Frogs are common amphibians recognized for their distinct sounds, often generalized as “ribbiting.” These vocalizations serve specific biological purposes. Understanding these calls reveals how frogs interact with their environment and each other.
How Frogs Make Their Calls
Frogs produce their calls using a specialized anatomical system. Sound originates in the larynx, where vocal cords vibrate as air passes over them. To amplify this sound, most male frogs possess a vocal sac, a flexible membrane of skin located under their throat or on the sides of their head. This sac inflates like a balloon, acting as a resonating chamber that significantly increases the call’s volume and projection.
The unique aspect of frog vocalization is that air is not expelled during calling. Instead, air is continuously passed back and forth between the lungs and the vocal sac. This allows frogs to produce prolonged calls without needing to inhale repeatedly, enabling them to vocalize even while submerged underwater. The muscles controlling the larynx also enable the frog to adjust the pitch and tone of its call.
The Many Meanings of Frog Calls
Frog calls are primarily a form of communication, with most vocalizations made by males. The most prominent type is the advertisement or mating call, used to attract females for breeding. These calls are species-specific, helping females identify and locate males of their own kind, which is crucial in environments with multiple frog species calling simultaneously. The quality and characteristics of a male’s call can also signal his size, health, and overall fitness, influencing a female’s choice of mate.
Beyond attracting mates, male frogs use calls to establish and defend their territory. These territorial or aggressive calls warn off rival males, signaling their presence and readiness to compete for resources or mates. Frogs also produce distress calls when in danger or pain, which can serve as a warning to other frogs or startle predators. Additionally, release calls are made by males or females who are not receptive to mating, signaling to another frog to let go.
When and Where Frogs Call
The timing and location of frog vocalizations are heavily influenced by external factors. Calling activity is most prevalent during specific breeding seasons, which typically occur from early spring through summer. The presence of water bodies such as ponds, wetlands, or streams is essential, as most frog species lay their eggs in water.
Environmental conditions play a significant role in triggering calling behavior. Increased humidity, changes in temperature, and especially rainfall are strong stimuli for increased activity. Many frog species vocalize at night or after rain, as these conditions provide higher humidity, cooler temperatures, and cover from predators, reducing the risk of dehydration. When many male frogs call together, they form a “chorus,” which can become quite loud and is a common sound in breeding habitats.