FRESNO COUNTY, CA—“Valley Dragons” have vanished from 85 percent of their San Joaquin Desert habitat—in the Diablo Range, Carrizo Plain, and southwestern San Joaquin Valley.
These endangered desert reptiles are officially known as blunt-nosed leopard lizards (Gambelia sila), and while they were some of the first species to be covered by the Endangered Species Act in 1967, like California condors and grizzly bears, the number of “Valley Dragons” has continued to shrink.
A recovery plan and an emergency breeding project at the Fresno Chaffee Zoo has come to the rescue.
Save Mount Diablo is helping with a $5,240 grant from our Mary Bowerman Science and Research Program to cover the cost of a custom weather station which will aid in research about the lizard’s needs.
“Blunt-nosed leopard lizards originally inhabited millions of acres of the San Joaquin Desert, as well as the intermountain valleys nearby, such as the Carrizo Plain,” says Joseph Belli, a wildlife conservation biologist, and expert on both the lizards and the Diablo Range.
“They ranged at least as far north as Stanislaus County, and there’s a highly credible record of one spotted near Corral Hollow as recently as 1960. Today, it’s doubtful that any persist north of the Panoche region.”
And the Panoche populations were shrinking.
Fortunately, thanks to the award-winning efforts of the Fresno-Chaffee Zoo “Valley Dragons” are getting a second chance.
In 2020, when it looked like several of the Panoche populations might vanish, the Fresno Chaffee Zoo sent a collection team to bring in lizards from the dwindling population, focusing on a group that was genetically distinct and considered particularly high risk.
Conservationists were especially concerned about how quickly this population might expire, seeing as the blunt-nosed leopard lizard has a very short lifespan in the wild—about two or three years on average.
They were lucky to retrieve seven lizards, with which the Fresno Chaffee Zoo established a captive breeding program.
Four years later, that program is responsible for hatching more than 150 lizards, 17 of which the zoo released back into the wild in 2023. The zoo released another 20 lizards into the wild in 2024.
Zoo staff reintroducing a blunt-nosed leopard lizard to the wild in the Panoche area on June 3, 2024. Photo: Fresno Chaffee Zoo
To assist in the reintroduction process for released lizards, the zoo equips the “Valley Dragons” with radio telemetry backpacks, specifically designed and tested to be worn in the wild.
These backpacks connect to an Automated Radio Telemetry System (ARTS) and send out pings to help track their progress.
At 894 hectares of coverage, this telemetry system was the largest in the world when it was created, which earned the Fresno Chaffee Zoo the North American Conservation Award.
However, many environmental variables aren’t tracked by the backpacks. The program needed a new weather station to track temperature, relative humidity, rainfall, and more.
The Panoche region in the Diablo Range. Photo: Scott Hein
Now, thanks to the grant from Save Mount Diablo, the new weather station was installed in the Panoche region in November.
The new weather station (in the foreground), which was installed in the Panoche region in late November. Photo: Fresno Chaffee Zoo
“I was 12 when I first learned about blunt-nosed leopard lizards, and 58 when I first saw them in the wild,” said Seth Adams, Save Mount Diablo’s Land Conservation Director. “The very first U.S. list of threatened and endangered species in 1966 included 78 species, some quite notable.
“California condors. Ivory-billed woodpeckers. Grizzly bears, timber wolves. Florida panthers, key deer and manatees. San Joaquin kit fox. American alligator. San Francisco garter snake. And the blunt-nosed leopard lizard.
“Four of them were from the Diablo Range. Just three were reptiles. Remarkably, most of those 78 endangered species are in better shape today.
“That’s not the case for the blunt-nosed leopard lizard. It’s continued to decline. When I learned the Fresno Chaffee Zoo was conducting an emergency breeding program and had already had some success, I immediately wanted to get Save Mount Diablo involved.
“We’ve helped with lots of rare wildlife projects, from reintroducing peregrine falcons to Mount Diablo to aiding the California condor program at Pinnacles. This is another step south in our Diablo Range expansion, with new partners in a new geography.
“I can’t wait, and I’m so excited to maybe witness young leopard lizards bred at the zoo being released this spring.”
Not only does the weather station have the capacity to track the aforementioned factors, but it also will be able to track crucial factors specific to blunt-nosed leopard lizards, like solar radiation, soil temperature, and soil moisture.
With that valuable data, zoo biologists can finally assess how variations in the climate are affecting blunt-nosed leopard lizards. The data will allow the zoo to directly assess how annual variations in climate affect lizard habitat, colonization, and persistence.
That data is essential for reintroducing blunt-nosed leopard lizards successfully, because these incredible reptiles are highly susceptible to changes in their surroundings.
Dr. Rory Telemeco, Director of Conservation Science at the Fresno Chaffee Zoo, says that given the program’s ongoing success, they intend to keep increasing the number of blunt-nosed leopard lizard introductions.
“We anticipate releasing up to 100 animals per year in future and will continue reintroductions until 50 or more natural-born females successfully reproduce for three consecutive years,” he said.
Dr. Rory Telemeco, Director of Conservation Science at the Fresno Chaffee Zoo, with the newly installed weather station. Photo: Fresno Chaffee Zoo
The insights gained from the new weather station combined with the existing Automated Radio Telemetry System have the potential to help not just the population in the Panoche area, but also serve as a guide for rewilding lizards in any of the other San Joaquin Desert habitats.
These insights will deepen our knowledge of this incredible species.
“I’m so excited to work with the Fresno Chaffee Zoo and the Bureau of Land Management, which manages 250,000 acres of the Diablo Range, especially in Fresno and San Benito counties,” said Sean Burke, Save Mount Diablo Land Programs Director.
“This small grant from our Mary Bowerman Science and Research Program is a first step. Four years ago, we made our first $3,000 grant to the Pinnacles condor recovery program for GPS tags and subscriptions for three condors.
“And the condors immediately proved our point that the Diablo Range is rich and intact by showing up at Mount Diablo. This year, we’re funding GPS for 20 condors.”
San Joaquin Desert
“The saga of the blunt-nosed leopard lizard stretches back perhaps 10 million years, when uplift along the Garlock Fault resulted in the rise of the Tehachapi Mountains, forming a barrier between the San Joaquin Valley and the Mojave Desert,” said Belli.
“Some species that once existed in both areas became separated, and over time isolation led to the evolution of taxa such as the San Joaquin antelope squirrel, San Joaquin coachwhip, and San Joaquin kit fox.
“The leopard lizards on the San Joaquin Valley side diverged from their Mojave Desert ancestors, their most noticeable adaptation being a truncated snout.
“They became blunt-nosed leopard lizards, found along the west side of the San Joaquin Valley and surrounding foothills and nowhere else.”
It’s only in the last few years that the San Joaquin Desert has been officially recognized as the newest, smallest desert in the United States.
In 2011, a group of scientists published a research article in the Natural Areas Journal, “The San Joaquin Desert of California: Ecologically Misunderstood and Overlooked.”
They concluded that the San Joaquin Desert “historically encompassed 28,493 km2 including the western and southern two thirds of the San Joaquin Valley, and the Carrizo Plain and Cuyama Valley to the southwest.
“However, this ecosystem has been reduced by up to 59% from agricultural, industrial, and urban activities.
“The conservation of the unique biodiversity of this region is dependent upon this ecosystem being appropriately managed as a desert and not as a perennial or annual grassland.”
The San Joaquin Desert overlaps with the Diablo Range’s east side, especially at Panoche, extending south and southeast of the range.
Blunt-nosed leopard lizards are directly tied to this unique desert ecosystem. They maintain a large territory of up to dozens of open acres with only enough vegetation so that they can hunt and hide.
Although they can dig their own burrows, they mostly depend on small mammals, such as kangaroo rats and ground squirrels, to create their hideouts, which the lizards need for overwintering in the wet months and as a place to escape extreme desert temperatures.
Blunt-nosed leopard lizards also form a precious link in the food web, serving both as a predator and a food source.
Blunt-nosed leopard lizard. Photo: Fresno Chaffee Zoo
Large adults can measure 15 inches from nose to tail tip; some lizards boast pale stripes and dark spots along their backs. Coloration can be markedly different between individuals.
They also boast another remarkable feature—in summer, the males flush to a peachy-orange underneath, and female “Valley Dragons” present fiery orange splashes along their sides.
Joseph Belli has remarked that the food supply for these incredible “Valley Dragons” has been particularly hard-hit by aerial pesticides sprayed across the west side of the San Joaquin Valley—so with their food either absent or poisoned, it’s no wonder that the population has been suffering.
Belli is an experienced wildlife biologist specializing in the Diablo Range, and a blunt-nosed leopard lizard expert. The fact that these lizards can dash several yards at a time, even on two legs, he says is a sight to behold.
Since the 1970s, Belli has been exploring the Diablo Range and working with endangered species such as California condors and blunt-nosed leopard lizards.
As with condors, he believes that the captive breeding program for these lizards is essential for their return to historically populated habitats.
The successful recovery of blunt-nosed leopard lizards in the Mount Diablo Range would signal a turnaround for a critically endangered species.
Save Mount Diablo’s participation in the effort will help popularize the Diablo Range for decision makers and help the public appreciate the Diablo Range’s incredibly rich biodiversity. Endangered species recovery galvanizes attention.
When we protect the charismatic species, we support the whole related ecology. A colorful little lizard could become a catalyst for helping to protect the Diablo Range. Isn’t it an inspiring idea, and a cause for hope?
About Save Mount Diablo
Save Mount Diablo is a nationally accredited, nonprofit land trust founded in 1971 with a mission to preserve Mount Diablo’s peaks, surrounding foothills, and watersheds; and its sustaining Diablo Range, through land acquisition and preservation strategies designed to protect the mountain’s natural beauty, biological diversity, and historic and agricultural heritage; enhance our area’s quality of life; and provide educational and recreational opportunities consistent with protection of natural resources. To learn more, please visit www.savemountdiablo.org.
About Fresno Chaffee Zoo
Fresno Chaffee Zoo inspires people to care for animals, create connections, build community, and save wildlife. To learn more, please visit www.fresnochaffeezoo.org.
Image Captions and Credits
- Blunt-nosed leopard lizard with a telemetry device. Photo: Fresno Chaffee Zoo
- Zoo staff reintroducing a blunt-nosed leopard lizard to the wild in the Panoche area on June 3, 2024. Photo: Fresno Chaffee Zoo
- The Panoche region in the Diablo Range. Photo: Scott Hein
- The new weather station (in the foreground), which was installed in the Panoche region in late November. Photo: Fresno Chaffee Zoo
- Rory Telemeco, Director of Conservation Science at the Fresno Chaffee Zoo, with the newly installed weather station. Photo: Fresno Chaffee Zoo
- Blunt-nosed leopard lizard. Photo: Fresno Chaffee Zoo
High resolution versions of images are available; please contact lkindsvater@savemountdiablo.org.
MEDIA CONTACT:
Laura Kindsvater, Senior Communications Manager
C: 925-451-8376, lkindsvater@savemountdiablo.org
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