Resilience in the California Desert: The Giant Kangaroo Rat's Remarkable Recovery

As twilight descended over California's Carrizo Plain, ecologist Ian Axsom moved slowly across the sandy ground. He carefully placed small aluminum traps ten yards apart. This grid covered an area as large as two baseball diamonds. These traps were designed to catch nighttime animals without hurting them. The last warm light of the September sun glowed on the metal. Axsom, a land manager for the Sequoia Riverlands Trust, was too busy to notice the beautiful sunset. He later said, "If you spend enough time out here, you will inevitably try to take pictures of amazing sunsets on your phone. It never quite captures the true colors."

Three colleagues followed behind him. They baited each trap with bird seed and set the sensitive triggers. They were hunting for the giant kangaroo rat (Dipodomys ingens). This small rodent is a keystone species for this ecosystem. This term means its actions shape the environment for many other living things more than any other animal. This trapping mission is part of a long scientific effort to watch the health of kangaroo rat populations. The Carrizo Plain sits on the southwestern edge of the huge San Joaquin Valley. While most of the valley has changed due to cities, oil drilling, and big farms, the Carrizo Plain remains mostly wild. It is one of the last natural grasslands and deserts left from before European settlers arrived. Scientists do regular surveys to know how the species is doing. This information helps them predict the impact of new projects, including two large solar energy farms built nearby.

The Carrizo Plain is one of Central California's best-kept secrets. This semi-arid grassland sits more than 1,500 feet above the valley floor. It lies between the Caliente Range and the Temblor Range. It is famous for the weeks-long superblooms that happen when a drought is followed by heavy rain. But for most of the year, very few people visit. As one visitor wrote in his blog, "In all the trips I've taken to the Carrizo, I still have seen far more pronghorn than I have other people."

For most of the year, human presence on the Carrizo is very rare. Axsom, who grew up in the nearby city of San Luis Obispo, did not know the plain existed until he was an adult. The region gets little rain, and it does not rain predictably. This has stopped people from doing intensive farming or building. Indigenous groups, like the Chumash and Yokuts, lived on the land for thousands of years and still have deep connections to it. Euro-American settlers started dryland farming and grazing in the 1800s. However, the big irrigation projects that changed the rest of the valley never reached this area. This saved the plain from being turned into big fields. Plans to build thousands of homes in the mid-1900s never happened. More recently, the area had a problem with illegal marijuana growing before two large solar farms were built in the 2010s. Today, the few people living there still use well water and bottled supplies.

Because people have stayed away, the plain has become a safe home for native animals. It holds one of the highest numbers of rare species in the state, with over 36 rare or endangered plants. Blunt-nosed leopard lizards and San Joaquin antelope squirrels come out during the day. San Joaquin kit foxes and American badgers wake up at night. In winter, migratory birds find rest at the temporary Soda Lake at the north end of the Carrizo Plain National Monument. Tiny fairy shrimp and brine shrimp there provide food for the birds. Herds of tule elk graze on the plain all year long.

Because human development is limited, the Carrizo Plain has become an essential home for many native animals. It holds one of the highest concentrations of vulnerable species in California, including more than 36 rare and endangered plant species. Diurnal activity features blunt-nosed leopard lizards and San Joaquin antelope squirrels emerging from their burrows. As night falls, San Joaquin kit foxes and American badgers commence their foraging. During winter months, migratory birds find sanctuary at the ephemeral Soda Lake, where minute fairy shrimp and brine shrimp constitute a vital nutritional resource. Herds of tule elk graze across the plain throughout the year.

"The Carrizo Plain and the surrounding San Joaquin Desert is not the prettiest place on Earth," observed Tim Bean, an ecologist at California Polytechnic State University. "But what makes it special are the animals that live here and are found nowhere else."

A metal trap shook with energy just after midnight. Under the bright beam of a headlamp, volunteer Courtney Tuskan, a wildlife biologist, tilted the trap to drop its occupant into a cloth bag. As she reached in to grab the squirming rodent, her colleague Lindsay Peria reminded her to weigh the bag first. "Man, I forget everything when I'm with an animal," Tuskan replied.

The foundation of this complex ecosystem is the giant kangaroo rat. Their underground burrows are scattered everywhere. To see predators coming, the rats carefully cut the grass and plants around their burrow entrances. This constant behavior creates bare patches, often called "crop circles," that are big enough to see from satellites in space. Science shows this "gardening" helps more types of plants grow, stops invasive grasses from spreading, and makes it easier for other animals to walk through the grassland.

"When you step back and look at what makes the San Joaquin Desert function, giant kangaroo rats just keep coming up over and over," Bean said. He added, "Plus, they're cute: Our state mascot should be the kangaroo rat."

A metal trap vibrated with energy shortly after midnight. By the focused beam of her headlamp, volunteer Courtney Tuskan, a wildlife biologist, carefully tilted the trap to transfer its occupant into a soft cloth sack. As she prepared to grasp the squirming rodent, her colleague Lindsay Peria reminded her to first record the sack's weight. "Man, I forget everything when I'm with an animal," Tuskan replied with a laugh.

The captured animal was an energetic young male, slightly bigger than a clenched human fist. Its large head gave it a somewhat hunched look, and its tufted tail moved back and forth. The rat's brindle-patterned fur was silky and warm. Its large cheek pouches were stuffed with seed bait, making it look like it was smiling.

Tuskan moved efficiently to record data. She measured the head size and hind foot length. She made a small, temporary mark on its belly with a marker so they would not count the same rat again. When they released it, the nervous animal calmed down quickly. Its first lazy hop landed it right against the toe of Axsom's boot. He gently stroked the rat's back before it jumped away into the darkness.

Today, giant kangaroo rats live in less than five percent of their original range, which once covered the whole San Joaquin Valley. Their populations collapsed in the 1960s because the California State Water Project allowed rapid farming expansion. This destroyed huge amounts of their native home. By the 1980s, the sharp decline led to the species being listed as endangered by both state and federal laws. This protection helped create the Carrizo Plain National Monument on the southern part of the plain in 2001.

Environmental groups worked hard to move remnant kangaroo rat populations back to parts of their old home. One move to the Carrizo Plain happened in 1989. Over the decades, these groups also fixed damaged land, cleaning up trash and poison from abandoned illegal marijuana farms. Land managers sometimes used short, controlled cattle grazing to change the plant growth and make better homes for endangered species.

This story is part of High Country News' Conservation Beyond Boundaries project, supported by the BAND Foundation.

Around 2010, when two energy companies planned solar farms next to the national monument, federal agencies forced them to pay for habitat conservation and research. The companies had to fund ongoing wildlife surveys, which is exactly what Axsom and his team were doing.

On the Carrizo Plain, the results of these conservation efforts have been very positive. The giant kangaroo rat population has recovered dramatically. It has bounced back from a few thousand in the 1990s to several million today. "The monument is working and doing its job," Bean stated clearly.

The Carrizo Plain is currently an ecological island, a preserved natural area surrounded by developed land. This isolation may not last forever. A new plan called the San Andreas Corridor, led by The Nature Conservancy, aims to connect the Carrizo to other protected areas. The main goal is to create a continuous 600,000-acre path for wildlife to move and share genes across the landscape.

A group of environmental organizations is buying private land from sellers. They also work with ranchers to create conservation easements. These are legal agreements that stop future development on private property forever. This protects the habitat while often allowing traditional uses like grazing.

The time was nearly 1:00 a.m. when Axsom's group finished checking the last trap. They stood in a circle with their headlamp beams meeting to count the catch. They had caught eight kangaroo rats, a number slightly lower than Axsom expected. He was not worried, however, because the area was full of signs of healthy rodent activity. There were dark droppings, neat piles of cut grass, and cleaned seed heads. They also saw the chalky-white droppings of San Joaquin kit foxes, a main predator of the kangaroo rats.

In the distance, the deep howls of coyotes echoed across the plain. The high-pitched screech of a pallid bat pierced the quiet night. Under a bright sky with no light pollution, the tired but happy team began their journey home. They looked forward to well-earned rest.