Scientists work to save endangered desert mammal

Amargosa voles, small rodents that inhabit rare marshes of the Mojave Desert, have faced dire circumstances in recent years. Loss of habitat, extreme drought and climate change brought this subspecies of the California vole to near extinction, leaving only a few hundred clinging to existence. It is now one of the most critically endangered mammals in North America. Its luck may be changing with the birth of the first set of pups from a new captive breeding program at the UC Davis School of Veterinary Medicine.

An interdisciplinary research team is working to study the vole and ultimately shore up the population so that it doesn’t go extinct. As part of that effort, the team began a captive breeding program. Ten females and 10 males, all about five weeks of age, were removed from the wild in mid-July and brought to UC Davis.

The research team includes members from UC Davis, the California Department of Fish and Wildlife, the Bureau of Land Management, the U.S. Fish and Wildlife Service, the U.S. Geological Survey and UC Berkeley.

In the field, researchers have observed fluctuations in the size of the Amargosa vole population.

“The numbers are at their highest just after breeding in the spring when the vegetation is still good,” said project lead Janet Foley, a professor of medicine and epidemiology at the UC Davis School of Veterinary Medicine. “But as the summer wears on and the limited marsh habitat dries up, the population may crash. This year, we saw their main marsh shrinking fast and we knew a large number would die in the coming months. If we wanted to save the species, we had to act quickly.”

During the first few weeks in captivity at Davis, the voles remained quarantined in individual enclosures. They underwent full diagnostic testing for pathogens and genetic analysis to ensure the most diverse breeding pool possible before placed together in breeding pairs.

By October, all three of the pairs produced pups. There are four healthy pups now. Eventually, the animals will be placed outside in large escape-proof tubs in a secure location. The tubs will be planted with bulrush to mimic their native habitat.

Researchers aren’t sure how long it will take the captive population to build. They also hope to learn about optimal breeding conditions – such as food, shelter, length of daylight and temperature – for the voles. Once a few hundred voles have been born in captivity, researchers plan to reintroduce them to the marsh areas in their home range.

“We know the population is already inbred, but we don’t know whether that has affected them as a species,” Foley said. “There’s so much we have yet to learn about this subspecies. This is a great opportunity to understand population genetics, basic ecology and behavior. Previously, we’ve made assumptions about those things, but now we can verify them.”

Taking a toll on the vole

The Amargosa vole (Microtus californicus scirpensis) inhabits sparsely located wetlands just east of Death Valley National Park. Those marsh habitats, which exist only in a few small, isolated patches throughout the desert, are increasingly threatened by drought, climate change and habitat modification by humans. The current drought has likely exacerbated their dire situation. Low water means fewer bulrushes – the wetland plants this subspecies depends heavily upon for habitat and food.

Once thought to be extinct, the Amargosa vole was rediscovered in the late 1970s by a state fish and wildlife biologist. It was listed as an endangered species in 1980 by the state and in 1984 by the federal government. Recent BLM research indicates an 82 percent chance that the species could go extinct within five years if immediate management action is not taken.

In the past few years, the research team has worked to update information about the number of voles and where they live. Researchers have looked at additional factors impacting the Amargosa vole, including infectious diseases, competition with other rodents, predation, and other environmental pressures.

“The commitment and collaboration demonstrated by the inter-agency/academia vole working group is a great example of what can be accomplished in a short time to conserve not only the Amargosa vole, but also its unique desert marsh habitat that other species also depend on,” said program co-lead Deana Clifford, CDFW wildlife veterinarian and assistant clinical professor at UC Davis. “By pooling our resources and working together we can increase the chances that healthy populations of Amargosa voles will persist well into the future.”

Funding for the research and captive breeding colony comes from BLM, CDFW, USFWS and the State Office of Emergency Services (drought funding). UC Davis and CDFW are donating personnel time, and a private landowner has been providing free field housing for the research crews.

About UC Davis

UC Davis is a global community of individuals united to better humanity and our natural world while seeking solutions to some of our most pressing challenges. Located near the California state capital, UC Davis has more than 34,000 students, and the full-time equivalent of 4,100 faculty and other academics and 17,400 staff. The campus has an annual research budget of over $750 million, a comprehensive health system and about two dozen specialized research centers. The university offers interdisciplinary graduate study and 99 undergraduate majors in four colleges and six professional schools.

About the School of Veterinary Medicine

Leading Veterinary Medicine, Addressing Societal Needs: The School of Veterinary Medicine serves the people of California by providing educational, research, clinical service and public service programs of the highest quality to advance the health of animals, people and the environment, and to contribute to the economy. For further information, please visit www.vetmed.ucdavis.edu/.

About the California Department of Fish and Wildlife

The California Department of Fish and Wildlife works to manage California’s diverse fish, wildlife, and plant resources, and the habitats upon which they depend, for their ecological values and for their use and enjoyment by the public.

Media Contacts:
Deana Clifford, CDFW/UC Davis, (916) 358-2378; Deana.Clifford@wildlife.ca.gov
Janet Foley, UC Davis School of Veterinary Medicine, (530) 754-9740, jefoley@ucdavis.edu
Dana Michaels, CDFW Communications, (916) 322-2420, Dana.Michaels@wildlife.ca.gov
Kat Kerlin, UC Davis News Service, (530) 752-7704, kekerlin@ucdavis.edu