Scientists suggest female frogs listen for changes in the male calls as a signal for when it's warm enough to mate.

These tiny frogs have an enormous voice for their size, and the recent warm evenings have been filled with their lovely chorus.

THE SANTA ROSA PLATEAU ECOLOGICAL RESERVE, Calif. — The scientist traipses to a pond wearing rubber boots but he doesn’t enter the water. Instead, Brad Hollingsworth squats next to its swampy edge and ...