Risky ripples: Frog's love song may summon kiss of death

Jan 23, 2014
The frog-eating bat, Trachops cirrhosus, uses several different senses to locate its prey the Tungara Frog, Physalemus pustulosus. Credit: Christian Ziegler

Male túngara frogs call from puddles to attract females. The production of the call incidentally creates ripples that spread across the water. Researchers at the Smithsonian Tropical Research Institute in Panama revealed that these ripples are used by other male frogs to assess the level of competition in the puddle. Unfortunately for the frogs, their main predator, the frog-eating bat, senses the ripples too, making the frogs easier targets.

The tún-gara sound of a tiny rainforest frog known to scientists as Physalemus pustulosus has been compared to a peacock's train. Female frogs are attracted in large numbers to the ponds from which the males call night after night. But these calls also make it easier for frog-eating bats, Trachops cirrhosus, to find their prey. New work by a team from STRI, the University of Leiden, the University of Texas at Austin and Salisbury University in Maryland shows that much more is going on.

"It's comparable to the use of lip reading," said STRI post-doctoral fellow Wouter Halfwerk from the University of Leiden. "While sound is the most obvious component of the frogs' communication, the call-induced alter the behavior of competing males that sense them. Bats perceive the ripples too, using echolocation, which shows that the costs associated with communication can be imposed through a sensory domain that is fundamentally different than the intended receiver of the frog's call."

Competing male frogs increased their call rate by more than double when presented with ripples and sound as opposed to sound alone. Males stopped calling when they were inside the 7.5-centimeter defended zone of ripple-generating rivals, suggesting that ripples are used for competitive interactions. Males did not respond to ripples alone, showing that the cues derived from them have to be integrated with the accompanying sound to elicit the appropriate response.

Ripples continue for several seconds after a male tungara frog has stopped calling. Credit: Ryan Taylor/Salisbury University

Bats preferred to attack models making calls with ripples compared to calls alone. However, when researchers added leaf litter to simulate the conditions in some natural pools, there was no attack preference, presumably because the echo-acoustic cues were broken up by the debris, making them harder to detect by bats.

Another twist is that cannot immediately stop call-induced ripples when a predator approaches. "When a bat flies by, the frog's first line of defense is to stop calling," said Rachel Page, a STRI staff scientist. "But the water ripples continue for another few seconds, effectively leaving a detection footprint for the approaching bat. This study shows how important it is to look at the full picture—perception not only of signals but also of their by-products by different receivers through different sensory channels can generate both costs and benefits."

This video is not supported by your browser at this time.

Explore further: Mysterious glowworm found in Peruvian rainforest

More information: "Risky Ripples Allow Bats and Frogs to Eavesdrop on a Multisensory Sexual Display," by W. Halfwerk et al. Science, 2014.

Related Stories

Bats: What sounds good doesn't always taste good

May 21, 2012

Bats use a combination of cues in their hunting sequence - capture, handling and consumption - to decide which prey to attack, catch and consume and which ones they are better off leaving alone or dropping ...

Vision stimulates courtship calls in the grey tree frog

Nov 19, 2012

Male tree frogs like to 'see what they're getting' when they select females for mating, according to a new study by Dr. Michael Reichert from the University of Wisconsin-Milwaukee in the US. His work, which is one of the ...

Croaking chorus of Cuban frogs make noisy new neighbors

May 31, 2013

Human-produced noises from sources such as traffic and trains can substantially impact animals, affecting their ability to communicate, hunt, or even survive. But can the noise made by another animal have the same detrimental ...

Lovelorn frogs bag closest crooner

May 20, 2013

What lures a lady frog to her lover? Good looks, the sound of his voice, the size of his pad or none of the above? After weighing up their options, female strawberry poison frogs (Oophaga pumilio) bag th ...

Recommended for you

Rare new species of plant: Stachys caroliniana

19 hours ago

The exclusive club of explorers who have discovered a rare new species of life isn't restricted to globetrotters traveling to remote locations like the Amazon rainforests, Madagascar or the woodlands of the ...

Mysterious glowworm found in Peruvian rainforest

22 hours ago

(Phys.org) —Wildlife photographer Jeff Cremer has discovered what appears to be a new type of bioluminescent larvae. He told members of the press recently that he was walking near a camp in the Peruvian ...

The unknown crocodiles

23 hours ago

Just a few years ago, crocodilians – crocodiles, alligators and their less-known relatives – were mostly thought of as slow, lazy, and outright stupid animals. You may have thought something like that ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.