for National Geographic Today
A red diamond rattlesnake lies motionless on the operating table at the San Diego Zoo hospital. With a quick slit of the skin, a veterinarian opens up the snake and inserts a radio transmitter the size of a double-A battery, then sews up the incision.
A week or so later, the snake slithers back into the wildbroadcasting a signal to researchers about where and how it lives.
In southern California real estate, as elsewhere, location is everything and both man and beast are competing for coveted locales.
"The San Diego area has more threatened and endangered species of plants and animals than any other county in the contiguous United States," says Tracey Brown, a reptile ecologist at California State University at San Marcos.
In fact, California's so-called Floristic Province125,000 square miles (325,000 square kilometers) of the western coast from northern Baja to southwestern Oregonis one of the world's most biologically diverse environments.
But only about 25 percent of the original habitat remains. Now the challenge is to balance development and conservation.
"We want to protect land that works for the animals," says Robert Fisher, a zoologist at the U.S. Geological Survey Western Ecological Research Center in San Diego.
Fisher and his colleagues are part of a broader effort to identify and conserve land essential to the animals' survival.
"We let the snakes tell us what they need," Brown says.
The snake-tracking research began in 1995 after Fisher and Ted Case, a biologist at University of California at San Diego, noticed that locally some snake species were declining and, in some cases, dying out.
Fisher and Case launched a project to survey the snakes. In 1999, the researchers began implanting radio transmitters in the snakes. In 2001, Brown, funded by the San Diego Zoo and the Favrot Fund, joined their efforts.
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