by Whit Gibbons

February 25, 2018

Springtime brings out questions about reptiles, which have spent most of their time in a dormant state since autumn. I recently received the following questions, one of which is a perennial one. They all pertain to American alligators.

Q: My son and I were fishing near Charleston last week on the first really warm day since last fall and saw a large alligator lying on the shore of a lake. Why would it sit motionless with its mouth open? It was that way when we saw it, so it wasn’t a show for us.

A: Years ago James Spotila, now a professor at Drexel University, conducted a study on mouth gaping by alligators to determine why these big reptiles, as well as crocodiles, will sometimes sit motionless with their mouth open while they are basking. The behavior has no apparent relationship to the presence of other alligators or humans. Previous studies on Nile crocodiles had proposed that gaping was a form of thermoregulation to lower body temperatures. However, Spotila’s study suggests that the behavior primarily lowers only the temperature of the head and brain. The researchers discovered that the open-mouthed display is a mechanism for keeping head temperatures of the animal in equilibrium while the rest of its body is being warmed by the sun during periods of cool air temperatures.

Although the physiological process may be different, mouth gaping in an alligator serves as a cooling mechanism similar to a dog’s panting. To appreciate how long it can take to get a scientific explanation for a commonly observed phenomenon, consider that mouth gaping by Nile crocodiles was first reported in writing in the 5th century BC.

Q: Who should I call about an alligator about 4 feet long that has come out along the shore of a lake in our neighborhood? We tried throwing something at it, but we can’t get close enough because of the chain link fence between us and the lake.

A: My suggestion is that you call your friends to come look at it and enjoy being able to see one of these awesome creatures outside of a zoo. I’m not sure why throwing something at it would be a good idea, as you would only scare it away. The wildlife departments of most states, including Alabama, Florida, Georgia and South Carolina where alligators occur naturally, generally do not have time to respond to calls about small alligators. An alligator of that size is no threat to a human or even to medium-size dogs.

Q: A friend from Alabama said she heard alligators bellowing from a river swamp. Do alligators really do this?

A: Yes. Alligators do make deep, resonant vocalizations, especially in the spring when they mate. Also, they are native to southern and central Alabama. I once heard an alligator bellowing along the Black Warrior River near Tuscaloosa. An adult alligator makes a rumbling sound, much louder and more guttural than a bullfrog, which might also be heard calling in any eastern state.

You can sense the vibrations of a bellowing alligator if you are standing close enough. Female alligators also make a thundering noise. I have heard one pair vocalizing for days during the spring. My impression is that the female is responding to the male’s bellows. Either would make a bullfrog’s call pale in comparison. The U.S. Fish and Wildlife Service provides audio of bellowing alligators at For comparison, you can hear what a bullfrog and other southern frogs and toads sound like on the University of Georgia’s Savannah River Ecology Lab website at

One reason for maintaining a high diversity of wildlife is that many species boost our enthusiasm for the natural world by stimulating curiosity. Alligators clearly spark people’s interest, and the high volume and variety of questions people ask about them is a positive sign that people are curious about our native wildlife. And that is good news for the wildlife.

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