Nature
Overview
Big Bend Ranch State Park is located in far west Texas in the remote, high desert setting of the northern Chihuahuan Desert where the summers are hot, the winters are mild, and there is not much rainfall. The scenery is magnificent and the landscape varies from river lowlands (about 2300 feet elevation along the Rio Grande), through deep canyons, across high plateaus, and up steep mountains (Oso Mountain at 5135 feet is the highest peak in the park). Ultimately, all of this is controlled by the underlying geology and the processes that created it over millions of years.
The park has a long and unique geological history beginning with rocks that are over 500 million years old and continuing today as the Rio Grande cuts its way along the southern boundary of the park. In fact, four of the major events that mark the geological development of North America converge in the park. At the Solitario, an uplifted and eroded dome in the northeast corner of the park, visitors can see rocks that were deposited as sediments in an old ocean 520 Ma. (million years ago), folded and faulted into ancient mountains around 300 Ma. (Appalachian/Ouachita/Marathon event) and subsequently eroded back down, then overlain by limestones deposited in a 100 Ma. ocean and in turn, uplifted and deformed by about 50 Ma. (Rocky Mountains event). The Solitario provides this window back in time because it was domed-up around 35 Ma. and erosion has exposed these older rocks in its core. The third event, a dramatic period of volcanic activity, occurred throughout western North America between 47 Ma. and 18 Ma., and as part of this activity at 27 Ma., eruption of extensive lava flows and abundant volcanic ash built up the Bofecillos Mountains in the high central part of the park. And finally, along the southern edge of the park, the Rio Grande flows through a series of elongated basins bounded by long, continuous faults which began forming 25 Ma. (Basin and Range event).
An example of the geology affecting other natural features of the park is shown by how the layered character of lava flows and tuffs with intervening eroded surfaces, particularly in the central part of the park, has resulted in the development of stacked aquifers (subsurface water bearing zones). When these aquifers intersect the ground surface in canyon walls and valley floors, water can flow out and form springs, some of which flow year round while others are more ephemeral. Not only does the geology control the large scale features of the landscape at Big Bend Ranch State Park, but it also in turn accounts for the many springs that are found in this desert setting. At best count, more springs are found here than in the larger Big Bend National Park. Conventional aquifers are developed in the sediment filled basins or bolsons as well, particularly along the Rio Grande. This relative abundance of groundwater, associated riparian areas, and the Rio Grande has attracted humans to the area for at least the last 11,000 years and up to present day park visitors.
Water and Hydrology
Springs are a key natural resource of BBRSP. Over 100 springs, mostly in the Fresno and Terneros Creek drainages, have been recorded. It is probable that more await discovery around the Bofecillos volcanic platform.
Many of the park's creeks are ephemeral in nature. However, the larger drainages, such as Alamito and Cienega Creeks, have permanent stream flow. All of the drainages in BBRSP are part of the Rio Grande drainage basin; all are subject to flash flooding.
A census of wells and windmills is in progress in the park. An inventory of wells and water levels and a spring survey will provide information about groundwater reserves in local aquifers.
Vegetation
Big Bend Ranch State Park is located in the Trans-Pecos Vegetation Area (Hatch et al., 1990). The flora and fauna are represented by a rich assemblage of species because of the high diversity of life found in the northern Chihuahuan Desert. The natural plant communities at BBRSP can be grouped into four major types:
- A riparian zone found near springs, along drainages and in the Rio Grande corridor.
- Mixed desert scrub characterized by an abundance of creosote, ocotillo, cacti and lechuguilla, a Chihuahuan Desert indicator species.
- Desert grassland.
- Open juniper woodland, occurring in only the highest elevations.
The mixed desert scrub is by far the most widespread of these communities. It has largely replaced the once dominant desert grasslands. The riparian corridors are of particular importance as areas of high biological diversity.
The flora of the park is influenced by elevation and past land use. Overgrazing and browsing, through historical land uses, has degraded the plant communities within the BBRSP. All but a few livestock have been removed and after many years many plant communities are recovering. Even so, 15 plant community types have been identified.
Uplands throughout much of BBRSP are dominated by an open desert scrub habitat with whitethorn acacia (Acacia constricta), mariola (Parthenium incanum) and creosote (Larrea tridentata) being the most common components. Along arroyos and other specialized areas (i.e. along the bases of cliffs) there is dense woody scrub. In areas with deeper soils and on slopes where the effects of livestock grazing were less intrusive, open desert grassland with extensive woody vegetation invasion can be found. Listed threatened species in BBRSP include: Lloyd's mariposa cactus (Sclerocactus mariposensis) and Hinckley's oak (Quercus hinckleyi).
Wildlife
The fauna of Big Bend Ranch State Park is also varied, particularly the mammalian and herpto-faunas. Forty-eight species of mammals have been documented from the park, including 16 species of bats with an additional eight more species of bats having the potential to occur within the park. There are at least 30 species of snakes and over 300 species of birds reported from BBRSP and the immediate vicinity. The park is home to a number of state-listed taxa including the zone-tailed hawk (Buteo albonotatus), reticulated gecko (Coleonyx reticulatus), Trans-Pecos black-headed snake (Tantilla cucullata), Texas lyre snake (Trimorphodon biscutatus) and Chihuahua shiner (Notropis chihuahua). Other mammals of interest that have been documented within the boundaries of the park include black bear (Ursus americanus), mountain lion (Felis concolor) and white-nosed coati (Nasua narica). Game species such as mule deer (Odocoileus hemionus) and collared peccary, or javelina (Tayassu tajacu), are common and offer limited hunting opportunities.
Texas is entering a promising new phase of a multi-partner effort begun in 1954 to restore desert bighorn sheep to Far West Texas. In the late 1800s there were perhaps up to 1,500 sheep in the rugged mountains of the Trans-Pecos. However, due mainly to unregulated hunting and diseases from domestic and exotic livestock, bighorn numbers dwindled to about 500 in 1903 and by the 1960s they were gone. Today bighorns are coming back, thanks to decades of work by Texas Parks and Wildlife Department, wildlife conservation groups, private landowners and others. Read about bighorn sheep restoration at Big Bend Ranch State Park
Rapidly becoming a threat to soil, water, native wildlife and vegetation resources are increasing populations of aoudad, feral burros and feral hogs. To date, the hogs are found in the Cienega area along Alamito Creek and aoudad are near the Rio Grande, especially in Tapado Canyon. Learn more about feral burros at Big Bend Ranch State Park.
Bird Watching
Big Bend Ranch State Park offers the opportunity to explore Chihuahuan Desert habitats including grasslands, desert scrub, canyons, and riparian woodlands and thickets. The greatest diversity and abundance of birds is normally found near the numerous springs and along streams scattered around the park. Large springs normally are found in association with riparian woodlands (cottonwood-willow-hackberry and shrub thickets). Over 300 species of birds reside in Big Bend Ranch State Park.
One of the premier birding locations within the park is found at Ojito Adentro (wayside stop #4). The trail from the parking area traverses desert scrub into riparian woodland. The song of the Bell’s vireo is a common sound of the thickets along arroyos and in the understory of riparian habitats, and can hardly be missed between early March and September. In the spring and summer, watch for the zone-tailed hawk, vermilion flycatcher, summer tanager, blue grosbeak and varied bunting. Canyon, Bewick’s and rock wrens are present year-round, and a wide variety of sparrows can be found here in winter. This area can be very productive during migration (late March through mid-May and late August through mid-October) when flycatchers, warblers and tanagers can be common. Migration in West Texas is not as spectacular as farther east, but surprises can be found. Some of the more interesting finds at Ojito Adentro include painted redstart and a variety of eastern warblers.
A walk along a dry arroyo in well-developed desert scrub will reveal a different group of 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 place to find these birds is along the arroyo that passes along the west side of the Sauceda headquarters complex. Two of the most abundant birds on Big Bend Ranch can be encountered almost anywhere. They are the scaled quail and black-throated sparrow. Keep an eye out for them as you travel along the park’s many roads. Be sure to pick up a copy of the park’s bird checklist, Birds of Big Bend Ranch State Park, to record your sightings.
