Traveler's journal

Frogs that count

Looking out at chain-link fences, gantry cranes, and a highway off-ramp at the edge of San Francisco Bay, I am in a very unlikely site to appreciate nature. But, at sunset, evidence of wildlife emerges: Suddenly, volunteer David Erickson and I are surrounded by a chorus of croaking frogs.

These aren't just ordinary croaks, either, but star-quality voices you've likely heard in movies. For 10 years, Erickson has been monitoring the Pacific chorus frogs' deep-throated, well-rounded ribbits. They produce the croak favored for Hollywood soundtracks.

Erickson is one of about 80 Bay Area volunteers listening to frog and toad populations in their backyards for Frogwatch USA, a National Wildlife Federation and United States Geological Survey project. To track the nation's declining amphibian population and pinpoint the most critical habitats, croaks are counted for three minutes every two weeks. Frogs are particularly vulnerable to disruptions of their habitat, so biologists consider them "indicator species" — like canaries in coal mines. As their numbers shrink, concern about environmental problems grows. But the first step to helping frogs is knowing where they are and how many are out there. Hence the counting.

Erickson was thrilled to discover frogs so close to his home. "I find it nothing short of a miracle in such an industrialized setting," he says. Visit www.nwf.org/frogwatchusa for more information.—LISA TAGGART