What Roosters Are Crowing About
How And Why Chickens Vocalize
By Kenny Coogan
Some days it sounds like The View is being recorded in my henhouse with all of the clucking that goes on. At other times the birds’ soft coos and caws are Zen-like. I often have wondered what determines if the noise a chicken makes will be a cluck, coo or crow. And with all that talking, are they actually saying anything at all?
Dr. Michael J. Darre, Professor of Poultry Science at the University of Connecticut, says vocalizations of animals may contain “information about the identity of species or an individual of a given species, about sex and rank of a group member, (or) about the biological context and the motivations the sender is experiencing when producing the sounds.”
As backyard poultry owners know, chickens can be very vocal birds. In two studies that analyzing red-jungle fowl calls identified up to 30 different vocalizations. “Most of the calls identified by both authors appear to be the same,” Dr. Darre says. The calls include distress cries, pleasure notes, fear and pleasure trills, clucking by hens, food calls, purring, courtship calls, contentment calls, contact grunts, singing, alerting calls and so on. Many of which I bet you can identify in your own flocks.
How Sound Is Produced
Birds have a unique way of producing sound. Dr. Darre says that the vocal apparatus for sound production in mammals and birds both utilize airflow within the respiratory system as a source of energy for sound production. All sounds begin with the generation of vibrations in some part of the animal’s body and, for birds, it is the muscular vibrations of a membrane or sac.
The avian vocal organ, the syrinx, is located at the intersection between the trachea and the two external primary bronchi. The syrinx contains structures that vibrate in airflow to produce sound. Thin membranes vibrate as air from the bird’s respiratory system is pushed outwards. The characteristics of the sound produced is mainly affected by the muscles inside and outside of the syrinx and the entire vocal cord of the bird. Air released from the lungs draws them even closer and sets them vibrating in a kind of hand-clapping motion. The sound produced could be a complex one with strong harmonics. The tone quality is influenced by the sound waves’ movements through the trachea. Both male and female chickens have the same equipment and can both produce the same sounds, but how often do you hear a hen crow?
Battle Of The Hormones
Dr. Darre says hens are more under the control of estrogen than testosterone, which changes their urges to make certain sounds. “A hen has the physical ability to crow and some do, but generally not until they are older and have stopped laying eggs, or they are the dominant hen with no rooster around,” he adds.
I suppose then that the more accurate idiom is the rooster may crow but the hen delivers the goods … unless the hen gets a boost of testosterone. With added testosterone, hens will also crow, as well as baby chicks — both male and female. The crow from the chicks will sound slightly different because their syrinx is not fully developed, but it will be a crow nonetheless. “Crowing of a rooster is a testosterone dependent behavior,” Dr. Takashi Yoshimura says. Yoshimura, a professor at the Graduate School of Bioagricultural Sciences at Nagoya University in Nagoya, Japan, says that although crowing is a genetically regulated behavior, its molecular mechanisms remain unknown.
Two years ago Yoshimura, along with Dr. Tsuyoshi Shimmura, published a paper in Current Biology titled: “Circadian clock determines the timing of rooster crowing.” Their study suggests that roosters, like many other animals, have a circadian clock — an internal biochemical mechanism — that alerts them that the sun is about to come up. The roosters anticipate the dawn and start to crow.
“Crowing,” Dr. Yoshimura says, “has been classified as a warning signal advertising territorial claims, and it challenges or threatens intruding males.”
During their research they noticed that the roosters crowed about two hours before it was dawn. Hoping to learn the relationship between body clocks and external stimuli, the researchers checked to see if shining lights on the birds or playing sounds into their enclosures also caused them to crow. They did learn, however, that the roosters were more likely to crow in the early day than later on, suggesting a strong connection with their internal body clocks.
While the researchers did not investigate how to prevent crowing, Dr. Yoshimura did notice that when kept alone, roosters would stop crowing since they did not need to advertise their territories.
“The reason the rooster crows is due to the hormone melatonin, which is secreted by pineal gland in the brain during dark hours,” Melaku Tefera, professor for the Head Department of Veterinary Bio-medical Sciences at Lilongwe University of Agriculture and Natural Resources in Lilongwe, Malawi, recently told me. He adds, “The rooster knows when it is light (day) as melatonin hormone deceases.”
Unfortunately, Professor Tefera says the researchers could not tell us why a rooster makes crowing sounds, at least opposed to other possible sounds that a rooster could possibly make. “Maybe it has evolutionary survival advantage like foraging and egg laying of hens,” he hypothesizes.
The sound structure of chicken is somewhat analogous to a human language sentence, where individual words combine to make up identifiable parts of grammar that give the sentence meaning.
Tefera says that modern breeds lack the ability to speak. Commercial breeds do not respond to as many acoustic stimuli and produce less syllables than broody, non-commercial breeds. “It was concluded that they do not know the language,” he adds.
Terfera says, for example, that white leghorns are commercial breeds and they do not know the language of red jungle fowl.
The next time you see your chickens in a circle clucking, take a minute to eavesdrop. They could be telling you something.
ONOMATOPOEIC WAYS TO CROW LIKE A ROOSTER
Researchers in Ethiopia identified 19 sounds and their meanings in Domestic Chicken (Gallus gallus) in 2012:
Kenny Coogan, CPBT-KA, is a regular pet and garden columnist and has authored an ecological themed children’s book titled “A Tenrec Named Trey (And other odd lettered animals that like to play).” He has a B.S. in animal behavior and is a certified bird trainer through the International Avian Trainers Certification Board. Please search “Critter Companions by Kenny Coogan” on Facebook to learn more.