To survive against stronger enemies, the leaf frog emits ultrasonic sounds – sounds that have frequencies beyond the maximum frequency detectable by human ears.
Leaf Frog – (Photo: National Geographic).
Leaf frog (Haddadus binotatus) is the most common frog species among the forest-dwelling frogs in South America. Despite their large population, they are very small, with the largest individuals measuring less than 64mm in length.
When faced with an opponent and unable to fight back, their defensive strategy is to emit ultrasonic calls.
Recently, researchers recorded the sounds of this frog species for the first time in Brazil. Although humans cannot hear these sounds, they are very distressing to predators such as bats, rodents, and small primates.
This call is part of the leaf frog’s overall defensive behavior: they arch their backs, raise the front part of their bodies, and open their mouths wide as if preparing to “scream.”
Illustration of Leaf Frog’s screaming behavior.
The frequency of their calls, as noted by the research team, ranges from 7 to 44 kilohertz, while humans can only hear sounds around 20 kilohertz and below.
The researchers believe that this wide frequency range, combined with the frog’s threatening posture, is intended to deter predators from attacking.
“Given that Brazil has the highest amphibian diversity in the world, with over 2,000 described species, it would not be surprising if other frog species also produce sounds at these frequencies,” said ecologist Mariana Retuci Pontes from Campina State University.
This study was published in the journal Acta Ethologica.
