Frog monitors explore Agua Hedionda Creek

By: QUINN EASTMAN - Staff Writer | Sunday, June 24, 2007 7:54 PM PDT ∞

VISTA ---- Eight-year-old Jamie Smith dipped his walking stick into Agua Hedionda Creek and moved it toward a tadpole that lay under the surface of the water.

"It's alive! It's moving," he cried.

Jamie and about 30 people from around San Diego County hiked into Dawson-Los Monos Canyon Reserve, just west of Buena Vista Park in Vista, on Sunday afternoon to learn about frogs and toads ---- animals that experts say can offer a glimpse into how environmental problems might one day affect humans.

The North County conservation group Preserve Calavera organized the trip to the 240-acre area along Agua Hedionda Creek managed by the University of California and not normally open to the public.

Diane Nygaard, a leader of the conservation group that organized the hike, described frogs as "canaries in the mine shaft," vulnerable to threats such as declining water quality, fungal disease and trace pollutants that pervert animals' development.

In a cool, shady clearing, Nygaard played a tape to emphasize the differences between a bullfrog's growl, a toad's squeak and the chorus of "ribbits" coming from a group of Pacific tree frogs.

"We'll do frog-watching mostly with our ears," she said.

Participants were encouraged to sign up for a nationwide volunteer frog monitoring program sponsored by the National Wildlife Federation. People who sign up are supposed to submit biweekly reports on the kinds of frogs they hear near their home.

"The chances are, you can walk down your street where you live and hear frogs," Nygaard said.

On Sunday, the hikers only saw a few frogs and tadpoles, partly because they visited the creek in midafternoon rather than around sunset, the time when frogs are usually loudest.

"There was one about the size of a quarter," said Vista resident Brian Foster. "I tried to get him to jump in my hat, but he wouldn't do it."

Organizers said future frog-listening hikes could be scheduled closer to dusk.

Nygaard said she had limited the size of the group and had a waiting list of more than a dozen people. Preserve Calavera visits Dawson-Los Monos Canyon Reserve once or twice a year, she said.

While exploring the oak forest lining the creek Sunday, the group also heard about and saw the effect coastal development is having on the creek.

As more homes and roads are built in the area around Carlsbad and Vista, water glides into the creekbed more quickly, preserve manager Isabelle Kay said. When rain washes into the creek rapidly, erosion cuts under the oak trees on the banks, she said.

"There didn't used to be this much water in the creek in the middle of the summer," she said. "This is all urban drool."

The extra water made it possible for young Jamie to spy tadpoles, crayfish and a tree frog, but it also brought a bright orange koi fish that he realized didn't quite belong.

"That may have escaped from someone's backyard," Kay said.

For Sunday's hike, Kay donned a special protective suit because repeated exposure to poison oak has sensitized her to the plant's irritating oils. The rest of the group did their best to steer clear of red-colored vines and leaves.

The Dawson family gave the land around the creek to the University of California in 1965 and still owns land nearby, Kay said. The reserve is used for entomology and botany research by UC researchers as well as for public education.

Contact staff writer Quinn Eastman at (760) 740-5412 or qeastman@nctimes.com. Comment at nctimes.com.