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Natural History Museum expedition explores Mexican mountains

By Deborah Sullivan Brennan |SDUT
6 A.M.JAN. 26, 2014


Sunrise on the first morning in the Sierra Cacachilas. / photo by Alan Harper

When a group of San Diego Natural History Museum scientists decided to study a remote mountain range in Baja California, they planned a party in Mexico.

Last fall, an expedition of 30 U.S. and Mexican researchers traveled to the Sierra Cacachilas. It’s a small mountain range near La Paz with a treasure chest of natural riches. It’s also what entomologist Michael Wall called a “black hole” of biodiversity data.

For two weeks in October and November, the scientists trekked through oak forests perched above desert scrub, searched canyon springs and combed abandoned silver mines.

They found a softball-sized cave spider, caverns full of bats and possibly new species of plants. They also learned how the area is connected to the Sierra de la Laguna, a larger mountain range 40 miles to the south that’s home to many locally unique species. In the Sierra Cacachilas they recorded new sightings — or range extensions — of some species previously found only in the Sierra de la Laguna.

And they explored how animals that are rare or threatened in the United States are faring in this Mexican sky island. Conservation and management in Baja California could affect migratory species of birds and bats in the U.S., said wildlife biologist Drew Stokes.

“Humans are the only ones who recognize the border as a boundary,” Wall said.

The researchers’ findings will help map out species in need of protection and offer insights for conservation as urban growth and resort development spread across the Baja peninsula.

The isolated range could also be a “hot spot for evolution” of unknown species, Wall said.

Traveling as a group assured extra sets of eyes on the ground, but also allowed the scientists to share expertise.

When botany curator Jon Rebman found distinctive plants, he alerted Wall, who then checked them for new insects. Wall, in turn, plucked a brown ground snake from a hiking trail and passed it on to the herpetologists. It turned out to be the only one of its kind collected on the trip.

The expedition reinforced cross-border research relationships, said herpetology curator Brad Hollingsworth, who set practical-joke protocol by planting huge, rubber rattlesnakes in the reptile traps.

And as a bonus with a large expedition, he said, “happy hour is a lot more fun.”

Wall and botany curator Jon Rebman will share their experiences of the trip during a Tuesday lecture for the museum’s members. Below are some of the scientists’ snapshots of the trip.


MICHAEL WALL, 41, CURATOR OF ENTOMOLOGY

“When I see these isolated mountains, I immediately start thinking: This is a nice little laboratory for natural selection and evolution. Are we going to find cool things we haven’t seen before? We found one spider in the bat mines that is in a family of spiders of which only one (other) was known on the peninsula. We think it’s a new species. The spider, from leg to leg, is about softball-sized. Its abdomen is the size of two quarters. It’s like a small-sized tarantula, but much daintier, not as husky. It’s quite bald, and its abdomen is mustard brown with iridescence. Is it deadly venomous? I don’t know. The group is well-known for having very painful bites. It’s in the same family as a venomous banana spider, the Brazilian wandering spider. It’s as yet unnamed. We think it’s new to science.”

JON REBMAN, 48, CURATOR OF BOTANY

“We didn’t have a clue what was in the area. Basically, it was completely unknown. It was fascinating, botany-wise. We found a new type of senecio (a daisy variety also called ragwort of butterweed.) It’s an herbaceous perennial that grows almost a meter tall. It may be a new species or a range extension. And we found a tiny annual from a genus only restricted to the state of Baja. I’m almost positive it will be a new species. It’s in the coffee family, and is an inch high, with a tiny, tubular pink flower. And we found species only found before in the Sierra de la Laguna. If something happened to them in the Sierra de la Laguna, we now know they are in the Sierra Cacachilas. I think this will help us understand the species in the Cape Region of Baja.”

DREW STOKES, 43, WILDLIFE BIOLOGIST AND BAT SPECIALIST

“We found 10 bat species, including five species considered sensitive or listed (as endangered or threatened) in the United States. Those are the California leaf-nosed bat, the lesser long-nosed bat, the pallid bat, the pocketed free-tailed bat and the big free-tailed bat. They’re insectivores, but the lesser long-nosed bat feeds on (the giant cactus) cardon. They are important pollinators of those cacti and agave. Bats are difficult to catch and extremely difficult to recapture. I feel that they were more abundant down there and they were much easier to catch. There appeared to be larger populations than you’d find in the U.S. We identified three mines with significant roosts. One had at least 1,000 bats. Abandoned mines are an attractive nuisance to people, and that disturbance affects bats. Gates can prevent disruption of the caves.”

BRAD HOLLINGSWORTH, 49, CURATOR OF HERPETOLOGY

“We used the expedition to jump-start a year-round study. We’ll compare diversity at the southern end of the peninsula with our local region. I guess the most abundant reptile was the red-spotted toad, which had just emerged from tadpole to toadlets. There were thousands of red-spotted toadlets all over the ravines. The year-round study will allow us to study the seasonality of when reptiles are common and active, and when they’re not common and dormant. We found two range extensions of the San Lucan alligator lizard and the cape spiny lizard. Having a chance to work very closely with my Mexican colleagues meant the world to me. Being on the ground and doing day-to-day work builds other studies, (and) you can’t pull practical jokes on email.”

LORI HARGROVE, 48, POSTDOCTORAL BIRD RESEARCHER

“This was my first binational expedition, so it was fun to work with binational researchers. For birds, one of the most exciting findings we had was the discovery of wintering gray vireo in the preserve. It breeds in the Southwest, particularly in San Diego County. Their winter ecology was unknown in Baja California. The gray vireo is known to be strongly associated with the elephant tree. We have a small population of elephant trees in Anza-Borrego State Park, and the gray vireo winters there. We’ve documented strong declines in the breeding range in California. It’s one of the species that has flown under the radar of ornithologists. So the Sierra Cacachilas population may be very important to conservation of that species.”

SCOTT TREMOR, 49, MAMMALOGIST

“We didn’t anticipate too much for non-volant (non-flying) mammals, because it’s not a very diverse community. We marked the bellies of mammals with Sharpies and then recaptured them. Only one real interesting thing came into the pitfall trap. We were actually able to capture a desert gray shrew. It’s the smallest mammal in California, with a body about two inches long and a half-inch long tail. We saw seven species of rodents plus mule deer, coyotes and a few jackrabbits. We were looking for a brush rabbit considered either extinct or very, very rare, and we didn’t find that. So that could be a project: the quest for the brush rabbit.”




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I think Scott Tremor missed his true calling>>>

Seismologist.

Fascinating to me. Thank you for posting this.

B

We have recently seen a growing number of eco-related study groups - both local and international - show interest in our region lately. One such group established a permanent camp out on San Martin Island within our federal zone (yes, they asked first) and are working on a two year habitat study project. Just last week an Italian group contacted us, asking if we would let their divers (some who are working on their doctorate thesis) accompany ours in the abalone restoration project. That will probably begin next year.

It truly inspires me and we do our best to support these groups. We learn a lot from them along the way and even manage to have some fun whole doing it...