Unlike most other frogs that call out to females, Litoria chloris calls out males.
When male frogs call out or trill to other frogs during mating season, they are mostly calling out to females in hopes of mating. The male orange-eyed treefrog (Litoria chloris) however trills to other males, according to a new study by Griffith University of Australia that helped to determine what the frogs transmitted as they called out to other frogs. According to a report in ABC Science, the study determined that the male belted out six different call signatures– trill frequency and duration, moan frequency, duration, number and number of pulses. Each unique call served as a different communication medium to other nearby frogs. The researchers found that the size of the frog correlated with trill frequency and that the larger the frog, the deeper its trill. The moan calls contained no differentiating information when it came to frog size that the researchers could determine.
According to the report, in other frog species, larger frogs grow faster and survive longer than smaller frogs and have greater fertilization success, and their offspring have better survival rates. These frogs trill their size to females and that call information helps a female to choose the ideal mate based on the information. This is known as intersexual indicator theory.
In the orange-eyed treefrog, which is native to Australia and can be found on the east coast, north of Sydney, the male frogs are using their call capabilities to communicate with other males to let their presence be known in a given pond and to help determine what frogs may be friendly and what frogs are strangers that could be potentially threatening. It is unknown how the female frog chooses its mate but it’s not by body size because if they did, the information would be determined by the moan calls, the researchers noted. The researchers are unsure how a female chooses a potential mate but they speculate that smell may be a factor.
An abstract of the report can be found here.