​Surveying species among California's redwoods

What better way to spend Sunday on a holiday weekend than taking a walk in the woods -- the redwoods, to be exact. Carter Evans will be our guide:

"In every walk with nature, one receives far more than he seeks" -- fitting words from America's most famous naturalist, John Muir. He was known as "the father of America's national parks."

Recently a new generation of natural "wanderers" embarked on a monumental task in the national monument named in his honor, the Muir Woods.

"Enjoy the rain, we're all going to get wet," said Glenn Plumb, chief wildlife biologist for the National Park Service.

He led a team of grade-schoolers into the woods armed with a video camera on a pole: "Now the fun thing about this is, we don't know exactly what we're going to find."

Plumb and his volunteers were part of a bold effort called a "bioblitz" -- a 24-hour inventory of every species living in the 116-square-mile area. It was organized by National Geographic and the National Park Service.

More than 300 scientists led swarms of school kids, families and volunteers on a mission to count every type of plant, animal and insect.

Plumb's part in the cataloging was to see if they could videotape bats sleeping deep in the hollows of giant redwoods.

Evans asked, "What would be one of the tell-tale signs that a bat has been here?"

"It could be guano, smear of guano," said Plumb. "Where there's guano, there's bats!"

Stretching from the edge of San Francisco to the towering redwoods of Muir Woods, the Golden Gate National Recreation Area receives 14 million visitors every year. But what scientists want to know is not who visits; rather, what calls the parks home.

Marine biologist Michael Reichmuth led his team of amateur scientists to Muir Beach, where the Redwood Creek meets the Pacific Ocean. "Normally, you'd have park rangers like me yelling. 'Get back on the trail,'" Reichmuth said. "But today you have a free pass!"

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Wading through the mud and brackish water in these newly-restored tidal lagoons, their goal was to tally every fish in their trawl. Found were plenty of baby sculpin and sticklebacks -- fish that have adapted to live in both the ocean and fresh water.

"When I see this, I think I actually see the kids making a connection with their natural resources," Reichmuth told Evans. "They're seeing that they actually do have fish in their backyard. And I think they get excited about it."