Snapping turtle vocalizations and nest emergence

Photo courtesy of Claudia Lacroix

If you thought baby turtles couldn’t get any cuter, think again. Research from the University of Toronto (click here to hear the talk on this research and if you want to hear the turtle sounds, please go to 3:50 on the video) has found that baby snapping turtle hatchlings produce sounds — including clicks and squeaks. The discovery that hatchling snapping turtles produce vocalizations opens up questions about turtle social behaviour, an oft-neglected subject in reptile biology.

The research was led by Claudia Lacroix from the Rollinson Lab at the University of Toronto for her third year undergraduate thesis. Now in her fourth undergraduate year, Lacroix explains, “Not many North American or freshwater turtles are known to vocalize. This was an opportunity to gauge what is happening in her freshwater ecosystems up north.”

Turtles were long believed to be voiceless, with tortoises being the exception to the rule. “If you go to a zoo, and it’s around February, you will notice courting tortoises,” says Lacroix. “They’ll make some funny grunting noises.”

The belief that turtles were silent eroded away as researchers and naturalists began sharing anecdotes about turtle noises. Now, more than 45 species of turtle are known to produce sounds.

Don’t expect to hear the wild calls of a turtle on your next cottage trip though. While turtles can produce noises within the human hearing range, it’s at a low volume. Add in a pile of sand covering nesting turtle eggs, and you’re out of luck hearing any hatchling turtle conversations from the surface.

To tackle this problem, Lacroix collaborated with Christina Davy, adjunct professor with Trent University, to eavesdrop on snapping turtle eggs that had been collected as part of Algonquin Park’s long-term study turtle study. She placed the eggs in simulated nests in glass aquariums. Lacroix also buried a microphone with the eggs to listen in on the hatchlings.

turtle hatchling eggs in box of sand and a microphone set up to hear their noises
Photo courtesy of Claudia Lacroix

So what sort of noises are snapping turtles making inside the egg? Lacroix was able to capture five types of vocalizations. “One of them is a very simple squeaking sound,” she says. “There’s another sound that has multiple pulses, so it sounds like a firing of clicks.“

And then there’s one noise that isn’t appropriate for polite company. “It’s a low frequency sound, it’s really short, and it sounds like a fart,” says Lacroix.

The hatchlings produced different sounds depending on the hatching period. In the pre-pipping stage, which is before turtles begin breaking through their eggshells, the hatchlings produced really simple vocalizations, says Lacroix. After the hatchlings broke their eggs and started emerging from the nest, the vocalizations became more complex.

turtle eggs
Photo courtesy of Claudia Lacroix

One hypothesis for chatty hatchlings is that the sounds cue hatchlings to emerge from the nest en masse. “When you’re crawling out of the nest, that takes up a lot of energy,” says Lacroix. If the turtles eat up all their energy during hatching, they won’t have the reserves left over to avoid predators or find a hibernation spot.

Turns out there is a benefit for hatchlings to emerge as a group in terms of energy consumption. When Lacroix placed hatchlings in a simulated nest with siblings, they hatched with a higher body mass than when they were placed in a nest solo.

Lacroix plans to continue her work on turtle vocalizations with a masters thesis in the Rollinson Lab. This time, she will be collaborating with the Turtle Conservation Centre to look at vocalizations in other Ontario turtle species.

“The idea is to compare the vocalizations between species, because each species has their own behavioural complexities. Maybe we’ll see more complex vocalizations in turtles with larger clutches, because there is a bigger need for cooperation between hatchlings.”

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