Near Coahuila, Mexico Photograph by © WWF-Canon/Edward PARKER   Southern North America: Northern Mexico into southwestern United States Deserts and Xeric Shrublands   196,700 square miles (509,500 square kilometers) -- about as big as twice Wyoming Vulnerable

· Bees and Bears
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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Bees and Bears

This vast desert spreads out between Mexico's two largest mountain chains, the Sierra Madre Oriental and the Sierra Madre Occidental, extending northwards into south-western United States. The ecoregion occupies most of the state of Chihuahua, northwest Coahuila, and northeast Durango and parts of Texas, Arizona, and New Mexico. Four river basins influence this desert -- the great Rio Grande (Bravo), the Rio Casas Grandes, the Rio Mapimi Bolsón and the Rio Mayrán. The climate is dry, with some summer and winter rains, and mild frosts during the fall and winter. Widespread and characteristic plant species are creosote bush, tarbush, viscid acacia, yucca, and cactus. This ecoregion is one of the richest deserts for plants in the Americas, and is likely the third richest desert for reptiles in the world. It contains the highest diversity of bees in Mexico, as well as the largest assemblage of endangered cacti in America.

Special Features

Like most deserts, the Chihuahuan is characterized by the near absence of precipitation. Temperatures are extreme and range from 100°F (over 38°C) to below freezing. This is the largest ecoregion of xeric scrub in North America and is one of the richest deserts in the world. At least 3500 plant species grow here, of which 1000 are endemic. Many endemic insects also occur here. It is home to the Bolsón desert turtle, the largest of the North American desert turtles. Nearly extinct in the wild, a small population of American bison also survive here. The highly endangered Mexican prairie dog finds refuge in the shrublands, as does the common prairie dog.

Despite its immense size, the Chihuahuan desert has suffered extensive human impacts. Agriculture and cattle farms have replaced vast portions of native vegetation. Livestock grazing damages sensitive desert scrubs and habitats along streams. Few areas have escaped grazing impacts. Loss of springs and diversion of streams by people greatly impacts wildlife that depends on water sources. Cacti and other exotic species are illegally extracted and traded. Black bear, are hunted for their fur and body parts.

Wild Side

The pronghorn used to roam the Chihuahuan desert, however a mere 24 individuals were last recorded in the state of Chihuahua. Mexican wolves and jaguars have also been largely extirpated. Mexican fire-barrel cactus and Arizona rainbow cactus dot the dry landscape, concealing Horned Texan lizards and Texan banded geckos. More conspicuous are the Coahuilan box turtle, black-tailed jack rabbit, collared peccaries, grey foxes and badgers which use the many arroyos to seek shade. Important bird species of this region are the loggerhead shrike, elf owl, burrowing owl, aplomado falcons, black-throated sparrow, cactus wren, and phainopepla. The rare Worthen's sparrow has a last refuge here in intact grasslands.

Cause for Concern

Despite its immense size, the Chihuahuan desert has suffered extensive human impacts. Agriculture and cattle farms have replaced vast portions of native vegetation. Livestock grazing damages sensitive desert scrubs and habitats along streams. Few areas have escaped grazing impacts. Loss of springs and diversion of streams by people greatly impacts wildlife that depends on water sources. Cacti and other exotic species are illegally extracted and traded. Black bear, are hunted for their fur and body parts.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.