This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Along the sandy banks of northern India's Chambal River, crocodile-like gharials glide silently through the water—but if a gharial spots a stranger, the quiet may be punctuated by a series of explosive pops. That popping sound—like a champagne cork being released from a bottle—has only recently come to scientists' attention.
It's unique to male gharials and results when one of the large reptiles fills its nasal cavity with water and then exhales rapidly: The water shoots through a bulbous outgrowth at the tip of the creature's long snout. The sounds, which are often produced in sequence, appear to broadcast the male's identity—each gharial's "pop pattern" is unique. The gharials aren't the only reptiles making surprising noises.
While mammals and birds are better known for their vocal communication skills, reptiles aren't just quietly slinking about in the wild—they create their own soundscapes with chirps, squeaks, bellows and roars. As researchers discover more of these sounds, they are also beginning to determine the importance of such vocal chatter to the animals' social lives, from mating to parent-offspring interactions. Reptiles have largely been thought of as secretive creatures and "underappreciated for a long time with regard to social behavior," says conservation biologist Sean Doody of the University of South Florida.
"There are hundreds of reptile species, and most of them are not studied at all," says Henrik Brumm, a behavioral biologist at the Max Planck Institute for Biological Intelligence in Germany. Now that scientists are taking note of these varied vocalizations, Brumm says, the idea is "to better understand what they're saying." When it comes to talkative reptiles, crocodiles are among the most well-studied. Scientists have long known that, like their bird cousins, baby crocodilians produce sounds while they are still in their eggs.
These noises appear to synchronize hatching among siblings and call to their mother for help extracting themselves from their eggshells and leaving the nest. But over the past decade or so, it's become clear that many turtles, too, make various clicks and chirps from within the egg. To better understand turtle noises, evolutionary biologist Gabriel Jorgewich-Cohen, now at the National Institute of Amazonian Research, and colleagues looked at species with chatty turtle babies, such as South American river turtles, as well as more taciturn species, such as the western swamp turtle.
The researchers found that while South American river turtles—with clutches of more than 100 eggs—have noisy turtle youngsters that synchronize their nest exit, hatchlings of species that lay fewer than 10 eggs are less likely to vocalize and leave the nest together. This suggests that chit-chat made by turtle tykes from large broods may help synchronize hatching, which can help the hatchlings work as a team to dig their way out of their underground nests. And since they have many siblings, making noise is not so risky: Their individual chance of being gobbled up by predators is low, says Jorgewich-Cohen.
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