Along the banks of the lower Rio Grande is the Santa Ana National Wildlife Refuge, a 2,088 acre refuge established in 1943 for the protection of migratory birds. Considered the ?jewel? of the refuge system, this essential ?island? of thorn forest habitat is host or home to nearly 400 different types of birds and a myriad of other species, including the indigo snake, malachite butterfly and the endangered ocelot.

At an ecological crossroad, Santa Ana is strategically located where subtropical climate, gulf coast, great plains and Chihuahuan desert meet. Thousands of birds from the Central and Mississippi flyways funnel through the area on their way to and from Central and South America. This small patch of midvalley riparian woodland is also habitat for about one half of all butterfly species found in the United States.

Before dams and control structures significantly reduced the flow of the Rio Grande, periodic floods cut shifting channels into the delta creating crescent-shaped oxbow lakes, referred to as ?resacas.? Santa Ana?s management program mimics the historical flooding of the Rio Grande, maintaining the bottom land hardwood forest and providing crucial nesting and feeding habitat for birds, watering holes for animals, and homes for countless amphibians, reptiles, crustaceans and insects.

With over 95 percent of the original habitat in the lower Rio Grande delta cleared or altered, Santa Ana is a reminder of the semitropical thorn forest that once dominated the area.

Bobcat, coyote, armadillo, long-tailed weasel and Mexican ground squirrel are a few of the mammals found on the refuge. The endangered ocelot and jaguarundi are also present but rarely seen.