The Rio Grande corridor in the Big Bend region contains the highest density and most complex archaeological sites known in the eastern Trans-Pecos. Systematic investigations in Big Bend National Park using environmentally stratified survey blocks revealed the river corridor to contain the greatest concentration of sites and the highest degree of feature and artifact diversity anywhere in the park. Campsites, burned-rock middens, lithic scatters, petroforms, and more complex habitation sites occur on riverside pediments and broad floodplains in much greater frequency than in upland zones. The river corridor also contains an unusual concentration of sites believed to have ceremonial functions. Petroforms—rock outlines constructed on the ground surface—some of which are believed to date as far back as 4,000 years ago, are especially common along the river. The study confirmed that the Rio Grande has functioned as a primary axis of human activity for thousands of years (see Keller et al. 2022)

Recent collaborative work with Texas Parks and Wildlife archaeologist Tim Gibbs in Big Bend Ranch State Park has reinforced this interpretation. Field investigations at proto-village sites, campsites, and locations interpreted as communal gathering areas suggest that the river corridor served not only as a subsistence and gathering zone but also as a place where dispersed groups periodically converged. One example is the Green Midden site—the most robust ring midden known along this stretch of the Rio Grande—that indicates repeated, likely seasonal, episodes of large-scale food preparation and communal gathering. This site likely articulates with other nearby sites, notably the site of Tapacolmes (Polvo), just upstream of the state park, a small village site of semi-sedentary farmers practing floodplain agriculture for some 500 years starting around AD 1200 at the far eastern edge of what is now known as La Junta de Los Rios Archeological District. 

One of the most important findings emerging from the recent work by Gibbs and geoarchaeologist Charles Frederick addresses site preservation along the river corridor. Prior expectations held that most archaeological deposits along the Rio Grande would have been destroyed by flooding. But recent excavations informed by geomorphic analysis shows that canyon constrictions and bedrock controls create hydraulic effects where deposits in some settings were preserved rather than scoured, where sediment accumulated rather than eroded. This work demonstrates that intact archaeological sites may be far more common along the river than previously thought. 

For all these reasons, large-scale ground disturbance associated with border barrier construction poses an enormous risk to archaeological resources in the Greater Big Bend Region—most of which remain unknown to science. Any work conducted without thorough cultural and environmental review will destroy sites representing thousands of years of human history along the Rio Grande. 

David W. Keller

10 March 2026

Keller, David W., William A. Cloud, Samuel S. Cason, et al. A Sampling of Archeological Resources in Big Bend National Park, Texas. n.d.

Wildlife and the habitats they depend on for survival will be significantly impacted by the construction of a 30-foot steel barrier accompanied by a 75–100-foot cleared corridor for patrol roads, lighting, and maintenance. Fourteen key impacts have been outlined below.

1. Habitat Destruction: The “Dead Zone”

Border wall construction typically involves clearing 75–100 feet of land for roads, staging areas, and maintenance access.

This corridor is stripped of all vegetation causing habitat loss for birds, reptiles, mammals, and insects, destruction of burrows and nesting sites, displacement of territorial animals, which often rely on specific territories and knowledge of local food and water sources.

Wildlife forced from established territories must relocate into unfamiliar areas, which can result in:

• Mortality from exposure
• Competition with established populations
• Inability to locate water or food
• Death along the wall itself when movement routes are blocked
  

2. Construction Disturbance

During construction, the following disturbances occur:

• Blasting and heavy machinery
• Prolonged human presence
• Noise and vibration
• Temporary infrastructure and worker camps

These activities force animals to abandon habitat long before the barrier is completed.

Once completed, the wall permanently blocks historic migration routes and daily access to water.

Sources:

Effects of Noise on Wildlife

How does construction affect biodiversity?

Why Is Habitat Fragmentation Shrinking Animal Territories

3. Artificial Lighting

Border walls in other regions have included floodlighting and continuous night illumination.

Lighting impacts include:

• disruption of migration and orientation for birds, bats, and insects
• increased predation risk due to illuminated open ground
• exposure of small animals attempting to reach the river

Predators exploit this condition much like roadside hunting corridors in Big Bend National Park, where owls and other predators take advantage of exposed prey.

4. Invasive Plants and Fire Risk

Cleared ground is highly vulnerable to invasive species colonization.

One major concern is buffelgrass, an African invasive grass already spreading in the region.

Impacts include:

• formation of dense monocultures
• increased fire intensity
• creation of “ladder fuels” that allow fire to spread into habitats that historically rarely burned
• Desert plants such as ocotillo and other native shrubs are not fire-adapted and may die following these hotter fires.

Source:

Fighting non-native plants in Big Bend National Park

5. Flooding Hazards

Walls can also function as barriers during flood events, trapping animals.

Mass wildlife deaths have been documented when animals are unable to escape floodwaters or fires because movement corridors are blocked.

Source:

More than 100 wild animals trapped by border wall killed in Texas wildfire

6. Spread of Invasive Trees

The invasive athel tamarisk (Tamarix aphylla) poses a serious threat to the Rio Grande ecosystem.

Management of this species currently requires:

• manual cutting
• chemical treatment
• physical removal

Questions raised by biologists include:

Would border barriers impede invasive species management?

Would maintenance access become more difficult?

Sources:

Nation Park Service to remove invasive Salt Cedar

Ecological Risk Screening Summary – Salt Cedar

7. Threats to Endangered Plants

Three federally listed endangered cactus species occur within 100–150 feet of the Rio Grande in limestone habitats:

• Chisos Hedgehog Cactus

• Bunched Cory Cactus

• Lloyd’s Mariposa Cactus

Construction clearing and ground disturbance could significantly damage these populations. In addition to the species listed here, many rare species likely occur along the river corridor but remain poorly documented.

8. Threats to Endangered Birds

The Western Yellow-billed Cuckoo nests in riparian forests along the Rio Grande.

Current protections in Big Bend National Park include:

• seasonal road closures near nesting sites

Key questions raised by biologists:

• Would construction halt during nesting season?
• Would riparian trees such as cottonwoods be removed for visibility?
• Tree removal could eliminate nesting habitat.
  

9. Water Use During Construction

Border wall construction can require large volumes of water for:

• Concrete mixing
• Dust suppression
• Site preparation

In Arizona, construction activity has been associated with lowering of local water tables.

In the Big Bend region:

• The Rio Grande Village spring-fed ponds support the critically endangered Big Bend Gambusia
• These ponds already require supplemental pumping during drought
• Construction demand could increase stress on this limited water supply
  

10. Large Mammal Movement Barriers

Large mammals that depend on large territories would be directly affected.

Species include:

• bighorn sheep
• elk
• mule deer
• white-tailed deer
• mountain lions
• black bears

Typical steel pedestrian walls include only 13 openings measuring roughly 11×14 inches per 100 yards.

• These openings are too small for large mammals and many medium-sized animals.

Observed effects elsewhere include animals repeatedly attempting to cross barriers. Even small animals, like the Sonoran desert toad, have been documented repeatedly jumping against steel barriers.

11. The Texas Black Bear Population

The American black bear population in the Chisos Mountains represents the only viable breeding population in Texas.

The estimated population is 30–40 individuals, fluctuating with drought.

Historical context:

• Black bears were extirpated from Texas for 75 years as a result of sport hunting, predator control, and habitat alteration.
• A female with cubs was documented in Big Bend National Park in 1988, marking their return to Texas.

Genetic studies show strong connections between Chisos bears and populations in the Sierra del Burro mountains in northern Mexico.

• Male bears migrate across the border, introducing vital genetic diversity.
• Without this genetic exchange, inbreeding risk increases and population viability declines

Sources:

Black Bear Denning Behavior in the Chisos Mountains
Black Bear in the Trans-Pecos
To Survive in Texas, Black Bears Need an Open Border

12. Ecological Role of Bears

Black bears play important ecosystem roles including:

• Seed dispersal through scat and fur
• Consumption of fruits and berries from cacti and shrubs
• Disturbance of soil while feeding on insects

Biologists have also observed bears exhibiting behavior that helps maintain forest and shrubland ecosystems:

• Climbing madrone and oak trees
• Breaking branches while feeding
• Inadvertently promoting seed germination and new plant growth

13. Fragmentation and Genetic Isolation

Wildlife barriers fragment ecosystems by isolating populations.

Consequences include:

• Reduced genetic diversity
• Increased disease vulnerability
• Long-term population decline
• As climate change alters habitats, species must move to track suitable conditions.

Barriers prevent this movement.

Stanford University researchers warn that such isolated populations may become “zombie species”—populations that are genetically and demographically doomed.

Source:

How would a border wall affect wildlife?

14. Broader Conservation Concerns

Conservation organizations have raised concerns about border barrier impacts on wildlife movement and habitat integrity:

• Backcountry Hunters and Anglers Statement

• The National Audubon Society’s analysis of borderland fragmentation

• Defenders of Wildlife report on Big Bend impacts
  

Summary

A border wall in the Big Bend region would likely create multiple overlapping ecological impacts:

• Permanent habitat destruction along the river corridor
• Disruption of wildlife movement and migration
• Increased mortality during fires and floods
• Spread of invasive plants and fire risk
• Threats to endangered species and sensitive habitats
• Genetic isolation of wildlife populations

Because the Big Bend region remains one of the largest intact desert ecosystems in North America, fragmentation here would have disproportionate ecological consequences.