Learned vocal expression is acquired by humans, dolphins, bats, elephants and sea lions among mammals; and in song birds like the zebra finches, canaries, crows, parrots and hummingbirds among the bird groups.
Recently scientists are doing more research in sound, communication and song because the behavioral methods of voice learning from humans who produce speech, and birds who emit song, are thought to be similar. The goal is to learn more about the functional role of dopamine in human speech. It may provide clues into diseases such as Parkinson’s, stuttering, Alzheimer’s and conditions such as stroke.
Song or Call
Birds of different species and types have many distinct vocalizations just as people from various parts of the world have their own language. There is a distinction however, between bird songs and “calls.” According to Donald Kroodsma, author of the book, Birdsong by the Seasons, complex, loud and prolonged special communications from prominent perches are mainly song meant to impress females during the breeding season. All of the others are “calls.” A call experts say, is typically shorter, not so loud, and used by both female and males during feeding, flocking, warning of predators, and, well, the bird duties of daily life.
So how do birds learn a song, what do they mean with their songs, and what is a song center? We will better explore that here.
There have been some interesting experiments to unlock some secrets to a bird’s brain. Researchers say that when a male bird serenades a female with the intention of wooing her, the female bird’s brain undergoes important changes—her dopamine receptors are triggered—this is an area that provides feelings of reward and pleasure. And one other nice coincidence, that when humans hear bird song, they also respond favorably. And research is very hot to find out how neurotransmitters, such as dopamine, modulate speech and song production.
Biologists have gone a step further in uncovering additional bird brain questions: for example, they have found out that a species called zebra finch that were reared in isolation can still create a song very similar to their cousins in the wild. That is what the word “innate” means—that the song culture is somehow part of their DNA.
The Anhinga Trail in the Everglades National Park in Florida is teeming with life. Pig frogs grunt, a black-crowned night heron quarks overhead, a green heron offers a soft skeow along with a blue heron who trumpets, creating duets in the distance. It seems as if there is a symphony of life when the barred owls hoot who-who-who-who-who-alll and then the caterwauling with others among the mangroves and pond apples begin.
A pair of Anhinga birds sits incubating hatching eggs and the handsome couple creates a duet as well. The two erupt into a clicking and chattering chitter-chitter-chitter-chee-cheer-chitter, rising and falling tones, repeating with their necks arched, bills open and heads swaying like two Bollywood dancers. This contagious calling observation is typical for avid birdwatcher and expert like Kroodsma, a former biology professor who now spends all his time making tapes of their music—finally doing what he loves best.
The best way to see birdsong is with a graph called a sonogram. Similar to sheets of music these visual images help identify certain characteristics. Like human music they are read from left to right and the frequency or pitch is on vertical lines. Instead of a scale of octaves and notes as in human music, the actual frequency is labeled in cycles per second—also called hertz—named after a German physicist who developed that system. And if the lines are extra black, that indicates loudness.
Two Voice Boxes
Some birds like the thrushes—Hermit Thrush, Wood Thrush and Swainson’s Thrush—have two voice boxes called the syrinx (a Greek word pronounced SEER-inks).
The sonogram has clearly revealed surprises such as how a bird uses his two voice boxes to produce two different sounds at the same time, sounds that are not harmonically-related and therefore cannot be produced by one voice box alone, but that blend harmoniously. An American robin for example, sings entirely different phrases above and below 5,000 hertz. There is truly no way to know though, if he is using his two voices successively or alternating between the two.
Birds have rhythm too as their song leaps through frequency and time.
Songs and calling are used for:
- Recognizing family
- Sharing songs with other similar species
- Alerting to danger
- Attracting a female
- Babbling and practice calling
Innate or Taught?
A hungry begging baby such as the cedar waxwing is going to be loud and frantic and his sounds are going to be innate—a way to communicate after it emerges from the egg. At about two weeks of age the youngster of a typical songbird species begins to memorize sounds from adults. This bird however, lacks true songs and after about three or four weeks the young birds begin to practice their seven trill-like calls. Experts think there are innate trills that are somehow deeply encoded into their DNA. Tonal sounds like seeee notes will come later.
Among song birds, ample evidence shows that birds can hear differences in songs and have remarkable memories and recognize more songs then they actually sing.
According to MotherNatureNetwork (mnn.com), Past studies, for example, found that bird songs make traffic noise more tolerable, make people feel less crowded, and can even mediate circadian rhythm, but few have looked at their broader impact on mental health.
In a crowded forest with lots of sound, a bird can pick out his own species among the cacophony and their brain cells respond to that sound alone.
Many famous composers such as Mozart, Beethoven, Bartok, Vivaldi and Chopin used bird song in their compositions.
- Beletsky, Les. Bird Song: 250 North American Birds in Song. San Francisco: Chronicle Books, 2006. Book and Player.
- Photo of Zebra Finch by Peripitus (Own work) under the GNU Free Documentation License via Wikimedia Commons
- Dopamine triggers in bird song: http://www.livescience.com/5117-love-songs-bring-pleasure-bird-brains.html
- Human mental health and bird song: http://www.mnn.com/earth-matters/animals/blogs/can-bird-songs-boost-your-brain#ixzz3GwGgLjj8
- Dopamine regulation in humans and birds: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3362661/
- Hear the dual voice box of a Thrush: http://birdnote.org/show/voices-and-vocabularies-exquisite-thrush-songs
- Kroodsma, Donald. Birdsong by the Seasons: A Year of Listening to Birds. New York: Houghton Mifflin Harcourt, 2009. Book and CD.
- “Probosciger aterrimus-20030511B” by Doug Janson - Own work. Licensed under Creative Commons Attribution-Share Alike 3.0 via Wikimedia Commons