In the 20th Century, two institutions—the California Academy of Sciences and the San Diego Natural History Museum—were dominant forces in supporting and documenting the majority of scientific efforts along the Baja California peninsula and its islands. The San Diego Natural History Museum began sponsoring expeditions in 1926 and occasionally joined efforts with the California Academy of Sciences on cooperative research projects until 1966. However, research in northwestern Mexico did not stop after 1966. From this point forward most of the activities were performed by separate individuals studying specific disciplines.

In the 20th Century, two institutions—the California Academy of Sciences and the San Diego Natural History Museum—were dominant forces in supporting and documenting the majority of scientific efforts along the Baja California peninsula and its islands. The San Diego Natural History Museum began sponsoring expeditions in 1926 and occasionally joined efforts with the California Academy of Sciences on cooperative research projects until 1966. However, research in northwestern Mexico did not stop after 1966. From this point forward most of the activities were performed by separate individuals studying specific disciplines.

Thirty years passed without the San Diego Natural History Museum conducting any large, multidisciplinary expeditions in Baja California, even though many areas had not been biologically explored. Our scientists were then charged with selecting one of the many natural areas in northwestern Mexico to focus on for the 1997 expedition. The region that was selected was in the northern part of the state of Baja California Sur. Two mountain ranges, the Sierra San Francisco and the Sierra Guadalupe, lie on the eastern edge of the Vizcaino Desert and provide a link between the tropical components of the southern peninsula and temperate influences of the north. The small amount of scientific documentation that had been conducted prior to this expedition indicated that a biological mosaic of species, of sorts, from both tropical and temperate climates existed in this area. Scientists hoped to find many endemic and new species in this region.

The San Diego Natural History Museum invited a team of scientists from both the United States and Mexico on this expedition. This binational, multidisciplinary group included specialists from such fields as botany, ornithology, entomology, mammalogy, paleontology, invertebrate zoology, and herpetology. This format fostered collaboration between Mexican and American scientific efforts and proved to be an important step in promoting and defining future binational cooperative expeditions.