Buenos Aires National Wildlife Refuge. The semidesert grassland supports the reintroduction of masked bobwhite quail and pronghorns. Prescribed and natural fires play a major role in maintaining and restoring the sea of grass that once filled the Altar Valley. Riparian (wetland) areas along Arivaca Cienega and Arivaca Creek attract an abundance of birds. Brown Canyon, to the west of the Arivaca Creek area, is nestled in the Baboquivari Mountains, where a sycamore-lined stream meanders through oak woodland.