Amphibian, reptile, bird and mammal populations that depend on freshwater marsh, streamside habitat and wet meadows are struggling most to endure the drought that has gripped California for more than four years, according to a comprehensive assessment released by the California Department of Fish and Wildlife (CDFW).
CDFW biologists ranked the vulnerability of the state's terrestrial species and gave top priority for additional monitoring and assistance to 48 species.
The greatest concentrations of these high-risk populations are found in Southern California coastal, mountain and valley regions, the Sierra Nevada mountain range, the Mojave Desert, Central Valley and the southern Cascade mountain range.
The majority of these "Priority 1" species are found in freshwater marsh, riparian and wet meadow habitats.
The species include the mountain yellow-legged frog, the giant garter snake, tricolored blackbird and the Amargosa vole.
CDFW researchers analyzed and assessed the vulnerability of more than 358 land species. Scientists then classified them into Priority I (most vulnerable) and Priority II (less vulnerable) categories.
All of the species evaluated were threatened, endangered or were otherwise considered species of special concern before the drought impacted them.
CDFW also determined the San Joaquin Valley, southern Sierra Nevada, western Mojave Desert and Owens Valley areas experienced the least amount of normal average rainfall during this extended drought. As a result, wildlife in these regions struggle most finding resources to survive.
"While many species are mobile and able to deal with periods of extended drought, some are more vulnerable than others," said CDFW Program Manager Karen Miner. "Each species plays an important role in the overall health of the ecosystem and contributes something that impacts other animals in the food chain. It's important to recognize that the effects of extended or more frequent extreme droughts may not be immediately apparent for some species."
CDFW is taking action to help the most vulnerable species. Funding for these projects comes from several sources including emergency drought response funds provided in the current state budget, California's Threatened and Endangered Species tax check-off program, federal grant programs, and contributions from a number of universities and other agencies working to save these rare animals.
In the Sierra Nevada and Northern California mountain ranges, amphibians such as yellow-legged frogs, Yosemite toads and Cascades frogs are struggling. Some species' tadpoles require multiple years to develop into juveniles and lack of suitable habitat has eliminated several years of breeding effort at once.
Removal of non-native predatory fish from select areas as well as assistance with disease intervention, translocations and reintroductions are under way to improve their chances of long-term survival.
In the Mojave Desert, researchers identified the Amargosa vole as a species of great concern. Voles play an important role as a prey species and were on the verge of extinction because their habitat had dried up. Juveniles were rescued and taken into captivity to establish a breeding population. Once suitable habitat is secured or restored, the voles will be released to the wild.
In southern Santa Cruz and northern Monterey counties, monitoring of the endangered Santa Cruz long-toed salamander revealed that over the last three years the breeding ponds dried up before the larvae could metamorphose into juveniles that are capable of surviving out of water.
CDFW and the U.S. Fish and Wildlife Service salvaged hundreds of larvae on a property jointly managed by the two agencies. The salamanders were raised in captivity and released back at the site after restoration was completed. Follow-up monitoring is ongoing.
In the San Joaquin Valley, biologists are working with UC Berkeley, Humboldt State University and other organizations to save the giant kangaroo rat, a keystone species that serves as prey or provides habitat for several other listed animals.
Kangaroo rats do not require direct water and get what they need from seeds. After several years without precipitation, seed availability was diminished and the population plummeted.
As a result, the threatened and endangered San Joaquin kit fox is also struggling because their primary prey is disappearing. Researchers are studying population responses to food resource availability to determine how best to intervene to save these species.
California has more native species and the greatest number of endemic species than any other state in the nation with approximately 68 amphibian species, 85 reptile species, 429 bird species and 185 mammal species, many that occur nowhere else in the world.
Identifying and saving at risk wildlife will secure the future for other populations in the years to come.
