Biologists Release Hundreds of Threatened Frogs in Santa Monica Mountains Streams

Biologists take tadpoles from mesh holding pens.
Biologists Mark Mendelsohn and Katy Delaney remove tadpoles from their mesh holding pens into plastic containers, shortly before their release into the stream. Approximately 850 of the threatened frogs were released earlier this week.

National Park Service

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News Release Date: July 25, 2014

Contact: Kate Kuykendall, 805-370-2343

THOUSAND OAKS, Calif. – Biologists from the National Park Service released hundreds of California red-legged frog tadpoles this week, part of the first-ever effort to expand the range of the threatened species in Southern California.
"California red-legged frogs haven't been seen in the Santa Monica Mountains since the early 1970s," said Katy Delaney, wildlife ecologist for the National Park Service. "Hopefully these tadpoles can help reverse the population decline of native frog species locally and across the state."
In March of this year, Delaney and her team transferred approximately 950 eggs from an isolated population in the Simi Hills. The eggs were deposited in mesh holding pens in two undisclosed streams in the Santa Monica Mountains. The holding pens protected the egg masses from predators as they began to hatch and grow.
Biologists have been visiting the pens twice weekly to feed the young frogs and monitor their health. Earlier this week it was determined that the tadpoles were ready to survive on their own and all 850 were released from their pens. The populations will continue to be closely monitored.
Because frogs have permeable skin that easily absorbs contaminants, they are considered an indicator species that provides important information about habitat health. Nationwide, USGS has documented precipitous declines among amphibians, which some speculate may be linked to habitat loss, invasive species and pollution.
In addition to the National Park Service, the project team includes California State Parks, the Mountains Recreation and Conservation Authority, the Mountains Restoration Trust, the Santa Monica Bay Restoration Commission, the U.S. Fish and Wildlife Service and U.S. Geological Survey's Western Ecological Research Center.
Santa Monica Mountains National Recreation Area (SMMNRA) is the largest urban national park in the country, encompassing more than 150,000 acres of mountains and coastline in Ventura and Los Angeles counties. A unit of the National Park Service, it comprises a seamless network of local, state and federal parks interwoven with private lands and communities. As one of only five Mediterranean ecosystems in the world, SMMNRA preserves the rich biological diversity of more than 450 animal species and 26 distinct plant communities. To learn more, visit 

Last updated: October 31, 2018

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