When Dr. Aiben, a zoologist at the University of Massachusetts, and his party investigated in the tropical rainforest of Sri Lanka, they found a black bird with a beautiful forked tail, and the name of this bird was "capuchin".
Capuchin
It is often customary to mix with other birds in groups. At that time, the curly tail flew down on a tree and stared at Aiben and his party with cold eyes. Suddenly, it emits a long series of sharp, bright calls, typical of the capuchins used to announce "the intruder has been found", a "quasi-attack" behavior of birds, which both alerts other birds to danger and declares to the intruder: "I have found you!" Next, the curly tail did something that surprised Eben: in addition to warning in its own language, it actually made other birds sound one after another, including the intermittent chirping of the orange-billed grebe, the discontinuous chirping, the sharp, loud chirping of the grey-headed harrier, and the old-fashioned telephone ringing of the Sri Lankan hook-billed stork... Finally, it even mimics the cries of the snake eagle, the most common predator in the rainforest. After that, it flew away, leaving Aiben and the others stunned.
It's hard to imagine that a variety of bird sounds can be made in the mouth of a curly-tailed one! Just like a person can speak a second or third foreign language. The capuchin mimics these specific calls, as if the birds were right next to it at the time. What's even more amazing is that this curly tail does not imitate the call of any bird at will, it has a strong purpose - except for the snake carving,
Snake carving
It mimics the chirping of birds that live with it!
There is a bird that mimics the chirping of a variety of birds, making you think that there is a large flock of different species of birds around you. This ability of birds to imitate is breathtaking.
A "parasite" in a team?
Capuchin belongs to the family Finches, with a body length of 230 to 300 mm, and its biggest feature is that the outermost pair of tail feathers on the outermost side of the body are the longest, and the end is slightly curled upwards, hence the name "curly tail". There are more than 20 species of capuchin, and the distribution range is very wide, from the south to the northeast of Australia and the north to the temperate and tropical regions of Asia. Unfortunately, the study of capuchins is very limited, and even bird watchers lack enthusiasm for them. In Australia, if you call a person "drongo" (capuchin), he will be seen as an insult to him, probably because capuchin birds are all unassumingly — gray or black throughout. Although their calls vary widely, and can even make holophonic chirps, this loud, even somewhat harsh sound cannot be compared with the "gentle and melodious songs" of some other birds.
Capuchin usually builds its nest in an open field or in the jungle. However, they always choose to perch on the canopy or on power lines, and patrol the surrounding area at fixed times every day, always vigilant. These birds are very aggressive by nature, often attacking "unkind invaders" in groups, and even in the face of predators who are much larger than them, they are still a group of brave fighters.
Capuchin feeds on insects flying in the air, and any situation that might cause insects to fly can attract their attention, such as a group of monkeys fighting endlessly, and wildfires that spontaneously combust in the jungle. The insects that are disturbed by the collective foraging of birds are also difficult to escape their eyes.
Sinharaja Rainforest in southern Sri Lanka,
It is the last well-preserved tropical rainforest on Earth, with a unique population of flora and fauna in the world, and has been declared a World Natural Heritage Site by UNESCO. Aiben et al. have long conducted research on the curly tail here. Many times, when they tracked the birds, they found the figure of the capuchin in it. This bird group usually consists of more than a dozen different birds, including about 40 birds, of which there are usually 2 to 4 capuchins. They found that while other birds struggled to find food hidden in the plants, Capuchin did nothing but wait quietly for the insects that flew into the air after being disturbed. As a member of the team, the capuchin can be described as a great benefit: a capuchin can eat nearly 40% of the insects that are startled by its companions, and its foraging speed is more than 3 times faster than that of the poor capuchin that forages alone.
It looks like the capuchins are like the "parasites" in this team, they don't have to work hard to find the insects, they just need to wait quietly for food to come to the door, which can be called "stealing the fruits of other people's labor". However, Aiben et al. used experimental methods to imitate the various chirps emitted by the capuchin, and found that the other birds in the whole team were attracted to this sound. It seems that the benefits that the other members of this group receive from the capuchins must be sufficient to offset the labor they have put in for this "hermit". So, what is the role of the capuchin in the team?
Competent "guards"
For the entire team, the biggest function of the capuchin is the "guard". In a bird colony, the role of "guard" is very dangerous. Because security guards are the most likely targets for intruders to discover first. The long-term observation of Aiben and others found that The Capuchin always maintained a high degree of vigilance against intruders. While other birds are busy foraging in the bushes, capuchins look around, "sounding the alarm" in the form of chirps when they spot "suspicious people." Although there are many other species of birds in the Jungles of Sri Lanka that also perform some alarm duties, none of them seem to be able to be reliable. Scientists have found that other "guards" make more mistakes than capuchins. They often sound false alarms, mistaking larger but non-threatening parrots or hornbills for predators. The capuchin, on the other hand, accurately identifies predators and alerts companions away from danger in the shortest possible time. Judging from the functionality of the entire bird cluster, a system of "mutual benefit" is formed between capuchin and other birds.
Capuchin not only uses its own call to sound the alarm, but also excels at mimicking the calls of other birds when they are in danger. In the Americas, there is a bird called the bright silk wren,
Bright silky wren
Like a capuchin, he also assumes the responsibility of alerting his partner. When other birds hear the imitation call of the bright silk bird, they will follow suit. Researchers believe that this imitation is undoubtedly a weapon, when other species of birds in the vicinity hear the alarm, they will gather from all directions, in groups to block the intruders, until they are finally driven away. Aiben believes that capuchins sound the alarm by mimicking the calls of other birds, and that this behavior should have the same intent.
The genius "linguist"
Capuchin uses superb imitation technique to make a series of birds chirp, making you think that there is a large flock of different species of birds around. But when you look closely, you will find that there are only one or two curly tails on the top of your head. Why should the capuchin imitate a series of calls from different birds instead of simply sounding an alarm?
Capuchins do not like to fly long distances, and they usually only move within a diameter of about 1.5 kilometers centered on nests.
Scientists have found through long-term observation that in the process of common activity of a bird swarm, if some of the birds fly out of the activity area of the capuchin, the capuchin will loudly chirp and imitate the calls of a variety of birds, which will often make the birds that fly away turn their heads and fly back to it. To verify that Capuchin did this to attract companions, the researchers recorded two sets of canapés during the non-alarm period, one for it to mimic the calls of other birds, and the other to have capuchin's own calls. They found that when the two sets of calls were played separately in the flock, the number of birds attracted to the first group of calls was more than twice as high as that of the second group. This suggests that the capuchin is imitating to attract the attention of other birds, bringing them back together to their side or guiding them to change the direction of their foraging. This behavior of the capuchin is full of "egoistic" overtones, and its purpose is to make it easier to get more food.
Another feature of the capuchin is that it will change the content of the imitation according to different occasions. It is well known that there are many songbirds in the world that are good at imitating other sounds, from the sound of the horn of the car to the sound of sawing wood, the content of the imitation is ever-changing, but they are not clear about the true meaning of these sounds, and these imitations are also random, usually humming a few times without any occasion. And many skilled male imitators, they do their best to imitate all kinds of sounds, just to get more female favor. In contrast, the imitation performance of the capuchin has different meanings in different occasions.
When an intruder approaches, the capuchin mimics the "alarm sound" characteristic of other birds. Incredibly, they can even imitate the cries of some predators such as gray and white giant squirrels! Some birds give different warning sounds when facing land-dwelling predators such as snakes and mongooses, or high-altitude predators such as eagle falcons. Amazingly, the tail can distinguish the difference between these sounds and choose to sound a specific alarm on a specific occasion. This all shows that they know the meaning of these calls.
In some cases, the capuchin mimics the "song" of other birds, which is the sound that flocks of birds make when they communicate with each other. Usually, a capuchin joins a bird colony after it leaves the nest, and perhaps from then on, it begins to pay attention to learning the calls of other birds and remembering the different calls made by other birds on different occasions. If The Curly Tail wants to perform its duties perfectly, it must take this sound lesson.
In terms of current research, in addition to capuchins, only parrots and dolphins are now known species that can accurately imitate the sounds of other animals. Much laboratory research has been done on both species, but it's unclear how they apply this imitation skill in the wild. Through long-term field observations, Eben found that the capuchin can not only distinguish the different calls made by other birds in warning or other situations, but also can make appropriate imitation sounds on different occasions. Capuchin has such a high level of cognitive ability that he can be called a "genius linguist"!
"Master of Ventriloquism"
The mystery
Some parrots and mynas are able to imitate human language in large part because their vocal tube structure is very similar to the structure of human vocal cords.
In 2016, the British Library released a video called "The Imitation of Birds", which is said to be compiled by a multi-disc audio tape in the Sound Archive of the British Library, "the world's largest database of natural sounds", which contains a variety of sounds that birds can imitate. If you've ever heard this disc, maybe when you hear your phone ringing again, you'll habitually stick your head out of the window to see if a clever bird is playing a prank on you.
Many of the world's birds are top "ventriloquists", whether they are insects, other birds, or some mammals, or even the sounds of cars, alarms, and alarms, they can imitate them perfectly. In the video "Birds Imitation", the imitation of the gardener bird in Papua New Guinea is recorded.
Gardener bird
This cute little bird not only imitates the sound of hammers and chainsaws, but also emits the sound of balls rolling inside paint cans, and myna, wrens, etc. can even learn to hum a complete tune! Why do some birds only emit simple syllables, while others have a melodious singing voice and even a breathtaking imitation technique? Studies have shown that the secret of these "ventriloquists" lies in their distinctive vocal structures – the vocal tubes and vocal muscles.
The song tube of birds is located at the junction of the lower end of the trachea with the bronchi, which is supported by many cartilage rings, and the inner and outer walls of the trachea thin into a membrane-like structure called the song membrane.
When the air flow of the trachea vibrates the membrane, it can make a sound, but this is far from allowing a bird to make a variety of calls. Anatomy shows that on the inner wall of the junction of the two trachea, there is also a ridge-like cartilage, the upper end of which protrudes into a half-moon membrane, which divides the vocal tube into two left and right vocal tubes. Under the control of the nervous system, the meniscus membrane in the vocal tube contracts or relaxes, oscillates in a whirlwind, and emits different chirping sounds. Birds that are not good at singing
The structure of the (non-songbird) song tube is usually relatively simple, emitting only a few monotonous syllables. The "singers" (songbirds) we are familiar with are relatively developed, they are like the players with the top oboe made by professional masters, not only can use the two sides of the pipe to take turns singing, and even can use one side of the pipe to sing a gradually rising note, with the other side of the pipe to sing a gradually decreasing note, thus completing a difficult duet.
Studies have pointed out: some parrots
parrot
The reason why He pug can imitate human language and make a muffled sound is largely due to the fact that the structure of its sound pipe is very similar to the structure of human vocal cords. The human vocal cords are about 20 centimeters from the throat to the end of the tongue, across the laryngeal cavity; and the song tubes of those birds who are good at imitation have a distance of about 15 centimeters from the throat to the end of the tongue, and have an obtuse angle of approximately right angle, and this angle is the key to determining the timbre, and the closer to the right angle, the more realistic the sound is.
mynah
Recognized "ventriloquists" such as parrots and starlings, in addition to having a more complex and perfect throat structure than ordinary birds, they also have another special structure - the song muscle. The vocal muscle is a special muscle attached to the vocal canal, which can be divided into internal and external vocal muscles according to the different attachment sites. Like the vocal tube, the vocal muscles can also contract or relax under the regulation of the nervous system, further controlling the diameter, vocal rate and tone of the vocal tube. Non-songbirds have relatively simple song muscles, most of which only have 1 to 2 pairs of song muscles, and most of them do not have internal sound muscles; songbirds usually have 6 pairs of song muscles, while "ventriloquists" can have up to 9 pairs of song muscles, of which there are 4 to 5 pairs of internal sound muscles alone. The "ventriloquist masters" are taking advantage of these unique advantages, coupled with the diligent practice of the day after tomorrow, perfectly controlling the flutter of the sound tube and the ringing membrane through these vocal muscles to form different scales, imitating a rich and diverse sound.
In addition, some people believe that the reason why parrots and wrens can imitate human sounds is not unrelated to their tongues. The tongue shape of these birds is very similar to that of humans, the front end is rounded, rounded and thick and soft, flexible, so it is easier to emit some simple but accurate and clear syllables that approximate the human voice. In the folk, people believe that before they can be taught to speak, they must first be "twisted tongue".
Tongue twisting
Some bird lovers believe that compared to parrots and wrens, the outer layer of the tongue of the myna has a hard shell attached to it, and if this hard shell is not removed, it is difficult to teach them to speak human language. The so-called "tongue twisting" refers to artificially rubbing the tongue of the myna to make the end of the tongue shed a layer of tongue shell. This job seems simple, but in fact, it is extremely difficult to grasp the technique and strength, and it will also bring great pain to the starlings. However, at least for now, there is no relevant scientific research that can prove that "tongue twisting" is an indispensable step in the process of learning the language of myna. What's more, it is not advisable to bring unnecessary harm to animal friends just to satisfy a little pleasure for us humans.