{"id":119758,"date":"2026-01-04T13:44:09","date_gmt":"2026-01-04T13:44:09","guid":{"rendered":"https:\/\/www.newsbeep.com\/us-ca\/119758\/"},"modified":"2026-01-04T13:44:09","modified_gmt":"2026-01-04T13:44:09","slug":"in-rugged-baja-canyons-san-diego-scientists-unlock-an-undersung-regions-biodiversity-san-diego-union-tribune","status":"publish","type":"post","link":"https:\/\/www.newsbeep.com\/us-ca\/119758\/","title":{"rendered":"In rugged Baja canyons, San Diego scientists unlock an undersung region\u2019s biodiversity \u2013 San Diego Union-Tribune"},"content":{"rendered":"

Sulphur butterflies glide across Zorrillo Canyon, hundreds of them, moving back and forth against the cerulean sky. It\u2019s nothing short of a fairy wonderland for the scientists below.<\/p>\n

At least, that\u2019s how Jon Rebman, curator of botany at the San Diego Natural History Museum, describes it as he begins the hike into the canyon on a late October morning.<\/p>\n

\"JonJon Rebman, curator of botany at the San Diego Natural History Museum, hikes through Zorrillo Canyon in the Sierra de las Cacachilas documenting plant species on Monday, Oct. 27, 2025. Rebman and his team have recorded more than 500 plant species. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

Rebman is four days into a weeklong expedition in the Sierra de las Cacachilas mountain range in Baja Sur, just outside of La Paz, part of a collaborative effort with Mexican and U.S. scientists to track the region\u2019s biodiversity.<\/p>\n

He and his botany team \u2014 along with dozens of other scientists from the NAT and Mexico studying mammals, insects and reptiles \u2014 have explored the nearby mountaintops and canyon washes, all while camping at Rancho Cacachilas, an eco-tourism destination the museum partners with to conduct its research.<\/p>\n

For many of the scientists, it\u2019s a return; this year\u2019s expedition serves as a follow-up to an investigation into the Sierra launched more than a decade ago in 2013. Until that first expedition, little was known about Las Cacachilas\u2019 biodiversity and opportunity for study.<\/p>\n

\u201cIt was like a black hole,\u201d Rebman says. \u201cThis entire Sierra had almost no historical collection.\u201d<\/p>\n

Today, they\u2019re expanding on that knowledge, and on their work to document all of the area\u2019s biodiversity. Their goals are twofold: They want to identify the species for the sake of science. But their research is also part of a larger effort to understand how Rancho Cacachilas\u2019 farming practices and land and water management are impacting the area.<\/p>\n

Rebman is perhaps one of the most qualified people to hike with in Baja \u2014 that is, if the goal is to learn the most information possible about the region\u2019s flora. \u201cI\u2019m usually botanizing all the time in my head,\u201d as he puts it.<\/p>\n

The result is a nearly encyclopedic knowledge curated over more than 30 years of research on the peninsula.<\/p>\n

\"AA striped hawk-moth sleeps in a flower after collecting nectar in the Sierra de las Cacachilas on Tuesday, Oct. 28, 2025. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

Rebman is a go-to authority on Baja and Southern California flora, authoring books and dozens of papers in his years in the field. He\u2019s played a key role in expanding the NAT\u2019s Baja herbarium since landing there in 1996; there are now more than 55,000 plant specimens in its Baja collection. Five species are named for him \u2014 soon six \u2014 and he\u2019s described more than 30 to science.<\/p>\n

In Zorrillo Canyon, he is eager to share as he hikes slowly, pausing every few yards to offer his team facts about surrounding plants and quiz his mentee, Abraham Sanchez, a 27-year-old master\u2019s student in taxonomy. Palo blanco, hierba de indio, an endemic cotton plant \u2014 the list goes on.<\/p>\n

\u201cYou want to hear a big pollination story?\u201d Rebman asks three hours in, launching into a tale of how wasps pollinate rock fig trees, like the one nestled among granite boulders above. He acknowledges his loquacious tendencies. (\u201cMucho blah blah blah,\u201d he says, apologizing with a chuckle.) But his insight is part of the point of the expedition.<\/p>\n

So is the collaboration between scientists. Sharing meals at camp, researchers excitedly tell each other about their findings. It\u2019s not uncommon for one to casually pick up a tarantula found near the morning coffee or hold a rosy boa after dinner.<\/p>\n

\"AA cape striped racer eats a lizard in the Sierra de las Cacachilas on Tuesday, Oct. 28, 2025. The mountain range is about a 40 minute drive outside of La Paz, Baja California Sur. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

There are missed opportunities, too \u2014 the shocked faces of herpetologists who weren\u2019t there to see a snake, a cape stripe racer, devouring a lizard under the shade of a tree.<\/p>\n

But then there are the simpler moments: scientists kneeling in the dirt and overturning rocks to spot bugs, calling to a small owl in the quiet of the night or frolicking with nets to capture winged insects.<\/p>\n

As Rebman and his group continue up the trail, a voice exclaims from across the canyon: \u201cI caught my first butterfly!\u201d<\/p>\n

\u2026<\/p>\n

The scientists are exploring a section of the Sierra that lies within Rancho Cacachilas, a tourism destination and series of ranches founded by Christy Walton \u2014 of the Walmart family \u2014 around 2011.<\/p>\n

The ranch is 40 minutes southeast of La Paz, the capital of Baja Sur, in a region famed for its adventure tourism. La Paz is known for its beaches, snorkeling, fishing and boat tours out to Isla Espiritu Santo, a UNESCO World Heritage Site. But its nearby mountains, less of a draw, are surrounded by cattle ranches and open space, the fishing villages a distant vista to the east.<\/p>\n

With this expedition, the first in a three-year project, scientists have been invited to Rancho Cacachilas to assess how the flora and fauna are responding to the ranch\u2019s land management practices.<\/p>\n

\"SeveralSeveral buildings peek out from thick vegetation at Rancho Cacachilas, an eco-tourism destination owned by Christy Walton in the Sierra de las Cacachilas on Monday, Oct. 27, 2025. The mountain range is about a 40-minute drive outside of La Paz, Baja California Sur. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

Rancho Cacachilas is a working ranch, growing vegetables and raising goats. Nearly 1,400 tourists come each year to enjoy its guided mule rides, mountain biking excursions and artisanal goat cheese workshops. But it also aims to serve as a model for sustainable agriculture and ranching, a longstanding livelihood in the area, explains Jose Manuel, the ranch\u2019s general manager.<\/p>\n

\u201cThe idea is to keep the people on the ground, give them opportunities and give them more ways to work and to preserve those traditions,\u201d he says.<\/p>\n

It\u2019s research the area needs: Decades of cattle overgrazing have led to erosion and degradation of the watershed in Las Cacachilas, and the area struggles with water scarcity. While ample rain decorated the hillsides in shades of green this fall, that\u2019s not always the case.<\/p>\n

As the scientists conduct their research, they are camping at Rancho Cacachilas \u2014 glamping, really. There are clean bathrooms with warm water and bucket showers. Three meals a day are served \u2014 gourmet, farm-to-table dishes including mole, tacos and pozole, complete with fresh cheese, vegetables and dessert after every dinner.<\/p>\n

\"SeveralSeveral employees with the San Diego Natural History Museum start the day doing a sunrise yoga session at the Sierra de las Cacachilas on Tuesday, Oct. 28, 2025. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

The comfort is welcome after long days hiking in 85-degree heat and humidity. The scientists rise around 5:30 a.m., even before the stunning sunrise over the Sea of Cortez, and tuck into their tents around 9 or 10 p.m.<\/p>\n

Many are used to the days of field work. Rebman arrived before the other scientists \u2014 driving nearly 1,000 miles from San Diego, mostly listening to 80s music \u2014 and will stay on a few days longer to do additional research.<\/p>\n

The NAT has been conducting research in Baja for over a century, with naturalists visiting the peninsula to document everything from its cacti to marine life.<\/p>\n

More recently, in addition to their work in Las Cacachilas, scientists have worked on a red-legged frog breeding program in the Sierra San Pedro Martir, in northern Baja, and helped organize a program to bring more women into botany.<\/p>\n

Rebman has been coming to Baja for more than 30 years and even lived here for a time. He\u2019s created strong friendships with the scientists, and his passion for the plants and the land is infectious.<\/p>\n

He warns he will use the word \u201cendemic\u201d countless times \u2014 referring to the term to describe species that only exist in a certain place. More than a quarter of all the plant species found across the Baja California peninsula are found exclusively in the region, with five endemic to Las Cacachilas.<\/p>\n

\"AbrahamAbraham Sanchez, a master\u2019s student in taxonomy at the Centro de Investigaciones Biol\u00f3gicas del Noroeste, hikes through the \u201ckill zone\u201d in the Sierra de las Cacachilas documenting plant species on Monday, Oct. 27, 2025. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

But as he sees it, despite the hundreds of miles from San Diego, Baja Sur is simply the furthest end of a connected natural gradient, separated only by a political border.<\/p>\n

\u201cThat is the original California,\u201d he said in his office the week before the expedition.<\/p>\n

\u201cIt is like this continuous grade of things all the way down the peninsula,\u201d he adds. \u201cA lot of it comes from our area and trickles down.\u201d<\/p>\n

\u2026<\/p>\n

Rebman can talk about anything \u2014 his music interests and family, love of the iNaturalist app, even the Barbie movie or how he no longer considers himself a romantic. But most conversations come back to plants.<\/p>\n

It wasn\u2019t always thus. Growing up in Illinois, the only plants he learned about were corn and beans. Instead, he dreamed of being a country veterinarian. He even lived in a dog kennel for a time, where he was paid to let the dogs out.<\/p>\n

That changed in college.<\/p>\n

\u201cI realized, \u2018Oh, my God, people don\u2019t know that much about the diversity of plants,\u2019\u201d he said. \u201cSo I started learning that diversity and have never stopped.\u201d<\/p>\n

\"JonJon Rebman, curator of botany at the San Diego Natural History Museum, hikes through the \u201ckill zone\u201d in the Sierra de las Cacachilas documenting plant species on Wednesday, Oct. 29, 2025. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

Rebman gradually made his way to southwestern desert landscapes \u2014 first Arizona, then on to Ensenada on a Fulbright. He eventually arrived in San Diego, a jumping point to the flora in Baja he\u2019d come to love so dearly.<\/p>\n

He\u2019s a specialist in prickly-pear and cholla cactus species. But as a field biologist, he actively collects or documents nearly every plant he sets his sights on. He has more than 37,000 specimens in his personal collection.<\/p>\n

In the years following the NAT\u2019s first expedition to Las Cacachilas, Rebman and his team ultimately recorded 500 plant species in the Sierra. But for Rebman, one of the goals of this trip is to identify more species and ultimately publish a scientific paper on the findings.<\/p>\n

To Sula Vanderplank, a British botanist who lives and works in Loreto, about 150 miles north, Rebman is an \u201colympian\u201d in the field.<\/p>\n

Vanderplank is a research associate for the NAT and a leader in land conservation for Pronatura Noroeste, an environmental organization in northwestern Mexico and one of the NAT\u2019s partners on the expedition. The museum also worked with universities in Baja California, the Biological Research Centre of the North-West and other groups to make the expedition happen.<\/p>\n

\"EvaEva Sofia Horna Lowell, an entomologist, catches butterflies and other insects in the Sierra de las Cacachilas on Tuesday, Oct. 28, 2025. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

Vanderplank, who has dedicated her work to the peninsula for 20 years, says the partnerships have helped bring more people into the research, with longtime experts like Rebman serving as a guide.<\/p>\n

\u201cI feel like it used to be the elite club,\u201d she said. \u201cWhat I love now is that it\u2019s more young people, more students, more up-and-coming researchers \u2026 a really nice change over time.\u201d<\/p>\n

\u2026<\/p>\n

There\u2019s no competition among the NAT scientists and their disciplines, Rebman says \u2014 well, except for a potential rivalry with Shahan Derkarabetian, the curator of invertebrate zoology at the museum, over how many species both scientists can identify.<\/p>\n

Derkarabetian makes a distinct foil to Rebman\u2019s style. Rebman barely lets a moment pass between sentences; Derkarabetian is quieter, offering information only when it\u2019s asked of him.<\/p>\n

\"SanSan Diego Natural History Museum\u2019s Shahan Derkarabetian, the curator of entomology, left, shows Jon Rebman, curator of botany, a macro photograph of a mite at the Sierra de las Cacachilas on Monday, Oct. 27, 2025. The teams congratulate each other on their successes. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

He finds peace in the field, overturning stones and trudging up leaf-covered hillsides in pursuit of the smallest of insects \u2014 \u201clooking for anything that looks like an arachnid, and any other weirdos.\u201d<\/p>\n

\u201cRock piles are my favorite thing,\u201d he says, off the trail in Zorrillo Canyon.<\/p>\n

That morning, he spots a tailless whip scorpion and an unnamed millipede, among other species familiar and unknown, capturing some to bring back and simply observing others.<\/p>\n

But Derkarabetian is here on a mission to find the Kevonones mexicanus, a rare arachnid that is known only from a specimen described in 1898 in Cabo San Lucas with a simple drawing.<\/p>\n

\"ShahanShahan Derkarabetian, the curator of entomology at the museum, uses a magnifying glass to look at a millipede in the Sierra de las Cacachilas on Tuesday, Oct. 28, 2025. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

Scientists collected one other specimen in 2016 during the first expedition to the Sierra. No others have been found since.<\/p>\n

\u201cIf it\u2019s there, I\u2019ll find it,\u201d he says.<\/p>\n

He still hasn\u2019t found it, but he\u2019s undeterred. For Derkarabetian, it\u2019s about the act of discovery, a love of scouring for unique insects that he\u2019s held since he was about 9 years old growing up in Rancho Cucamonga.<\/p>\n

Later that night, a black witch \u2014 a moth about the size of a small human hand \u2014 lands on a light trap the team set up to attract the insects. Once he spots it, Derkarabetian quietly exclaims, \u201cOh my goodness, oh my goodness.\u201d<\/p>\n

It\u2019s not the first time he\u2019s seen one, but the thrill hasn\u2019t waned.<\/p>\n

\u2026<\/p>\n

Over the course of the expedition, there\u2019s a look toward the future \u2014 not only of the land and its plants and animals \u2014 but of who will carry on the veteran scientists\u2019 research, like Rebman and Derkarabetian\u2019s, in the decades to come.<\/p>\n

In recent years Rebman has lost his parents, his sister and two brothers-in-law. He knows he won\u2019t live forever, and in his garrulousness, he\u2019s conveying to younger scientists an important message: This will one day be in your hands.<\/p>\n

\"JonJon Rebman, curator of botany at the San Diego Natural History Museum, shares research he and his team has been conducting in the region during a community event in El Sargento on Wednesday, Oct. 29, 2025. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

\u201cWho\u2019s gonna be able to assess diversity loss?\u201d he wondered. \u201cIf you can\u2019t recognize everything, how do you know what you\u2019re missing?\u201d<\/p>\n

On the final night of the expedition, the scientists gather at a community event in El Sargento, about a 15-mile drive east from Rancho Cacachilas. Each team has a table set up with photos and live specimens, showing the public what they\u2019ve found in the nearby wilderness.<\/p>\n

Beyond inspiring the next generation of curious minds, it\u2019s clear the work these scientists are doing is fueling them now.<\/p>\n

As the evening comes to a close, Derkarabetian heads out, tired. He hasn\u2019t found the rare arachnid he was hoping for \u2014 the discovery that could bridge the gap between his research and that of scientists over a century ago.<\/p>\n

But this wasn\u2019t the worst thing.<\/p>\n

\u201cI\u2019ve had species that have taken me years,\u201d he says, a glint of excitement flashing in his eyes. \u201cI like a challenge.\u201d<\/p>\n

\"TheThe sun rises over the Sea of Cortez on Tuesday, Oct. 28, 2025. (Ana Ramirez \/ The San Diego Union-Tribune)<\/p>\n

\u00a0<\/p>\n","protected":false},"excerpt":{"rendered":"Sulphur butterflies glide across Zorrillo Canyon, hundreds of them, moving back and forth against the cerulean sky. It\u2019s…\n","protected":false},"author":2,"featured_media":119759,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[28],"tags":[23,100,74,76,75,645,1696],"class_list":{"0":"post-119758","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-san-diego","8":"tag-local-news","9":"tag-news","10":"tag-san-diego","11":"tag-san-diego-headlines","12":"tag-san-diego-news","13":"tag-science","14":"tag-top-stories-sdut"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/119758","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/comments?post=119758"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/posts\/119758\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media\/119759"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/media?parent=119758"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/categories?post=119758"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/us-ca\/wp-json\/wp\/v2\/tags?post=119758"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}