Birds sing, squirrels chatter, alligators…bellow?
When you think of the sounds of nature, the American alligator most likely isn’t top of mind (your thoughts may drift to birdsong instead). Alligators do not strike most people as vocal animals. However, they are capable of making a wide array of sounds, including hisses, grunts, and growls.
Alligators can also pop their jaws against the water to make a ‘head slap’ sound. Perhaps their most impressive vocals of all are the primordial bellows they can make.
But why do alligators bellow?
Alligators bellow to communicate their body size to territorial rivals and potential mates. This helps them avoid conflict with rivals and attract females to their location. The lower the acoustic resonance of a bellow, the bigger the alligator making the sound is.
Let’s take a deeper dive into what an alligator is communicating when it bellows.
What Does It Mean When an Alligator Bellows?
As you can imagine there isn’t just one interpretation, so let’s see what possible reasons alligators might have to bellow!
Reason 1: They Are Avoiding Conflict With Rivals
Territorial conflicts are a common trend in the animal kingdom. As such, many animals have evolved behavioral mechanisms to help them identify and avoid potential conflicts. Bright colors, warning calls, and threat displays are all examples of this.
Alligators are massive animals, so it’s no wonder that a clash between two of these titans could result in crippling injury or death to one of the alligators involved. In other words, it is not beneficial to either alligator to engage in unnecessary fighting.
The success in a territorial conflict is often determined by which alligator is larger. That being said, scientists have found that there is a direct correlation between an alligator’s body size and the frequency of their bellows. The larger the alligator, the longer its vocal tract. The longer the vocal tract, the lower frequency of sound it emits.
Conflicts can arise between alligators competing for the same territory, especially during mating season. Bellowing affords smaller crocodilians the opportunity to avoid running into a larger rival.
Since swimming alligators are mostly submerged, it can be difficult to tell the true size of an American alligator while it’s in the water. In comparison, the frequency of an alligator’s bellow is very reliable.
Does communicating large body size always repel other alligators? Not necessarily!
Reason 2: They Are Attracting a Mate
Female alligators only accept mates that are larger than them. For this reason, male alligators are especially vocal during courtship, which starts in early April, leading into their summer mating season. These vocalizations communicate their body size to females over a great distance with startling accuracy.
Here is an example of the head and tail lift that male alligators do during their courtship display.
A bull (male) alligator’s bellow during courtship is more than just one isolated sound. During his ‘water dance’, the bull alligator inhales, filling his chest cavity with air, then lifts his tail and head out of the water at an angle.
The first ‘sound’ he produces is infrasonic waves, beyond the range of human hearing. This sub-sonic frequency creates ripples in the water around his torso, causing water droplets to ‘dance’ on his back. As he exhales, his subsonic mating call turns into a low-frequency, rumbling bellow.
Just like in territorial conflict, this bellow communicates an alligator’s size with great accuracy. While size may be a deterrent in conflict, it is considered a boon by females during mating season.
The larger the male, the greater his chances of attracting a female. Both males and female American alligators bellow, but only males produce the ‘water dance’ display. You can see an example of a bull alligator’s courtship display in the below video.
That courtship behavior is exclusive to males of the species. The ‘water dance’ display is usually performed multiple times in a row, with the bull alligator pausing to re-inflate his lungs and reassume his impressive posture.
Reason 3: Females Protecting Their Offspring
Female alligators are devoted mothers who will guard their nests with the utmost tenacity. If she hears the metallic, chirping bark of her babies in distress, she can respond to the threat with an impressive roar.
However, a female responding to the alarm call of her offspring does not do the ‘water dance’ display that bull (male) alligators perform during courtship. And while some people may use the terms ‘roar’ and ‘bellow’ interchangeably, they are different from one another.
So, a protective female is more than likely roaring, not bellowing. Even so, a mother alligator’s roar is a magnificent sound.
Here is an example of what a baby alligator’s distress call to its mom sounds like.
Reason 4: Responding to Unexpected Loud Noises
The fourth reason an alligator might bellow is of an artificial nature. Low-flying aircrafts or loud, unexpected sounds like a car muffler backfiring can provoke alligators into bellowing. Even a human being mimicking a growl or rumbling sound can get this response (though it is not encouraged to provoke wildlife).
In this case, the argument could be made that the alligator is still trying to accomplish one of the two main purposes of a bellow: warning possible rivals to steer clear. The only difference is that the suspected ‘rival’ is an imposter!
A Final Word
Just like many things in nature, the bellow of an alligator boils down to protecting territory, attracting mates, and protecting their offspring. And while these motivators may not appear particularly groundbreaking, it drives home just how effective an alligator’s bellow is in the preservation of their species.
Compared to many other species in the modern world, crocodilians have endured for 95 million years. Through the use of specialized adaptations, like vocalizations, these enormous animals have survived in an ever-changing world. An American alligator bellow is a testament to its resilience. And we have the privilege of witnessing it!