Laguna Atascosa National Wildlife Refuge is the largest protected area of natural habitat left in the Lower Rio Grande Valley.

[3] The Laguna Atascosa National Wildlife Refuge was created following World War II in 1946 to protect habitat for migratory birds and waterfowl, specifically redhead ducks (Aythya americana).

[1][2] By 2010, it had grown to encompass a total of 65,096 acres (26,343 ha) in a landscape of "an interspersed pattern of meandering resacas (oxbow lakes), lomas (brush-covered sand/clay dunes), coastal prairies, and wetlands.

[4][5] The Peregrine Fund began reintroducing captive-bred northern aplomado falcons (Falco femoralis septentrionalis) to the refuge in 1985, which had been nearly extirpated from the Southwestern United States; by 2009, it was home to 26 pair.

Nine other endangered or threatened species inhabit the refuge, such as the Texas ocelot (Leopardus pardalis albescens) and (formerly) the Gulf Coast jaguarundi (Herpailurus yagouaroundi), rare wild cats.