You’ve likely heard a frog call at some point in your life, perhaps even in your own yard or neighborhood.
But have you ever thought about why frogs call, and what their calls mean?
Frogs may communicate through sound, by calling, singing, or croaking. Most calling frogs are male, and amplify their calls through the inflation of a vocal sac on the throat. Others may communicate through visual means, vibration, or other channels.
Typically, frogs communicate for breeding purposes, to display dominance, or to defend their territory (Gerhardt, 1994).
Frogs communicate in a wide range of unique ways.
Let’s dive into what frog communication is, what types of communication frogs use, and how frog communication works.
Communication Through Sound
The most common type of frog communication is through sound, and these frog calls are typically for the purpose of reproduction.
In most frog species, males call as an “advertisement” to reveal their location to female frogs for the purpose of mating.
A frog call happens in a series of steps that result in a loud, powerful call that can travel a far distance.
- The frog fills its lungs with air.
- The frog closes its mouth and nostrils, so it can push the air out of its lungs without it escaping the frog’s body.
- The frog pushes the air from its lung across its larynx, or voice box, to create sound.
- The air travels into the frog’s vocal sac, a pouch on the frog’s throat that inflates like a balloon when filled with air.
- The air-filled vocal sac acts as an amplifier, making the frog’s call louder and able to travel further.
The male sits still while calling, so the female frog can follow his call to find him and mate with him.
Once the frogs have successfully found each other, they enter amplexus, the breeding position.
In amplexus, the male frog holds on to the female’s back to fertilize her eggs as they are laid.
The male frog may continue calling to warn off other males that may try to overtake him (Gerhardt, 1994).
Each species of frog has its own unique call.
This is especially true amongst different species within the same geographic range (Duellman et al. 1983).
Many frog species are not capable of interbreeding with other species.
This necessitates a means of identifying other members of the same species.
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Since calls are the main way frogs find their mates, diversifying their calls is an effective way to allow frogs to find mates of their own species.
However, frogs may also call as a way to defend their territory, display dominance in a group, or express displeasure.
I personally have experienced the latter in my own pet frogs. I keep a group of Fire-Bellied Toads (Bombina orientalis).
On numerous occasions, I have witnessed a frog get stepped on or jumped on by another frog, and let out a series of angry squeaks until the offending frog has retreated.
Communication Through Movement
Sound may be an efficient means of communication for many frogs, but it is not the ideal form of communication for all environments.
In loud environments, such as near rushing water, auditory communication such as frog calls may be lost in the noise, or be indistinguishable to other frogs.
In such cases, some frog species may exhibit visual communication, such as “foot-flagging”- waving a foot to stop another frog from encroaching on claimed territory (Preininger et al. 2009).
Foot-flagging may also be used alongside advertisement calls to help direct the female’s attention to the calling male.
Visual signals have been known to occur in unrelated species and groups living in continuously loud environments.
These visual signals are also substantially more common in diurnal species in which the frogs are awake and active during the day, as opposed to nocturnal species who rely more heavily on auditory calls while active at night (Preininger et al. 2009).
Additionally, colors such as the aposematic coloration, or warning coloration, of dart frogs can be considered a form of visual communication, since the bright colors warn predators of a potential danger, such as toxicity in the case of dart frogs.
Dart frogs, like the species that utilize foot-flagging, are diurnal.
Even though most frogs are nocturnal, those relying more heavily on visual forms of communication must be active during the day for their communication to be seen and received properly by other animals.
Communication Through Vibration
Some frogs have been observed communicating through vibration.
The white-lipped frog (Leptodactylus bilabris) of Puerto Rico is actually thought to have one of the highest levels of sensitivity to vibration of any animal.
Male white-lipped frogs have been observed to “thump” their feet on the ground at the beginning of each call, thereby allowing other frogs to observe their presence through either sound or through vibration (Lewis et al. 1985).
Red-eyed Tree Frogs (Agalychnis callydrias) are known to communicate through vibrations created by rapidly raising their bodies off of plants and lowering them again, in a motion compared to high-speed push-ups.
These communications are frequently seen in males defending their mates from other encroaching males.
However, they can take place in any confrontation between two males, even without a female present.
These small frogs will claim a territory of up to half a meter from which to call as an attraction for females, and defend it against any intruding males (Caldwell et al. 2010).
This article was written in collaboration with another Master Herpetologist certified by the Amphibian Foundation.
Gerhardt, H. C. (1994). The Evolution of Vocalization in Frogs and Toads. Annual Review of Ecology and Systematics, 25(1), 293–324. https://doi.org/10.1146/annurev.es.25.110194.001453
Duellman, W. E., & Pyles, R. A. (1983). Acoustic resource partitioning in Anuran Communities. Copeia, 1983(3), 639. https://doi.org/10.2307/1444328
Preininger, D., Boeckle, M., & Hödl, W. (2009). Communication in noisy environments II: Visual signaling behavior of male foot-flagging frogs Staurois Latopalmatus. Herpetologica, 65(2), 166–173. https://doi.org/10.1655/08-037r.1
Lewis, E. R., & Narins, P. M. (1985). Do frogs communicate with seismic signals? Science, 227(4683), 187–189. https://doi.org/10.1126/science.227.4683.187
Caldwell, M. S., Johnston, G. R., McDaniel, J. G., & Warkentin, K. M. (2010). Vibrational signaling in the agonistic interactions of red-eyed treefrogs. Current Biology, 20(11), 1012–1017. https://doi.org/10.1016/j.cub.2010.03.069