Access is limited to tour groups and those with permission to enter the ranch.

This vast 362,885-acre ranch lies in south-central New Mexico along the Rio Grande River. The vegetation is Chihuahuan and semi-desert grasslands with cottonwood, willow, and salt cedar riparian along the river. The Fra Cristobal Mountain range is home to a successfully reintroduced and subsequently delisted desert bighorn sheep population (click here for desert bighorn sheep listing on the Turner Endangered Species Fund site). Other species on the ranch include bison, pronghorn, desert mule deer, mountain lion, javelina, and oryx. The lava tubes of Jornada lava field are the summer home for one of the largest bat populations in North America.

Wildlife research projects conducted on the Armendaris include scaled quails, bobcats, kit foxes, badgers, bison, and prairie dogs.  Research has also been conducted on the effect of fire on range grasses and the recovery of native riparian species after the removal of salt cedar. Endangered species on the Armendaris are managed by the Turner Endangered Species Fund (TESF).  Projects include the aplomado falcon and bolson tortoise, along with populations of silvery minnows and willow flycatchers present on the ranch.

The historic Camino Real de Tierra Adentro, a 1,000-mile trail from Mexico City to Santa Fe, traverses the ranch over a 42-mile distance. A Spanish mine dating back to 1658 is also located on the ranch in the Fra Cristobal mountains.