Who has never heard a symphony of “was-no-was”?
Coacho is also called vocalization, being one of the most efficient ways for anuran amphibians (toads, frogs and tree frogs) to communicate and save energy. That's right: save energy!
Imagine yourself, who expends more energy in an hour: a boxer or an opera singer? I hope you answered the first alternative!
For a male anuran, a vocal contest with another male is far more economical and less risky than contesting in physical combat, whether for territory or females – and that's what happens. As these animals have not very developed eyesight, this is their way of “perceiving” who they are dealing with.
The song offers information about the male's physical attributes. A frog larger than another of its species may indicate, through its song, that it is probably older, which means that it has survived the inclement weather. So, this one is possibly stronger and, in a physical contest, would likely be the winner.
Thus, when realizing that another male has “more attributes”, it is easier and less costly to flee and look for another territory, female or male for disputes. It would be almost the same as the opera singer of the example wanting to fight Mike Tyson for a chair and realizing that if she doesn't give up on the idea, she will suffer great losses.
Studies show that lower frequency vocalizations are typical of larger males and these drive away other males and attract more females - an effect that also occurs in repertoires with more songs per minute. This attraction to females is for the same reason, as females of any species have a tendency to look for stronger and healthier partners and thus likely to secure offspring with such attributes.
By Mariana Araguaia
Graduated in Biology
Source: Brazil School - https://brasilescola.uol.com.br/biologia/anfibios-anuros-seus-coachos.htm