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Habitats of the Llano Estacado
Prairie to Mesquite Brushland

Introduction

The prairie is a changing ecosystem. A remarkable diversity of habitats is inseparably linked with grasses. A multitude of plants and animals act and interact with one another under the constant pressures of nonliving forces: soil, weather, and geologic change. The prairie is about relationships and adaptations. Life on the prairie must adapt to wind, drought, cold, and fire.

Fire was once a major determinant of the prairie ecosystem. Lightening from thunder storms catches the prairie on fire and the flames are driven by wind. Fire consumes dead stalks of grass and invasive woody shrubs. After a fire, the grass is generally greener and more nutritious for grazing animals. But the effects of fire vary considerably with such factors as the weather, the time of year, the intensity of the fire, and the interval between burns.

Plants

Grasses evolved with grazing animals and fire. As grasses grow, they produce new stems from buds that develop from old stem bases near the surface of the ground. When the new stems become numerous, they form a cluster or bunch. Other grasses produce underground stems (rhizomes) that grow horizontally. Vegetative propagation enables grasses to persist for many years without seed formation. Grasses also have another provision for regrowth. Each grass leaf grows from its base instead of its apex (tip).

When the apex of the leaf is eaten, growth continues from its base. Grasses provide food and cover for many types of animals and are important for building and stabilizing soil.

Cane bluestem, blue gramma, sideoats gramma, and buffalo grass were climax grass species of the buffalo prairie. Numerous wildflowers are also associated with the prairie. It is believed that yuccas are the “stakes” of the Staked Plain – the Llano Estacado.

The grassland of the southern Llano Estacado blends into mesquite brushland. The spread of mesquite was once held in check by fire, buffalo, and prairie dogs. Now livestock eat mesquite foliage and pods. The seeds pass through their digestive tracts and grow where they fall, contributing to the rapid spread of mesquite across the prairie. Mesquite produces extensive root systems to locate water. With adequate rainfall a mesquite can grow to a height of about thirty feet, but most on the Llano Estacado are less than fifteen feet tall. Many mesquites have tasajillo cacti growing underneath where a bird deposited the seeds after eating the bright red berries.

The following video was produced by Sibley Nature Center's own Richard Galle and narrated by Burr Williams.



Birds

Grassland birds, such as horned larks and meadowlarks, walk or run over ground foraging on seeds and insects. They also build their nests on the ground. The eastern and western meadowlarks look very similar to each other, and their ranges overlap on the plains. But very little hybridization occurs between the two species. The songs of the two are very different and serve as an effective reproductive barrier.

The brown-headed cowbird was originally presumed to be associated with the buffalo, but now is adapted to feeding near cattle, snatching up insects disturbed by grazing animals. Cowbirds do not build nests. Instead, they lay their eggs in the nests of other birds. Although more than 100 species have been found to serve as host to this brood parasite, tyrant flycatchers, vireos, warblers, and finches are preferred hosts.

The curved-billed thrasher and cactus wren are common in open growth of mesquite interspersed with cacti. Both are ground feeders: the curved-billed thrasher digs vigorously in the ground with its curved bill for insects and seeds, and the cactus wren inserts its bill underneath movable objects for insects. Both prefer to nest in cholla cacti.

The pyrrhuloxia lives in mesquite and feeds on seeds and the bright red fruit of the tasajillo cactus often growing in association with mesquite.

Burrowing owls live in abandoned prairie dog holes. They mostly eat insects like grasshoppers and beetles. Burrows occupied by owls can be distinguished from those of prairie dogs by the accumulation of hair, bone fragments, insect scraps, and owl pellets around the entrance. Male burrowing owls stay all year, but females and young migrate to Mexico for the winter.

Mammals

Until the 1870s, five million buffalo (bison) roamed the Llano Estacado with 500 million prairie dogs and a million pronghorn on the same range. Prairie dogs kept the prairie diverse by constantly disturbing the soil. Many species of plants only grow in disturbed soil that provided nutritious grazing for buffalo. Fossorial mammals like prairie dogs, pocket gophers, and ground squirrels till and aerate soil, graze, and provide weed management.

The climax ecosystem of the buffalo prairie has been transformed into a mesquite brushland. Livestock overgrazed the prairie in the early days of ranching creating the opportunity for different species of animals and plants to move in, find a niche, and develop a new ecosystem. The mesquite brushland has become home to more species of plants and animals than the original prairie. Porcupines, raccoons, opossums, javelinas, deer, and mountain lions have moved into the prairie brushland.

Reptiles

Snakes are common on the Llano Estacado. Prairie dog towns are the favored habitations for rattlesnakes. Burrows provide shelter from heat in the summer and a place to hibernate in the winter. Food is usually abundant in the form of young prairie dogs and
burrowing owls, mice, rabbits, lizards, toads, and salamanders. Young rattlesnakes also have predators. Coyotes, foxes, hawks, eagles, and owls are efficient predators of snakes. However, it is believed that the greater roadrunner takes more young rattlesnakes than all other predators combined.

The Texas blind snake is a tiny, predominantly subterranean snake that feeds on the eggs, larvae, and pupae of ants and termites. Its eyes are vestigial and are no more than dots of dark pigment. It often lives with a small species of army ant.

Bullsnakes vary greatly in temperament: some are very docile, but others will elevate their body, hiss menacingly, and attempt to bite. Bullsnakes are voracious, and as a result are economically beneficial in destroying mice, cotton rats, gophers, and young rabbits.

Coachwhips, kingsnakes, and hognose snakes are often diurnal and are the most commonly seen snakes.

Invertebrates

Many of the processes of the prairie ecosystem can be traced to insect activity. All animal life on the prairie ultimately depends on the plants within a particular niche. And the existence of plants depends not only on how efficiently wind or insects pollinate them, but also on how extensively their flowers, leaves, stems, and roots are eaten by insects. The greatest herbivores among insects on the prairie are grasshoppers.

Grasshoppers are among the best-known insect songsters. Their songs are produced mainly by stridulation, that is, by rubbing one part of the body against another. Songs play an important role in their behavior, and is done mostly by males in establishing a territory and attracting a female. Combinations of favorable environmental conditions allow some species of grasshoppers increase to tremendous numbers and migrate considerable distances, causing damage of catastrophic proportions. But when their numbers are low, grasshoppers remain stationary.

Hosts of burrowing beetles, bees, wasps, and ants help loosen prairie soil so that it can absorb moisture. Grassland termites are major recyclers of nutrients. Insects are crucial in the decomposition of carrion and animal waste. Dung beetles bury grazing animal manure and fertilize the soil. Carrion and scarab beetles and blow flies feast upon the dead. And a multitude of butterflies, moths, bees, and beetles are pollinators of prairie flowers. Some pollinators are very specific: the yucca moth, Pronuba, is the only pollinator of yuccas. Spiders and other arachnids are important predators on the prairie. Red velvet mites (“rainbugs”) are related to spiders. They are major predators of termites.

Related Resources

The following resources for learning more about the Prairie to Mesquite Brushland habitat are available on this website:

Essays

Photoessays

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