Toe-tapping is a behavior observed in some species of frogs. It involves the rapid up-and-down movement of the middle toes of the hind legs, and it usually happens when the frog is hunting for insects. When frogs tap their toes, they produce vibrations that travel through the substrate (e.g., leaf litter, plant stems, or soil). These vibrations will be detected by any nearby insects, and the tapping is hypothesized to be an example of predators manipulating the behavior of their prey – in this case, startling the insects and causing them either to move away or to freeze, either of which may make them easier targets for the frog.

A recent study published in Evolutionary Ecology describes the vibrational qualities of toe-tapping in Dendrobates truncatus, a poison dart frog found in Colombia. The authors, which included Dr. Rex Cocroft, developed an apparatus to record this toe tapping behavior in a controlled setting. The recordings were used to characterize the temporal parameters of the vibrations, including duration, number of taps, and intervals between taps. According to the authors, it is “the first descriptive study of the vibrational temporal parameters of toe tapping associated with foraging behavior in anurans.” One interesting finding was that the frogs often accelerate the tapping just before attempting to capture an insect. Further research is needed to determine the exact function of toe-tapping in frogs; however, this study is a valuable step forward in understanding this fascinating behavior.

The Cocroft lab actively works to foster research in the field of vibrational ecology. The lab develops relatively inexpensive sensors, playback devices, and software for use by other labs; provides training and advice to young researchers; and facilitates new research in other labs by making available their hardware and software solutions to technical challenges. This study, says Cocroft, is an example of the exciting new research these activities and collaborations generate.

“This work was spearheaded by a very talented pair, an undergraduate and a PhD student in Colombia, and it sets the stage for their planned experimental tests of how the frogs’ behavior may translate into increased foraging success.” 

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[Image caption: Yellow-striped Poison Dart Frog (Dendrobates truncatus). Image by José Gabriel Julio Guzmán, licensed under a Creative Commons Attribution 4.0 Generic license. Source: Wikimedia Commons]