Why do male frogs call during the breeding season?

During the breeding season, male frogs produce mating calls primarily to attract females to the breeding site. These vocalizations serve several critical functions in reproductive behaviour:1

• Species Recognition: Mating calls act as a primary isolating mechanism, allowing females to discriminate between the calls of their own species and those of others, which prevents hybridization.1
• Information Signaling: The calls encode information such as the caller's sex and species. Additionally, the vocalizations can indicate the number of other males in the vicinity, providing females with clues about the quality of the habitat for egg deposition.2
• Territorial Defense: Beyond attracting mates, calling serves to repel other males. Many species defend specific calling territories, and males may engage in aggressive behaviors—such as wrestling, kicking, or biting—to protect their sites from intruders.21

To produce these sounds, males inflate a vocal sac, which acts as a resonating chamber to amplify the sound produced by air moving over the vocal cords.31