Lower Rio Grande Valley brush habitats

The endangered ocelot and Altamira oriole occur nowhere in the nation except the Lower Rio Grande Valley.

The Lower Rio Grande Valley of South Texas is a rich natural and cultural region which is a ecological transition zone between Texas and Mexico. The Valley encompasses a dozen natural communities and more than 40 rare or threatened species. Many animals and plants that live in the Valley are found nowhere else in the United States. On the dry hills of Starr and Zapata counties, brushlands of grayblue cenizo, thornladen acacias, and cacti hide niches that support 11 endangered plants as well as threatened fauna such as horned lizard and Texas tortoise. Further down the Valley in Hidalgo and Cameron counties, dense subtropical woodlands of ebony, granjeno, anacua, and sabal palm grow along with Mexican shrubs and flowers at the northern edge of their ranges. Colorful songbirds that cross the border in these woodlands include the tropical parula, rosethroated becard, and Altamira oriole. These riparian woodlands are some of the rarest natural communities in Texas. Much of the upland brush country is still productive natural habitat used by deer, quail, dove, javelina, turkey, and many other species, but the areas rapid population growth is bringing change to areas outside the Valley as well.

More than 90 percent of the Rio Grande Valley floodplain has been converted to cropland, with only small remnants left of native woodlands. The Rio Grande, the region's lifeblood, is almost dry near its mouth because of

The thorn scrub of South Texas and the Rio Grande Valley is productive habitat for many important game and nongame species. A free-flowing, 50-mile stretch of the Rio Grande below Falcon Dam shelters native brush and the nations only groves of Montezuma baldcypress.

upstream diversion, and channel dams now prevent the floods that are necessary to sustain riparian woodlands. Small preserves of brushland have been protected along the Rio Grande, but existing preserves are probably not sufficient to ensure survival of plants and animals such as the endangered ocelot, which ranges north into South Texas along the Laguna Madre. Working with landowners to restore and protect dense brush habitat will be necessary for the ocelot to survive in Texas.

The Valley has tripled in population since 1970, and the population is predicted to double again in the next 20 years. This rapid growth threatens to crowd out wildlife. Efforts to restore and enhance natural habitats have met with mixed success. It is vital to conserve the last remnant tracts of habitat that furnish foothold for many species of animals and plants which are unique to the region. More preservation and education are needed to ensure that the Valleys unique natural and cultural heritage are not lost.

Unusual soil conditions in brush habitats of Starr and Zapata counties support endangered plants such as star cactus, left.

Places to see Lower Rio Grande Valley brush habitats: Protected Acreage of Rio Grande Riparian Woodlands in South Texas: 1,600 acres Lower Rio Grande Valley National Wildlife Refuge (many units) Santa Ana National Wildlife Refuge, McAllen   Falcon State Park, Roma