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Habitats of the Llano Estacado
The Breaks and Canyons

Introduction

Canyons are diverse and in a state of constant change. The formation of the canyons along the edges of the Llano Estacado is an incremental process that is simultaneously old and new. For the last three million years water falling on the plains and leaking from the subterranean aquifers under gravity’s influence has cut the landscape downward and inward toward their sources, deepening draws and arroyos into canyons. Canyon sculpting is also as new as the most recent thunderstorm, flash flood, freeze, and windstorm. Six major geologic periods – the Permian, Triassic, Jurassic, Cretaceous, Tertiary, and Quaternary – are exposed in the walls of the canyons of the Llano Estacado. It is also in the canyonlands of the Llano Estacado that the romantic allure of the American cowboy, comancheros, and pastores had their origins.

Plants

The canyons of the Llano Estacado represent an ecotone or transition area between adjacent ecological communities, which is also influenced by diverse climatic conditions. From the Brazos River toward the north, there is a Great Plains and Rocky Mountain influence on the plant communities. The southwestern canyons of the Pecos River are strongly influenced by the Chihuahuan Desert while the Edwards Plateau influences the southeastern canyons of the Colorado and Concho Rivers. Animals living in transitional ecotones can exploit more than one set of habitats within relatively short distances. Plants of the canyons and breaks must be adapted to extremes in temperature, precipitation, wind, light, and erosion.

Juniper trees are common to all canyons of the Llano Estacado; however, there is an isolated forest of Rocky Mountain junipers in the wetter, north facing slopes along the Caprock Escarpment.

The eastern cottonwood is found in moist soil, mostly along streams. They grow into large trees over 100 feet tall. They are fast growing and can average up to 5 feet of height annually. They are relatively short-lived (about 30-60 years). The long petioled leaves flutter in the slightest breeze, giving a light shade, reflecting flashes of sunlight, and making pleasant rustling sounds.

Purple coneflower has a thick black root that was used by Native Americans for many medicinal purposes. Its juice was used as an analgesic for toothache, coughs, colds, sore throats, insect stings, and snakebite. Purple coneflower also has a following in some circles of western human and veterinary medicine for treating a number of ailments involving pain, swelling, and inflammation.

Reptiles and Amphibians

The canyonlands of the Llano Estacado possess an amazing array of fossil reptiles and amphibians dating back to the Triassic Period of 208-245 million years ago. The canyons reflect a time before the existence of the Llano Estacado when West Texas and Eastern New Mexico had a subtropical, hot and arid, monsoonal environment. Dense forests and swamps of conifers, cycads, and ginkgoes also covered the landscape.

The desert massasauga is a retiring little nocturnal rattlesnake seldom encountered by humans. This species is not evenly dispersed and is generally quite uncommon.

The Great Plains rat snake’s most distinctive feature is the spear-shaped marking on top of the head. It kills its prey by constriction: especially rodents, ground-nesting birds, frogs, and lizards. It is sometimes confused with the bullsnake.

The Brazos water snake and the Concho water snake are subspecies of the Harter’s water snake, and are the only endemic snakes of Texas. They are found only in the Brazos and Colorado and Concho River basins respectively. They favor fast flowing streams of water with rocky shores. They feed primarily on fish and amphibians and are nonvenomous.

The collared lizard lives in rock piles where cover is convenient, but also with open space for running. It is a voracious diurnal lizard that feeds on just about anything smaller than itself, including insects, spiders, lizards, and snakes. When it runs at top speed, it lifts its forelegs and body off the ground and speeds along bipedally, with forelegs close to its body.

Mammals

The canyons of the Llano Estacado have exposed a rich history of the development of mammals. Evidence of early mammals and mammal-like reptiles have been documented from the Triassic deposits near Post, Texas. It is the later Tertiary and Quaternary deposits that have preserved a rich assemblage of extinct bison, proboscidians, camels, rhinos, horses, antelopes, big cats, ground sloths, giant armadillos, and short-faced bears.

The Palo Duro mouse is a subspecies of the pinon mouse restricted to rocky outcrops in juniper forests on the canyon slopes and floors in the Palo Duro Canyon region. It prefers areas in juniper-mesquite association that have large, massive boulders.

The western pipistrelle bat is associated chiefly with rocky situations along watercourses. It retreats into cracks and crevices of canyon walls or cliffs, under loose rocks or in caves during the daytime. They are among the most diurnal of bats, beginning their foraging flights very early in the evening and often remaining active throughout the early morning. On the wing, pipistrelles have a slow, fluttery flight restricted to small foraging circuits.

Ringtails are cat-sized carnivores resembling a small fox with a long raccoon-like tail. They live in a variety of habitats, but prefer rocky areas and canyon walls, and are expert climbers capable of ascending vertical walls. They are almost wholly nocturnal. Ringtails eat a wide variety of food items including small birds and mammals, snakes and lizards, insects and arachnids, toads and frogs, and a variety of plant fruits such as persimmon, hackberry, and mistletoe.

The western spotted skunk occupies a variety of habitats, but is most often found in association with rocky bluffs, cliffs, and brush-bordered canyon streams. They are also adept at climbing. Their defensive behavior consists of a rapid series of warning handstands. Their foul-smelling musk can be accurately discharged for a distance of 4-5 meters.

Feral pigs in Texas are descended from introductions of European wild hogs for sporting purposes, and from escaped domestic swine that have established feral populations. Feral pigs can have measurable influences on native wildlife and plant communities as well as domestic crops and livestock. Extensive disturbance of vegetation and soil occurs because of their rooting habits.

Aoudads, or barbary sheep, are native to the dry mountain areas of northern Africa. They are adapted to dry, rough, barren, and waterless habitats. They were introduced into the Palo Duro Canyon where they have become firmly established. They live in small groups comprised of old and young animals of both sexes. They are expert climbers, ascending and descending precipitous slopes. There is some evidence that they directly compete with mule deer for food.

Birds

In a biological sense, eastern North America meets western North America along a broad line paralleling the eastern breaks of the Llano Estacado. East of that line, birds typical of the southeastern, eastern, and northern United States may be found. West of that line, the birds are more characteristic of Mexico, New Mexico, and Arizona with Rocky Mountain migrants. Many species of birds are very selective in their habitat preferences, but powerful weather fronts, severe winter storms, and occasional hurricanes drive birds out of their normal ranges. Because of its size, geographic location, and abundant playa water sources, the Llano Estacado has an incredibly diverse and often unexpected avifauna.

The common raven is a bird of mountains, deserts, canyons, forests, tundra, and coasts in the Northern Hemisphere. They are highly intelligent and consummate aerialists. They feed largely on carrion, but will also eat small vertebrates, insects, and fruit. The raven figures prominently in the legends of many cultures.

The black-crested form of the tufted titmouse inhabits the woodlands of the breaks, feeding on a mixed diet of insects, spiders, seeds, and berries. In the winter months they forage in mixed-species flocks. They are active, boisterous and often tame little birds.

One of the most beautiful of all bird songs belongs to the canyon wren. The clear, ringing song reflects off canyon walls and is audible a half mile away. The canyon wren creeps along over rocky walls in its territory probing with its long, curved bill for insects and other invertebrates.

The canyon towhee has been described as a “plain overgrown sparrow.” It is often a wary ground-dwelling bird, constantly on the move keeping near or under shrubbery. In parks and campgrounds it often becomes quite tame. It inhabits rocky, brushy hillsides and wooded canyons.

Invertebrates

Crayfish are freshwater crustaceans that are closely related to lobsters. They breathe through gills and are found in bodies of water that do not freeze to the bottom. There are many different species.

In mid-summer, cottonwood borers gnaw holes in the base of softwood trees to deposit their eggs. The eggs hatch in about three weeks. The larvae bore into the bark and into a major root by fall. The larvae can live up to 20 years in seasoned wood. Cottonwood, poplar, and willow are the favored trees.

Horse and deer flies are in the same family: the Tabanidae. Females bite hard and feed on blood. They are often serious pests of humans and animals. Males feed on pollen and nectar. The larvae of most species are aquatic. The adults are often found near water, but are strong fliers and may travel several miles.

Bagworm moth larvae construct silk cases covered with portions of leaves and twigs. They will pupate within the bag. Adult males emerge with well-developed wings, but the females are wingless, legless, and wormlike and never leave the bag in which they pupated.

Resources

The following resources for learning more about the Breaks and Canyons habitat are available on this website:

Photo Essays

Essays

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Sibley Nature Center
1307 E. Wadley, Midland, Texas 79705
phone 432.684.6827
email info@sibleynaturecenter.org