Invasive Water snakes in California Might Threaten Local Wildlife, Researchers Warn

Southern water snakes commonly eat mole salamanders, a group that includes two endangered species in California. (Photo : J.D. Willson/University of Arkansas)

Invasive water snakes in California might threaten local snakes and amphibian species.

According to researchers at the University of California, Davis, water snakes - which are commonly found in rivers and lakes in Eastern U.S. - have the potential to compete with native species.

Researchers don't know exactly how many of these snakes are lurking in the waters of California. Biologists have found at least 300 snakes belonging to two species in Sacramento area (Roseville and Folsom), and 150 in Long beach. The two species are common water snake and the southern water snake.

Water snakes are non-venomous, who belong to the genus Nerodia and are often confused with venomous Water Moccasins (Agkistrodon piscivorus). According to researchers, water snakes were probably introduced in California by snake owners.

"The issue is not yet out of control," said lead author Jonathan Rose, from the UC Davis Graduate Group in Ecology, according to a news release. "However, we recommend that action be taken now to control emergent populations of these non-native snakes while they remain somewhat restricted in California. Waiting until they become entrenched could cost more ecologically and economically."

In the present study, researchers identified areas where water snakes could gain a stronghold. The team found that the potential territory of the snakes could overlap with the region of garter snake and the California tiger salamander - both of which are already on the federal list of threatened species. The water snakes could act as predators or competitors of the local species, pushing them out of existence.

According to researchers, water snakes are expected to not only spread in Central California, but also travel to Oregon's Willamette Valley and to central Washington. Southern water snakes require certain climate conditions to thrive so it might not move out of California. But, water snakes can interbreed and reproduce offspring that might tolerate wider climatic conditions.

 "Water snakes are not picky eaters," said co-author Brian Todd, a conservation biologist in the UC Davis Department of Wildlife, Fish and Conservation Biology. "With their predatory nature and generalist diets, our already imperiled native fish, amphibians and reptiles have much to lose should introduced water snakes become more widespread."

The study is published in the journal PLOS One.