Scientists at Work in Baja California

In late October 2013, more than 30 researchers, students, and volunteers converged on a small mountain range near La Paz in Baja California Sur for a binational multidisciplinary expedition. “Binational multidisciplinary expedition” is a mouthful but encapsulates a lot about the Museum’s collaborative approach to research.

The binational part is easy: the Museum’s mission is focused on southern California and the peninsula of Baja California. “While our region comprises two countries, it is one natural area,” said Michael Wall, vice president of research and public programs at the Museum. “We work together with our colleagues in Mexico to better understand our shared natural history.”

The multidisciplinary part reflects one of the Museum’s core beliefs that collaboration makes better results. “We were lucky to have a geologist from Arizona State University with us on the trip,” remarked Jon Rebman, curator of botany at the Museum. “Steve (Reynolds) pointed out some interesting geological features in the landscape in which I collected some rare plants. We can now use this information to see if it helps locate more populations.” Researchers with specialties in plants, insects, spiders, birds, mammals, lizards, snakes, geology, and fish were represented in the expedition.  

The expedition part evokes romanticized images of pith helmet-clad scientists hiking through dense vegetation followed by mules overloaded with gear and equipment. Other than the pith helmets, this picture is not too far from the truth. While in close proximity to La Paz, the mountains are rugged and access to the interior high evaluation can only be accomplished by foot and mule. Historical collections from the heart of the mountains are very rare, making it a “black hole” of biodiversity information. This is why the Sierra Cacachilas were identified by Museum scientists as a prime location for an expedition.

While the scientists are still sifting through the collections and data, they found several new discoveries with scientific and conservation implications. Of particular conservation note is the use of the Sierra Cacachilas as an important overwintering area for migratory species of conservation concern. “We found good numbers of the Gray Vireo, 14 in total, always in patches of fruiting elephant trees,” explains Lori Hargrove, postdoctoral researcher at the Museum. Phil Unitt, the Museum’s curator of ornithology, added “This was an interesting discovery since the wintering ecology of the Gray Vireo in Baja California is essentially unknown. But our research with the San Jacinto Centennial Resurvey and San Diego Bird Atlas indicates this species has undergone tremendous decline in its southern California breeding range.”  

Similarly, the Sierra Cachachilas may serve as an important overwintering ground for several species of migratory bats of conservation interest in the United States. The Sierra Cacachilas are peppered with several abandoned silver mines that now serve as roosts for several species of bats. “One mine had two species that are considered sensitive species in the United States,” remarked Drew Stokes, bat biologist at the Museum. “The California leaf-nosed bat is a species of special concern, and the Lesser long-nosed bat is a federally endangered species.” Clearly these migratory bats and birds do not recognize borders, and by studying them throughout their range, our researchers are better able to inform conservation strategies.

Many of the scientists found examples of species previously known only from other areas, but discovered for the first time in the Sierra Cacachilas. “We are still going through our material, but we found at least 12 species in the Sierra Cacachilas previously only known from the Sierra de la Laguna,” noted Rebman. Sierra de la Laguna is a biosphere reserve more than 40 miles south of the Sierra Cacachilas noted for having many species known only from that area. In addition to the plants, researchers found many insects and a few vertebrate species that repeated this pattern. “This expedition is helping us accumulate evidence that the Sierra Cacachilas are an important outlying portion in the range for species primarily restricted further south,” remarked Wall. “Outliers are important in evolution. Just think about the uniqueness of Hawaii and the Galapagos Islands.”

Of course, no expedition is complete without the discovery of new species, and preliminary results indicate the prognosis is good. Remarking on a large spider found in an abandoned mine, Maria Luisa Jiménez, a spider biologist at the Centro de Investigaciones Biológicas del Noroeste (CIBNOR) said, “It belongs to a genus which isn’t known from the peninsula, but I can’t identify it to species. It could be a new species.” In addition to a few plant species that are possibly undescribed, the entomologists on the trip are confident they have found some species that are new to science. “Until we get material under the microscope, it is difficult to say for sure,” remarked Wall, “but I’d eat my butterfly net if we didn’t collect more than a couple new species.”

In addition to the potential new species, range extensions, and conservation findings, our researchers are creating a legacy of information for future researchers. Using standardized repeatable survey techniques, they have developed a baseline of knowledge for future comparison. “We aren’t just interested in what species are there, but we are interested in how abundant those species are,” explained Brad Hollingsworth, curator of herpetology. “Using these standard techniques will allow us to make better comparisons between areas and monitor population changes over time.”

Perhaps one of the greatest achievements of the expedition was in developing a stronger collaborative relationship with partners in Mexico to better understand the natural history of our shared region. “The research we do as an organization only gets stronger with collaboration,” remarked the Museum’s President and CEO Mick Hager. “Periodic binational expeditions like this bring together old friends and create new relationships.”

It is through these relationships that our researchers continue to fulfill our mission: promoting understanding of the evolution and diversity of southern California and the peninsula of Baja California, and inspiring in all a respect for nature and the environment.

To find out more about the natural history of the Sierra Cacachilas, please visit

Posted By theNAT.

Subscribe to our blog. Receive an email once a week that recaps the latest blog posts about our research, exhibitions, cool science news, and more