TEXAS GEMS - LAGUNA ATASCOSA NATIONAL WILDLIFE REFUGE (LANWR)
Laguna Atascosa National Wildlife Refuge (LANWR) is located on the lower Gulf Coast about 25 miles east of Harlingen, Texas. It is the southernmost waterfowl refuge in the United States. It also provides habitat for 10 federally endangered or threatened species and has the most bird species documented (411 species) of any national wildlife refuge. Typical of the Texas Coastal Plain, the refuge is virtually flat with most elevations below 5 feet above sea level. The landscape is an interspersed pattern of meandering resacas (oxbow lakes), lomas (brush-covered sand/clay dunes), coastal prairies, and wetlands.
Date When Information Last Updated:
Laguna Atascosa National Wildlife Refuge encompasses 65,096 acres. An additional 6,640 acres are managed by LANWR, but are owned by or under conservation easement with the Lower Rio Grande Valley NWR. The 71,736 acres managed by LANWR are divided into the following management units: (1) Laguna Atascosa Unit, 45,187 acres; (2) Redhead Ridge (Bahia Grande) Unit, 19,909 acres; (3) Lower Rio Grande Valley NWR Unit, 6,640 acres.
Area of Influence:
Watershed 12110208 - South Laguna Madre (USGS Hydrologic Units, Texas
4c - Gulf Coast Prairies and Marshes: Upland Prairies and Woods and 5 - Coastal Sand Plains (Ecoregions and Sub-regions of Texas).
Ecological and Cultural Characteristics
LANWR consists of approximately 30,100 acres of marsh, open-water, and tidal wetlands, 19,800 acres of coastal prairie, 11,400 acres of upland brush, 700 acres of savannah, 1,600 acres of grassland, and 1,500 acres of fallow cropland.
Gulf Coast Jaguarundi Herpailurus yagouaroundi cacomitli
Northern Aplomado Falcon Falco femoralis septentrionalis
Brown Pelican Pelecanus occidentalis
Hawksbill Sea Turtle Eretmochelys imbricata
Kemp’s Ridley Sea Turtle Lepidochelys kempi
American Alligator Alligator mississippiensis
Green Sea Turtle Chelonia mydas
Loggerhead Sea Turtle Caretta caretta
At least 95 species of birds are known to nest on LANWR, including the aplomado falcon. Forty-two species of mammals, 10 species of amphibians, and 33 species of reptiles have been documented on the refuge, most of which have resident breeding populations. The refuge supports one of only two known breeding populations of ocelots in Texas. About 60 species of fish are found on LANWR. Many saltwater species come into the shallows seasonally and return to the Gulf of Mexico as adults. Some freshwater and brackish species complete their entire life cycle in the ponds, resacas, and impoundments found on the refuge.
LANWR is an important foraging area for a vast array of species, including wintering waterfowl and raptors, migrating shorebirds and songbirds, and all of the year-round resident wildlife that occurs in the area.
LANWR is used both as a wintering area and as a spring and fall stopover point for many species of migratory birds. About 20 species of ducks, as well as geese and sandhill cranes winter on the refuge. LANWR is especially well known for its concentration of wintering redhead ducks, which use the refuge’s freshwater areas for drinking and loafing and which feed in large numbers in the Laguna Madre. Thousands of shorebirds can be seen feeding at the refuge during the winter and especially during spring migration. Many visitors come to LANWR during April and early-May specifically to see the colorful display of warblers, buntings, orioles, vireos, and flycatchers that stopover at LANWR to feed and rest briefly on their way north.
The refuge is sheltered from the Gulf of Mexico by South Padre Island, a barrier island, and the hypersaline Laguna Madre bay system. A series of resacas, or old river oxbows, meander through LANWR and Redhead Ridge Units of the refuge. These resacas have become isolated from the main river channel, but they still retain the ability to hold water from rains and periodic flooding. Tidal mud/sand flats comprise nearly one-quarter, or 10,300 acres, of the 45,187-acre Laguna Atascosa Unit. The Redhead Ridge (Bahia Grande) Unit contains about 10,000 acres of restorable estuarine wetlands.
LANWR represents the largest protected block of wildlife habitat in the Lower Rio Grande Valley of Texas. It provides a place for hundreds of plant and animal species to survive, and allows many people with a unique opportunity to view local wildlife.
Uniqueness of Natural Community:
LANWR is an unusual place where species from the temperate north, the tropical south, the maritime east, and the arid west can all be found in the same area. Because the refuge is at the crossroads of different environmental, physiographic, and climatological conditions, it hosts a variety of habitats that can support a large variety of plant and animal species, both common and rare. About 450 plant, 400 bird, 42 mammal, 60 fish, and 43 reptile and amphibian species have been documented on the refuge.
Archeological and Cultural Significance:
From an archaeological standpoint, LANWR is situated within the Brownsville Complex. The Brownsville Complex is relatively rich in archaeological resources in spite of the fact that many types of artifacts do not survive well in the saline soils. This Complex is a late prehistoric manifestation of the Rio Grande Delta and southern coast which is tentatively dated from A.D. 1200 to historic times.
The Laguna Atascosa Unit of the refuge has two archaeological sites which have been excavated and at least two others have been identified but not disturbed. In 1976, the Unland Site was discovered during construction of a refuge service road. This site yielded burials of three male individuals along with some stone and shell artifacts. In 1992, human skeletal remains were discovered eroding out of a vertical clay dune face on Horse Island. This burial site was that of a female who was interred about 1,200 years ago. Cultural artifacts from more recent historic times are also present on the refuge, including structures built during World War II when much of the refuge was an aerial gunnery range.
On the Redhead Ridge Unit, an important cultural resource is an abandoned railroad bed that bisects the Bahia Grande wetland. The railroad bed consists of local fill and windblown sand/clay drifts around approximately 2.5 miles of degraded cypress pilings on which a narrow gauge railroad trestle was historically supported. This railroad was originally constructed in 1865 under command of General Phil Sheridan to move Union troops between Brownsville, Texas and Port Isabel, Texas. Later, in 1872, Simon Celaya converted the army railroad to a “42-inch gauge” railroad, and named it the Rio Grande Railroad. The railroad ran a total of 24 miles between Brownsville and Port Isabel. Some of the railroad bed is deteriorated and some pilings are missing; therefore, this resource is only partially intact.
Current and Potential Use of the Site
Existing or Potential Educational Use:
More than 200,000 people visit LANWR annually. The refuge has areas open to public access for wildlife oriented recreational activities including wildlife observation, photography, hiking, biking, fishing, and hunting. There are two designated self-guided auto tour routes, a system of walking/biking trails, a photo/observation blind and a visitor center. Overnight camping and a boat ramp are available in the Adolph Thomae, Jr. County Park, located within the refuge near Arroyo City.
Existing Monitoring Activities:
Threats to Ecological Integrity:
The primary threat to the ecological integrity of LANWR lies in the increased development of the surrounding area. Land-use outside of the refuge’s boundary is increasingly switching from agriculture (farming/ranching) to commercial and residential development. State-owned roads, especially FM 106 and State Highway 48, that pass through or border the refuge are also being expanded. With improved roads, traffic volume and speeds will increase, which is expected to increase ocelot mortality from vehicle strikes. Improved roads will also encourage additional commercial and residential development. The ability of wildlife to move safely between the distinct units of the refuge, and units of the Lower Rio Grande Valley NWR, are becoming increasingly difficult as the habitat becomes more fragmented. Disposal of spoil materials on and near the refuge from the Gulf Intracoastal Waterway (GIWW) disrupt the natural water regime along parts of the refuge. The increased turbidity in the Laguna Madre caused by the dredging reduces the production of sea grasses, an important food source for redhead ducks and other wildlife.
Sources of Information
Laguna Atascosa National Wildlife Refuge Proposed Refuge Expansion Plan, September 1999.
Laguna Atascosa National Wildlife Annual Narrative Report, Calendar Year 2001.
Laguna Atascosa National Wildlife Refuge Watchable Wildlife List, July 1999.
Laguna Atascosa National Wildlife Refuge Bird List, January 1998.