Frogs produce noises to attract mates, defend territories, dissuade predators and identify themselves. The most common calls are those used to defend territory and attract mates during the breeding season. While male frogs are much more vocal than females, the females of some species are capable of producing sounds as well.
Frogs produce calls by inflating their vocal sacs with air and then forcing the air out through their mouths and noses. Each frog species has a characteristic call that differs from those of all other species. This allows the frogs to find mates via sound alone. In fact, some species, such as the gray tree frog and Cope’s gray tree frog, are visually identical but produce different calls.
Sometimes, male frogs attempt to breed with other male frogs. When this happens, the frog that has been misidentified as a female gives a short call that identifies it as a male. Upon hearing this, the overly aggressive breeder releases the other frog. As explained by PawNation, frogs emit loud screams, called alarm calls, when they are grasped by a predator. These calls may startle the attacking predator, allowing the frog to escape.
Male frogs of many species, such as bullfrogs, have larger tympanums than females do, which makes it easy to distinguish between males and females. A tympanum is a membranous resonator in a sound-producing organ.