El Solitario aerial - @TPWD.With its dramatic geology and diverse plants and animals, Big Bend Ranch State Park is a fascinating place to study nature.


Big Bend Ranch State Park is located in far west Texas in the high desert setting of the northern Chihuahuan Desert. Summers are hot, winters are mild, not much rain falls, and the scenery is magnificent.

The landscape varies from river lowlands to deep canyons, from high plateaus to steep-sided mountains. The elevation ranges from about 2,300 feet along the Rio Grande up to 5,135 feet at Oso Mountain. Geologic changes born of water and fire and taking place over millions of years created this dramatic terrain.

Four of the major events that mark the geological development of North America converge in the park.

You can see evidence of two of the events at the Solitario, a dome in the northeast corner of the park. The Solitario provides this window back in time because it uplifted around 35 million years ago. Subsequent erosion exposed the older rocks in its core.

The oldest rocks began as ocean sediment over 500 million years ago. They were folded and faulted into ancient mountains around 300 million years ago, in the Appalachian/Ouachita/Marathon event. Over time, the mountains eroded. Another ocean covered the area with sediment around 100 million years ago. This in turn was uplifted and deformed by about 50 million years ago in the Rocky Mountains event.

Volcanoes erupted throughout western North America between 47 and 18 million years ago. This was known as the Trans-Pecos Volcanic event. Extensive lava flows and abundant volcanic ash built up the Bofecillos Mountains in the high central part of the park 27 million years ago.

Finally, the Rio Grande flows through a series of elongated basins with long, continuous faults. This area began forming 25 million years ago (Basin and Range event) and the process continues today. The Rio Grande curves along the southern boundary of the park and offers a long, verdant corridor in the desert environment.

All creeks in Big Bend Ranch State Park drain into the Rio Grande. None of the creeks, including Alamito, Cienega and Fresno, flow year-round. Dry arroyos dominate the desert landscape. Creeks, arroyos and river can and do flash flood.

The park’s visitor centers and ranger station sell reference guides on the geology of the park. Park rangers also lead geology tours (see Activities page for information).

For more detailed information:


A wide variety of mammals, snakes and birds make their home in the high desert environment of Big Bend Ranch State Park. Forty-eight mammal species have been spotted in the park, including 16 species of bats. At least 30 types of snakes occur in the park. More than 300 species of birds have been recorded.

Mountain lions live in the park, while black bears wander through occasionally. Mule deer and collared peccary or javelina are common. (Check the TPWD Public Hunts page for hunting opportunities.)

Lizards are abundant, especially during warm weather. Grey foxes, coyotes, kangaroo rats, jackrabbits and desert cottontails are frequently seen.

Bighorn Sheep: Native bighorn sheep vanished from the rugged mountains of the Trans-Pecos by the 1960s. Decades of work by TPWD, conservation groups, private landowners and others led to the reintroduction of bighorn sheep to the area. Bighorns now range across the Bofecillos Mountains within the park. The best place to see them is at La Cuesta. Read more on our Bighorn Sheep Restoration page.


The Chihuahuan Desert offers lots of opportunities for an adventurous birder. Habitats vary from grasslands, desert scrub and canyons, to riparian woodlands and thickets. Cottonwood, willow and hackberry woodlands and shrub thickets usually surround large springs. Birders can find the greatest variety and largest number of birds near springs and along streams.

Vermilion Flycatcher

Ojito Adentro is one of the park’s premier birding spots. From the parking area, visitors cross through desert scrub into riparian woodland. Listen for the song of the Bell’s Vireo, commonly heard in the thickets along arroyos and in riparian areas.

In the spring and summer, watch for Zone-Tailed Hawks, Vermilion Flycatchers, Summer Tanagers, Blue Grosbeaks and Varied Buntings. Canyon, Bewick’s, Cactus and Rock wrens live here year-round, and a wide variety of sparrows reside here in winter.

During migration (late March through mid-May and late August through mid-October), visitors will see flycatchers, warblers and tanagers. While migration in west Texas is less spectacular than farther east, birders can still be surprised. Painted Redstarts and a variety of eastern warblers have passed through the park in recent years.

Walking along a dry arroyo in well-developed desert scrub will reveal different birds. Say’s Phoebe; Verdin, Curve-billed and Crissal thrashers; and Black-tailed Gnatcatcher join more Bell’s Vireos in this habitat. An easily accessible arroyo lies along the west side of the Sauceda Headquarters complex.

Scaled Quail and Black-throated Sparrows are two of the most abundant birds, and can be encountered almost anywhere.

Find more information on the birds of Big Bend Ranch State Park:

For more information on other animals of Big Bend Ranch State Park:

Check out these resources for kids:


The northern Chihuahuan Desert hosts a wide variety of plant species. The natural plant communities fall into four major types:

  • Riparian zones extend around springs, along drainages and in the Rio Grande corridor.
  • Mixed desert scrub consists of creosote, ocotillo, cacti and lechuguilla (a Chihuahuan Desert indicator species).
  • Desert grassland.
  • Open juniper woodlands occur only at the highest elevations of the Chihuahuan Desert, but do not occur in the park.

The mixed desert scrub is by far the most widespread plant community. It has largely replaced the once-dominant desert grasslands. Riparian zones (areas along rivers and creeks) are very important here, as they are home to a wide variety of species. Look for cottonwood trees in these areas; they are especially colorful in the fall.

Elevation and past land use determine what plants grow in the park. Overgrazing and browsing damaged many of the plant communities here on what used to be a working ranch. All but a few livestock animals have been removed and many plant communities are recovering.

Open desert scrub dominates the uplands of the park. The scrub is made up primarily of whitethorn acacia, mariola and creosote. Dense woody scrub lines arroyos and the bases of cliffs. Open desert grassland appears in areas with deeper soil and less livestock damage.

Watch Big Bend Plants (Texas Parks & Wildlife YouTube video) for more information on the plants in this area.