In the 1800's, the Altar Valley was an open grassland teeming with large herds of pronghorn. Masked bobwhite quail calls filled the early morning summer air. The grasslands blanketed the landscape, uninterrupted as far as the eye could see.

In the 1850's, Pedro Aguirre, Jr. came to this location and started a stagecoach and freight line that would connect Tucson and the mining towns of Arivaca, Arizona, and the town of Altar in Sonora, Mexico. He built a homestead here in 1864 and named it Buenos Ayres, or "good air," because of the constant winds found there.

Aguirre was the first person to develop artificial sources. He began by constructing a large reservoir near the head of the watershed at the confluence of the Lopez and Compartidero washes. With water in place, Aguirre and his neighbors could capitalize on the abundance of forage in the central Altar Valley.

The cattle industry in southeastern Arizona exploded on the landscape as the water supply was secured. Then came the railroads that opened new markets. But the cattle industry would suffer a setback. A severe drought in the region lasted from 1885-1892 and it would result in the loss of 50 to 70 percent of the cattle herds. Bones of the dead cattle lay dead on the range, their bones littering the landscape. The cattle that remained stripped the land bare. When the rains returned, there was no vegetation left to absorb the water and the rain eroded the landscape creating the washes and gullies we see today.

The landscape was so barren it could not even support the wildfires that naturally swept through the region. Wildfires added vital nutrients to the soil and also served to prune the landscape. Without this important natural process, brush and mesquite trees soon invaded. More mesquite was put on the landscape by ranchers who planted the trees in the washes to provide shade and food for livestock. The mesquite would spread across the valley and by the end of the 19th century the grasslands were gone, as were the masked bobwhite quail that depended on this unique habitat.

Between 1909 and 1985, Buenos Aires Ranch changed ownership several times. It became one of the most prominent and successful livestock operations in Arizona. From 1926 to 1959, the Gill family raised prize-winning racing quarter horses. During the 1970s and 80s, the Victorio Land and Cattle Company specialized in purebred Brangus cattle, which are well suited to hot, dry climates.

On February 20, 1985, the Secretary of the Interior Donald Hodel announced that the U.S. Fish and Wildlife Service would purchase the Buenos Aires Ranch as a national wildlife refuge for the endangered masked bobwhite. At that time, Secretary Hodel expressed the agency’s belief that the Buenos Aires Ranch was the only place in the United States providing suitable habitat for the masked bobwhite. Since that time, refuge staff, wildlife biologists, volunteers and many partners have worked together to restore the original landscape of open, semidesert grasslands and bring back the native wildlife that once called these lush prairies home.