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Nature - Adventure - Parks     Rio Grand Valley-1      2

TEXAS GEMS - Lower Rio Grande Valley National Wildlife Refuge

Ecological and Cultural Characteristics
Habitat Type:

The U.S. Fish and Wildlife Service identified eleven biotic communities in the Land Protection Plan for Lower Rio Grande Valley National Wildlife Refuge (1985): Chihuahuan Thorn Forest, Upper Valley Flood Forest, Barretal, Upland Thornscrub, Mid-Valley Riparian Woodland, Sabal Palm Forest, Clay Loma/Wind Tidal Flats, Mid-Delta Thorn Forest, Ramaderos, Wooded Potholes and Basins, and Coastal Brushland Potholes.

Rare/Endangered Species:

The following species are identified as endangered or threatened by the U.S. Dept. of Interior:

Wood Stork, Bald Eagle, Aplomado Falcon, Piping Plover, Least Tern, Jaguarundi, Ocelot, American Alligator, Green Sea Turtle, Hawksbill Sea Turtle, Loggerhead Sea Turtle, Kemp’s Ridley Sea Turtle, Leatherback Sea Turtle. Tx. Parks and Wildlife Dept identify numerous additional species as threatened or endangered including: Reddish Egret, Hook-billed Kite, American Swallow-tailed Kite, Common Black Hawk, Gray Hawk, White-tailed Hawk, Zone-tailed Hawk, Ferruginous Pygmy-owl, Northern Beardless Tyrannulet, Rose-throated Becard, Black Capped Vireo, Golden-cheeked Warbler, Botteri’s Sparrow, Coues’ rice rat, Coati, Texas tortoise, reticulated colared lizard, Texas horned lizard, speckled racer, Texas indigo snake, black-striped snake, northern cat-eyed snake, black-spotted newt, Rio Grande lesser siren, Mexican burrowing toad, giant toad, Rio Grande chirping frog, white-lipped frog, Mexican treefrog, sheep frog, river goby, and blackfin goby

Breeding/Nursery Area:

The refuge provides breeding habitat for numerous coastal wetland, inland wetland, and upland migratory bird species; nesting sea turtles, including Kemp’s ridley sea turtle; and numerous other amphibians, reptiles, and mammal species.

Forage Area:

The refuge provides foraging habitat for numerous coastal wetland, inland wetland, and upland migratory bird species; nesting sea turtles, including Kemp’s ridley sea turtle; and numerous other amphibian, reptile, and mammal species.

Migratory Species:

The refuge provides habitat for numerous coastal wetland, inland wetland, and upland migratory bird species.

Geomorphic Features:

Portions of the Refuge are juxtaposed at the mouth of the Rio Grande, adjacent to South Bay. Features include: Beach dune systems; lomas; and tidally influenced sand, mud, and algal flats. Lands managed by the Refuge extend upstream to Falcon Reservoir and include additional tracts surrounding the La Sal del Rey, La Sal Vieja, and East Lake inland salt lakes.

Ecosystem Function:

When this project began in 1979, ninety-five percent of the Lower Rio Grande Valley’s unique habitat had been eliminated or altered, primarily for agriculture. Consequently, the Refuge protects much of the remnant Lower Rio Grande riparian forest and adjacent xeric ecotone. Much of the land purchased by the Refuge has been, and continues to be, actively cultivated. To address this, the Refuge has developed an extensive cooperative farming and revegetation program that restores between 750 and 1000 acres of farmland per year to native habitat. The earliest restoration efforts have matured to produce habitats that are harboring native species of plants and animals that can not be seen elsewhere in the United States.

Uniqueness of Natural Community:

The protected lands of the Refuge support perhaps the richest and rarest biodiversity in the continental United States. The Refuge manages habitats supporting 13 federally threatened and endangered species, two recently down listed species, and 57 state protected species. In total, 485 species of birds, 294 species of butterflies, 115 species of reptiles and amphibians, and 83 species of mammals are known to occur in the Lower Rio Grande Valley and adjacent Gulf of Mexico coastal waters. Presently, 776 plant species are documented on the Lower Rio Grande Valley National Wildlife Refuge, but an estimate of the total number of plant species occurring in the Refuge’s area of ecological concern is placed at 1,200 species.

Archaeological and Cultural Significance:

Included as a National Historic Landmark, the Palmito Ranch Battlefield is the site of the last land engagement of the Civil War. Union and Confederate soldiers fought here on May 12-13, 1865, more than a month after Gen. Robert E. Lee surrendered at Appomattox. The Union force under Col. T.H. Barrett was defeated by the Confederate troops under Col. "Rip" Ford.

Listed on the National Register of Historic Places, El Sal Del Rey has been the site of salt harvest for at least 3,000 years. Warring Native American tribes set it aside as a truce area. In the 1500’s Spanish explorer’s claimed it for Spain. In the 1930’s it provided the legal precedent establishing mineral rights in the State of Texas.
Current and Potential Use of the Site
Existing or Potential Educational Use:

The Refuge supports various educational activities carried out by both individuals and groups. Throughout the school year, area public and private schools use the refuge by for field trips and outdoor classroom activities. Students doing graduate or post-graduate research conduct wildlife research under Special Use Permits.

Recreational Use:

The refuge offers wildlife observation and photography, and seasonal hunting and fishing access.

Commercial Use:

Oil and Gas activities: All of the subsurface mineral rights below the refuge are privately held and exploration, and production activities are ongoing.

Private Use:

The refuge is used by private entities for public use related activities, for example bird tours.

Management Status
Land Ownership:

LRGVNWR is owned and administered by the National Wildlife Refuge System, Fish and Wildlife Service, U.S. Department of the Interior.

Existing Designations:

The Refuge manages two nationally significant historical sites: Palmito Ranch Battlefield , a National Historic Landmark; and El Sal Del Rey, listed on the National Register of Historic Places.

Management Status:

The refuge is managed by the U.S. Fish and Wildlife Service as a unit of the National Wildlife Refuge System, a network of lands and waters for the conservation, management and restoration of the fish, wildlife and plant resources and their habitats for the present and future generations of Americans.

Existing Monitoring Activities:

The refuge conducts numerous biological monitoring activities including: sea turtle patrols, shorebird surveys (including Piping Plover), ocelot surveys, and a variety of academic research is permitted.

Site Viability
Threats to Ecological Integrity:

The most significant threats to the refuge and the Lower Rio Grande Ecosystem are primarily related to development: urban, suburban, and industrial; including specific issues such as flood control and water demand and competition (most notably as water demand relates to instream flow and the health of the river and associate estuary as a nursery for numerous aquatic species). Additional significant threats relate to illegal immigration, drug smuggling, and border law enforcement activities.

Management Potential:

The most significant action necessary to maintain the viability of the refuge and the ecosystem is continuation of refuge land acquisition program. All 77,000 acres of the refuge have been purchased since 1979 and the refuge has authority to purchase additional lands up to 132,500 acres total. Additionally, continued enhancement and development of the refuge law enforcement program will contribute to diminished impacts to refuge resources.

Nature - Adventure - Parks     Rio Grand Valley-1      2