A crystal clear creek at LaBarque, and crayfish and whirlgig beetles were stirring. It was cloudy and a storm was upon us, when we spotted a figure moving slowly up stream. At first we thought it might be a muskrat or beaver, but as we approached, I was delighted to see a corrugated shell and claws— belonging to no other than a snapping turtle (Chelydra serpentina). The snapper didn’t flee, but tucked itself against the streambank, freezing and lowering the head when it perceived me. It periodically raised its head to the surface, only sticking out the tip of its nose to breathe, then it would resubmerge back to safety. Very few predators have the gumption to take adult snappers down, but otters and coyotes are sometimes up for the task. Snapping turtles are infamous for their powerful bite, which is as effective at catching prey as for predator defense. They can jut out their necks out at astonishing speeds and exert over 30 pounds of force when clamping down with their sharp jaws. Together with their monstrous spiny tails, the ability to overwinter under ice without breathing for hundreds of days… and live well over a hundred years(!), they are truly a relict to behold.
Unlike their aquatic crocodilian relatives, turtles have received less attention regarding vocal communication. Turtles may not have the best hearing, but they are well-suited to detect low frequency sound, having maximum sensitivities around 100-600 Hz in freshwater and marine species. Over the past few decades, calls have been described in over 50 turtle species, some of which have extensive vocal repertoires. For example, the Australian long-necked turtle (Chelodina oblonga) has over 17 distinct calls that vary from percussive clicks to harmonic chirps and sustained pulses lasting 10 minutes. Acoustic signals are used in various ecological contexts, such as courtship, mate choice, parent-offspring communication, and hatchling emergence. For the common snapping turtle, hatchling sounds and vocalizations have also been documented, and call patterns become increasingly complex as the embryos mature. Vocalizations may help synchronize hatching among siblings in a clutch, which increases the chances of successful emergence from buried nests and reduces susceptibility to predation. However, cues from multiple sensory modalities likely play a role in coordinating hatching, including perception of egg vibrations and detection of embryonic heart beats throughout development.
Another common snapping turtle (Chelydra serpentina), found making its way across a hilly road. Only about palm-sized, this juvenile was reluctant to bite in self-defense. Instead, the turtle tucked its head into the shell and closed its eyes. Before I picked it up, the turtle kept positioning its shell towards my hand as a shield, anchored and rotated by its hind legs and rigid tail. Similar behaviors are described in this natural history note.
Photographed when released at a nearby park