Frog Sings Like a Bird, Bobs Head for Mates

Brazilian torrent frogs clearly do not want to be ignored, as new research finds they sing, squeal, wave their arms, tap their toes and more when around other frogs, and particularly members of the opposite sex.

The frogs (Hylodes japi) could have the most complex communication system of any amphibian, suggests the paper, published in the journal PLOS ONE.

Fábio Perin de Sá of Sao Paulo State University and colleagues wrote that the communication of the frogs “is undoubtedly more sophisticated than we expected and that visual communication in anurans (tailless amphibians) is more widespread than previously thought.” They added that “this is especially true in tropical regions,” likely because of the higher number of frog species there and ecological factors, such as diverse microhabitats.

The following three videos, which run in sequence, illustrate only some of the frog's skills, such as singing like a bird and doing leg displays.

De Sá and his team made the recordings in the biological reserve of Serra do Japi in the state of Sao Paulo, southeastern Brazil. The forested region provides important habitat for many species of plants and animals.

The researchers documented the calls as well as the visual displays of the frogs. The latter consisted of toe trembling, toe flagging (which reveals the frog’s silver-white underside), foot shaking, hand shaking, arm waving, head bobbing, full body jerks, and much more.

A particularly complex move is the "head snake." Males seem to use this to mesmerize females. While approaching prospective mates, the males will move their heads from side to side as snakes do when in front of a snake charmer. The males do this looking right into the eyes of the desired female and at very close range, but not touching her.

Actual courtship is quite a scene. While peeping and squealing, the males tremble their toes, engage in toe flagging, foot shaking, hand shaking, arm lifting, head bobbing, body jerking and perform throat displays. While all of this is going on, the females remain motionless. Only later, with a subtle lift of an arm as if to say, "Yoo hoo, I'm ready," does a female often signal her willingness to mate. She then rubs part of her body on the male's back, with her hands gently touching him. Intercourse usually starts thereafter.

The scientists also observed that females could stimulate males to emit courtship calls with just a lift of their arm, most often the left one. Such control has never been documented before in frogs.

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