Southmost Preserve is located on a meandering bend of the Rio Grande at the southernmost part of Texas. As part of the Boscaje de la Palma region of the Lower Rio Grande Valley Wildlife Corridor, the 1,014-acre preserve encompasses one of the last stands of native sabal palm trees in the country. This land has been called the "Jewel of the Rio Grande Valley" and many would argue that Southmost Preserve is one of the most ecologically important pieces of land remaining in the Valley.
This preserve is home to one of the only two remaining large stands of native Mexican sabal palm/Tamaulipan thornscrub stands in the United States. It also encompasses a large resaca, an old oxbow of the Rio Grande, that provides both riparian and wetland habitat. These natural vegetative communities provide important habitat for a number of rare, threatened and endangered species, including the southern yellow bat, Texas tortoise, Coue's rice rat, black-spotted newt and speckled racer. Rare amphibians, such as the sheep frog, Mexican white-lipped frog and Rio Grande lesser siren, depend upon the preserve’s resacas; ocelot and jaguarundi also rely on this area.
Located on the Central Flyway migratory route, Southmost attracts birders from all over the world. Nearly 500 avian species pass through the Rio Grande Valley; birds that have been observed on the preserve include the Altamira oriole, chachalaca, green jay, tropical parula, buff-bellied hummingbird, black-bellied and fulvous whistling duck, groove-billed ani, Couch's kingbird and olive sparrow. The wooded fringes of the resacas offer some of the last remaining nesting habitat known for two rare subspecies of birds, the Brownsville common yellowthroat and the Lomita Carolina wren.
The Lower Rio Grande Valley has been ranked by the U.S. Fish and Wildlife Service as one of the most biodiverse areas in the United States—but scientists are increasingly concerned about the long-term impacts of the U.S.-Mexico border wall. Several hundred miles of the wall stretch along the Texas/Mexico border and more than 85 percent of Southmost Preserve currently sits behind the structure.
But the wall runs adjacent to a levee and blocks the usual dispersal path for a number of animals that once crossed the embankment freely. It also negatively impacts reptiles and mammals like the state-threatened indigo snake and Texas tortoise, as well as the ocelot. Conservation staff have noted an increase in wildlife sightings across the preserve; animals such as javelina and white-tailed deer, which were once uncommon on the preserve, are seen now more frequently. The prevailing theory is that the border fence has obstructed the animals’ normal travel routes and left them unable to access other suitable habitat.
Recent calls to extend the border wall have heightened these concerns. Reports indicate that a new wall will directly impact the national wildlife refuges in the Rio Grande Valley, stretching from the Santa Ana National Wildlife Refuge in Hidalgo County to Far West Texas—a region that shares an extensive border with the Mexican states of Chihuahua and Coahuila. The prospective wall will threaten some of Texas’ most successful habitat-conservation projects and a long list of species that depend on the corridors on both sides of the Rio Grande to survive.
The Conservancy acquired the Southmost property in 1999 from Julia Jitkoff, who had used the tract for a variety of agricultural enterprises, including citrus production. Preserve management efforts include ecological research, native brush and resaca restoration, and a thriving native thornscrub seedling nursery. The nursery produces as many as 70,000 seedlings each year for area restoration efforts, which represent more than 30 native brush, tree and thornscrub species.
Southmost also serves as a research site for area universities, and the Conservancy partners with area farmers to test water-wise farming techniques.