Places We Protect

Lennox Foundation Southmost Preserve


A field of green palm trees.
Southmost Preserve This TNC preserve is located at the southernmost part of Texas. © Dero Sanford

One of the most biodiverse areas in the nation, this region has been called the “Jewel of the Rio Grande Valley.”

Safeguarding the Southmost Tip of Texas

Safeguarding the Southmost Tip of Texas (5:14) The southern tip of Texas was once home to a vast forest of Sabal Palms, nurtured by rich South Texas soil. But over time, those forests have been almost completely cleared for agriculture. Now, efforts are underway to protect, conserve and restore this natural heritage at TNC's Southmost Preserve.



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. This subtropical region has been called the "Jewel of the Rio Grande Valley," and many would argue that Southmost Preserve—chief among its natural gems—is one of the most ecologically important pieces of land remaining in the valley today. Located on a meandering bend of the Rio Grande Delta (the land around the mouth of the river, where it flows into the Gulf of Mexico), in the southernmost part of Texas, the natural vegetative communities found at The Nature Conservancy’s (TNC) 1,016-acre preserve provide habitat for several rare, threatened or endangered species, including the southern yellow bat, Texas tortoise, Coues' 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, or oxbow lakes, while palm/thornforests provide habitat for ocelots. These resacas developed from channels of the Rio Grande that became isolated over time and, now enlarged by water captured from nearby irrigated crop fields, serve as a major source of water, supporting the preserve’s diverse habitat and species.



Visitation is by appointment only outside of scheduled events/volunteer opportunities


Seedling production


1,016 acres

Explore our work in Texas

A woman and a man stand on a trail lined by foliage.
Biodiversity Abounds TNC's Lennox Foundation Southmost Preserve protects one of the most biodiverse regions in the country. © Kenny Braun

Why This Place Matters

Situated in the Boscaje de la Palma region of the Rio Grande Delta, the preserve is home to one of the only two remaining large stands of native Mexican sabal palm/Tamaulipan thornforest in the United States. Of the original 40,000-plus acres of riparian Mexican sabal palm forest that once stretched along the banks of the Rio Grande, only 37 acres of protected palm forest exist today.

Located on the Central Flyway migratory route, the subtropical environment of South Texas attracts birders from all over the world for good reason. Nearly 500 migratory and resident avian species pass through the Rio Grande Valley. Observations at Southmost Preserve include the Altamira oriole, chachalaca, green jay, tropical parula, buff-bellied hummingbird and black-bellied and fulvous whistling ducks, as well as groove-billed ani, Couch's kingbird and olive sparrow. In addition, the wooded fringes of the resacas offer some of the last remaining nesting habitat for two rare subspecies of birds, the Brownsville common yellowthroat and the Lomita Carolina wren.

Although Southmost Preserve is teeming with biodiversity, scientists are increasingly concerned about the long-term impacts of the border wall there. More than 85% of Southmost Preserve currently sits behind the wall that stretches along the Texas-Mexico border. The border wall runs adjacent to a levee and blocks the usual northern dispersal path for a number of animals that once crossed the embankment freely. Conservation staff have also noted increased sightings of wildlife like javelina and white-tailed deer across the preserve, presumably due to the obstruction of normal travel routes caused by the border fence, which prevents them from accessing other suitable habitat.

Photos from Lennox Foundation Southmost Preserve

Discover the diverse plant life and wildlife at this Mexican sabal palm/Tamaulipan thornscrub preserve.

A cluster of palm tree trunks with long fronds.
A butterfly with orange wings with black and white spots balances on a green fern.
A man and three women volunteers place bright green seedling plants in crates.
A small black snake with red and yellow stripes slithers over green vegetation in a pond.
A woman and man stand together talking in a field with palm trees in the background.
A large black bird perches on a brown branch.
A turquoise blue river is lined with dense vegetation on both sides of its banks.
A wall runs along the length of a gravel road.
A woman and a man sort plant seedlings into blue crates.
A field filled with hundreds of flying, white birds.
A woman holds green seedlings in both hands.
Native Seedlings Seedlings produced at the Southmost nursery are used for restoration efforts on partner and government lands, as well as TNC properties. © Kenny Braun

What TNC Is Doing

TNC acquired the Southmost property in 1999 from Julia Jitkoff, who had previously used the tract for various agricultural enterprises, including citrus production. Preserve management efforts include ecological research in partnership with area universities, native brush and resaca restoration and running a native seedling nursery that focuses on producing native plant species for area restoration projects. The thriving nursery produces as many as 40,000 seedlings each year for restoration efforts, representing more than 30 native plant species.

TNC also provides area universities with preserve access for conservation-related research, in addition to partnering with other regional organizations and individuals. 

Learn More

Visitation is limited to volunteer workdays and various special events. An appointment is needed for visits outside of these organized events. For more information, contact Preserve Manager Marcos Ruiz ( or Director of Landscape Initiatives Sonia Nájera (snajera@TNC.ORG).