Why does the rooster crow at night?

1. The rooster crows to convey information between chickens

Everyone knows the story of "the rooster crows in the middle of the night", but why do the chickens crow?

Paul Siegel is a Ph.D. who studies chickens, and he understands the language of chickens. Although to most people, the language of chickens is nothing more than "cluck" when hens lay eggs and "cluck" when roosters crow, Dr. Siegel can understand about 30 different kinds of "chicken speech." This is not surprising at all, chickens are social animals and polygamous animals always have a lot of household chores to deal with. Especially the rooster, as the parent, has to shoulder many commanding and decision-making tasks. For example, when a rooster finds food, it crows to call its wives and concubines to come and share it. If it finds something delicious like earthworms or beans, its call frequency will be higher; otherwise, its call frequency will be lower.

Researchers found that if hens hear high-frequency calls, they will run over happily, but are not so enthusiastic about low-frequency calls. Similarly, if a chicken detects a threat, it will also sound a warning. Whether the threat comes from the air or the ground, the warning sound is different, and other chickens will respond differently.

As for the rooster's crow, experts in chicken language tell us that it is a "declaration of sovereignty". On the one hand, it reminds family members of its supreme status, and on the other hand, it warns approaching roosters not to attack its family members. Just like a dog can smell a lot of information from a puddle of dog urine, a chicken can hear a lot of information from a crow.

Bryant Furlow and others at the University of New Mexico in the United States tried to decode the crowing sound of the rooster. They used highly sensitive directional microphones, high-end recorders, audio analysis software and Apple computers; as for the "singers", they were 20 one-year-old male jungle fowl Gallus gallus, which is a wild species of domestic chicken.

After recording and analysis, Flo and the others obtained a bunch of data filled with "fundamental frequency", "main frequency" and "overtones". In short, the crowing of roosters is closely related to the level of androgen in their bodies. The higher the androgen level, the louder and deeper the crowing. At the same time, such roosters have larger combs, stronger bodies, and stronger combat effectiveness.

"Chicken Sichen" means the hen crows. In fact, readers who have lived in the countryside will know that the rooster laying eggs is nonsense, but the hen crows are common. This is because only the left ovary and fallopian tube develop in the hen's body, while the right one remains undifferentiated. If the left ovary fails, the undifferentiated ovary on the right develops into a testicle and produces androgens. Under the urging of androgen, the hen will do the cheese morning task.

When does the rooster crow? Of course it's morning, wrong. In fact, the rooster crows all the time. Someone has calculated that during the day, a rooster crows about once an hour. However, the first rooster crow in the morning breaks the tranquility of dawn. Not to be outdone, the approaching roosters declare their sovereignty. The relay continues in this way, which is impressive. In the noisy daytime, people will not pay much attention to these crowing roosters.

2. The rooster's "Chen" function is activated by melatonin

Why does the rooster crow in the morning? First of all, we need to know that there are only a handful of night owls among birds. Except for the various orders of owls and the adjacent order of nightjars, most other birds are patients with night blindness. Chickens are no exception. Generally, chickens sleep at night. Under this premise, we need to do further anatomy and take a look deep into the chicken's head.

There is a small area in the chicken's brain called the pineal gland. This small gland was once an important part of the visual system of our ancient ancestors. But now it is located in the center of the brain, but it is still disconnected from the optic nerve. The pineal gland secretes a substance called melatonin.

The pineal gland is controlled by light. The pineal gland will secrete melatonin only when you can’t see your fingers. If light enters the eyes (in fact, the eyelids cannot block too much light), melatonin will occur. The secretion of hormones is inhibited. Melatonin has complex biological functions and can inhibit the secretion of sex hormones.

In addition, biologists have long discovered that there are a large number of melatonin receptors distributed in the cerebral cortex of birds responsible for singing, especially in male birds. In other words, melatonin directly controls when birds singing.

During the day, when the morning light appears, the secretion of melatonin is suppressed, and the rooster can't help but "get up in the morning"; throughout the year, when the days gradually become longer in the spring, the secretion of melatonin in the bird's body When melatonin levels drop, they begin to "call spring," followed by an increase in sex hormone levels in the body, signaling the arrival of the annual breeding season. The man who carries the birdcage in the park also knows this truth. Usually the birdcage is covered with a thick cloth. Once the cloth is removed, the light wakes up the bird's "song center" and the singing session begins.

In the past, people lived from sunrise to sunset, and roosters could also enjoy the dark and quiet night. However, sometimes when there is a full moon, the bright moonlight will occasionally stimulate the overly sensitive rooster to "wake up at night". In times of war, roosters and dogs are restless, and the probability of roosters crowing at night when disturbed by sound and fire is greatly increased. Therefore, the ancients regarded "roosters crowing at night" as a bad omen of war.

In modern society, especially in vast cities, the popularization of artificial lighting has long eliminated the difference between day and night. Compared with 100 years ago, people's "dark night" is generally shortened by several hours. Not only are humans themselves suffering from various health problems caused by the reduced melatonin levels brought about by "artificial daylight" (such as precocious puberty in children, high incidences of breast and colon cancer, and more general mood swings), but other animals that mix with humans are also affected. Disaster followed.

There are often reports that "unscrupulous residents" in a certain community raise chickens without authorization. As a result, the chickens crow continuously in the middle of the night, causing neighborhood disputes. The national bird of the UK is the Eurasian robin. This little bird, commonly known as the robin, is no longer a "robin" at all. According to the Royal Society for the Protection of Birds, in many places in the UK they chirp all night long because of street lights. .

It can be seen that turning off the lights on the earth for one hour is not enough for humans or other animals including chickens.