Big voice

THE Pacific tree frog is more than ready for its croak up. The standard frog “ribbet” that Hollywood uses in films comes from the diminutive amphibian, according to the website of the U.S. Geological Survey’s Northern Prairie Wildlife Research Center in North Dakota. The frog also is described as the most commonly heard voice on the West Coast due to its range from British Columbia to northern Baja California. The amphibian amplifies its call by extending a vocal sac as big as its body to loudly woo females and scare away rival males. “You can easily recognize its call. It’s very distinctive,” says Glenn R. Stewart, who teaches herpetology at Cal Poly Pomona. Unlike South American tree frogs, the California cousins aren’t found in treetops, but in ponds and marshes or, occasionally, climbing on reeds. Some even turn up in suburban gardens. But don’t be misled if you’re out in the wilds looking for them: They’re often green but can also be brown or black, with some changing colors within a few minutes. Look for the telltale dark band that runs through the eye and toward the front leg, which you might not see on film unless Hollywood zooms in for a close-up.

-- Mary Forgione