threshold in the phoebes. Mercury levels of 0.5 micrograms reduced egg laying and hatching in mallards, and at 1.2 micrograms reduced clutch size, increased nest desertion and reduced nesting territory in common loons. In this study, all five sample species had mercury levels above threshold for protection of fish-eating birds (threshold levels of selenium and mercury have not been established for Peregrine falcons). Research results reveal that the persistent and toxic compounds, selenium, mercury and DDE, are accumulating in the food chain along the Rio Grande. They may be implicated in reproductive failures and reduced reproductive success of the Peregrine falcon in the Big Bend. Having returned so far from the brink of extinction, Peregrines still face challenges to their survival. This "nearly perfect natural flying machine" still merits our protection. Through research and application of findings the solutions for their continued presence may be found.

Mountain Lions

Big Bend is Mountain Lion Country!
If Big Bend had a symbol, it might well be the mountain lion—the embodiment of freedom and wildness. Solitary and secretive, this mighty creature is the unquestioned lord of its natural world. As one of Big Bend’s top predators, Felis concolor—"cat all of one color"—is vital in maintaining the park’s biological diversity. In the delicate habitats of the Chihuahuan Desert, mountain lions help balance herbivores (animals that eat plants) and vegetation. Research shows that cats help keep deer and javelina within the limits of their food resources. Without lions, the complex network of life in Big Bend would certainly be changed.

Encountering a mountain lion, however, can lead to conflicts in maintaining the balance between natural processes and visitor enjoyment and safety. Since the 1950s, there have been more than 2,700 sightings of mountain lions by visitors. Each year, over 150 lion sightings are reported by park visitors. While over 90 percent of these sightings were along park roadways, encounters along trails have also occurred. Since 1984, four lion and human encounters have resulted in attacks on people. In both cases, those attacked recovered from their injuries and the aggressive lions were killed, preventing them from playing out their important natural roles. The more we know about lions, and the less we seek an encounter, the better able we will be to make life easier for them and for us.

How much do you really know about this powerful and wild cat? Mountain lions live throughout the park, including the Chisos Mountains where they prefer to use trails. Your chances of encountering an aggressive lion are remote. What can you do to minimize the consequences of an encounter? Avoid hiking alone or at dusk or dawn. Watch children closely; never let them run ahead of you.

Like all predators, the mountain lion's role is a part of the health and welfare of the entire ecosystem. Research and further human understanding of the cat's habits pave the way for conservation efforts in its behalf. As we discover more about the lion, we fear it less and appreciate it more. For many visitors, just seeing a track—or just knowing lions are out there—will be reward enough.


The collared peccary (Tayassu tajacu), commonly known as the javelina, is found as far south as Argentina and as far north as Texas, New Mexico, and Arizona. Collared peccaries are in the even-toed, hoofed mammal order of Artiodactyla. Javelinas are often called pigs but they really are not. They are in different family than pigs.

Javelinas thrive in a variety of habitats and are able to adapt easily to different areas in their territory. The javelina is a herbivore (plant eater) and frugivore (fruit eater). They eat wide variety of fruits, tubers, rhizomes, bulbs, acorns, grass, green shoots of annuals, stems of prickly pears, lupines, mesquite beans, and lechuguilla. They are also opportunistic and take animal matter as food when it is easily available or accidentally ingest it while foraging for other things. Succulent prickly pear pads make it possible for the javelina to survive until rainfall brings many new annual food plants and water sources. Javelina will drink when water is available, but it is not essential if succulents are available.

The collared peccary can breed any month of the year, but most births occur in May, June, or July, after a five-month gestation period. This may be to correspond with the summer rainy season. They first breed at about one year of age and only death or disease ends the ability to breed and bear young. Collared peccaries live in groups, but do not form long-term pair bonds. The female gives birth standing up and nurses the young for two months. The average litter size is two, but occasionally is as high as five. By six weeks of age the young are eating solid food like their mother. By forty weeks the young are full-grown. There is typically a 50% or higher mortality rate for the young.

Coyotes, bobcats, black bears, and mountain lions prey upon javelinas. On average they live 7.5 years in the wild. Herd size ranges from five to twenty seven animals, with an average of fourteen per herd in Big Bend National Park.

A typical day for a javelina in Big Bend begins at daylight when the herd gets up from the bedding site and feeds until mid-morning. Food will include lechuguilla, roots, prickly pear, seeds of woody plants, fruits, and forbs when available. The herd feeds by spreading out in a loosely knit group. As they day heats up the javelina seek shelter in cooler canyons, caves, and areas of dense shrub. They will feed again in late afternoon until dark. Feeding time increases in cooler months and resting time increases in the summer. Javelina may even feed at night during the hottest months. After feeding, the herd will bed down under rocky overhangs, in caves, and in shallow depressions with heavy brush cover. They will huddle together in a group for warmth and protection when bedding down.

Javelina hides were shipped east and to Europe for gloves and hairbrushes in the late 1800's and early 1900's. The hides were used as barter in many trading posts along the U.S.-Mexico border. Since the 1940's the javelina has been considered a sporting game animal in Texas. It provides a source of income for landowners and the State of Texas for the hunter's fee. In Big Bend National Park the javelina is protected. It is often seen in the campgrounds feeding and has been known to raid coolers and picnic tables when they are left unattended. The javelina is common in Big Bend and a welcome site to many visitors.


From drought-resistant exoskeletons, to their secretive lifestyles, scorpions have all the traits of desert specialists. Some visitors however may not be able to look beyond their own "fear factor" to see how interesting scorpions really are.

Creepy features of scorpions include the pincers (pronounced pinsers) which are used for feeding purposes only, and of course the stinger or telson, which injects the venom used to kill prey. Whether it is the pinching or the stinging, we should not feel threatened at all. Very few park visitors even see a scorpion, and believe it or not, it is likely that during your entire Big Bend visit, you will not be stung or pinched by a single one.

The truth is, a scorpion would never actually attack a human. When a human is stung, it is a defensive warning, the message being "do not cross this line." Backpackers and campers should check bedding, clothing, and shoes if they've been left out overnight. Never walk in the dark here without a flashlight. A sting is painful, much like a honeybee, but may also cause a tingling sensation throughout the body as nerve endings react to the witch's brew of chemicals in the venom. Deadly to insects, the venom causes only discomfort in larger creatures. Many scorpion predators, including coyotes, owls, snakes, bats, and hawks might eat a lot more of them if they didn't have to face a possible sting.

Scorpions are predators as well as prey. They receive most of their moisture from eating tiny insects and even other scorpions. Nocturnal creatures, from a dark perch they wait until prey approaches. Once near, the pincers lash out and grasp the victim like two pairs of strong pliers. If it struggles, the prey is stung and immobilized...dinner is served.

The scorpion is nothing to be feared. Instead, admire this desert specialist's unique features and ability to thrive in the harsh wilds of Big Bend.



As a desert park, only a few places in Big Bend support fish. The Rio Grande, and its two tributaries Tornillo and Terlingua Creeks are the only inhabited locations. Although catfish (blue, channel, and flathead) are commonly caught in the Rio Grande, most of the park's 40 species of fish are minnow sized. One of the most famous of these is the endangered Big Bend Gambusia, or Big Bend Mosquitofish (Gambusia Gaigei) which is found only within one tiny spring-fed pond near Rio Grande Village. This is the smallest geographic range of any known vertebrate.

Sadly, we have seen a decline in populations of fish along the Rio Grande in recent years. Two species of fish that had once inhabited the river have not been seen since shortly after the creation of dams upstream and downstream. The last American Eel (Anguilla rostrata) was taken from the Rio Grande near Castolon in 1954; later the last Atlantic sturgeon (Acipenser oxyrhynchus) was taken in the lower canyons. In both cases the fish were dependant on traveling to the ocean in order to breed and it would appear that large impoundments have become their misfortune.

Fishing permits are required to fish in Big Bend and are available at any visitor center.

Wildlife Sightings

Big Bend is a wild place, dynamic and wide open, complete with the age-old life and death struggle of competition, survival of the fittest, a wildlife paradise. With over 650 species of vertebrates and 3,600 species of insects, Big Bend is a living, breathing laboratory of biodiversity. Visitors see it in action daily, often reporting their encounters with javelinas, sighting a mother bear with cubs, or delighting in the antics of the roadrunner chasing its lizard prey.

Below are summaries of black bear and mountain lion sightings, taken from wildlife sighting cards turned in by park staff and visitors. Rare bird sightings are also collected and posted on a quarterly basis.

Remember, we can only list the sightings you report. Always report unusual sightings to a park ranger.

You Asked About Birds?

An introduction to the birds of Big Bend National Park
Halfway between Laredo and El Paso, the Rio Grande swings southward to form a huge bend that is also the southern boundary of America's finest desert preserve - Big Bend National Park. Established in 1944 to save 1,100 square miles of Chihuahuan Desert and mountain grandeur, it contains & wide variety of Southwestern scenery. From the three great canyons of the Rio Grande to the rolling slopes and Jagged peaks of the Chisos Mountains, the birder is offered exciting discoveries all months of the year.

It is this diversity that creates the great variety of plant zones, where more than 400 kinds of birds have been recorded. Yet Big Bend is best known for its specialties that occur nowhere else in the United States except within the Chisos Mountains or just within the border country of Texas to Arizona. Such unique birds as the Mexican duck, the Lucifer hummingbird, the Mexican jay, the black-capped and gray vireos, the Colima warbler, and the varied bunting do occur here at different times of the year.

Chisos Woodlands
Best known of these is the Colima warbler that summers in the high canyons of the Chisos Mountains and south in less accessible mountainous areas of Mexico. It arrives in the Chisos in mid-April and departs for its wintering grounds in southwestern Mexico by mid-September. In wet years, the Colima, is common down to about 5,900 feet. A high of one hundred and sixty-six individuals was counted in an early May census in 1969. A ground-nester, it prefers the oak-maple environment of Boot Canyon and similar high, cool niches from Laguna Meadow to Boot Canyon and the South Rim. From May through mid-July, it is easily detected by its rapid, melodic song. But its songs become less frequent as the summer progresses.

Other breeding birds of the high Chisos canyons that are likely to be seen include the band-tailed pigeon, the white-throated swift, Rivoli's and blue-throated hummingbirds, the common flicker, the acorn woodpecker, the western flycatcher, the white-breasted nuthatch, and the canyon wren. Watch for the golden eagle among the many turkey vultures overhead; and, if you search carefully, you can usually find a zone-tailed hawk over the ridges of lower Boot Canyon. Camp overnight in Boot Canyon if you wish to see the night birds. Usually it is not too difficult to find both the screech and the flammulated owls, as well as the whippoorwill there after dark.

Although the Boot Canyon vicinity contains a number of unique trees and shrubs, such as Arizona cypress, Douglas-fir, Texas madrone, and a number of Chisos oaks, the area which surrounds the canyon is more typical of the widespread pinyon-juniper-oak woodlands. This is the most extensive woodland zone in the park and occurs from 4,500 feet to near the summit of Emory Peak (7,832'), the highest point in the Chisos. Although bird life in these woodlands becomes relatively scarce during the June and July dry period (which follows the initial spring blooming and nesting season In April and May), the summer rainy season of August and September produces a second flowering period as well as another nesting cycle. Many bird species do not nest, particularly in dry years, until August and September when there is an abundance of seeds and insects.

Common nesting birds of the pinyon-juniper-oak woodlands include the broad-tailed hummingbird, the ash-throated flycatcher, the gray-breasted Jay, the tufted titmouse, the bushtit (both color phases), the Bewick's wren, the blue-gray gnatcatcher, the brown-headed cowbird, the black-headed grosbeak, the spotted and brown towhees, and the rufous-crowned sparrow. Less numerous are the poor-will, Hutton's vireo, and the hepatic tanager.

Grasslands/Desert Scrub
Below the mountain woodlands are the grasslands and the desert scrub. Fingers of these zones extend into many parts of the mountains, therefore birds that prefer these habitats are often found quite high on the mountain slopes. As an example, Laguna Meadow, at 6,300 feet contains a desert-like environment along its western and northern edges. There you can find nesting the crissal thrasher and the black-chinned sparrow. In wet summers, the Colima warbler has been found nesting in the cool canyon adjacent to the trail just below the meadow.

The desert scrub-grassland zone circles the Chisos Mountains and forms an irregular band between 1,800 and 4,500 feet. This is the area which supported the famous West Texas cattle country of the late 1800s and early 1900s. By the 1920s, much of this land had been so badly abused that the lush grasslands were depleted and the desert scrub had invaded high into the Chisos foothills. This condition still exists today. However, the grasslands have made progress in recent years and now occur in places down to 3,200 feet.

The Window Trail below the Basin campground offers the birder an interesting smorgasbord of higher desert scrub and grasslands interspersed with oaks, pinyons, and junipers. An early-morning hike to the Window in the summer almost always produces such avian species as the ladder-backed woodpecker, Say's phoebe, Bewick's and cactus wrens, the mockingbird, Scott's oriole, the pyrrhuloxia, the blue grosbeak, the brown towhee, and black-chinned and rufous crowned sparrows. Less numerous are the gray vireo and the varied bunting. Almost all of the same species can be found in the lower Green Gulch area as well. The scaled quail, the common raven, the black-tailed gnatcatcher, and Cassin's and black-throated sparrows can usually be found there, too.

Along the River
Big Bend's Chihuahuan Shrub Desert extends down into the lowest parts of the park. It is not until you reach the river or one of the isolated springs that lie scattered over the desert that another habitat and a different group of nesting birds can be found. The floodplain occurs adjacent to the Rio and throughout its entire length except where sheer walls or artificial devices introduced by man make it otherwise. A few groves of cottonwood, tamarisk, and willow occur at springs and where the river channel has deserted an old terrace. The localities of riparian growth such as the flats below Castolon and at Rio Grande Village are excellent birding places. Common nesters there include the mourning dove, the yellow-billed cuckoo, the black-chinned hummingbird, the ladder-backed woodpecker, Bell's vireo, the yellowthroat, the yellow-breasted chat, the brown-headed cowbird, the orchard oriole, the summer tanager, the cardinal, the blue grosbeak, and the painted bunting. Less common but present in small numbers are the white-winged and ground doves, the screech-owls and the elf owl, the vermilion flycatcher, and the hooded oriole.

As you can readily see, Big Bend is truly a birder's paradise. So grab your binoculars, your bird book, your checklist, and start looking. Please report any birds that are unusual, either in location or in time of year, at the nearest visitor center.

Happy Birding!


Big Bend National Park is an amazing place to observe many different snakes. There are 31 species known to exist in the park and three more snakes are listed as hypothetical. Keep in mind that all wildlife in the park are protected from harming, handling, or otherwise being disturbed by visitors.

The red racer, or western coachwhip, is the most often seen snake in the park, due to both its bright reddish-pink color and its habit of lying across roads, where it may stretch across an entire lane.

Bullsnakes are the largest snakes seen in the park, reaching over 6 feet in length and reaching several inches in diameter. Its heavy body, flat head, and patterning lead some people to mistake it for a rattlesnake. The bullsnake hisses and rattles its tail when threatened, and when it does this in dry leaves, the effect is very similar to that of a rattlesnake buzzing.

Hikers may find patchnose snakes in both the mountains and the desert. These slender snakes have a tan background color with two longitudinal dark brown stripes lining a central brown stripe. Look for the triangular "patchnose" scale on the snake's snout.

Garter snakes, both black-necked and checkered, are found around water, where they most commonly hunt for frogs and toads.

Rat snakes can be found often at dusk near the side of roads. There are two species here Baird's and the Trans-Pecos which is more common and easily identified with its pattern of H marks running down its back.

After summer rains many more snakes will be active and we encourage visitors in the park to photograph snakes and report rarities or oddities to us from time to time. Remember that you are not permitted to handle or disturb snakes in the park in anyway. Current park regulations do not allow the use of artificial light to illuminate wildlife.

For more information:

Dayton, G. 2002. Amphibians and reptiles checklist Big Bend National Park Rio Grande Wild and Scenic River. Big Bend Natural History Association. Big Bend National Park

Dixon, J. D. and J. E. Werler 2005. Texas Snakes. University of Texas Press. Austin, Texas. 384 pp.


Spring Migration

"I never for a day gave up listening to the songs
of our birds, or watching their peculiar habits."
—John James Audubon, Journals

If, like Audubon, you enjoy the morning songs of birds awakening to a new day, and find pleasure in seeking them out at their hidden perches, then Big Bend in the spring is the right place to be. For years people have flocked to Big Bend National Park in the spring, drawn by the opportunity to see an incredible diversity of birds that passes through in the annual migration. Over the years observers have reported 446 species in the park. Of this total, nearly 190 (42 percent) are migrants headed north to their breeding grounds. Many of these species represent a special group called "neotropical" migrants, referring to birds that nest in the United States and Canada, and winter south of the United States. Within this group are the "vagrants," birds off course and wandering far from their normal range or migration routes. During the spring of 1996 two species listed as "hypothetical" on the park list visited the area, much to the delight of the lucky few who were able to see these rarities. For two days in March a violet-crowned hummingbird visited the Barker House near Rio Grande Village. A Mexican species whose breeding range extends into the United States normally only to southeast Arizona, the hummingbird seen here represents one of only four sightings recorded in Texas. Not quite so far out of range but never before fully documented in the park, a Swainson's warbler seen May 4th in Boot Canyon provided a number of detailed reports for park records.

Even more intriguing were the observations of two individual flame-colored tanagers, another Mexican species that had previously been recorded in the United States only in southeast Arizona. These two individuals were well documented with photographs and represent the first-ever Texas record. With potentials like these, it's no wonder that people come from all over the world to tap this "river of birds," add new species to their lists, and marvel at the phenomenon of migration.

Migration may be defined as an extensive, seasonal movement between breeding regions and wintering regions. Birds do not hold exclusive domain in the area of migration. Certain insects migrate, as do some mammals, like the Mexican long-nosed bat found in Big Bend. For most people though, the word "migration" brings to mind birds. Approximately half of the world's 9,000 bird species are migrants. In North America, approximately 600 of the 800-plus species recorded are migrants. We tend to think of the birds in the backyard as "ours," but migrants really are a shared gift. While many people take notice of the seasonal changing of bird communities in their backyards, few pause to consider what a tremendous feat those migrant birds have accomplished.

Some species travel thousands of miles, crossing over large bodies of water or vast expanses of arid land. Along the way there are many dangers that can result in death. Predators, extreme weather, and obstacles such as power lines, all take their toll. The very act of migrating requires a tremendous expenditure of energy. Migrants can lose anywhere from 26 to 44 percent of their body weight during the passage from south to north. Many fall exhausted and dying after fighting strong head winds and storms. Even if a migrant bird makes it to the breeding area there is still no guarantee of success.

Birds that migrate give up their territories each year, and must reclaim them at a cost of energy. Not all individuals are successful in securing a territory and finding a mate on the breeding grounds. Those that do find a mate still have trials to overcome. A study of nesting American redstarts in New Hampshire found that up to 70 percent of redstart eggs and nestlings were lost to predators, even in relatively intact forest habitat. Given these odds and the perils of the passage, it's a wonder that birds migrate at all. That they do is an indication that there are advantages to this behavior. Some are immediately obvious. Birds that migrate take advantage of better climates for living. This is especially true for long-distance migrants. In moving between areas, migrants exploit different habitats for food. A variety of habitats means a greater variety of food and increases the probability of a more nourishing diet throughout the year. Some migrants change their diet to take advantage of seasonally abundant food sources in the two areas. The Nashville warbler, a fairly common migrant through Big Bend in the spring, is mainly an insectivore during the breeding season. When it arrives on wintering grounds in central Mexico and Guatemala, the warbler will switch to feeding on nectar from flowers just coming into bloom. While abundant food and hospitable climates are easily identified benefits of migration, others do not become obvious until we look at a map.

Most of the spring migrants that pass through or stay to breed in Big Bend spend their winter in Mexico and Central America. Only a few, like the Swainson's hawk, yellow-billed cuckoo, and cliff swallow, winter as far away as South America. In fact, almost 50 percent of the migrant land birds of North America winter in just five countries: Mexico, the Bahamas, Cuba, Haiti, and the Dominican Republic. Compare the land mass area of these five countries to that of Canada and the United States. The combined area for the five countries is approximately 836,000 square miles. That of Canada and the U.S. is 6,230,000 square miles. Wintering birds are more tolerant of close association and often form mixed flocks of several species. When these same birds are ready to breed, their tolerance level goes way down. By migrating to a North American breeding ground they find more room and expend less energy establishing a territory than if they stayed in the crowded wintering ground. Other benefits of geography have less to do with available space and more with available light.

We all are aware that summer days are longer. Most of us even participate in the annual ritual of turning the clock forward in spring to "save" one more hour of precious daylight. Migrants traveling north in the spring are practicing the same principle. The longer days of the northern summer provide longer working hours for adult birds to forage for food. Even though the summer season is short the longer daily period of food gathering allows birds to raise their young more quickly. This is very important as birds are most vulnerable to predators and parasites while they are in the nest, either as brooding adults or nestlings. Given that the breeding season is short and the time required for migration long, most neotropical migrants have only enough time to raise one brood. If the brood is lost to predators, storms, or disease, then the entire season is a disaster. Despite the many perils involved and the possibility that either the adults or the young will die, migration continues. For millions of years migration has been a successful response to changing environmental conditions. This success story though, may be changing.

Since 1966 the U. S. Fish and Wildlife Service has conducted Breeding Bird Surveys (BBS) across the country. Over the years the accumulated data have provided a fairly accurate picture of the status of breeding birds in the United States. In the first years of the survey observers witnessed huge migration fronts and a healthy diversity of species. Beginning in the 1970s and accelerating through the 1980s and 1990s, declines began to be documented in many populations. In Texas surveys, neotropical migrant species declined by 54 percent between 1980 and 1989. In an effort to pinpoint causes many researchers have taken to the field, often following the migrants to their winter homes. Though the problem is complex and much is still not known about migrant species biology, several potential factors have been identified.

Initially much of the blame for the decline was attributed to deforestation on the wintering grounds. There is no question that forest removal in Latin American countries is occurring at a rapid rate. Some estimates for the felling of mature tropical forest are as high as 74,000 acres per day. For species that rely on mature tropical forest for wintering habitat the impacts are bound to be negative. The summer tanager, a migrant and breeder at Big Bend, winters in tropical lowland forests from Mexico to South America. Since 1980 summer tanager populations have declined by 17 percent. The olive-sided flycatcher, a migrant through Big Bend, winters in temperate and cloud forest areas at higher elevations in the Andes. This habitat is also under siege and populations of olive-sided flycatchers have declined 22 percent since 1980. Not all neotropical migrants, however, utilize mature forest for wintering habitat. Some prefer secondary growth, scrub lands, and coffee plantations. For these species, the felling of mature forest may actually benefit their survival. To further complicate the picture, recent studies have shown that many species can tolerate a very high level of disturbance on their wintering grounds. Since the size of a breeding population is directly related to the number of young fledged the previous summer, perhaps more serious problems exist on the breeding grounds.

Habitat destruction on the northern breeding grounds, particularly in the forested areas of the United States, has fragmented suitable habitat into areas that are dangerous and unsuitable for nesting. Consider the sequence a breeding bird follows upon arriving in the north. First it must find suitable habitat, then attract a mate, and finally construct a nest, lay eggs, and raise young. If the habitat has been fragmented it takes longer to find a good area, decreasing the time available to raise young and increasing the chances of starvation. Fragmentation of habitat on the breeding grounds also makes it easier for predators (jays, owls, rodents, and house cats) and brood parasites (birds which lay their eggs in the nest of other birds, like the brown-headed cowbird) to find a nest. Brown-headed cowbirds parasitize over 100 different species and have driven some, like the black-capped vireo, to the brink of extinction. Recall that most neotropical migrants have time to raise only one brood. A breeding pair that loses its eggs or young to predators, or spends its season raising a brown-headed cowbird, has lost a year. If this happens to many individual pairs in a population, the whole declines. Many researchers point to these events as the most important factors in the decline of neotropical migrant populations.

Another factor is the importance of stop-over areas along the migration route. Migrating birds, particularly long-distance migrants, need suitable habitat in which to rest and refuel before continuing on. Disturbances in these areas could cause serious impacts. Researchers acknowledge that habitat destruction at all three points, breeding, wintering, and stop-over points, is cumulative and critical. Hunting, persistant environmental contaminants, and other unknown factors further complicate the issue. Add to this the political boundaries which birds do not recognize but that we cannot ignore. The situation is grim, but not hopeless.

Most populations still number in the hundreds of thousands to millions and extinction is not imminent for all. If we act now, there may still be time to effect a change. That we need to act now may be hard for some people to understand because, after all, these are only birds. But, there is a bigger picture. Dick Cunningham, devoted birder and former Chief of Interpretation of the Western Region, National Park Service, perhaps said it best: "Birds provide an excellent barometer of environmental change. They remind us that change, especially accelerated, unnatural change, can be destructive to all types of life. This is as true for human beings as it is with all the other organisms with which we share this planet. Thus changes in the status of migratory birds provide clues to the quality of the earth's environment."

As understanding of this concept dawns, and with the alarm bells sounding, efforts are beginning. Concerned individuals are planting native vegetation around their homes to provide habitat for wildlife, participating in research, and organizing activities that promote education and understanding. On a larger scale, programs like the Partners in Flight project seek to create partnerships between the key players involved: state and federal agencies, non-governmental organizations, private landowners, and other nations. The focus of the project is to change current land management practices based on a single species concept to ones that foster an ecosystem approach and managing for biological diversity. Such practices would benefit many life forms, including neotropical migrants and, in the long run, us.

Most people enjoy birds, whether they be casual watchers in the backyard or hard core birders chasing elusive rarities around Big Bend National Park. Every year bird watchers spend millions of dollars on books, equipment, and travel in their quests for new species on the list. Every day, somewhere, someone raises his or her head to watch a passing flock or to listen to the song of a hidden bird. It is appropriate then, that birds serve as the rallying point for people from all over the world to join together in search of solutions to environmental decline. We can only hope that we are in time and that the river of birds that rushes through spring skies doesn't diminish to a trickle.

What makes an insect an insect?

What makes an insect an insect and separates insects from other small hard-bodied creatures?
First, all insects are arthropods, animals that lack backbones and have jointed legs and external skeletons, or exoskeletons. Arthropods include such diverse animals as roaches, millipedes, tarantulas, and lobsters. Second, all insects have three distinct body parts: a head, a thorax, and an abdomen; many other arthropods have either more or fewer body areas. Third, almost all insects have wings. No other group of arthropods can fly. Fourth, all insects have two antennae and six legs. Most other arthropods have eight or more legs. Their tiny size, quick reproduction rate, and ability to fly enable insects to explore and exploit almost every environmental niche imaginable.

Rivers and Streams

The Rio Grande is the defining feature of the Big Bend. It is here that the river swings abruptly to the northeast after flowing south and southeast for nearly 1,000 miles.

In the desert life clings to water, and it is along the Rio Grande and intermittant streams that wildlife is often found. Both humans and animals are attracted to and depend on the limited water of the Rio Grande.

Natural Features & Ecosystems

When Big Bend was chosen to become a national park it was the biological and geologic diversity here that  helped sway policy makers.

The scenery found in Big Bend is unmatched elsewhere in Texas. We encourage park visitors to enjoy sunsets from scenic vistas, soak their tired bones in the hot springs, and explore Big Bend's geologic history. 


That portion of the earth’s surface known as the Big Bend has often been described as a geologist’s paradise. In part this is due to the sparse vegetation of the region, which allows the various strata to be easily observed and studied. It is also due to the complex geologic history of the area, presenting a challenge to students and researchers from all over the world.

Not all field geologists, however, refer to the Big Bend as a paradise. For some, this land of twisted, tortured rock is a nightmare. The abundance, diversity and complexity of visible rock outcrops is staggering, especially to first-time observers. From 500 million year old rocks at Persimmon Gap to modern-day windblown sand dunes at Boquillas Canyon, geologic formations in Big Bend demonstrate amazingly diverse depositional styles over a vast interval of time. For most of us, time is measured by the passing of days, years and generations.

The concept of geologic time, however, is not so easily understood. Events that occurred 2 million, 26 million or as many as 120 million years ago are, at best, difficult to comprehend. Since astronomers now place the age of the earth at approximately 4.6 billion years we should perhaps consider ourselves fortunate that the oldest rocks found in the Big Bend are only about 500 million years old. Initial commentary on the geology of the Big Bend was provided by early-day explorers and adventurers in the 1800’s. Subsequent studies by numerous 20th century researchers enable us now to reasonably reconstruct the complex geologic history of the Big Bend.

For a period of at least 200 million years, ending some 300 million years ago in the Paleozoic Era, a deep-ocean trough extended from present-day Arkansas and Oklahoma into the Big Bend region of far West Texas. Sediments from highlands to the north accumulated in that trough to form layers of gravel, sand and clay. With the passing of time, these layers became sandstone and shale beds. About 300 million years ago these strata were “squeezed” upward by collision with a continent to the south to form the ancestral Ouachita mountains. Subsequent erosion over an interval of 160 million years left only the roots of those mountains visible. These remnants may be observed today in the Ouachita Mountains of southeastern Oklahoma, in the immediate vicinity of Marathon, Texas, and in Big Bend National Park near Persimmon Gap.

A warm, shallow sea invaded the Big Bend during the Cretaceous Period, some 135 million years ago, providing the setting for deposition of lime mud and the remains of sea-dwelling organisms such as clams and snails. Limestone layers formed from those shallow muds are now visible throughout much of the Big Bend. They comprise the dramatic walls of Santa Elena, Mariscal and Boquillas canyons, the entire range of the Sierra del Caballo Muerto (Dead Horse Mountains) and the magnificent cliffs of the Sierra del Carmen in Coahuila, Mexico, towering above Rio Grande Village. Approximately 100 million years ago the shallow Cretaceous sea began a gradual retreat to its present location, the Gulf of Mexico. Sandstone and clay sediments that formed along the retreating shoreline are found in lowlands surrounding the Chisos Mountains. Shallow water strata of this episode contain the fossil remains of oysters, giant clams, ammonites, and a variety of fishes and marine reptiles. Near-shore deposits in Big Bend have yielded petrified wood, fossil turtles and crocodiles--one almost 50 feet long! Deposits from further inland contain fossil remains of a variety of dinosaurs. Perhaps the most famous of Big Bend’s fossil treasures from this period is the giant flying reptile, Quetzalcoatlus northropi, with a wingspan over 35 feet. (A replica of the bones of one wing is now on exhibit at the Panther Junction Visitor Center.)

Near the end of the Cretaceous Period, a west-to-east compression of the earth’s crust marked the beginning of the second major mountain-building period in Big Bend. This compression, which began in Canada, moved gradually southward, uplifting and folding ancient sediments to form the Rocky Mountains. In Big Bend National Park, Mariscal Mountain represents the southernmost extension of the Rockies in the United States. Broad uplift punctuated by upward folding exposed both the erosion-resistant lower Cretaceous limestones and the less resistant overlying sandstones and clays to the onslaught of erosion. Limestone cliffs throughout the region continue to be eroded today; most of the more easily removed sandstone and clay is gone from the mountains.

For almost 10 million years after uplift ended, non-marine sediments of the Tertiary period constitute the only record of events in the Big Bend. Dinosaurs had long been gone from the land, their places taken by a proliferation of mammals, many of whose remains have been found in Big Bend...horses, rhinos, camels and rodents, as well as fossils of the plants on which they thrived. All was not to remain quiet for long. Near the present northwest boundary of Big Bend National Park, the first of a long series of volcanic eruptions occurred approximately 42 million years ago. Upwelling magma lifted the mass now known as the Christmas Mountains, fracturing and weakening overlying strata, allowing massive outpourings of lava to spread across the land. The oldest volcanic rocks in Big Bend owe their origins to this eruptive cycle. Between roughly 38 and 32 million years ago Big Bend itself hosted a series of volcanic eruptions. Initial activity in this cycle centered in the Sierra Quemada, below the present South Rim of the Chisos Mountains. Subsequent volcanic activity at Pine Canyon, Burro Mesa, near Castolon and elsewhere in the park is responsible for the brightly colored volcanic ash and lava layers of the lower elevations and for most of the mass of the Chisos Mountains.

Volcanic activity was not continuous during these eruptive cycles. Periods of hundreds of thousands or perhaps millions of years passed between eruptions. During the quiet interludes the forces of erosion carved new landscapes, many of which were destined to be buried under layers of ash and lava from later eruptions. Life returned to the land only to be displaced by future eruptions. Elsewhere in the Big Bend rising magma sometimes failed to reach the surface. Instead, it spread within existing layers of rock, uplifting and fracturing overlying strata. Once the magma cooled and crystallized it formed solid masses of erosion-resistant intrusive igneous rock which have now been exposed by erosion of the overlying material. Maverick Mountain, the Grapevine Hills, Nugent Mountain and Pulliam Ridge are among many examples in Big Bend of such “frozen” magma chambers.

Beginning some 26 million years ago, stresses generated along the West coast of North America resulted in stretching of the earth’s crust as far east as Big Bend. As a result of these tensional forces fracture zones developed which, over time, allowed large bodies of rock to slide downward along active faults. The central mass of Big Bend National Park, including the Chisos Mountains, from the Sierra del Carmen to the east to the Mesa de Anguila to the west comprises such a block of rocks dropped downward by faulting. Direct evidence of this faulting is readily observed at the tunnel near Rio Grande Village. There the limestone layer through which the tunnel passes is the same layer that forms the skyline of the Sierra del Carmen to the east, dropped down over 4800 feet by faulting. To the west, at the mouth of Santa Elena Canyon the highest elevation rises 1500 feet above the river, while at the parking area the same layer lies some 1500 feet below the surface. Displacement along these faults did not occur in a single event, rather in a series of lesser episodes of faulting punctuated by earthquakes. The 1995 magnitude 5.6 earthquake near Marathon, Texas, 70 miles north of Panther Junction indicates that the responsible stresses are still active. The western slopes of the Chisos Mountains provide evidence of additional activity within the same fracture zones. Near the old ranch on the Ross Maxwell Scenic Drive stand a number of parallel ridges to the east of the road. These ridges are the eroded remains of tabular intrusions of magma along the Burro Mesa fault. The layers of volcanic ash into which the magma intruded are being actively removed by erosion, leaving the more resistant “dikes” of intrusive rocks standing in bold relief.

Mountain building by compression, volcanism and tension all served to form the framework for today’s landscapes in Big Bend National Park. Erosion of higher lands resulted in the filling of surrounding basins. Eventually basins from El Paso to Big Bend were filled and subsequently linked by the Rio Grande. Achieving through-flow to the Gulf of Mexico only within the last 2 million years, the Rio Grande ranks as the youngest major river system in the United States. Once established, the Rio Grande served, and continues to serve, as the conduit for material removed by erosion. The processes of erosion comprise the most active aspect of Big Bend’s geology today.

Erosion in Big Bend is best defined by rapid runoff and flash-flooding following summer thunderstorms, but there are other active agents of erosion. Water droplets in the atmosphere capture carbon dioxide to form carbonic acid, a very weak naturally occurring acid which has virtually no effect on man. One mineral, however, is vulnerable to attack by carbonic acid: calcite, which comprises the bulk of all limestone in the Big Bend. Every drop of rain that falls on limestone dissolves a tiny bit of calcite which is transported away by runoff, perhaps to a final destination in the Gulf of Mexico.

The beautifully etched limestone cliffs in the Sierra del Caballo Muerto and in Big Bend’s canyons owe their origin to mother nature’s own version of acid rain! Rainwater also contains free oxygen which reacts with sulfur-bearing minerals in igneous rocks.

Virtually all igneous rocks in Big Bend contain minor amounts of pyrite, or Fool’s Gold, which is iron sulfide. Oxygen-bearing water attacks individual pyrite grains, replacing the sulfur with oxygen to form iron oxide, better known as rust, which provides the warm red and brown colors of igneous rocks in the Big Bend.

Plant and animal activity is also vital in the shaping of the land. As plants grow their root systems expand, forcing rocks ever farther apart, until, eventually, rocks are dislodged and fall. The same roots also extract needed minerals from rocks, weakening the rocks and rendering them more vulnerable to removal by flowing water. Similarly, animals crossing a rocky slope often dislodge rocks, sending them crashing downslope to collide with yet other rocks, which, in turn are dislodged. Though plants and animals play significant roles in erosion, the key player remains water. From chemical weathering by water-borne carbonic acid and oxygen to mechanical removal of soft and broken rocks, to scouring ever deeper and wider the canyons of the Big Bend, water is today, as it has been in the past, the major tool in the shaping of the land.

The Greek philosopher Heraclitus once said “There is nothing permanent except change.” This phrase could have been directed to the Big Bend where geologic processes have been constantly changing the land for over 500 million years. Each time you return to Big Bend National Park it will be different, for with every passing day the land is indeed changing.

Geologic Research

On The Shoulders of Giants
The dramatic and diverse geology of the Big Bend has attracted geologists for over a century.  Early geological reports were published by R.T. Hill in 1902 and by J.A. Udden in 1907.  These early studies by two legendary pioneers of Texas geology were an auspicious beginning for the study of a very complex and important region. In subsequent years many other geologists have contributed to our understanding of the area.

The most ambitious and important study thus far was undertaken by a group of four men led by Ross Maxwell, who also served as the park’s first superintendent.  Maxwell and his colleagues John T. Lonsdale, Roy T. Hazzard, and John A. Wilson worked on the area’s geology during the 1940s, 1950s, and 1960s, finally publishing “Geology of Big Bend National Park, Brewster County, Texas” in 1967.  This is the preeminent geologic report on Big Bend, and the geologic map that was published in the report is available to park visitors as an insert in Ross Maxwell’s “Guidebook 7, The Big Bend of the Rio Grande.” 

We still rely on this map and report today, but despite the excellence of this work, its authors faced handicaps that limit its usefulness in modern science.  Most problematic was the lack of topographic maps at the time of the study.  This resulted in the geologic map having distortions that cannot be corrected, so the geology cannot now be overlain onto topographic maps. Additionally, great advances in technology and geologic understanding have been made in the 50 years since this work was performed, providing new techniques for geologic study and new ideas about how the earth works. 

A New Map
The largest geology research project currently underway in the park is an attempt to create a new geologic map.  Led by the U.S. Geological Survey, dozens of scientists are collaborating on the project, with some geologists dividing up mapping duties and other experts studying various specialized problems.  The group includes USGS geologists, National Park Service geologists, and numerous university professors and their graduate students, some of whom have studied the park’s geology for decades.

The new map is an opportunity to consolidate the past half-century of geologic research in the park, much of which is unpublished.  This fresh look at the park’s geology will apply modern understanding of earth processes, and this will change some of the interpretations suggested by Maxwell and others.  The park is already providing updated interpretations of some geologic features, such as Goat Mountain, by installing new wayside exhibits.

Perhaps most importantly, the new map will fit the topography, allowing it to be used in powerful computer-driven analyses, such as the Geographic Information System (GIS).  GIS permits park managers to analyze the effects and interactions of all park resources, such as rocks, soils, plants, animals, water, and human history.  Geology is a vital part of this analysis so the new map will fill a crucial need.  For visitors interested in geology, the new map should be available in park bookstores in about 2 years.

Dinosaurs, Volcanoes, and Other Research
In addition to the big re-mapping project, a wide range of geologic research is currently under way in the park.  Fossil studies include dinosaurs, large turtles, petrified wood, ancient mammals, and marine invertebrates called ammonites (similar to the modern chambered nautilus).  The park’s rich volcanic history has always been an area of research interest.  Current topics include geologic history of the Pine Canyon caldera, the lava flows of the South Rim and Chisos formations, and detailed studies of igneous intrusions such as dikes and laccoliths.  Graduate students and university professors are also studying the stratigraphy and deposition of various sedimentary rocks, including the Boquillas Formation, the Chisos Formation, and the Banta Shut-in Formation.