Cows produce croaking calls when looking for their calves.

The Philippine Government raised gasoline and fuel oil prices by nearly 20 percent today, producing calls for strikes.

The smallest frogs must consume lots of energy to produce calls.

That the Enron case has produced calls for such sweeping changes in the way accountants are regulated "strikes me as fairly odd," he said.

The oil companies' mind-boggling profits have produced calls for a windfall profits tax.

Some frogs choose to produce less energetic calls and remain in chorus for longer periods of time.

Males will exploit these preexisting preferences and produce calls that are known to be favorable for females.

Not only are some birds known to detect infrasound, but one species has been shown to produce infrasonic calls.

When a cow has mated, her family may produce calls of excitement known as the "mating pandemonium".

They produce three categories of sounds: clicks, whistles, and pulsed calls.