Thriving Vs. Surviving
WILDLIFE RESEARCHERS STUDY ELK AND PRONGHORN IN CARRIZO PLAIN TO DETERMINE WHY ONE SPECIES REBOUNDS WHILE THE OTHER STRUGGLES
APRIL 2025
BY NICK WILSON
Wide-ranging terrain in eastern San Luis Obispo County with vast stretches of grassy open space, Native American rock art and brilliant wildflower patches also is home to two awe-striking deer-like species — the tule elk and the pronghorn.
Centuries ago, a trek across the Carrizo Plain would have revealed healthy populations of spiky-headed tule elk and fleet-footed pronghorn (as well as foxes, coyotes, birds and lizards, among other fauna now threatened by humans).
Of late, Cal Poly biological sciences Professor Tim Bean has strived to learn about how tule elk and pronghorn, once near extinction, cope with changing climate and habitat conditions on the plain, including droughts, water shortages and affected food resources.
Periods of increased human hunting in the 1800s caused a severe decline in the numbers of tule elk and pronghorn. But in recent decades, land and wildlife management strategies have been implemented in efforts to revive them.
While tule elk are thriving in the Carrizo Plain National Monument — a preserve managed by federal, state and nonprofit agencies — the region’s pronghorn populations have yet to rebound.
“Tule elk have slowly repopulated due to conservation and wildlife refuges, and thousands now exist in California,” Bean said. “They’re doing well and expanding across the Central Coast. That’s where the trajectories of elk and pronghorn separate.”
A pronghorn population of about 100 in the Carrizo Plain area has remained static since the 1990s. Meanwhile, hundreds of thousands thrive elsewhere, such as in areas of Wyoming and Colorado.
Top left photo: tule elk (Cervus canadensis nannodes). Top right and above photos: pronghorn antelope (Antilocapra americana). Photos taken at Carrizo Plain by Brandon Swanson
While many factors contribute to lack of population growth on the plain — including coyote predation, available food and water resources and limitations to migration because of man-made barriers like fences — Bean and his students aim to better understand the impact of climate change and how best to manage the land sustainably.
“The work we’re doing has implications beyond just these two animals and could affect thinking about climate mitigation and resilience for a lot of different species,” he said.
His research has revealed that tule elk, endemic to California, change their patterns of behavior during periods of extreme drought, depending on water availability.
Between 2005 and 2017, Bean collected location data using GPS collars attached to 36 tule elk, noting the following in an article in California Fish and Wildlife Scientific Journal:
In the dry season, tule elk gathered around water sources, but in the wet periods they gravitated to areas farther from water with greater forage abundance.
High-quality forages and road avoidance were the primary factors influencing their whereabouts and ability to thrive.
“With less water, there’s very little food available, and dry grass is much harder to digest,” the educator said. “When they have more water, it’s much easier for them to digest. So having access to water likely means that they can eat more food of better quality.”
As the Carrizo Plain becomes hotter and drier, tule elk have found ways to maintain body weight and thermal regulation through diet, while avoiding predators and disturbances.
In contrast, the pronghorn, a type of antelope, appears to demonstrate less capability to adapt.
“Elk will eat a bunch of different grass in comparison with the pronghorn,” Bean said. “Pronghorn have weirdly sensitive lips and pick out individual flowers that they’re eating when they’re grazing. They have a really limited diet that is harder to manage, and to know where and what they’re eating.”
Pronghorn populations are migratory and leave cold places in the winter in search of warmer climes and food, he said. But pronghorn can’t jump fences as easily as elk and frequently run into obstacles that can block their journeys.
The research, which incorporated climate change projections and modeling, will help guide future pronghorn conservation and recovery efforts, including where and how to manage lands.
To encourage sustainability, Bean said installing wells strategically and monitoring wildlife interactions with water sources will help determine land decisions.
Tim Bean (left), Samara Kaplan-Zenk and Ethan Barnes in the
Fisher Science Hall Vertebrate Muesum. Photo by Alexis Kovacevic
“We have proposals in for grants to hire Cal Poly students to help monitor cameras at well sites so whenever an animal comes to drink, the camera data would document what species are coming and provide information for estimates of pronghorn numbers, fawn survival and other data,” he said.
Ethan Barnes, a first-year biological sciences major from Arroyo Grande, California, is embarking on pronghorn research with Bean.
“I have 50 million questions about the pronghorn,” Barnes said. “Why do their noses look the way they do? What kind of predators did they used to have, and what are their predators now? And how do their habitats differ from the pronghorn in Africa?”
Samara Kaplan-Zenk, a fourth-year environmental management and protection major from Seattle, also joined the pronghorn study team “to ultimately protect and manage the environment.”
“Combining science and policy to promote the survival of animals is very interesting to me,” Kaplan-Zenk said. “And pronghorn are just incredible. They’re one of the fastest mammals (running up to 60 miles per hour).”
Research supported by: The Nature Conservancy, Cal Poly, California Department of Fish and Wildlife and Rocky Mountain Elk Foundation.
Read this group's research publication:
